Fest3D User Manual
Fest3D Online Help
The Fest3D help system is organized into the following main topics:
Introduction
What is Fest3D.
Tutorial
Manual
Guided tour of Fest3D features. Recomended for new users.
Using Fest3D - reference manual.
Elements database
Description of the elements supported by Fest3D.
2.1 Fest3D Introduction
The objective of this introduction is to explain the motivations behind Fest3D development and the target of Fest3D
software, as well as the approach and basic concepts used by Fest3D.
The introduction contains the following topics:
Objective
Features
The objective of Fest3D.
Main Features in Fest3D.
Terms and Concepts
Terms and concepts widely used in Fest3D and in this documentation.
Features
Fest3D is an efficient software tool for the accurate analysis of passive components based on waveguide technology.
Fest3D is the first commercial software capable to integrate high power effects in the design process.
Analysis
Fest3D is able to efficiently analyse different type of passive microwave structures in waveguide technology. Basically,
Fest3D is based on an integral equation technique combined with the Method of Moments. Additionally, the
Boundary Integral-Resonant Mode Expansion (BI-RME) method is employed for extracting the modal chart of
waveguides with non-canonical shapes. These methods ensure a high degree of accuracy as well as reduced
computational resources (in terms of CPU time and memory).
On this basis, Fest3D is capable to simulate complex microwave devices in extremely short times (of the order of
seconds or few minutes) whereas general purpose software (based on segmentation techniques such as finite
elements or finite differences) can spend hours for the same calculation.
Furthermore, unlike mode-matching techniques, the electromagnetic algorithms employed in Fest3D minimize the
problems of relative convergence leading to more confident results. Moreover, the integral equation technique
extracts part of the frequency dependent computations, allowing a faster computational time per frequency point
when compared to mode-matching techniques. This benefit is more evident when many modes are required for an
accurate analysis of the component.
Based on these methods, the user can analyze a wide range of passive components with Fest3D:
Filters (dual-mode, evanescent, bandstop, interdigital, waffle-iron...)
Multiplexers
Dual-mode filters
Couplers
Polarizers
Waffle-iron filters
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Evanescent filters
Power Dividers
Bandstop filters
Infinite phased array antennas
Synthesis
Fest3D includes the possibility to automatically design several types of components from the user specifications
making use of the so-called Synthesis Tools. Up to now, the user can easily design band-pass filters, low-pass filters,
rectangular tapers, dual-mode filters in circular wavwguide.
The synthesis stage performs full-wave simulations to consider higher waveguide modes. Thanks to this and to
particular algorithms employed in each case, the synthesis process provides very good responses with respect to the
user specifications. In particular, bandpass filters can be designed with up to 25-230 % of BW without the need of
post-optimization, as well as dual-mode filters in circular waveguide with different order and making use of different
resonant modes.
Once the synthesis process is finished, the full structure is simulated and the full-wave result is shown.
Optimization
Fest3D has an optimization tool (OPT) for the refinement of the component geometrical parameters to get the desired
response. The OPT supports multiple optimisation algorithms such as:
Downhill simplex method.
Powell's direction set method.
Gradient method.
The OPT also supports weighted constraints in the form of equalities or inequalities between a left and a right
expression of the parameters being optimised. This allows, for instance, controlling the maximum length of a filter or
to ensure that an element length is larger than a particular value.
The OPT progress can be monitored in real time, as well as stopped, reconfigured and resumed from the Graphical
User Interface (GUI) at any time. Moreover, the results from the previous optimization iteration and the current one
are shown, which allows identifying the source of the improvement in the response.
Tolerances
Fest3D also allows performing tolerace analysis in the components by varying their dimensions according to a
gaussian deviation. The different tries are shown altogether and the user can control the whole process.
High Power
Fest3D can be easily used to analyse high-power breakdown phenomena in several type of components. In particular,
multipactor and corona (arcing) modules are fully integrated into Fest3D which is capable to determine the
breakdown level in complex passive components.
Export 3D geometry
Fest3D can export the 3D geometry to SAT format. This allows an easy interaction with other EM tools and using
Fest3D exported file in, e. g., milling machines.
Export Project to CST MWS®
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Fest3D projects can be exported to a CST Microwave Studio® project.
Export Project to CST Design Studio®
Fest3D projects can be exported to a CST Design Studio® project.
Terms and Concepts
Several terms and concepts are used in Fest3D. Even though some of them may be well known to some users, these
terms may have different meanings in Fest3D, or some users may not associate them to millimeter-wave and
microwave circuits.
Circuit
Element
The kind of circuit currently supported by Fest3D: passive, linear millimeter-wave or microwave
circuit composed on cascaded discontinuities based on rectangular and circular waveguides (and
perturbed variants of them). The full list of the supported waveguides and discontinuities is
available in the Elements Database.
The term element is very generic. In Fest3D it indicates each elementary building block of a
passive, linear millimeter-wave or microwave circuit. A synonym also used in Fest3D is component.
The elements, or components, supported by Fest3D are divided in two classes: waveguides and
discontinuities. See also the Elements Database.
Component
A synonym for element.
Waveguide
A classic microwave waveguide, optionally open-ended (I/O port) or closed on a load, and
attached to something else (one or two discontinuities). A whole section of this manual is
dedicated to the various waveguides supported by Fest3D.
Discontinuity A component connecting two or more waveguides. Discontinuities often have a non-uniform
cross-section and may have non-trivial 3D geometry. In Fest3D you can only connect a waveguide
to a discontinuity, and vice-versa. A whole section of this manual is dedicated to the various
discontinuities supported by Fest3D.
Port
GUI
EMCE
OPT
Ports are used to connect elements together. Each element has a number of ports equal to the
number of elements it is connected to. Each port of an element is connected to a port of another
element. The connections between elements are represented as black lines in the GUI.
Graphical User Interface. The part of a program devoted to interaction with the user. The Fest3D
GUI activates the other parts of Fest3D on user demand, by launching external executables.
ElectroMagnetic Computational Engine. The part of Fest3D that actually performs the simulation
of millimeter-wave and microwave circuits.
OPTimization service. The part of Fest3D devoted to optimization. In order to optimize a circuit,
the OPT repeatedly invokes the EMCE. See the Optimizer section in this manual.
Synthesis
Tools
Additional programs integrated in Fest3D, capable of performing microwave circuits synthesis
from user specifications. See the Synthesis Tools section in this manual.
Engineering
Tools
Additional programs integrated in Fest3D, used to perform unit conversions and small
computations. See the Engineering Tools section in this manual.
Convergence
Study
Convergence Study is an essential technique to reasonably ensure the accuracy of EMCE results.
A brief, but incomplete, summary is that the simulation must always start with low numeric
accuracy parameters, continuously increasing them until the response converges. A single
simulation with high numeric accuracy parameters is definitely not enough to ensure accuracy of
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the results. In Fest3D, numeric precision parameters include all the number of modes and also
element-specific parameters.
See also the tutorial section Accuracy or Speed?
MoM
Method of Moments. A mathematical model of microwave propagation physics, used in Fest3D.
Integral
Equation
BI-RME
A mathematical model of microwave propagation physics, used in Fest3D.
Boundary Integral - Resonant Mode Expansion. A very efficient electromagnetic model of
microwave propagation physics, used in Fest3D.
2.2 Fest3D Tutorial
The goal of the tutorials is to show you how to use the basic features of Fest3D to create, edit, analyze and optimize a
millimeter-wave or microwave circuit.
The first three tutorials are provided to familiarize you with the Fest3D user interface. Tutorials 4 and 5 treat more
complex topics, like the Arbitrary Shape Editor and the Optimizer. Tutorial 6 shows how the EM field analysis tool
works, and tutorials 7 and 8 cover high power issues, Multipactor and Corona, respectively.
To learn the basic features of Fest3D, you are recommended to work through tutorials in the order they are presented.
It is also essential to play around with the list of examples provided to you during the installation in the folder
"Examples".
1. The First Circuit is a step by step guide to the creation of a simple microwave circuit.
2. Running the Simulation shows you how to configure and execute the analysis (simulation) of a microwave
circuit.
3. Accuracy or Speed? introduces you in the world of numeric methods, where high accuracy often means long
computation time.
4. The Arbitrary Shape Editor shows you how to create and edit the arbitrary shapes used by some elements.
5. Optimizer is a group of tutorials describing how use the Fest3D Optimizer:
5.1 Optimizer: setup describes how to prepare a circuit for optimization and how to configure Fest3D
Optimizer.
5.2 Optimizer: run shows how to start an interactive optimization and what you can do during it.
5.3 Optimizer: export to CST Studio shows how to export a circuit as a Design Studio project in CST
Studio and run an optimization task.
6. EM field Analysis is a step-by-step guide on how to use the EM field analysis module
7. High Power Analysis is a step-by-step guide on how to use the High Power analysis.
2.2.1 Tutorial 1: The First Circuit
In this tutorial, you will learn how to create and edit millimeter-wave and microwave circuits with Fest3D.
Tutorial 1 is divided in four lessons. In order to get maximum benefit from the tutorial, you are recommended to work
through the lessons in the order they are presented.
1.  Important Concepts: waveguides, discontinuities, connections, coordinate systems gives an overview of
the approach used by Fest3D to represent millimeter-wave and microwave circuits.
2.  Creating elements gives a step-by-step guide on how to create the elements contained in a simple circuit.
3.  Editing elements explains how to view and modify the properties of created elements.
4.  Connecting Elements shows you how to connect the elements together.
Important Concepts: waveguides, discontinuities, connections,
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coordinate systems
In Fest3D, circuit means a passive, linear millimeter-wave or microwave circuit. This is what Fest3D supports.
In Fest3D, elements are the basic blocks used to build a circuit. They are represented by icons with a schematic
picture of their 3D shape.
A circuit is composed by a set of elements connected to each other, respecting certain connection rules.
The connection between two elements goes through the ports of these elements. A port is where the modal
expansion is defined according to a certain coordinate system. When connecting two elements through their ports,
the coordinate systems should match each other. In most of the cases, Fest3D adjusts the coordinate systems of the
elements automatically, but there are some exceptions that need user interaction. The situation of the coordinate
system is defined in the documentation of each element.
Elements are divided into two main groups: waveguides and discontinuities.
Waveguides are the simplest elements. They usually have uniform cross-section, and they can be attached to other
elements at both sides (front and back). Two simple examples are the rectangular waveguide and the circular
waveguide.
The complete list of supported waveguides is in the Waveguides section of this manual.
Discontinuities are used to connect waveguides together. A discontinuity often has non-uniform cross-section and
non-trivial 3D geometry. A discontinuity may have a 3D volume or may be a zero-thickness surface. Two simple
examples are the step and the T-junction.
In Fest3D you can only connect a waveguide to a discontinuity, and vice-versa.
The complete list of discontinuities supported by Fest3D is in the Discontinuities section of this manual.
The following figures show a simple circuit (an asymmetric one-pole cavity) in Fest3D main window and its 3D
geometry:
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In order to interactively view the 3D geometry of the circuit, click on the 
 icon: the 3D Viewer window will open.
In this example, the circuit is composed by five rectangular waveguides (
represent the connections among them.
) and four steps (
). The black lines
As you can see, Fest3D main window is divided in three parts:
1.  the menubar and toolbar at the top
2.  the canvas in the center
3.  the canvas in the bottom
The menubar lets you access most Fest3D features, including the usual File Load and Save, cut-and-paste and Fest3D
specific features. The complete description of menubar contents is in the Main Window Menubar section in this
manual.
The toolbar duplicates the most used features of the menubar for faster access.
The canvas in the center contains the current circuit and lets you edit it.
The canvas on the bottom is used to show the output information of a simulation.
In the right side there is a bar containing the Fest3D elements (elements bar). This bar is used to select the element
to be created in the main canvas. The elements bar can be hidden and pop-up by means of the rectangular icon in
the toolbar.
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Creating elements
In Fest3D, creating an element consists in two steps:
1.  click on the icon of the element type you want from the elements bar. The icon will stay pressed.
2.  click on the canvas. An element of that type will be added where you clicked.
If you click again on the canvas background (not on an element or a connection) further elements of the same type
will be added.
Let's say you want to create the asymmetric one-pole filter seen above. For this purpose, create five rectangular
waveguides and four steps. You should obtain something like the left figure:
Now click on the menubar command structure | show icons. The elements should change to something like the right
figure. If the numbers are ordered differently, you can move the element around as explained below. This is not
needed in general (there is no requirement that the elements you connect have any particular ordering), but you
would better know how to perform such basic operations on elements.
You can move elements on the 
button on an element in the canvas and drag it.
 icon button at the top of the elements bar, then press mouse left
You can select more than one element by pressing mouse left button on the canvas background, then dragging the
mouse. A rectangular selection area will be created, and all elements inside it will be selected.
You can now move all selected elements at once by dragging them with the mouse.
You can also cut, copy or delete all selected elements at once using the corresponding commands in the menubar or
in the toolbar.
After a cut or copy, you can undo the operation or you can paste the contents of the clipboard using the
corresponding commands in the menubar or in the toolbar.
Now that you have learned how to do it, order all the elements as shown in the right picture above and proceed with
the next part of this tutorial.
Editing elements
This part of the tutorial explains how to view and edit the properties of the created elements.
Click with the right mouse button on the rectangular waveguide [1] you created in the canvas. The following
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Element Properties dialog box will appear:
Now you can enter the values for the geometric parameters A, B and L (in millimeters) of the rectangular waveguide.
In this tutorial you are building the one-pole cavity seen above, so enter the following values then click on the OK
button:
A 22.86
B 10.16
L 10.0
Since these dimensions correspond to a standard waveguide, you could have clicked on the standard waveguide
box, and select the WR-90. Doing this, the A and B dimensions (22.86, 10.16) are automatically obtained.
The rectangular waveguide [2] of the circuit has different geometric parameters: A 8.0, B 10.16, L 2.0.
The rectangular waveguide [3] has geometric parameters: A 22.86, B 10.16, L 15.0.
The rectangular waveguide [4] has the same geometric parameters as [2]: A 8.0, B 10.16, L 2.0.
The rectangular waveguide [5] has the same geometric parameters as [1]: A 22.86, B 10.16, L 10.0.
In general you may also want to edit the waveguides Common Properties, but in this case you can leave them to the
default values.
You need instead to change the SubType of rectangular waveguides [1] and [5] to Input/Output Port, in order to
inform Fest3D that they will be the external interfaces of the circuit. Set rectangular waveguide [1] to have I/O Port
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Number 1 and rectangular waveguide [2] to have I/O Port Number 2.
It is now time to edit the four steps. Click with the right mouse button on the step [1]., then click on the Ports page.
The following Element Properties dialog box will appear:
Enter the values for the geometric parameters:
X offset (mm) of port 2  4.0
Y offset (mm) of port 2  0.0
Rotation (degrees) of port 2  0.0
The step [2] is identical to step [1] but of opposite sign, edit it too and enter the values: X -4.0, Y 0.0, Rot 0.0.
The step [3] and step [4], have instead the following values: X 5.0, Y 0.0, Rot 0.0. and X -5.0, Y 0.0, Rot 0.0.,
respectively,
That's all. In the next part of this tutorial you will connect the elements together.
Connecting elements
This part of the tutorial explains how to create and edit the connections among elements.
Click on the connect (
pencil.
) button at the top of the elements bar. The mouse pointer shape will change to a
Press and hold the left mouse button on the first rectangular waveguide. Drag the mouse to the first step: a black
line connecting the two elements will appear. Release the left mouse button.
Repeat the same procedure until you completed all the connections as in the left figure:
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Click again on the menubar structure ->  show icons command, you will obtain the right figure.
You can delete connections by clicking on the arrow (
press mouse left button on a connection in the canvas to select it, finally click on the menubar edit -> delete
command or hit the delete key on the keyboard.
) button at the top of the elements bar, then
In Fest3D there is a subtlety in definition of the connections. The reason is that for some discontinuities (Step, N-Step,
T-Junction, Constant width/height arbitrary shape, Y-Junction) the various ports where you can connect waveguides
are not equivalent. But when you connect two elements, you have no way to specify the ports to use... a simple first-
free first-used algorithm is used. In other words, the first element you connect is considered as port 1, the second
element as port 2, and so on.
In particular, you saw that a step has two ports but you can specify X offset, Y offset and Rotation only for the second
port.
The Edit Connections dialog exists for changing the port definition. Click on the move (
top of the elements bar, then click with the right mouse button on one of the connections (the black lines) of the
discontinuity. The Edit Connections dialog will appear.
) button at the
This dialogs allows the user to specify the ports of a discontinuity where each connected waveguide should be
attached. For each connected element, a row of radio-buttons is available to specify which port it should use.
Attaching more than one waveguide on the same port is not allowed.
2.2.2 Tutorial 2. Running the Simulation
Tutorial 2 is divided in two parts. In order to get the maximum benefit from the tutorial, you are recommended to
work through the lessons in the order they are presented. In particular, this tutorial assumes you have read,
understood and practiced the topics treated in Tutorial 1 and you have a circuit already loaded in Fest3D (preferrably
the circuit you created in the previous Tutorials).
Configuring explains how to configure the frequency/angle sweeps and the global circuit parameters. These
windows are explained in detail in the sections Frequency specifications and General Specifications.
Running shows how to compute S parameters or multi-mode S, Z or Y matrices of a Fest3D circuit.
Configuring
Once you have created a millimeter-wave or microwave circuit, there are two main things that must be configured
before  you run a simulation on it:
Frequency/angle sweeps configuration
General modes/symmetries configuration
Frequency/angle sweeps configuration
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For this purpose, click on the Frequency Specifications command in the execute menu bar, or click on the
Frequency Specifications (
appear:
) button in the toolbar. A dialog box, typically looking as the following figure, will
This window lets you edit the frequency range and points　where the circuit should be simulated as well as the
method (discrete/adaptive) to be used. In case your circuit contains Radiating Array elements, you can also perform an
angle sweep (theta or phi) instead of a frequency sweep.
The frequency (or angle) sweep is specified by its start and end frequencies in GHz (or degrees for angles), and by the
sampling.
Fest3D supports three different sampling modes:
1.  step lets you specify the distance between consecutive points to be sampled.
2.  number of points lets you specify the total number of points to sample, including start and end points.
3.  manual selection of points lets you manually edit each and every point you want to simulate. Only the last
sampling mode allows non-uniformly distributed points.
For further details, see the General Specifications section in this manual.
In our case (the asymmetric one-pole cavity)  you should enter the following values:
Frequency Start 9.0
Frequency End 12.0
Frequency Step 0.001
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Once the frequencies/angle sweeps are defined. It is necessary to configure the global symmetries and the default
waveguides parameters for the circuit.
General specifications
For this purpose, click on the General Specifications command in the execute menu bar, or click on the General
specifications button (
)
For a detailed explanation of the meaning of the various global symmetries and default waveguides parameters, see
again the General Specifications section in this manual.
The asymmetric one-pole cavity example you created, in particular, has constant height and is invariant under
translations along the Y axis. So the Constant height (H plane) symmetry can be applied. Click on it. In this case no
other symmetry is applicable.
Since you are using symmetries, you can (and should) lower the various number of modes used in waveguides. Enter
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the following values:
Number of accessible modes 4
Number of MoM basis functions 10
Number of Green function terms 100
The other parameters can stay at their default values:
Dielectric Permittivity 1.0
Dielectric Permeability 1.0
Dielectric Conductivity 0.0
Metal Resistivity 0.0
Number of Taylor expansion terms 1
Running
Computing the S parameters is really simple: click on the Analyze (
progress messages produced by the Electromagnetic Engine (EMCE) integrated in Fest3D.
) button in the toolbar and watch the
If the Autoplot option in the graphics menu is active, or if you execute the Plot command (still in the graphics
menu) at the end of the simulation, the S parameters graphical plot will be displayed.
With Fest3D you can also compute the multi-mode S, Z or Y matrix of a circuit, to reuse it later as a single block in a
bigger circuit.
You can stop a running simulation at any moment by clicking on the stop (
) button.
The following figures show Fest3D main window during the simulation and the produced plot:
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2.2.3 Tutorial 3. Accuracy or speed?
In this tutorial it is explained how to manage and balance for your purposes the tradeoffs between simulation
accuracy and speed that is typical of Fest3D and other numerical simulation software.
This tutorial assumes that you have a circuit already loaded in Fest3D (preferrably the circuit you created in the
previous Tutorials). This tutorial is divided in two parts.
1.  Accuracy Parameters explains which parameters control numeric accuracy in Fest3D, their meaning and the
effect of changing them.
2.  Balancing shows how to choose a trade-off between accuracy and speed in Fest3D.
Accuracy Parameters
In Fest3D, each element (waveguide or discontinuity) can be configured independently from the others.
Several elements also contain numeric accuracy parameters.
To simplify the task of configuring manually the numeric accuracy (and other) parameters common to all waveguides,
by default their Common page is set to Use General Specifications, i.e. to use the default values stored in the
General Specifications dialog box you used in Tutorial 2.
This allows configuring the parameters common to all waveguides at once, unless you manually set some waveguides
not to use the default values.
Waveguides Common Parameters
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Let's start with the numerical parameters Number of accessible modes, Number of MoM basis functions and
Number of Green function terms.
Here we will not describe the electromagnetic theory and models behind Fest3D, which would be needed to
understand the meaning of the above parameters.
We will only say that Number of accessible modes is the number of modes in a waveguide that are treated as
accessible or propagating by Fest3D i.e. only those modes are assumed to transport E.M. fields and energy across the
whole length of a waveguide.
Increasing these three parameters (Number of accessible modes, Number of MoM basis functions and Number of
Green function terms) will yield more accurate results at the price of higher memory usage and longer computation
time.
Typical values are:
Parameter
Low Accuracy
Medium Accuracy
High Accuracy
Number of accessible modes
Number of MoM basis functions
Number of Green function terms
10
30
300
20
60
600
40
120
1200
For simple circuits, starting with Low Accuracy (i.e. 10 accessible modes, 30 MoM basis functions and 300 Green
function terms) is usually enough to deliver satisfactory results.
Of course, this is true if no symmetries are considered. If symmetries are taken into account, the circuit parameters can
be dramatically reduced, keeping accuracy but increasing speed. This is particularly important if the circuit is going to
be optimized.
Anyway, there is no guarantee that certain fixed values for numeric accuracy parameters will yield satisfactory results
for your particular circuit. It is thus of critical importance to always perform a Convergence Study.
Some elements contain also other numeric accuracy parameters, as explained in the following paragraphs.
Arbitrary Rectangular
The Arbitrary Rectangular waveguide, which is also used as base for all waveguides in the RECT-CONTOUR BASED WG
section in the palette of elements, contains the Number of reference box modes parameter:
The Number of reference box modes is the number of modes to be used in the rectangular cavity to compute the
modes of the arbitrary rectangular waveguide.
The required value for this parameter depends a lot on both the role of the arbitrary waveguide and the ratio between
the reference box area and the arbitrary waveguide area. If the arbitrary rectangular waveguide is smaller than the
surrounding waveguides to which it is connected, i.e. it is playing the role of an iris, the number of generated modes
must be slightly higher than the number of the MoM basis functions of such an arbitrary waveguide. Therefore, the
number of reference box modes has to be adjusted to reach this condition.
If it is set to zero by the user, Fest3D will automatically calculate its value.
On the other hand, if the arbitrary waveguide is larger than one of the waveguides to which it is connected, the
number of generated modes has to be slightly larger than the number of Green function terms of the arbitrary
waveguide. Therefore, the number of reference box modes has to be modified to accomplish such a rule.
In order to get enough generated modes, this number of reference box modes will need to be increased if the area of
the arbitrary waveguide is much smaller than the area of the reference box. By default, the number of reference box
modes is set to the double of the number of Green function terms.
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The Number of reference box modes is also important for another reason: Fest3D can directly connect to each other
two Arbitrary Rectangular waveguides or derivatives using a Step or N-Step. In this case, the coupling integrals
between the two sets of modes are computed by convoluting two coupling integrals matrices. Since the matrices are
only known numerically, in order to obtain accurate results Number of reference box modes and Number of terms in
Green's function should be high enough.
In case you have Arbitrary Rectangular waveguides with TEM modes (the cross section must be non-simply
connected), which propagate even at zero frequency, the two numbers above become more and more important at
frequencies much lower than the cutoff of the first non-TEM mode, since the circuit behaviour strongly depends on
the exact couplings between TEM modes.
With so low frequencies, the Number of accessible modes and Number of MoM basis function will have very little
effect on the overall accuracy, since only the TEM modes will be accessible.
Known accuracy limitations exist in Fest3D if you try to analyze a circuit with TEM modes at extremely low frequencies
(< 0.2 GHz): due to the TEM-TEM couplings being computed numerically and not with analytical exactness, the results
produced by Fest3D will be less and less accurate as frequency decreases.
To solve this problem, you need to progressively increase the Number of reference box modes and Number of
Green's function terms until you get convergence  in the frequency range you are
using.
Arbitrary Circular
The Arbitrary Circular waveguide, which is also used as base for all waveguides in the CIRC-CONTOUR BASED WG
section in the palette of elements, contains two basic precision parameters: the number of box modes and the
Distance between points.
The number of box modes (in this case, the box is a circle!) has the same meaning as for the ARW case, so the same
can be said.
Balancing
This section gives basic guidelines to the art of finding a compromise between accurate simulations and fast
simulations. Due to the sheer size an complexity of the topic, only a brief explanation of high-level strategies can be
summarized here.
First of all you should understand which of your goals and needs are immediate, and which can be postponed.
Accuracy issues can be usually postponed, while fatal errors reported by the EMCE should be addressed immediately.
1.  Split large circuits and use the User Defined element to import generalized Z matrices generated from sub-
circuits. Apply the rest of this section on each subcircuit if appropriate (i.e. you often cannot optimize a sub-
circuit since you only know the results you want from the complete circuit). This divide-and-conquer strategy
costs some time to set up, but can really make life easier when tackling very large circuits.
2.  Once you have created a circuit in Fest3D, the next step should be to complete its simulation without errors.
At this early stage accuracy has no importance at all, but rather can be an obstacle by slowing down each
simulation you perform and halting the simulation due to accuracy errors. For this reason, you should usually
stick down to the "Low Accuracy" values listed above in Accuracy Parameters section.
Now continue retrying to simulate your circuit until you have solved all geometry and numerical errors that the
EMCE may report. Depending on the errors you get, finding a solution may be tricky. It is possible that you
tried to do something not supported by Fest3D, or maybe you made some mistakes and the geometry you
created is not what you think it is. The 3D Viewer section may help you.
3.  Ok, now the simulation completes successfully and produces a result. You can be confident that many times
this result will be, at least, inaccurate.
It's now time to think about the next step: Global Symmetries. Enable all the symmetries that apply to your
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circuit, since they will increase the accuracy. If you made mistakes and your circuit does not respect the
symmetries you think it respects, Fest3D will report the error. As above, keep retrying until you have solved all
errors.
4.  Understand what is your final goal.
If the geometry you are using is already fixed (i.e. you are only analyzing a pre-defined circuit and you are not
planning to tune or optimize it), then skip all the rest of this section and immediately perform a Convergence
Study. Otherwise, you should start tuning accuracy and speed together.
5.  Tuning accuracy and speed together. You will need a lot of compromises, and only you can be the final judge.
Some tips and tricks you may find useful are:
each simulated frequency point costs time. Consider using the Adaptive Frequency Sampling to solve
the frequency sweep, or in case of using the discrete solution, reduce the number of frequency points to
the minimum you can live with. Consider editing manually the list of sampled frequencies.
you don't need a complete Convergence Study, but a quick check that your results are not too far from
convergence is necessary. At this point is very useful to employ the Comparing results tool available in
Fest3D to compare the record of simulation results.
If you use Fest3D optimizer:
do not use too many parameters simultaneously, they slow down optimization and make more difficult
for the algorithm to reach the target (your goal functions).
remember that at any time you can stop the optimizer, manually change some parameters, then
perform one-shot analysis and/or resume optimization.
if possible, use formulas instead of constraints: formulas reduce the effective number of free parameters,
speeding up the optimization.
if a certain optimization algorithm does not reach the goal functions you want, try alternating among
different algorithms and/or slightly change the parameters values manually.
6.  Don't forget to perform a Convergence Study.
2.2.4 Tutorial 4. Arbitrary Shape Editor
In this tutorial it is described how to use the Arbitrary Shape Editor to view and edit arbitrary shapes for the Fest3D
elements Arbitrary Rectangular, Arbitrary Circular and Constant width/he¡ght discontinuity .
This tutorial is divided in four parts:
1.  Introduction what is the Arbitrary Shape Editor.
2.  Terms and Concepts terms and concepts widely used in the Arbitrary Shape Editor and in this documentation.
3.  Contours and Region of Interest the high-level structure of an arbitrary shape: how to use them
4.  Points, Segments, Arcs, Elliptical Arcs the basic blocks of an arbitrary shape: how to use them
5.  Caveats and Differences between Arbitrary Rectangular, Arbitrary Circular and Constant width/height arbitrary
shape discontinuity
Introduction
Some elements supported by Fest3D (Arbitrary Rectangular, Arbitrary Circular and Constant width/height arbitrary
shape discontinuity) do not have a predefined 3D geometry. They allow the user to arbitrarily define their shape or
cross section in a 2D plane, and they are invariant under translations in the direction orthogonal to that plane.
The Arbitrary Shape Editor is a 2D shape editor, allowing to view and edit the arbitrary shape of such elements.
The different kinds of elements allowing arbitrary shapes have slightly different features and limitations. For this
reason, the Arbitrary Shape Editor offers similar, but not identical, functionalities when editing the different arbitrary
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shapes corresponding to the Arbitrary Rectangular, Arbitrary Circular and Constant width/height arbitrary
shape discontinuity elements.
The following figure shows a typical Arbitrary Shape Editor window as it appears on the screen:
Terms and Concepts
Several terms and concepts are used in Fest3D Arbitrary Shape Editor. Even though some of them may be well known
to some users, these terms may have different meanings in Fest3D, or some users may not associate them to arbitrary
shapes of millimeter-wave and microwave circuits.
Contour
A planar, continuous, non self-intersecting and possibly closed curve composed by
Segments, Arcs and Elliptic Arcs. An arbitrary shape is made of one or more contours
(possibly enclosing one another, but not intersecting) plus some prescriptions to decide
which connected area contains the electromagnetic fields.
Region of Interest
A user-specified Point which must be inside the area intended to contain the
electromagnetic fields.
Point
The start or end point of a segment, arc or elliptic arc. If two Segments, Arcs and Elliptic
Arcs arcs have a Point in common, they are consecutive and belong to the same contour.
The user can modify the coordinates of a Point only if it is the start or end point of
segments, not arcs or elliptic arcs.
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Segment
Port
Arc
A normal, straight segment. In the Constant width/height arbitrary shape it is also possible
to change a Segment into a Port.
A Segment used to connect the arbitrary shape with other elements. Only supported by
Constant width/height arbitrary Shape element. Drawn in pink.
A mathematical arc of circle.
Elliptic Arc
A mathematical arc of ellipse.
Contours and Region of Interest
If an arbitrary shape contains multiple contours, the contours must not intersect to each another.
A contour may completely contain other contours (again, contours must not intersect to each other).
Using multiple contours also raises an ambiguity: if there are more than one connected areas, which one is intended
to contain electromagnetic fields? The following example comes from the Arbitrary Rectangular waveguide:
The shape of the example defines the areas S,S1,S2 or S3 but only one of them can be simulated at once. The user
needs a way to resolve this ambiguity, or at least know which area will be used by Fest3D to simulate the
electromagnetic fields propagation. To do so, the user has to specify the coordinates of a Point (the Region of
Interest): the area containing the Region of Interest will be the one used for the simulation. The Region of Interest
is drawn as a blue cross (
).  
Creating and Deleting Contours
You can create a Contour from the Add Contour command in the Edit menu. The following dialog will appear:
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You can only create Contours with a standard shape (rectangular, circular, elliptical) but you are free to modify the
Contours as you want after you created them.
To delete a Contour, click on a part of it (Point, Segment, Arc, Elliptical Arc), then execute the Delete Contour
command in the Contour menu.
If you deleted something by mistake, use the Undo command in the Edit menu.
Editing Points, Segments, Arcs, Elliptical Arcs
These are the building blocks of contours, and thus of arbitrary shapes.
The basic idea behind the Arbitrary Shape Editor is that complicated Contours can be created incrementally, by
progressively creating and editing its building blocks (Points, Segments, Arcs, Elliptical Arcs).
Starting from a simple Contour, you can edit or split its Points, Segments, Arcs, Elliptical Arcs.
If a Point is only connected to Segments, you can edit it and freely change its coordinates.
To edit a Point, Arc or Elliptical Arc (Segments can only be viewed, not edited) do the following:
Select the Point, Arc or Elliptical Arc you want to edit by clicking on it with the mouse left button. It will
become red.
Choose the command you want to perform from the menu bar, or from the popup menu that appear by
pressing the mouse right button.
Editing Points
By selecting a Point, the following Point menu will be accessible, either from the menu bar or pressing the mouse
right button:
Delete Point: deletes the selected Point. The two adjacent Segments, Arcs or Elliptical Arcs are deleted and
replaced by a single segment.
Change corner to arc: changes the Point and the two adjacent Segments, Arcs or Elliptical Arcs into a single
Arc.
Smooth corner: smoothes the corner having the Point as vertex. The user has to define the Radius (value
greater than zero). NOTE: the point must be adjacent to Segments (Arcs or Elliptical Arcs not allowed).
Edit Point: opens a dialog showing Point X,Y coordinates and allowing the user to modify them. NOTE: the
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point must be adjacent to Segments (Arcs or Elliptical Arcs not allowed).
Editing Segments
By selecting a Segment, the following Segment menu will be accessible, either from the menubar or pressing the
mouse right button:
Delete Segment: deletes the selected Segment and extends the adjacent Segments until they converge.
Split Segment: splits the selected Segment in 2 new Segment whose dimensions are defined by means the
‘Split percentage (%)’ value (specified by the user).
Multi-split Segment: splits the selected Segment in N equal segments. The number N is specified by the user.
Change to Arc: allows to change the Segment into an Arc. The user has to define the Radius. Using the
default value the generated Arc will be 90° wide.
Change to Port: allows to change the Segment into a Port. Available only for the Constant width/height
arbitrary shape element.
Toggle Invisible: makes the selected Segment Invisible allowing to create an Open Contour.
Segment Properties: opens a dialog showing Segment properties: extrema coordinates and segment length.
Editing Arcs and Elliptical Arcs
In the following paragraph, the term Arc means both circular Arcs and Elliptical Arcs, unless explicitly stated
otherwise.
By selecting an Arc or Elliptical Arc, the following Arc menu will be accessible, either from the menubar or pressing
the mouse right button:
Delete Arc: deletes the selected Arc and extends the adjacent segments until they converge.
Split Arc: splits the selected Arc in 2 new arcs whose dimensions are defined by means the ‘Split percentage
(%)’ value (specified by the user).
Multi-split Arc: splits the selected Arc in N homogeneous Arcs. The number N is specified by the user.
Polygonize Arc: approximates the selected Arc by N homogeneous Segments. The number N is specified by
the user.
Change to Segment: changes the Arc into a Segment.
Reverse Arc: changes the Arc orientation.
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Edit Arc: opens a dialog box allowing to view and edit Arc properties, as shown in the following figures:
In case the selected Arc is circular, both the Arc and Elliptical Arc pages are active. You can modify the Radius
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or Extent parameters on the Arc page or change the Arc from circular to elliptical modifying the Major Axis
and Minor Axis parameters in the Elliptical Arc page.
Otherwise if the selected Arc is elliptical, only the Elliptical Arc page is active. To transform an Elliptical Arc
back into a circular Arc, set both Major Axis and Minor Axis parameters to the same value and click on the ‘OK’
button. It is also possible to apply a Rotation to an Elliptical Arc.
 Caveats and Differences
The elements Arbitrary Rectangular, Arbitrary Circular and Constant width/height discontinuity contain some
differences and caveats the user should be aware of in order to use the arbitrary shape editor properly.
Some differences have been already explained above, here they are only summarized:
Constant width/height discontinuity has no Reference Cavity, the other elements have it and implicitly define it.
Constant width/height discontinuity  editor is the only one allowing ports.
2.2.5 Tutorial 5. Optimizer
The goal of this tutorial is to show you how to use Fest3D Optimizer to tune a circuit.
Tutorial 5 will guide new users through the procedure of optimizing (tuning) the circuit you created in the previous
tutorials. Even though it is possible to execute this tutorial on a different circuit, this requires some practice and is not
recommended for new users.
Concepts
In Fest3D, optimization is performed by varying some (user-specified) parameters following an (user-specified)
algorithm in order to minimize the difference between the circuit output and the target (user-specified) output.
The rest of this tutorial explains how to specify the parameters, target and algorithm in Fest3D Optimizer, how to start
and control the optimization, and finally some advanced techniques.
Index
Tutorial 5 is divided in two parts:
5.1 Optimizer: setup describes how to prepare a circuit for optimization and how to configure Fest3D
Optimizer.
5.2 Optimizer: run shows how to start an interactive optimization and what you can do during it.
5.3 Optimizer: export to CST Studio shows how to export a circuit as a Design Studio project in CST Studio and
run an optimization task.
2.2.5.1 Tutorial 5.1. Optimizer: setup
This tutorial is the first of the three tutorials dedicated to Fest3D Optimizer.
In this tutorial you will learn how to prepare a circuit for optimization and how to configure Fest3D Optimizer.
Tutorial 5.1 will guide new users through the procedure of setting up an optimization for the circuit you created in the
previous tutorials. Even though it is possible to execute this tutorial on a different circuit, this requires some practice
and is not recommended for new users.
Tutorial 5.1 is divided in three parts:
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1.  Choose which parameters to optimize explains how to prepare Fest3D to optimize the circuit parameters you
want.
2.  Define formulas, goal functions and constraints shows how to setup the target output you would want your
circuit to produce.
3.  Choose and configure the algorithm shows how to choose and configure one of the optimization algorithms
supported by Fest3D.
Choose which parameters to optimize
This part of the tutorial explains how to choose the circuit parameters that will be optimized (tuned).
By opening the Parameters window  (
parameters to be optimized. Remember to check the opt button to enable each of the parameters to be
optimized (the opt button must be green). Choose the parameter names at your convenience, for instance:
) buttons in the Toolbar, you may introduce the
) or Optimizer (
IrisW = 8.0
IrisL = 2.0
CavityL = 15.0
IrisOffset1 = 4.0
IrisOffset2 = 5.0
Once the parameters have been defined, open the element dialog windows to use the parameters to set the
corresponding element properties:
IrisW to set rectangular 2: A and rectangular 4: A
IrisL to set rectangular 2: L and rectangular 4: L
CavityL to set rectangular 3: L
IrisOffset1 to set step 1: X offset
-IrisOffset1 to set step 2: X offset
IrisOffset2 to set step 3: X offset
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–IrisOffset2 to set step 4: X offset 
Define formulas, goal functions and constraints
Open the Optimization Window from the Execute menu or from the corresponding button (
Toolbar. The following window should appear:
) in the
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Create the following constraints in the Constraints page with the Add Constraint button:
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These constraints are intended to keep the circuit total length (2*IrisL+CavityL) small, as well as to keep the
irises (IrisL) narrow. The weights are determined empirically.
Now it is time to create Goal Functions for this optimization. A common technique for circuits with only two I/O
Ports is to create two Goal Functions, one to tune circuit's S11 and the other for S21. This is what you will be
instructed to do.
In general, for each Goal function you can either choose between creating a mask of points consisting in a
constant target value applied to a range of frequencies, or creating an arbitrary mask of customized target
values applied to specific frequency points. For this tutorial, the two types of masks will be used in order to
illustrate how to work with each one of them.
First, click on the Add Goal Function button and select a Constant mask, configured as shown in the picture
below:
When clicking on the Ok button, the Goal function will be included in the Optimizer window. Now, you need to
select the S Parameter of the circuit, and the Equality/Inequality operator. The constant mask of this goal
will be applied to the magnitude in dB of parameter S11, and <= operator will be used, meaning that you
desire the S11 parameter to be less or equal than -15 dB in the range of frequencies from 11.2 to 11.3 GHz.
Finally, we will modify the default mask name to "Mask S11" to identify more clearly the purpose of the mask
in the results window when the optimization process is running. At this point, the Optimizer window should
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look like this:
Now, click on the Add Goal Function button again. This time, an Arbitrary mask will be used. To configure this
mask, you will insert in first place 21 in the number of frequency points and click on the Apply button:
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The next step is to enter the values of the frequency points for this arbitrary mask. As you have seen in Tutorial
2 this circuit has a resonance at about 11.1 GHz. We are interested in the frequencies close to it, so enter 11.0
in row 1 of the value column and enter 11.5 in the row 21 of the same column.
Entering all the intermediate frequency values would be tedious and error-prone, so Fest3D is designed to help
you here. Select with the mouse (clicking on the left button) all the cells in the Frequency column. Those cells
should now be hilighted (usually in blue) as shown in the following figure:
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Next, click on the Linearize button. All the intermediate values will be created automatically, as shown in the
next figure:
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Now it is time to configure the target values. Experiment with Linearize on the Target column selecting only a
subset of the rows to find the easiest way to define the following values:
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and
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Finally, click on the OK button to include the new goal in the Optimizer window. This second goal will be
applied to the magnitude in dB of parameter S21, and you will set the <= operator as in the case of the first
goal function. Finally, also set the mask name to "Mask S21". After that, this should be the appearance of the
window:
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Choose and configure the algorithm
The last step for setting up the Fest3D optimizer is choosing and configuring the algorithm.
Click on the Algorithm button on the bottom to select the algorithm among the allowed ones and configure
it. Currently supported algorithms are Simplex, Powell, and Gradient.
For this tutorial, you will use the Simplex algorithm. Click on the corresponding Simplex button, then click on
OK:
The default values for the algorithms configuration are good in most cases, no need to modify them here.
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2.2.5.2 Tutorial 5.2. Optimizer: run
This is the second of the three tutorials dedicated to Fest3D Optimizer.
In this tutorial you will learn how to start, control, stop and resume the optimization of a circuit using Fest3D
Optimizer.
This tutorial supposes you have read, understood and practiced the topics treated in Tutorial 1, Tutorial 2, Tutorial 3
and Tutorial 5.1 and you have already completed the optimizer setup as explained in them.
Tutorial 5.2 will guide new users through the procedure of interactively running an optimization for the circuit created
in the previous tutorials.
Tutorial 5.2 is divided in two parts:
1.  Just Run and Watch explains how to start Fest3D Optimizer and observe its progress in real time.
2.  Stop, Edit and Resume shows how to interact with setup the target output you would want your circuit to
produce.
Just Run and Watch
This section explains the minimal steps required to run Fest3D Optimizer. They reduce to:
Ensure the Auto Plot button (
will let you watch the circuit output (S parameters) as they evolve.
) in the Toolbar is clicked and the corresponding Plot Window is visible. This
Click on the Optimize button (
identical button is present in the Main Window Toolbar, but has a completely different function (runs an S-
parameter simulation).
See the progress. You should see something analogous to the following figures:
) in the Optimization Window to start optimization. Beware that an
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If the optimization succeeded (and it always should in this simple example), you now have a circuit whose
resonance is approximately at 11.25 GHz, instead of the original 11.1 GHz. You can Stop the optimization when
you think the result is good enough, or you can wait for it to stop either because the maximum number of
iterations was reached or because a possible minimum was found.
Click on "Apply Parameter changes" to save your tuned parameters into the file, or click on "Discard
Parameter changes" if you are not satisfied with the results. 
Note that if you close the Optimization Window, the Parameters labels and expressions, Goal Functions, Constraints
and Algorithm configurations are not lost. Open again the Optimization Window and you will get them back.
Actions while using optimizer
While using the optimizer you can discard, save or backup your current optimization status, these are the main
differences:
Discard all optimization steps: This will replace all the current values with the initial values since the last time
you saved your project. If you have not saved it, it will revert to the original status.
Apply opt changes and save project. This will save your current optimization status to the current .fest3
project file.
Save status into a backup file: This option lets you creating a clone of the current optimization status for
future use. So you can keep optimizing and experimenting with new goals/constraints/algorithms and you will
be always capable to revert to the status you had when you created the backup file. The backup file is just a
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.fest3 file  so you can re-open it with the open button.
Stop, Edit and Resume
You are recommended to experiment with parameters, goal files and their weights in order to learn how the optimizer
reacts to changes and how to guide the optimization algorithms to your target.
At any moment, you can Stop the Optimizer, edit the setup as you did in Tutorial 5.1 then restart the Optimizer. This
allows changing the Parameters values, the Goal Functions, Constraints, Algorithm and every other aspect of
optimization without losing the progress you already achieved in tuning the circuit.
Try the following experiments:
Change the value of one or more parameters, then restart optimization. Watch whether the
algorithm is able to restore the parameters values to the ones before you modified them or not.
Modify the goal functions to be centered at 11.35 GHz, then restart the optimization. With a little
patience, by repeating this procedure you can move the resonating frequency even by large
frequency intervals.
Goal files. Learn by experiments that using goal files whose dB values are very far from circuit
output can create local minima in the error function and prevent optimization from succeeding.
You will recognize this case by observing that the optimizer is tuning the circuit to have
maximums or minimums of the output exactly at one of the sampled frequencies, instead of
moving them around.
Change the expressions. Learn that the optimization algorithms do not touch or even know
about parameters having an associated expression: they are simply set to whatever value their
expression dictates, independently from the algorithm being used.
Change the constraints. Learn that constraints are only used as additional terms to the error
function, so they are soft constraints and they are not guaranteed to be exactly
satisfied/respected. However, to mitigate this, one can set a very large weight to the constraint
when a hard constraint is needed.
2.2.5.3 Tutorial 5.3. Optimizer: export to CST Studio
This tutorial is the third of the three tutorials dedicated to Fest3D Optimizer.
Tutorial 5.3 will guide new users through the procedure of exporting the circuit you created in the previous tutorials as
a Design Studio project, and run an Optimization task from CST Studio.
This tutorial supposes you have read, understood and practiced the topics treated in Tutorial 1, Tutorial 2, Tutorial 3
and Tutorial 5.1 and you have already completed the optimizer setup as explained in them.
Tutorial 5.3 is divided in three parts:
1.  Export the circuit to Design Studio explains how to export your circuit to Design Studio project, including the
settings for the Optimizer.
2.  Configure an Optimization goal using arbitrary mask shows how to set up an Optimization goal in CST
Optimizer that uses the data of an arbitrary mask imported from the Fest3D circuit, as an optional step.
3.  Run the Optimization task shows how to start the Optimization process in CST Studio and check the
evolution of results.
Export the circuit to Design Studio
This part of the tutorial explains how to convert the circuit of the previous tutorials into a Design Studio project.
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After completing the set-up explained in Tutorial 5.1 and saving the Fest3D project, you can export it as a
) button in the Tool bar, or going to Export -> Export project to
Design Studio project by clicking on the (
CST Design Studio in the Menu bar.
A window for setting export options will be shown. Since we are not interested in using a 3D Simulation project
for this Tutorial, you can optionally uncheck the option Create 3D Simulation Project. This will save some
time in the export operation. What is important is to ensure that the option Create Optimization Task is
selected, to be able to run an optimization from CST Studio. The option shall appear marked by default, since
this circuit contains parameters and goal functions defined from Tutorial 5.1.
Click the Ok button and a File Selector window will appear. Select the name and location of the Desing Studio
project that will be created. You can just use the name proposed by default, based on the name of the Fest3D
project and located at the same path.
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Click on Save and the exportation process will begin. A Design Studio project tab will automatically appear,
including:
A Fest3D block linked to the Model of the Fest3D project that you have exported. The block includes the
necessary port connections, based on the number of accessible modes defined for the input/output
ports of the Fest3D circuit.
One or several S-Parameter tasks. The number will depend on the the number of frequency sweeps
enabled for simulation, and also on the number of frequency sweeps associated to goal functions in the
Fest3D project. For this example, there will be 3 tasks: one from the main frequency sweep defined for
simulation in Tutorial 2, and two from the goal functions defined in Tutorial 5.1
An Optimization task, called FEST3D Block Optimization. This task will also include another S-
Parameter task (namely SparamOpt), which will be the one used for the optimization process. This S-
Parameter task will be defined with a frequency range that contains all possible frequencies used for all
the frequency sweeps of the Fest3D project, including those considered for optimization. By double-
clicking on the Optimization task in the File tree of the project, you can see that that the task is already
configured, including a default Optimization algorithm (Trust Region Framework), and the parameters
imported from the Fest3D project.
In the Goals tab of the Optimization task window, you can find as well some optimization goals
already created, depending on the number of goal functions that have been defined using constant
masks in the Fest3D project. For this example, in Tutorial 5.1 a constant mask had been used for the
goal function applied to S11 parameter. The optimization goal included in this Optimization task will be
defined with the same frequency range, target value, weight value and comparison operator.
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Configure an optimization goal using arbitrary masks (optional)
If you remember from the set-up of Tutorial 5.1, there was another goal function defined for S21 parameter using an
arbitrary mask. This type of mask cannot be converted automatically to Optimization goals in the Optimization task of
the Design Studio project during the export process, but it is possible to manually create optimization goals that will
try to match the computed results with an external file containing the data of the arbitrary mask. This can be
achieved by defining some Template Based Post-Processing results.
In this section, we wil show a a guideline for creating these Template Based Post-Processing results. Following this
guideline is optional, and other strategies can be adopted depending on your particular needs, for example:
A) Just ignore goals with arbitrary masks if there are more goals available which are enough for producing a
good optimization of the circuit.
B) Define alternative goals with constant target values that might help adjusting the desired S-Parameter curve
in a similar way as in the case of the arbitrary mask. Those alternative goals can be either defined in the Fest3D
project in first place and then exported to Design Studio (exporting the project again), or created directly in the
Optimization task in the Design Studio project.
Nevertheless, it is recommended to use the guideline if the optimization in a Fest3D project was defined in order to
adjust the circuit response for matching results with respect to the response of another circuit or with respect to
curves based on theoretical values. If you want the optimization process in Design Studio to behave in a similar way as
the optimization process in Fest3D, then you need to apply the procedure below.
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In order to create the optimization goal in the Design Studio project using the data of an arbitrary mask of Fest3D
optimizer, you can follow these steps:
1.  First, you need to update the results of the S-Parameter task associated to the Optimization task. This is
required since in subsequent steps you will define Template Based Post-Processing results based on result
curves which must be created from this task. In order to do so, just select the SparamOpt task under the
FEST3D Block Optimization task in the Project tree, right-click on it and click on Update, as shown in the
figure:       
2.  Now open the optimization task window, go to the Goals tab and click on the Add New Goal button. This will
open a new window in order to define and configure the new goal. The first thing to do is to click on the
Result Template... button, as shown in the figure:
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3.  The Template Based Post-Processing window will pop up. Go to the Add new post-processing step combo
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        and select Load data (1D or 0D)
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4.  The Load 1D Data File window will pop up. Select the radio button external folder in Data File section, and
make sure that 1D is marked in Template Type section. Now go for Browse file button:
and navigate to the folder where your Design Studio project has been exported. In this folder, you will
find that there is a text file with the name of the arbitrary mask. This file was automatically created when the
project was exported from Fest3D. Select the file and click on Open.
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5.  Now click on Ok in the Load 1D Data file window. The first Template Based Post-Processing result will be
shown:
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6.  Now a second Template Based Post-Processing result will be included. Go again to the Add new post-
processing step combo and this time select Mix template results :
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7.  In the Mix template Results window, you need to configure the following:
In the Expression chart, you shall enter the formula: "abs(A-20*log10(abs(B)))"
Variable A is already selected as the external data file imported from your previous Template Based
Post-Processing result.
For Variable B you must select the S parameter you want to adjust from the list of results of the S-
Parameter task. For this example, the purpose is to work with the S21 parameter.
After these steps, the window should look like this:
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The configuration above has been defined in order to compute the absolute difference between the magnitude
of the S21 parameter computed by the S-Parameter task and the magnitude of the S21 parameter written in
the external file. Since the external file was exported by Fest3D with the magnitude expressed in dB, it is
necessary to convert the result parameter of the task to dB, because the plain value of that result is linear by
default.
The formula used here in the Expresion chart is therefore only suitable for working with magnitude of S-
Parameters. If other types of quantities are to be optimized, like phase of group delay, then a different version
of the formula shall be used (e.g: "abs(A-B)"), in order to compute the absolute difference between the
desired external and computed values.    
8.  Now a second Template Based Post-Processing result will appear included in the Template Based Post-
Processing window. Clin on the Close button, and you will go back to the window that defines the new goal.
9.  Now it is time to configure the goal:
In the Result Name combo, find and select the Mix 1DC result, which is the one corresponding to the
second Template Based Post-Processing result that was created in the previous steps.
Select Real part in the Type of value.
Select Operator "=" and set Target value as 0. Define an appropiate weight for this goal. For this
example, value 1 will be used, as in the case of the original Fest3D project.
Select a proper Frequency range in which this goal will be applied. For this example, the data of the
arbitrary mask is defined between 11 GHz and 11.5 GHz, so you may enter the values here.
Select Sum Of Squared Differences  in the Goal Norm combo. This is for applying the same
criterion as in the Fest3D Optimizer.
The window should look like this:
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10.  Finally click on OK and the goal will be included in the Goals tab of the Optimization task:
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Run the Optimization task
Once the optimization goals are defined, you can just click on the Start button in the Optimization task window. In
the Info tab, some information will be shown, such as the number of evaluations, the values of the error functions and
the current parameters used.
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The Optimization task has been configured to store all intermediate results computed during the process. In the
Project tree, all the results will appear grouped in different items under the FEST3D Optimization block:
algorithm statistics, evolutions of the goal function values, of the parameters, of the result curves for S-Parameters
considered by the goals... All these results can be inspected whereas the optimization process is running.
As an example, the figure belows shows the comparison of the initial and best case achieved so far for the S11
parameter:
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2.2.6 High Power
2.2.6.1 Tutorial 6: Electromagnetic field Analysis
In this tutorial, you will learn how to configure and launch an electromagnetic (EM) field analysis in Fest3D. For more
detailed information on EM field analysis, visit EM Field Analysis section in the manual.
Tutorial 6 presents a guided example in which the EM field analysis process is explained step-by-step. It is divided in 3
parts.
1.  Preliminaries. We open an example and see what considerations should be taken prior to the EM field
analysis.
2.  Launching an EM Field Analysis. The main parameters are set and the analysis is launched.
3.  Plotting the Fields It gives an overview of the visualization tool Paraview.
Preliminaries
First we need a circuit for EM field analysis. In the tutorial 1 the main steps to create your own circuit are given. In this
example we will open one of the circuits in the examples folder.
Click on the examples icon (
) and open Analysis/Rectangular/Lowpass/lowpass.fest3x file.
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In order to increase the accuracy of the EM fields, increase the number of accessible modes and green functions. Click
on the Global Specification window (
) and change the global parameters to:
Num. of accessible Modes: 10
Num. of MoM basis functions: 15
Num. of Green's function terms: 100
Num. of Taylor expansion terms: 1
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Launching an EM field Analysis
Click on the EM button (
) to open the Configure Field Monitors window:
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Now configure the following settings:
Add a new Excitation Signal and set the frequency to 9.5 GHz.
Activate the checkbox "Compute whole circuit". This will include all the elements of the circuit in the mesh
where the EM fields will be evaluated.
Set the mesh size value to 1 mm. The number inserted in this text box is the default mesh size, in millimeters
or inches, used to generate the mesh where the EM field shall be evaluated.
Once the specifications have been set, the Configure Field Monitors window should look like this:
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Finally, press the "Ok" button in order to confirm the settings and close the window.
Running and plotting the fields
To perform the EM field analysis, simply press the button (
results will be automatically visualized. 
) and the computations will start. After finishing, the
The main window looks like this
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With the left, right and center button of your mouse you can rotate, zoom and translate the camera view. In the menu
bar there is a display list where the different fields (electric, magnetic, Poynting vector) can be selected.
Fest3D also includes predefined 2D cuts that allow visualizing the fields inside the structure. On the left side of the
window, the main object and the 2D cuts are shown in a tree-like distribution. You can show or hide any of them by
simply clicking on their corresponding "eye" icons.
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Computing voltage with Paraview
With Paraview it is also possible to compute the voltage as the integration of the electrical field between two points in
the mesh. In Fest3D, the fields are defined for an input power of 1W, therefore the computed voltage is also at 1W,
called V1W. This can be useful for multipactor to translate from breakdown power to breakdown voltage and compare
results with theoretical parallel-plate predictions. The expression to convert from power to voltage is the following:
Be careful because the voltage computed this way depends on the selected path in the mesh. In order to have
meaningful results, the device geometry and fields should be similar to a parallel-plate case.
V=V1W√P
The process is as follows:
1.  Apply paraview filter "plot over line"
2.  Specify the coordinates of the line
3.  Apply paraview filter "Integrate variables".
In this particular case we will compute the voltage in the center of the centre iris, where the maximum field is located.
In order to do so, one has to select the "Plot Over Line" filter in Filters->Alphabetical->Plot Over Line menu.
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Select the line for displaying the data by either moving the start and end points with the mouse, or by inserting
coordinates manually. In this case, just press "y axis" button to automatically orient the line properly. Then press
"Apply" button.
A 2D plot with the fields displayed along the selected line appears. Now, apply another filter called "Integrate
Variables" in Filters->Alphabetical->Integrate Variables. This filter will integrate all quantities displayed in the 2D plot.
In this case, we obtain a voltage at 1W of V1W= 17.8 V as shown below.
Note: Line start and end points must be adjusted to be inside a valid data region. If any of the line nodes lies
outside, NaN integration values may appear.
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 More information on Kitware's Paraview can be found in https://www.paraview.org .
2.2.6.2 Tutorial 7: High Power Analysis
In this tutorial, you will learn how to configure and launch a High Power analysis in Fest3D by defining the settings of
the EM field analysis, and then launching Spark3D. For more detailed information on the High Power analysis, visit
the High Power Analysis: Multipactor and Corona section in the manual.
Preliminaries
First we need a circuit for the analysis. In the tutorial 1 the main steps to create your own circuit are given. In this
example we will open one of the circuits in the examples folder.
Click on the examples icon (
) and open Analysis/Rectangular/Lowpass/lowpass.fest3x file.
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In order to increase the accuracy of the EM fields, increase the number of accessible modes and green functions. Click
on the Global Specification window (
) and change the global parameters to:
Num. of accessible Modes: 25
Num. of MoM basis functions: 100
Num. of Green's function terms: 500
Num. of Taylor expansion terms: 4
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For realistic results, the simulation should be done for frequencies in the transmission band of the circuit. Therefore,
we will run first a circuit analysis to determine the right frequencies for the High Power simulation.
Press the analyze button (
) in the menu bar, the frequency response of the circuit is plotted.
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For this particular example, we will consider 3 frequency points at the middle of the analysis band: 9 GHz, 9.5 GHz and
10 GHz.
Click on the Configure Field Monitors button (
) and set the following:
1.  Add 3 Excitation Signals with the frequencies 9, 9.5 and 10 GHz.
2.  Enable the checkbox "Compute whole circuit".
3.  Set the mesh size value to 1 mm.
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Finally, press the Ok button to confirm and save the settings.
Launching the simulation
Click on the button (
) (or alternatively click on Execute -> High power analysis in the menu bar). By doing this,
Fest3D will compute the EM fields of the circuit. After that, a Spark3D project file will be automatically created and
opened with Spark3D. This project will contain the information of the fields computed by Fest3D for the 3 different
signals. At this point, the same topics explained in the Tutorial example of the Spark3D manual can be consulted:
Specifications of analysis regions that will be used. 
Definition and execution of Corona and/or Multipactor configurations, as well as associated Video
Configurations.
Definition of multicarrier signal using imported signals if a multicarrier analysis is desired in Multipactor
analysis
2.3 Fest3D Manual
This section describes the structure of Fest3D and documents the features of each subsystem Fest3D is composed of
(Graphical User Interface, E.M. Engine, Optimizer, Convergency Study).
The Fest3D manual contains the following topics:
Architecture
The top-level architecture of Fest3D
Requirements
The minimum hardware and software requirements needed to run Fest3D.
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Graphical User Interface
(GUI)
Description of the Graphical User Interface, its features and how to use it
E.M. Engine (EMCE)
Description of the E.M. Engine, its features, and how to activate/control it from the GUI
Optimizer (OPT)
Description of the Optimizer, its features, and how to activate/control it from the GUI
Tolerance Analysis (TOL)
Description of the Tolerance Analysis, its features, and how to activate/control it from
the GUI
Synthesis: The Synthesis
Tools
Description of the Synthesis Tools and how to use them to create full filters with a few
mouse clicks
E.M. field analysis
Description of the E.M. field computation.
High Power
Description of the corona and multipactor threshold calculations
Engineering Tools
Small tools to perform unit conversions and simple computations
Compare Results tool
Tool for easily comparing Fest3D output results.
Convergence Study
This section explains in detail the procedure to be followed in performing convergence
studies.
Architecture
Fest3D is a CAD tool for linear, passive millimeter-wave and microwave components, based on cascaded
discontinuities in waveguides. It allows the user to design waveguide structures, activate E.M. analysis, optimization
and synthesis and perform the result visualization using an intuitive, user-friendly graphical interface. The list of
elements supported by Fest3D is described in the Elements Database.
At the top-level, Fest3D is composed of three subsystems:
Graphical User Interface (GUI)
ElectroMagnetic Computational Engine (EMCE)
Optimizer (OPT)
Furthermore, the publicly available Gnuplot program integrates the functionalities of the GUI by providing plotting
capabilities.
The GUI is a Java application. It is the part of Fest3D program in charge of interacting with the user and also executes
and coordinates the other subsystems at user's demand.
The EMCE implements the electromagnetic capabilities of Fest3D (except for some parts provided by the Synthesis
Tools and Engineering Tools). The EMCE is designed and tuned for performance and exploits state-of-the-art
techniques both in the electromagnetic and information technology research fields.
The OPT provides the optimization capabilities of Fest3D. It implements a loosely coupled architecture, where the OPT
is a standalone executable and exchanges data with the EMCE and reports status and progress to the GUI and thus to
the user. It uses general-purpose optimization techniques, usually irrespective of the model physics, to perform
variation of the parameters being optimized. Integrated with the other subsystems, the OPT aims at being an
interactive and extensible optimization framework, where the user can view and interact in real-time with the
optimization.
Millimeter-wave and microwave circuits composed of supported elements can be analyzed, obtaining insertion and
transmission losses, as well as the phase and the group delay, versus frequency. The results of the computation are
displayed in graphic form and can also be printed.
The multi-mode S, Z or Y matrix of such circuits can also be computed, effectively reducing a whole circuit to a single
block which can be then reused as a User Defined element in a more complex circuit or system, or exported to other
E.M. simulation tools.
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Finally, circuits can be interactively tuned by using the optimizer to reach the desired output.
2.3.1 Requirements
Fest3D installation requirements are covered in the common document of the CST Studio Suite placed in:
<installation folder>/Documentation/CST Studio Suite - Getting Started.pdf
2.3.2 Graphical User Interface (GUI)
This section describes the architecture of Fest3D Graphical User Interface (GUI), documents its features and how to
use it.
The GUI section contains the following topics:
The Main Window
How to use the GUI to design and edit circuits, execute the E.M. Engine (EMCE) and
Optimizer (OPT).
The Elements bar
Contains all the buttons of the currently supported Fest3D Elements.
The Parameters Window
The dialog to define parameters to be used in the circuit creation, its optimization or
tolerance analysis.
The General Specifications
Window
The dialog to view and edit circuit specifications such as symmetries and global
numeric parameters.
The Frequency
Specifications Window
The dialog to view and edit frequency sweeps to be simulated and its mode (discrete or
Adaptive Frequency Sampling).
The 3D Viewer Window
Draws the 3D geometry of a circuit.
The Preferences Window
The dialog to customize and configure Fest3D.
2.3.2.1 The Main Window
This section describes the Fest3D Main Window and how to use it to create, edit and analyze millimeter-wave and
microwave circuits. The other windows and dialogs that can be opened from the Main Window are also listed.
The Main Window section contains the following topics:
Menubar
Toolbar
Canvas
Element
Properties
Edit
Connections
The top menu bar with standard commands: Load, Save, Quit, Copy, Paste ... and also Fest3D
specific commands.
The toolbar on the top, containing buttons for frequently used Menu commands.
The drawing canvas, where circuit can be created and edited.
The dialog box to view and edit elements.
The dialog box allowing to reorder the connections to an element.
S parameters
A small dialog to choose which S parameters are plotted.
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The Fest3D Main Window typically looks as follows
Menu bar
The menubar at the top of the Main Window gives access to all the GUI functions. The user can select any of them by
using the mouse or by pressing ALT + the underlined letter of the menu item. The following figure shows the
menubar as it typically appears on the screen
The menubar contains the following menus:
1.  File
New is used to begin a new project, the old structure is discarded after a confirmation request.
Open a browsing dialog box for file selection appears. By default, the user can choose among *.fest3
files.
Open Examples a browsing dialog box for example file selection appears.
Merge allows to load several Fest3D structures in the same canvas.
Save stores the structure with the name defined before (written at the top of the window) or acts as
Save As if a name was never defined.
Save as stores the structure with a new name, this name becomes the new current name.
A list of the last 5 opened files.
Quit ends the program (closing all windows) asking the user to save modifications if not previously
saved.
2.  Edit
Copy copies the selected elements and connections in the clipboard, you can Paste them later.
Paste places in the editing area the elements and connections stored in the clipboard, near the original
ones; the pasted element are automatically selected so that they can be moved. Warning: pasted
elements may appear over existing ones, move them immediately to avoid errors in the analyzis stage
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due to non connected elements.
Cut erases the selected elements and connections and stores them in the local clipboard for future
Paste.
Delete erases the selected elements and connections. They can be recovered only if you immediately
execute an .
Enable sets the selected elements to enabled status (normal).
Disable sets the selected elements to disabled status. Disabled elements are ignored by the EMCE and
OPT.
Toggle Enable inverts the enabled/disabled status of the selected elements.
3.  Execute
S-Parameter Analysis starts the E.M. engine to analyze the structure. If errors are detected in the
structure, a message appears and the analyzis is not performed. The resulting single-mode S parameters
are stored in a file with the same name as the input file and with the extension .out. This file is saved in
the same directory as the input file. The S parameters are also automatically plotted at the end of the
simulation.
EM Field Analysis starts the E.M. engine to compute the electromagnetic field distribution of the device
under simulation.
High Power Analysis opens Spark3D for performing Multipactor and/or Corona simulations on the
electromagnetic fields calculated on the device under simulation.
Compute Generalized Z matrix starts the E.M. engine to compute multi-mode Z matrix of the
structure. The result is written in a file with the same name as the input file but with .chr extension. This
file is saved in the same directory as the input file. Such .chr files are suitable to be loaded by User
Defined elements.
Compute Generalized S matrix performs exactly the same multi-mode structure analysis as in
Compute Generalized Z matrix, but produces instead multi-mode S matrix of the structure.
Compute Generalized Y matrix performs exactly the same multi-mode structure analysis as in
Compute Generalized Z matrix, but produces instead multi-mode Y matrix of the structure.
General Specifications opens The General Specifications Window, allowing to edit the circuit
specification data: frequency range and points, symmetries, global numeric parameters. Refer to EMCE
code documentation for detailed description of each parameter.
Frequency Specifications opens The Frequency Specifications Window, allowing to set-up the
frequency sweeps that will be used in the simulation.
Stop Simulation interrupts any running simulation (EMCE) or optimization (OPT). Incomplete data is
lost.
Compare results opens a the compare results tool for selecting and comparing different results of
previously performed simulations.
Show Optimizable Parameters allows to choose which parameters to optimize in each circuit element.
In the Element Properties dialog, a small 
parameter. Clicking on the button, it will change to 
Optimization Window opens the Optimizer (OPT) window, where the OPT can be configured,
interactively executed and monitored.
Tolerance Analysis Window opens the Tolerance Analysis window, where the tolerance analysis can be
configured, interactively executed and monitored.
 button will appear near the name of each optimizable
 indicating that the parameter will be optimized.
4.  Export
Export 3D geometry (closed ports) allows the user to create a SAT file with the geometry of the circuit
built as a single metallic piece. Additionally, the existing dielectric volumes will be individually included
in the SAT file as well.
Export 3D geometry building blocks (closed ports) allows the user to create a SAT file with the
geometry of the circuit, in which all the different Fest3D elements that have 3D volume are included as
individual pieces.
Export Project to CST MWS opens a wizard that allows to automatically build a CST MWS project with
pre-defined settings that contains the geometry of the current Fest3D circuit, ready to be analyzed.
Export Project to CST Design Studio allows to automatically build a CST Design Studio project with
pre-defined settings that contains the geometry of the current Fest3D circuit as an imported block with
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the pins, frequencies and s-parameter task fully ready to be analyzed.
Export S-parameters to Touchtone file converts the Fest3D output file to a TOUCHSTONE format.
5.  Structure
Select Element allows the user to select and move elements and connections in the Canvas.
Connect Element starts the connection mode. Connections between elements are established by
pressing left mouse button on an element, dragging the mouse to another elements, finally releasing
left mouse button.
Element Properties opens the dialog box containing the selected Element Properties and allows the
user to modify them.
Show Icons changes the view mode from icons to numeric labels and vice versa.
Add element allows selecting a new element to place in the editing area. The Elements bar can be used
to perform the same operation.
6.  Synthesis allows to choose and open the Synthesis Tools dialog boxes, configure and execute them.
7.  Tools allows to choose and open the Engineering Tools dialog boxes.
8.  Options
Edit Preferences opens the Preferences window, allowing to configure the cache system, and set the
number of processors used.
Auto-Save Options at exit if active, Fest3D options will be automatically saved at program exit (on by
default).
Clean Cache for current project deletes the cache files related to the open project.  See Preferences to
activate/deactivate the cache system.
Clean Compare Folder deletes the content of the compare folder (located in the workspace folder).
Change workspace configuration allows the user the change the directory used as workspace for
Fest3D.
Reset preferences resets the Preferences to the default installation values.
9.  Help
Toolbar
About shows Fest3D version information.
Help opens Fest3D Online Help.
License diagnostics checks the license server status and writes information on the screen. This can be
used in case that there is a problem with the license system.
The toolbar is the horizontal row of buttons at the top of the window, it duplicates the most frequently used menu
commands, allowing to perform the basic functions: new, open, save, print circuit, undo, copy, paste, cut,
specifications, analyze, stop computation, optimization window, field monitors window, execute EM field analysis,
execute High Power analysis with Spark3D, plot, help, 3D viewer... The following figure shows the toolbar as it typically
appears on the screen
Canvas
The wide area in the middle of the main window contains the block diagram representation of the current structure.
Pressing the New button in the toolbar or selecting New from the File menu erases the existing structure and
starts a new one.
To add an element to the structure, press the left button of the mouse on an element of the Elements bar,
move the mouse in the editing area where the element must be located, and press again the left button.
To edit the properties of an element press the right button of the mouse on the element (or do it later after the
structure is completed). The Element Properties dialog will appear.
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To connect elements, set mode to connecting by pressing the Edit Connections dialog will appear. Connections
are always between a waveguide and a discontinuity.
You can use the Undo, Copy, Cut, Delete and Paste functions to edit the structure.
To erase a connection or delete elements press the arrow button of the elements bar, select the connection or
the elements with the left button and press the scissors button (Cut) in the toolbar or select Cut or Delete
from the Edit menu. To move the editing area use the scroll bars or press the middle mouse button (if
available) and move it.
Element Properties
To see and modify the element properties press the right button on the element in the editing area. A dialog box,
allowing the user to view and edit the element properties will appear. The exact content of the dialog box depends on
the element you are editing, see the Elements Database for details. The following figure shows a typical element
properties dialogs as they appear on the screen.
Edit Connections
The order of the connections is relevant for some elements. To modify it, the user just needs to click with the right
mouse button on the connection. The Edit Connections dialog will appear, typically looking as the following figure:
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This dialogs allows the user to specify the ports of an element where each connected element should be attached. For
each connected element, a row of radio-buttons is available to specify which port it should use. Attaching more than
one element on the same port is not allowed.
2.3.2.2 Elements bar
The elements bar gives access to all the elements supported by Fest3D, as well as to the Select and Connect
menu commands. The figure on the left shows the elements bar as it typically appears on the screen.
The first button (select) executes the Select command: the user can now select, move, copy, delete
elements or edit properties. Use the left mouse button to select and move elements, the right one to
edit properties. The middle button (if it exists) can be used to move (pan) rapidly the editing area.
The second button (connect) executes Connect command, used to connect elements together. Press
the left mouse button on an element, move the mouse on another element and release the left
button. The order of the connections is relevant for some elements, to modify it select the arrow
button and click with the left mouse button on the connection. The Edit Connections dialog will
appear. Connections are always between a waveguide and a discontinuity.
The other icons are used to place the corresponding elements to the Canvas.
2.3.2.3 Frequency Specifications
This section explains how the user can create multiple sweeps and the types of algorithms that can be chosen to
solve such sweeps.
In order to configure the sweeps in a Fest3D project, click on the Frequency Specifications in the execute menu bar, or
click on the Frequency Specifications (
image), will pop up:
) button in the toolbar. The frequency specifications window (see next
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Frequency Specifications window
A typical window for the configuration of the frequency specifications is shown in this figure:
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In this window, different sections are highlighted:
- Section 1: Selection of the type of sweep for this project. Fest3D allows selecting between frequency, theta
and phi sweeps.
- Section 2: Add sweep: With this button, new sweeps can be added. Fest3D allows simulating multiple
sweeps.
- Section 3: This is a list of all sweeps created for this project. Modification of all parameters can be done per
sweep.
- Section 4: This is the list of the sweeps used by the optimizer. This is a read-only list to have an easy way to
see the sweeps defined in the optimizer. Optimizer sweeps can only be changed by editing the data defined for
goal functions in the optimizer window.
Algorithms for sweep solution
Discrete algorithm: This is the typical sweep where all the points defined are simulated. So, for
instance, if the user defines 100 frequency points, Fest3D will solve the problem in ALL 100 points. 
Adaptive sampling: This method is used to reduce the number of simulated points. This method is
explained in detail in the section Adaptive Frequency Sampling method.
Parameters of the adaptive sampling 
There  are  two  parameters  to  configure  for  the  adaptive  sampling:  target  error  and  the  scattering  parameters  to  be
used in the error calculation (and its relative weight).
In order to configure the parameters for adaptive sampling, the button "Config" must be selected, see image below:
The window that appears to configure the parameters for adaptive sampling is the following:
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These parameters are available after pushing the button "Advanced" in each adaptive sweep in the window Sweeps. In
addition, each sweep is configured separately.
Target  error:  The  method  stops  when  the  current  error  is  below  this  value  during  3  consecutive
iterations.  The  default  value,  0.001,  guarantees  the  convergence  of  the  response  in  a  wide  range  of
circuits and cases.
Parameter relevance:  The  internal  calculations  will  be  done  only  using  the  parameters  selected  by  the
user. In addition, in the case that two or more parameters are used, the relevance of those parameters
can be selected with the "weights" column.
Note  2:  Regardless  of  what  parameters  are  used  in  the  internal  calculations,  the  final  response  will  contain  all
parameters of the circuit.
Note 3: Internally, the weight of the selected parameters is normalized to one.
2.3.2.4 The General Specifications Window
This section describes the General Specifications Window and how to use it to view and edit the circuit specification
data:  "symmetries" and "global numeric parameters". This window is opened from the toolbar on the top of the main
window.
The general specifications window section contains the following topics:
Global Symmetries
The global symmetries flags supported by Fest3D.
Global Waveguide Settings
Default values for parameters common to all waveguides.
The general specifications window typically look as in the following figure:
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Global Symmetries
Global symmetries and global circuit parameters can be configured from the general specifications window right tab.
The following global symmetries are available, even though most elements only support a subset of them :
All-Inductive (H plane, constant height) The circuit has a fixed height and is invariant under vertical (Y)
translations. All components must have the same height. In all discontinuities, Y offsets and Rotation must be
zero. With this symmetry the Rectangular waveguides use only the TEz(m,0) modes.
All-Capacitive (E plane, constant width) The circuit has a fixed width and is invariant under horizontal (X)
translations. All components must have the same width. In all discontinuities, X offsets and Rotation must be
zero. With this symmetry the Rectangular waveguides use only the TEz(1,n) and TMz(1,n) modes.
X symmetric (symmetric under horizontal reflection) The left half and right half of the circuit are symmetric:
reflecting the circuit across the plane X = 0 does not change it. In all discontinuities, X offsets and Rotation
must be zero. With this symmetry the Rectangular waveguides use only the TEz(2m+1,n) and TMz(2m+1,n)
modes.
Y symmetric (symmetric under vertical reflection) The upper half and lower half of the circuit are symmetric:
reflecting the circuit across the plane Y = 0 does not change it. In all discontinuities, Y offsets and Rotation
must be zero. With this symmetry the Rectangular waveguides use only the TEz(m,2n) and TMz(m,2n) modes.
All-Cylindrical (All-Centered Circular waveguides) The circuit is invariant under rotations around the Z axis. The
circuit can only contain Circular waveguides and Steps. In all Steps, X and Y offsets must be zero. With this
symmetry the Circular waveguides use only the TEz(1,n) and TMz(1,n) modes.
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TEM (All-Centered) The circuit is invariant under rotations around the Z axis. The circuit can only contain
Circular, Circular coaxial waveguides, and Steps. In all Steps, X and Y offsets must be zero. With this symmetry
the Circular waveguides use only the even TMz(0,n) modes and the Circular coaxial waveguides use the TEM
and even TMz(0,n) modes. Circuits with such a symmetry should begin and finish with Circular coaxial
waveguides.
Only one symmetry can be specified for a circuit, except for the following cases:
All-Inductive symmetry also allows simultaneous X symmetry
All-Capacitive symmetry also allows simultaneous Y symmetry
X symmetry and Y symmetry be specified together if no other symmetry is active
All-Cylindrical symmetry allows X and Y symmetry. Indeed, an All-Cylindrical circuit is always symmetric
respect X and Y since no offsets are allowed. Then, in the GUI, when the All-Cylindrical symmetry is activated
the X and Y symmetries are automatically activated as well.
Symmetries are used to discard unnecessary waveguide modes, so they allow using fewer modes which in turn results
in lower computational time.
If symmetries are added to a circuit, the following numeric parameters related to number of waveguide modes
should be reduced accordingly. In the following section aproximate rules are explained to easily modify the numeric
parameters.
Number of accessible Modes, Number of MoM basis functions, Number of green function terms.
If instead symmetries are removed from a circuit, the same numeric parameters should be increased accordingly.
The exact amount to increase or decrease these numeric parameters depends on the circuit and there is no general
formula. The following approximate rule can be used, but users are recommended to perform Convergence Study on
each circuit:
All-Inductive allows replacing all the number of modes with their square root
All-Capacitive allows replacing all the number of modes with the double of their square root
X symmetry allows dividing all the number of modes by 2 (exact rule)
Y symmetry allows dividing all the number of modes by 2 (exact rule)
All-Cylindrical allows replacing all the number of modes with the double of their square root
TEM allows replacing all the number of modes with the half of their square root
In order to specify a certain symmetry in a circuit, all elements in the circuit must allow such a symmetry. The
symmetries that are allowed by each element, can be found in Allowed Symmetries section
Global Parameters
Global symmetries and global circuit parameters can be configured from the general specifications window right tab.
The following global parameters are available. They are used as default values for parameters common to all
waveguides.
Dielectric Permittivity Relative permittivty constant of the homogeneous dielectric medium that fills the
waveguide (default: 1.0 i.e. vacuum).
Dielectric Permeability Relative permeability constant of the homogeneous dielectric medium that fills the
waveguide (default: 1.0 i.e. vacuum).
Dielectric Conductivity Intrinsic conductivity of the homogeneous dielectric medium that fills the waveguide,
in S/m (default: 0.0).
Metal Resistivity Intrinsic resistivity of the metallic walls of the waveguide, in Ohm · m (default: 0.0).
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Number of accessible Modes Number of accessible (i.e. connecting, propagating) modes of the waveguide.
Only the accessible modes of a waveguide are assumed to transmit E.M fields (and energy) across the whole
waveguide length. (default: 10).
Number of MoM basis functions Number of modes used in the internal MoM to calculate the discontinuities
attached to the waveguide (default: 30).
Number Green function terms Number of terms in the frequency-independent (static) part of the Green's
function, which describes the discontinuities attached to the waveguide (default: 300).
Number of Tailor expansion terms Number of terms in the Taylor expansion of the frequency-dependent
(dynamic) part of the Green's function, which describes the discontinuities attached to the waveguide (default:
1).
Reference port 3D Number of I/O port of the circuit used as a global reference coordinate system. See.
2.3.2.5 3D Viewer
This section describes the 3D Viewer integrated with Fest3D, documents its features and how to use it.
Features
The 3D Viewer window can be opened from the Fest3D GUI Main Window by clicking on the icon:  
3D Viewer
The 3D Viewer is a tool that allows the user to visualize a graphical 3D model of the circuit that is currently opened in
the Fest3D GUI. This 3D model is created as a SAT file that contains the different elements of the circuit, classified in 3
main groups:
Ports: A list of the intput/output surface ports of the circuit, sorted by ascending number.
Waveguides: A list of the waveguides of the circuit with the same names that appear in the canvas, sorted by
ascending number.
Discontinuities: A list of the discontinuities of the circuit with the same names that appear in the canvas,
sorted by ascending number. In addition, the internal details of discontinuities that belong to the coaxial library
and the helical resonators groups are also shown as independent geometries.
The user must also bear in mind that waveguides and discontinuities in the circuit whose geometry is not drawn
as a volume (for example Step discontintuities, or waveguides with length equal to zero) will be ommited from
the 3D model and therefore will not appear in the corresponding list.
A typical view of the 3D model is shown in the figure below:
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Interaction with the 3D View
This view shows the 3D model. Hovering with the mouse over this view will highlight elements that are currently
located under the mouse. Highlighted items in the 3D view are highlighted in the navigation pane as well.
The following mouse interaction is supported:
Holding the left mouse button down allows changing the perspective of the view. Depending on the currently
selected Mouse Mode , the view can be rotated, panned, or zoomed.
Clicking the right mouse button shows a context menu, which allows invoking the actions listed in the table
below.
Action
Description
Hide
Element
Mouse
Mode
Mouse
Mode >
Only appears if the mouse is placed on an element of the 3D model. Allows hiding that specific
element.
Sub menu to change the mouse interaction mode of the 3D view.
Rotate the 3D view.
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Description
Rotate the 3D view in the current view plane.
Move the 3D view.
Zoom the 3D view in and out.
Action
Rotate
Mouse
Mode >
Rotate in
Plane
Mouse
Mode > Pan
Mouse
Mode >
Zoom
View Mode
Sub menu to change the perspective of the 3D view.
Predefined perspective view.
Rotate the model to view its front face.
Rotate the model to view its back face.
Rotate the model to view its left face.
Rotate the model to view its right face.
Rotate the model to view its top face.
Rotate the model to view its bottom face.
Rotate the model to the nearest axis.
View Mode
>
Perspective
View Mode
> Front
View Mode
> Back
View Mode
> Left
View Mode
> Right
View Mode
> Top
View Mode
> Bottom
View Mode
> Nearest
Axis
Fit View
Zoom the current view to fit the 3D model.
Resize To
Sub menu to allow resizing the 3D view. Available resolutions are: 1920x1440 , 1200x900 , 1024x768 ,
800x600 , 640x480 , and 400x300 .
 In addition, the following keyboard interaction is supported:
Keyboard shortcuts:
Space : Fits the entire 3D model into the view.
0 : Change to perspective view.
1 : Change to perspective view.
2 , 3 , 4 , 5 , 6 , 8 : Change view to Bottom , Back , Left , Front , Right , Top
Navigation & Visualizing Model Internals
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The navigation pane shows a list of available elements in the loaded model. By default, a tree view is shown. If desired,
a flat list view is available as well through the context menu. When one or more elements are selected in the
navigation pane, the 3D view shows all deselected elements transparently. This way the user can visualize internal
details that are otherwise hidden. By default, the first input Port of the circuit will be always selected in the 3D View.
In addition, it is possible to hide elements. This can be done through the context menu by choosing Hide or Hide All .
The action Show All forces all elements to be visible again.
Toolbar Actions
The toolbar allows the user to quickly access the following actions:
Action
Description
Navigation
Show / hide the navigation pane.
Rotate
Switch mouse interaction to rotate the 3D view.
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Action
Description
Rotate in Plane
Switch mouse interaction to rotate the 3D view in the current view plane.
Pan
Zoom
Switch mouse interaction to move the 3D view.
Switch mouse interaction to zoom the 3D view in and out.
View Mode
Popup menu to change the perspective of the 3D view.
Fit View
Zoom the current view to fit the 3D model.
Save Picture
Save a picture of the 3D model as file.
Cutplane
If enabled, allows setting the cutplane through the 3D model along the x, y, and
z axes. The position of the cutplane can be set through either the edit field, or
the slider.
Help
Popup menu to access this documentation as well as the about dialog.
2.3.2.6 The Preferences Window
This section describes the Preferences Window and how to use it to customize and configure some parameters of
 Fest3D.
The preferences window look as in the following figure:
The parameters that can be configured are:
Create compare files if active, all the simulation results are saved also in the folder Compare inside the
installation directory of Fest3D. This allows comparing several results of the same or different circuits.
Enable cache system. This option is activated by default. When the cache system is activated, Fest3D  will
store, in disk , data that can be reused later on in the computations of next simulations. Fest3D automatically
identifies if there were elements analysed in previous simulations that are equal to elements in the current
simualtion, and loads their data from cache files avoiding to repeat certain computations. This may result on a
great CPU time saving. The files containing cache data are stored in the project folder, which is located in the
same folder as the input file with its same name. Thus, each Fest3D project will store and have access only to its
own cache data. Since these data may consume hundreds of MB, it is recommended to delete the cache files if
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not needed, or even deactivate
the cache system.
Number processors used : Independently of the number of logical cores available of the processor, the user
can select any number of logical cores to be used when resolving circuits.
Units (mm or inches) : Selects whether to use millimeters or inches when defining the circuit parameters.
Changing this will force to restart the program.
2.3.2.7 Parameters configuration
This section describes how to define parameters (Par) in the Fest3D user interface.
The use of parameters in a model has many advantages:
It allows the user to parametrize different properties in your model that might have the same value
or that might be related to other properties by means of mathematical expressions.
The parameters are used to perform an optimization procedure or a tolerance analysis.
The Par section contains the following topics:
How to define/set parameters
(parameters window)
Describes how to define parameters and set their expressions in the
parameters window
Using parameters to set Model
properties
Details how parameters can be used to set Model properties
How to define/set parameters (parameters window)
To add a new parameter, click on Add Parameter button. An empty parameter will appear. You can easily
introduce/modify the parameter:
Name, the name uniquely identifies the parameter (it is case sensitive). You may give any name you
want to the parameter. You only need to take into consideration that special characters are not
allowed, and some key words are reserved, such as some mathematical functions or Visual Basic
keywords
Expression, allows setting direct values or mathematical expressions which define the parameter
value or its relationship with other parameters.
Expression can contain trigonometric and other functions. In particular:
sin(x), the sine of x, x is in radians.
cos(x), the cosine of x, x is in radians.
tan(x), the tangent of x, x is in radians.
sinh(x), the hyperbolic　sine of x.
cosh(x), the hyperbolic　cosine of x.
tanh(x), the hyperbolic tangent of x.
log(x), the logarithm (base e).
exp(x), the exponential value of x.
sqrt(x), the square root of x.
abs(x), the absolute value of x.
Description, this is an optional field that may be used to make any annotation about the parameter.
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Any parameter, whose expression is a numerical value, can be selected to be used in the optimization procedure or in
the tolerance analysis.
The user can delete any parameter by clicking in the minus button at its right-hand side. When a parameter is deleted,
it will be replaced by its value in any expression in which it was being used.
Using the parameters configuration window
Once the parameters have been defined in the Parameter Window, they can be used to set any property of the Model.
To do so, one can directly use them in the desired element dialog window, or even use a mathematical expression as
shown in the following example:
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If the user inserts an undefined parameter to set a property, the parameter window will pop up automatically with the
undefined parameter already introduced.
2.3.2.8 Compare Results tool
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The "Compare Results" Tool is used for comparing output results of Fest3D. This can be very useful if, for instance, a
convergency analysis wants to be performed.
By default, this tool is deactivated in Fest3D. To activate it, go to Options -> Edit Preferences -> Preferences. The
following window should appear:
Activate the "Create compare files" by clicking in the corresponding box. Now, you can take a particular Fest3D input
file and run it. After that, modify the file a little bit (the geometry for instance) and run again the simulation. It is
important that the simulation arrives until the end of the frequency sweep. After this, please go to "Execute ->
Compare Results". A window like the following one should appear:
In this case, we chose to run a file called six_pole_triple_mode_w_losess.fest3. Fest3D has saved both simulations by
adding to the output file the date and time of the simulation. Now you can select both input files (for instance,
keeping pressed the "control" key) and press "open". The compare window will appear:
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It is seen that both results are compared. By defult, the comparison will show the Module (in dB) of the Scattering
Parameters of the all the ports of the circuit. The type of result (Phase, Group Delay, Module) and the number of
scattering parameters which are compared can be modified at any moment, as in the normal results window. Please,
notice that you can compare more than two results. Moreover, the Fest3D input file is also saved each time, so you
can recover the input file of a particular simulation. This is very useful while performing a convergence analysis.
2.3.3 Analysis
This section describes all the analysis capabilities that are present in Fest3D:
EMCE
Explanation of the Electromagnetic computational engine.
Adaptive Frequency
Sampling Method
Explanation of the Adaptive Frequency Sampling algorithm that allows speeding up
performance in frequency sweeps.
Engineering tools
Explanation of Engineering tools, a set of tools that helps you in the creation of your
project.
EM Field analysis
How to perform an EM Field analysis with Fest3D.
Convergence Study
How to perform a convergence study with Fest3D.
Parallelization
Explanation of parallelizaton of Fest3D and how to use it efficiently.
2.3.3.1 ElectroMagnetic Computational Engine (EMCE)
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This section describes the structure of Fest3D E.M. Engine (EMCE), documents its features and how it can be activated
from the User Interface and from the command prompt.
The EMCE section contains the following topics:
Features
Description of EMCE features and capabilities.
Using the
EMCE
How the EMCE can be activated and controlled from the User Interface or, in case you need, from
the command prompt.
Features
The EMCE supports passive, linear millimeter-wave and microwave devices, composed on cascaded waveguides and
discontinuities. The full list of the supported elements is available in the Elements Database.
Millimeter-wave and microwave circuits can be analyzed, obtaining insertion and transmission losses, as well as the
insertion phase, versus frequency. The results of the computation are displayed in graphic form and can also be
printed.
The multi-mode S, Z or Y matrix of such circuits can also be computed, effectively reducing a whole circuit to a single
block which can be then reused as a User Defined element in a more complex circuit or system, or imported from or
exported to other E.M. simulation tools.
Multimode Network Representation
The EMCE uses an equivalent multimode network representation, where each element is represented by a Z matrix.
This way, all computations are performed in a multimode space. By combining the Z matrices of all network elements
(waveguides and discontinuities), a new Z matrix representing the whole network can be created. The network
structure can be excited to calculate the scattering (S) or the Z matrix. All this is done for each point of the requested
frequency range. Thus, the EMCE produces as final result the scattering (S) or Z matrix at the input/output ports of the
network for each frequency point.
Frequency-independent and Frequency-dependent parts
Furthermore, for an efficient analysis, the computation of the Z matrix for complex structures like discontinuities,
where heavy calculations take place during the simulation, is divided into two parts: the frequency-independent
(static) and the frequency dependent (dynamic) parts. This is possible since the splitting is used also in the Integral
Equation approach: the used integral equation is based on a kernel which has been split into these two parts. Fest3D
EMCE first initialises all the network elements using the algorithms that do not depend on the frequency. This is done
outside the frequency loop and the computed quantities are also stored in cache files, to allow reusing them in
subsequent runs. After that, the EMCE enters the frequency loop where the frequency-dependent part is computed
and combined with the frequency independent one, obtaining the Z matrix at each frequency point.
Using the EMCE
The EMCE is completely integrated with the Graphical User Interface. Starting the EMCE is just a matter of clicking on
the Analyze button in the Main Window, watch the progress messages, and look at the plot produced at the end of
the simulation. Clicking on the Stop button in the Main Window will interrupt the simulation.
Almost surely, you will want to open the General Specifications window to edit the analysis specification data:
frequency range, symmetries, global numeric parameters, etc. Refer to EMCE code documentation in order to have a
detailed description of each parameter.
The Simulation Output window automatically opens when a simulation is running, and progress is reported in real
time. If errors are detected during the simulation, a diagnostic message is produced in the Simulation Output window.
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The scattering (S) matrix is stored in a file with the same name as the input file and with .out extension. The result of Z
matrix computation is written in a file with the same name as the input file but with .chr extension. Both .out and .chr
files are saved in the same directory as the input file.
2.3.3.2 Adaptive Frequency Sampling Method
This section explains the adaptive analysis method, how it is configured and provides key points to maximize the
efficiency of the analysis.
The adaptive sampling [1] is a method used to reduce the number of simulated points (reducing thus the
computational time) without losing accuracy in the simulated response. The reduction is possible because the
response in a broad frequency range (or angle, depending of the sweep variable) is approximated by a rational
function using a reduced set of points. These points are found automatically by the method by comparing consecutive
approximations.
In order to perform an adaptive analysis of a sweep, the option "Adaptive"  in the column Algorithm must
be selected.
Note 1: The adaptive sweep only works for sweeps with more than 5 points.
Example using discrete and adaptive algorithms
This section shows the difference between the discrete and adaptive algorithms in terms of computational time and S
parameters results.
Let's consider the following band-pass filter (from the list of examples in Fest3D):
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In a particular computer, the resolution of the 100 frequency points takes (only the simulation time in the frequency
loop is considered):
Discrete method: 4 seconds
Adaptive sampling: 0.9 seconds
The S parameters perfectly match in both cases, as shown in the following figure, where one can verify that the results
are virtually the same.
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How adaptive sampling works
The steps followed by the method are:
Step 1: The method starts by developing two rational approximations of each scattering parameter, one
with 2 support points and one with 3 support points. The approximation with 2 support points uses the
start point and the end point of the sweep. The approximation with 3 support points add a new point in
the middle of the sweep to the previous ones.
Step  2:  An  error  curve  between  approximations  is  calculated  using  the  approximations  with  2  and  3
support points of each scattering parameter.
Step  3:  An  error  value  is  calculated  from  the  error  curve.  This  error  term  tends  to  cero  when  the
difference between approximations decreases. In other words, when the approximation converges to a
final response.
Step 4: A new point is selected in the maximum of the error curve. By using this point and the previous
points, a new approximation is done. The error curve is updated, and the new error is also determined.
Step 5: The step 4 is repeated until the error value is lower than a threshold value selected by the user
during three consecutive steps. 
Efficiency of the adaptive sampling
The error quantifies the variations between consecutive approximations and is normalized to 1, therefore the value of
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0.001 for Max error means that the final response has converged and stays stable, because the variations between the
latest approximations in the whole range are less than 0.1%.
The cost of the rational approximation is independent of the circuit and increases with the number of iterations. This
cost  depends  of  the  number  of  points  of  the  sweep  (Figure  1)  and  the  number  of  parameters  used  in  the  internal
calculations (Figure 2). In addition, increasing the number of threads used reduces significantly the time of the rational
interpolation (Figure 3).
If  the  cost  of  performing  each  rational  approximation  remains  negligible  with  respect  to  the  cost  of  each
electromagnetic simulation, the time saving will be related directly with the number of points which are not calculated
but interpolated.
If  many  iterations  are  needed  to  converge  to  the  final  response  (for  example  in  complex  circuits  as  multiplexers  or
multiband filters), it is recommended to divide the sweep in several smaller sweeps. This can accelerate the simulation.
As mentioned before, the number of S parameters which are taken to determine the error affects significantly to the
time savings. In most circuits, just by enabling the parameter S11 is enough to guarantee a right convergence. This is
typical in a bandpass filter (in a bandstop filter it is better choosing S21 to calculate the error).
In  complex  circuits,  it  may  be  interesting  to  add  to  the  S11  any  significant  S  parameter  in  the  particular  range  of
analysis.
Figure 1: Evolution of the cost of the rational approximation with respect to the points of the sweep (1 S-parameter
and 1 thread).
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Figure 2: Evolution of the cost of the rational approximation with respect to the number of scattering parameters
(sweep with 500 points and 1 thread).
Figure 3: Evolution of the the cost of the rational approximation with respect to the number of threads (sweep with
500 points and 1 S-parameter).
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2.3.3.3 Engineering tools
The Engineering Tools are a collection of useful tools for general Electromagnetic Design.
These tools, based on analytical formulas [N. Marcuvitz, Waveguide Handbook, New York: McGraw-Hill Book Co.
1951] & [G. L. Matthaei, L. Young, and E. M.T. Jones, Microwave Filters, Impedance-Matching Networks and coupling
Structures, New York: McGraw-Hill Book Co., 1964], help the user in the process of designing a passive component
e.g. quality factor, constant of propagation, sorting of modes, manufacturing tolerances and so on.
The Engineering Tools are activated through clicking the Tools->Engineering Tools menu on the GUI menu bar.
Fig.1. GUI menu for the Engineering Tools
Next, the different Engineering Tools are described. As will be seen, they are easy to use, giving a nearly instantaneous
output.
(M,N) Modes Propagation in RectWG
This tool provides the propagation constant of the propagating modes and losses under cut-off for a given length in a
rectangular waveguide.
Fig. 2. shows its GUI, composed of the following input parameters:
Width of the Rectangular Waveguide [mm]
Height of the Rectangular Waveguide [mm]
Length of the Rectangular Waveguide [mm]
Operating Frequency [GHz]
Maximum M for the (M,N) modes list
Maximum N for the (M,N) modes list
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Fig. 2. GUI for the (M,N) Modes Propagation in RectWG Engineering Tool
Once all the parameters are specified, the output (Fig. 3) sorts the propagating modes in the waveguide together with
the propagation constant and losses in dB.  Alpha is given as a negative number and Beta as positive.
Fig 3. Results given by the (3,3) Modes Propagation in RectWG Engineering Tool
Resonances in Cylindrical Resonator
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This Engineering Tool gives the resonances of a cylindrical resonator according its dimensions. The list of Input
parameters are:
Diameter of the cylindrical resonator [mm]
Length of the cylindrical resonator [mm]
Reduction factor for the unloaded Quality Factor [0-1]
Maximum M for the (M,N,P) modes sorting
Maximum N for the (M,N,P) modes sorting
Maximum P for the (M,N,P) modes sorting
Conductivity [Siemens/m]-->Introduced by the user or selected by default (Fig. 4)
Fig. 4. GUI for Resonances in Cylindrical Resonator Engineering Tool
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Its output sorts the modes in the cylindrical resonator according to its frequency, together with its unloaded and
reduced / practical Quality Factor (Fig. 5).
Fig. 5. Results given by the (3,3,3) Resonances in Cylindrical Resonator Engineering Tool
Resonances in Rectangular Resonator
It gives the resonances for a rectangular resonator according its dimensions. Similarly to the cylindrical resonator, here
are the requested specifications:
Width of the rectangular resonator [mm]
Height of the rectangular resonator [mm]
Length of the cylindrical resonator [mm]
Resonance frequency [GHz] or length [mm] of the rectangular resonator
Reduction factor for the unloaded Quality Factor [0-1]
Maximum M for the (M,N,P) modes sorting
Maximum N for the (M,N,P) modes sorting
Maximum P for the (M,N,P) modes sorting
Conductivity [Siemens/m]-->Introduced by the user or selected by default
The selection between the resonance frequency or the length of the rectangular resonator is up to the user (Fig. 6). If
the resonance frequency is selected, the different modes with the required length are shown (Fig. 7); on the other
hand, by filling in the length of the rectangular resonator, the different modes are sorted as seen in Fig. 5.
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Fig. 6. GUI for Resonances in Rectangular Resonator Enginnering Tool
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Fig. 7. Lengths given by the (3,3,3) Resonances in Rectangular Resonator Tool (geometry fixed)
Q values at 3 dB Bandwidth in Resonators
This Engineering Tool calculates the loaded, unloaded and external Quality Factor, requiring for such a calculation the
following parameters (Fig. 8) :
Insertion Loss [dB]
Center Frequency [GHz]
3dB Bandwidth [MHz]
Fig. 8. Input Parameters for the Q values at 3dB Bandwidth in Resonators tool
Please note that, as specified in the output (Fig. 9), a symmetric coupling input-output is assumed for the calculations.
The formulas to calculate all the Quality Factors are also described in order to avoid the user's confusion.
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Fig. 9. Quality Factors calculated by the Engineering Tool
Losses in CoaxWg
The Input parameters are:
Dielectric Permittivity
Operating Frequency [GHz]
Conductivity for inner conductor [Siemens/m]
Conductivity for outer conductor [Siemens/m]
Tan delta of permittivity * Dimensions of the outer conductor [mm]
Diameter of the inner conductor [mm]
It is possible to choose the outer conductor between a squared or coaxial waveguide as seen in Fig. 10. The tan of
delta is used for the losses calculation.
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Fig. 10. Input parameters for the Losses in CoaxWg Tool
As seen in the output (Fig. 11), not only the losses but also the Impedance and the 1st higher order mode are
calculated, all of them with their corresponding units.
Fig. 11. Output given by the Losses in CoaxWg Tool
Losses in RectWg
This Engineering Tool calculates the losses in a Rectangular Waveguide. The user has to fill in the following
parameters (Fig. 12) :
Dielectric Permittivity
Working Frequency [GHz]
Width of the Rectangular Waveguide [mm]
Height of the Rectangular Waveguide [mm]
Length of the Rectangular Waveguide [mm]
Tan delta of permittivity
Conductivity [Siemens/m]-->Introduced by the user or selected by default
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In this case, the output produced gives more specific information regarding the losses in the rectangular waveguide
(Fig. 13), separating the losses by conductivity and permittivity. Note that when tan delta is zero, there are no losses
by permittivity. The skin depth is provided in the output as well.
Fig. 12. Losses in RectWg Engineering Tool input
Fig. 13. Losses in RectWg Engineering Tool output
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Losses in CircWg
Similarly to the previous Engineering Tool, the input (Fig. 14) requested is:
Dielectric Permittivity
Operating Frequency [GHz]
Diameter of the Circular Waveguide [mm]
Length of the Circular Waveguide [mm]
Tan delta of permittivity
Conductivity [Siemens/m]-->Introduced by the user or selected by default
Fig. 14. Losses in CircWg Engineering Tool input
The produced output is similaro to the one for the Losses in RectWg Tool (Fig. 13).
Tolerance of Chebycheff filters
This Engineering Tool gives the manufacturing tolerances for a Chebycheff band pass filter. Therefore, the input
parameters are:
Degree of the filter
Return loss [dB]
Center frequency [GHz]
Bandwidth [MHz]
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Fig. 15. Tolerance of Chebycheff filters Tool
The output, given in micrometers, is depicted below in Fig. 16.
Fig. 16. Tolerance of Chebycheff filters output
Insertion Loss
This Engineering Tool calculates the Insertion Loss for a band pass filter given the following specifications:
Degree of the filter
Return loss [dB]
Center frequency [GHz]
Bandwidth [MHz]
Unloaded Quality Factor
The GUI for the input parameters and its output are shown in Fig. 17 and 18, respectively:
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Fig. 17. Insertion Loss Tool input
VSWR <> S11 <> RefCoef <> Ripple
Fig. 18. Insertion Loss Tool output
This Engineering Tool differs from the previous ones because instead of giving an output, it shows the relationship
among the following parameters:
VSWR (Voltage Standing Wave Ratio)
S11 / Return loss [dB]
Reflection Coefficient
S21 / Ripple [dB]
When the user changes one of the parameters and presses Enter, the rest of values are automatically updated
according to the new specification provided. Fig. 19 shows an example, where VSWR, Reflect. Coef. and S21/Ripple
have been changed automatically once the user has introduced the new value for S11/Return Loss (i.e. S11 = 30 dB).
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Fig. 19. VSWR<>S11<>RefCoef<>Ripple Tool
dB Transformation
This Engineering Tool, like the previously seen WG Dimensions Tool in the GUI of Fest3D (Fig. 1), is composed of two
submenus: W<>dBm<>dBW<>dBc and dB<>Np<>Abs tools.
W<>dBm<>dBW<>dBc
As in the VSWR<>S11<>RefCoef<>Ripple tool, this tool gives the relationship among the following
parameters seen in Fig. 20:
Watts [W]
dBm
dBW
dBc and carrier [W]
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Fig. 20. The W<>dBm<>dBW<>dBc Tool
In Fig. 20 the power in Watts has been changed to 40Watts, changing the rest of the parameters once Enter
has been pressed.
dB<>Np<>Abs
This tool follows the same approach but considering the following units (Fig. 21):
Decibel [dB]
Neper [Np]
Absolute value
WG Dimensions
Fig. 21. The dB<>Np<>Abs Engineering Tool
These tool gives the waveguide dimensions for either a rectangular or circular waveguide according the established
standard waveguides. As the dB transformation Tool, it is composed of two submenus depending on the type of
waveguide.
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Fig. 22 GUI for the RectWG standard dimensions tool
RectWG standard dimensions As seen in Fig. 22, the user selects the type of waveguide among all the list of
standard waveguides. Once this action is performed, the fields corresponding to the dimensions and frequency
range are updated.
CircWG standard dimensions It follows the same approach seen in the last point, but in this case for a circular
waveguide (Fig. 23):
Fig. 23 GUI for the CircWG standard dimensions tool
2.3.3.4 EM Field Analysis
The EM field analysis section contains the following topics:
Definition
Limitations
Errors
What is exactly done when using this Fest3D feature.
What are the limitations you should be aware of.
The possible errors produced when computing the EM fields, and solutions or
workarounds to them.
Using the EM field
computation
How to use this feature in Fest3D from the User Interface or, in case you need, from the
command prompt.
Visualization of EM fields How are the EM fields visualized in Fest3D.
Hints
Non-trivial properties of the computation of the EM field.
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Definition
The EM field analysis computes the electromagnetic fields inside components. The structure is always excited with an
average input power of 1 W. The fields are given in peak values.
Limitations
The EM field analysis can be used in components based on rectangular, circular, coaxial, rectangular-arbitrary and
circular-arbitrary waveguide elements. Most of the discontinuity elements which have 3D volume can perform EM
field computations as well. If a particular circuit contains elements which are not supported, the EM fields will not be
calculated on those specific elements, but only on the supported ones.
In the case that the circuit contains lumped elements, the EM field can not be computed.
Errors
No errors are reported for this feature.
Usage
Before starting  the EM field analsyis, it is recommended to set-up in first place the specifications for this analysis. This
is done by pressing the EM button (
) on the toolbar, which opens the Configure Field Monitors window:
In this window, the following settings can be controlled:
Excitation signals
Each excitation signal contains the frequency value in GHz at which the EM fields will be computed. At least
one excitation signal must be defined in order to perform the EM field analysis.
There is no limit to the number of signals that can be defined in the window, and the EM Field analysis will
consider all of them. Including different signals is useful for monitoring the behaviour of the EM fields at
different frequencies, or use the results for multicarrier analysis when performing Multipactor analysis with
Spark3D.
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Remark: The frequency of each signal must be contained within the range of the analysis bands defined in the
Frequency Specifications window. 
Compute whole circuit
By activating this checkbox (default option), the EM fields shall be computed in the whole device, when
launching the EM field analysis.
Remark: If this checkbox is not selected, then one or more Elements must be selected individually for EM field
analysis in the properties window corresponding to the desired elements. This is done by activating the
"Selected for EM Field Analysis" checkbox as shown in the figure:
Individual selection of elements can be useful  in order to speed up calculations by just focusing in some areas
of interest, without the need of meshing and computing fields for the rest of the geometry.
Mesh size
This parameter allows the user to control the general resolution of the electromagnetic field. This value
represents the mesh size in mm or inches used to generate a second order element mesh of the
geometry containing all selected elements in the circuit. Values must be greater than 0. The default value is 1.
It is also possible to override the mesh size value for a specific element by clicking on the EM Field tab on the
element properties window. In the next figure it is shown how to change the value:
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Remark: Care should be taken when increasing the resolution. As a rule of thumb: reducing the mesh size by a
factor of 2 increases, in general, the number of sampling points in each direction by a factor of 2. For a 3D
representation the number of sampling points thus increases approximately by a factor of 23=8.
Once the specifications for the EM field analysis have been confirmed, the computations are performed by clicking on
) on the toolbar. Alternatively, the same action can be performed by selecting Execute -> EM Field
the button (
Analysis in the menu bar, or pressing the shortcut key "E".  The EM fields will be computed and visualized
automatically at the end of calculations. In case that the there are previous results for the EM fields and no changes
have been applied to the circuit, the computations will be skipped and the results will be visualized directly.    
Output data
The calculation provides the following vectorial quantities in the complete volume of all elements:
Mag(Max_E) (V/m) In time domain, the maximum value of the magnitude of the electric field in a period.
Mag(Max_H) (A/m) In time domain, the maximum value of the magnitude of the magnetic field in a period.
Max_E (V/m) In time domain, the maximum value of electric field in a period.
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Max_H (A/m) In time domain, the maximum value of magnetic field in a period.
S_re (V*A/m2) In frequency domain, the real part of (1/2)*(E x H).
S_im (V*A/m2) In frequency domain, the imaginary part of (1/2)*(E x H).
E_re (V/m) In frequency domain, the real part of the electric field.
E_im (V/m) In frequency domain, the imaginary part of the electric field.
H_re (A/m) In frequency domain, the real part of the magnetic field.
H_im (A/m) In frequency domain, the imaginary part of the magnetic field.
Running EM Field Analysis from command prompt
It is also possible to execute the EM Field Analysis from command prompt. The executable name is fest3d.exe on
Windows platform and fest3d on Unix-like platforms, and is located in the directory where Fest3D is installed.
Executing the command fest3d -h (prefixed by Fest3D installation directory if necessary) will show all command-line
arguments and options supported by the EMCE, including how to specify input and output files. A typical invocation
of the EM Field Analysis looks as follows:
<full-path-to-fest3d/fest3d.exe> --action=computFields --input=<full-path-to-working-
directory\mycircuit.fest3x> --nthreads=number-of-cores-to-use
If any of the paths and/or names contain spaces, you should add double quotes. IE: --input="C:\path with spaces\my
Circuit.fest3x"
Visualization
The 3D quaintites explained in the Output Data section are visualized by means of Paraview. This software is
automatically launched when the button (
The structure appears in the main canvas. The 3D geometry selected for the analsyis will be shown for each one of the
excitation signals that have been defined. The geometry can be rotated with the left mouse button. The quantity to be
visualized (Magnitude of E-field by default) can be  selected in the top left side combobox. The scalar bar is activated
pressing the button situated in the left side of the previous combobox.
) is pressed.
Paraview allows you to perform many operations on the data you are plotting.  By default, 3 predefined 2D cuts
(central XY, XZ and YZ planes) are automatically included by Fest3D for each excitation signal.
See the EM field tutorial for more information about visualization.
Hints
It is important to take into account that:
For any circuit, the computational cost of EM field analysis is usually greater than the computational
cost of S-parameter analysis, specially if the circuit contains complex elements like cavities with resonators.
This computational cost depends strongly on the total number of points of the second-order mesh generated
for the 3D geometry containing  elements selected for the analysis.
The computational cost of the EM field analysis also has a linear dependency with the the number of
excitation signals. That is, for a particular circuit, the time required for computing one signal will be multiplied
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by the total number of existing signals.
In order to avoid unnecessarily slow simulation times for EM field analysis, a trade-off should  be considered
between the number of elements selected for the computations (the total geometry that will be meshed), the value
of the mesh size (resolution of the mesh), and the number of signals defined for the analysis (the times that
computations will be applied for each point in that mesh). This trade-off will depend on each particular circuit.
2.3.3.5 Convergence Study
This section explains in detail the procedure to be followed in performing convergence studies. Such a convergence
study consists of several steps, which require changing all the numeric accuracy parameters involved in the Integral
equation technique used in Fest3D, as explained below:
1.  Number of accessible modes. To fix the optimum value of this parameter, we must start our study with a very
reduced number of accessible modes (i.e. 5), and moderate values for the remaining parameters (i.e. 200 basis
functions, 1000 Green function terms). To proceed, we must increase the number of accessible modes and see
the evolution of the simulated response. If such response does not change, it means that the initial value for
the number of accessible modes already provides convergent results, and then we must move to the next step,
tuning the Number MoM basis functions. On the contrary, if the simulated response changes, it means the
convergence has not been reached, and it will be required to increase the number of accessible modes (in
steps of 5 to 10 additional accessible modes) until the response is fixed (i.e. no longer changes).
2.  Number of MoM basis functions. To fix this parameter value, the user must always employ the number of
accessible modes determined before, and fix the number of Green function terms to 1000. With regard to the
initial number of MoM basis functions to be considered, it will be set to the previously selected number of
accessible modes plus 1, with a minimum of 20. Then, we will run the software to obtain an initial response.
Since the initial number of MoM basis functions is very low, this number will have to be increased (for instance
in steps of 10 to 20 each time) and the new response will be computed. If no changes between both responses
is observed, we can fix the number of basis functions and proceed to the next step (Number of Green
function terms). If the responses are different, we must continue increasing the number of MoM basis
functions until convergence is reached. It can happen that convergence is never reached even when the
maximum number of basis functions allowed is used (the maximum is number of Green function terms minus
one). In such a case, the number of Green function terms must be increased and the whole procedure for fixing
the optimum number of MoM basis functions must be repeated.
3.  Number of Green function terms (also named Number of kernel terms). The third parameter to be fixed is
the number of Green function terms. To proceed, the number of accessible modes and MoM basis functions
will be fixed to the optimum values already determined, and the initial value for the number of Green function
terms will be the same employed in the previous step (i.e. 1000). In this case, the convergence analysis is
performed in the following way: starting from the initial value for the number of Green function terms, it will be
reduced (in steps of 100 to 200 terms each time) until the simulated response starts to change. The optimum
value for this parameter is the previous one before the response has moved. It can happen that the response is
moved with the first reduction of the number of Green function terms. In such a case, the initial number of
Green function terms considered must be increased, and the convergence study must return to the step 2
(adjustment of the Number of MoM basis functions).
Once these convergence studies are finished, it is recommended to compare the responses provided by Fest3D using
the optimum values just determined and employing extremely high values each parameter (much higher than the
optimum values found). If both results are very similar, it is guaranteed that the convergence study has provided
optimum values that can be used in the next simulations of the structure under consideration.
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2.3.3.6 Fest3D Parallelization
Many computations in Fest3D can run in more than one processor simultaneously. In the following, it is explained how
this multi-threading feature works.
The parallelization section contains the following topics:
Enabling multicore simulations
How to switch on the multicore mode.
How it works
Special elements
Nested parallelism
Known limitations
How it works
Description about how Fest3D runs in parallel.
Notes about special elements and parallelization.
Elements which can use more than one thread.
Problems that can happen during a parallel simulation.
Switching on the multicore option can be done in the combo box located at the top-right corner of the Main Window
, selecting the number of the threads wanted between one and the maximum of physical cores. By
default, the number of cores for simulations will be chosen as the maximum value between one and the total number
of cores detected in the machine minus one.
Nested parallelism
In Fest3D, all computations are divided in a static part (frequency independent) and in a dynamic part (frequency
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dependent). The parallelization applies to both parts in a different way.
Static part
Fest3D without parallelism computes each element separately one after another. The total time taken to finish this
part is the addition of the time needed to compute each element. When more of one core is selected, each waveguide
or discontinuity is assigned to a core if idle. Therefore, each thread solves the associated element it and waits for a
new element to be solved. If there are no more elements, it will wait (suspended) to the frequency dependent part.
There are some dependencies between elements in Fest3D. For example, a discontinuity cannot be computed until its
attached waveguides are solved, or if an element is equal to another (from network), the original one has to be
computed first.
Time estimations here are difficult. On an hypothetical circuit in which all elements take a similar amount of time and
the number of elements is multiple of the cores used, the computational time will be approximately the time needed
in sequential mode divided by the number of threads. This is, of course, the optimum case. However, if an element is
very slow compared to the rest of the elements in the circuit, the computational time shall be similar to the sequential
case.
Besides, some elements have nested parallelism inside them. In other words, the solution of the element (its static
part) can be solved also in parallel. See the nested parallelism section for more information.
Dynamic part
In this part, for each frequency, the generalized impedance (Z) matrices of each element are computed in
parallel, similarly as done in the static part. But the total number of cores used for this task will not be the one
specified at input. Instead, this number will be fixed to an optimum value depending on the specific circuit. 
However, despite this parallelization the solution of the resulting system of equations (which is built by putting
together all Z matrices) is solved in sequential. In some case, it is possible that the Z matrices are solved very fast and
then the multi-threading leads to a small slow down of the simulation. It is also possible that, if the circuit is too big
and/or has many bifurcations, the frequency part is not significantly accelerated since the solution of the system of
equations takes the longest time.
Additionally, in case that a frequency sweep is solved using the Adaptive Frequency Sampling algorithm, the rational
interpolation performed for the parameters not selected for optimization is also computed in parallel using all
available cores.
Nested parallelism
These are the elements that can use more than one thread simultaneously during their own solution.
Waveguides based on the arbitrary circular/rectangular waveguides.
TE and TM modes are calculated in different cores if possible.
Constant width/height library
TE and TM modes are calculated in different cores if possible.
Coaxial cavity library
In the coaxial cavity library elements multicore is used to speed up the building of complex full matrices employed in
the electromagnetic kernel.
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EM Fields
The Field analysis has an additional issue related to parallelism. The use of external tools that are not "thread-safe"
forces Fest3D to run them in sequential, loosing performance. In other words, the mesh generation cannot be done in
parallel. Everything else runs concurrently, just like during an S-parameter analysis.
Known limitations
Computer overload
It is highly recommended not to select the maximum number of cores unless the computer is going to be used mainly
for the Fest3D simulation because it can slow down other actions to be done in the computer. Also, if you are running
heavy simulations with other (or even Fest3D) software tools at the same time, the parallelism can be seriously
affected and the simulation time can be even larger than with just one processor. It is recommended in such a case to
reduce the number of threads to be used.
RAM use
Fest3D usually requires more RAM in parallel mode than in sequential mode. The same simulation that works in
sequential can fail with several cores if there is not enough memory available. As a consequence, slowdowns in the
computer may occur if the circuit contains several different high memory-consuming elements such as those present
in the coaxial cavity library.
2.3.4 Design
This section describes the optimizer and tolerance analysis that are typically used to design circuits:
Optimizer 
Explanation of Fest3D optimizer and the methods available
Tolerance analysis 
Explanation of the Tolerance analysis tool
2.3.4.1 Optimizer (OPT)
This section describes the structure of Fest3D Optimizer (OPT), documents its features and how to configure,
interactively execute and monitor it from the User Interface and from the command prompt.
The OPT section contains the following topics:
Features
Description of OPT features and capabilities.
Using the
OPT
How to configure, interactively execute and monitor the OPT from the User Interface or, in case you
need, from the command prompt.
Features
The OPT is completely integrated with the GUI and allows the user to interactively access all functionalities using
mouse, canvas and dialogs:
Define parameters
Choose which parameters to optimize
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Define expressions, goal functions and constraints
Choose and configure the optimization algorithm
Start, monitor, stop, resume the optimization algorithm
Manually change the parameters and run the EMCE or OPT with the modified values.
The OPT currently includes the following three algorithms:
Simplex
Powell
Gradient
Using the OPT
A step-by-step guide to use Fest3D OPT is also available in the Tutorial 5. Optimizer section of this manual.
Performing a circuit optimization with Fest3D OPT can be divided in four steps:
1.  Choose which parameters to optimize In the left side of each parameter there is a button that indicates if the
parameter is selected to be optimized. Click on it to activate (green color) or deactivate (red color) its
corresponding parameter. Only parameters whose expressions are a number and are used to set a model
property, can be chosen to be optimized. Parameters whose expression are a mathematical expression are not
eligible to optimize, for this reason the button is directly crossed out. By default, all optimizable parameters are
deactivated.
2.  Define expressions, goal functions and constraints Open the Optimization Window from the Execute
menu or from the corresponding button (
parameter's label. Create and enter constraints as you need in the Constraints tab. Create Goal Functions with
the Add Goal Functions button, choose a goal function file (or enter a non-existing file name) and create or
edit its contents with the Goal Functions Editor. Choose which circuit S parameters to compare with which
goal function S parameters with the Sxy and Compare buttons. Change the Weight as you need.
) in the Toolbar. Enter expressions as you need near each
3.  Choose and configure the algorithm Click on the Algorithm button on the bottom to select the algorithm
among the allowed ones and configure it. Currently supported algorithms are Simplex, Powell and Gradient.
4.  Start, monitor, stop, resume the optimization algorithm To start the optimization click on the PLAY button
(
). The parameters values, iteration count and error function will be updated in real time. If Auto Plot in the
main window Graphics menu is active, the graphic plot of the circuit analysis results will be updated in real time
too. The optimization stops when the algorithm finds a (possible) minimum, or the error function reaches the
target error, or the maximum number of iterations is reached. You can also stop it in any moment by clicking
). In all cases, clicking on the Apply parameter changes button, you can apply to the
on the Stop button (
current circuit the values of optimization parameters obtained during the last optimization loop. At any
moment that optimization is not running, you can modify the optimization parameter expressions, constraints,
goal functions and algorithm.
The Fest3D Optimization Window typically looks as follows
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Parameters
The upper part of the window contains the parameters to optimize, which can be configured and edited in the same
way as can be done in the Parameters configuration  (
). Each parameter is defined by the following:
Name, the name uniquely identifying the parameter, it is case sensitive. You may give any name you want to
the parameter. You only need to take into consideration that special characters are not allowed, and some key
words are reserved, such as some mathematical functions or Visual Basic keywords.
Expression allows setting direct values or mathematical expressions which define the parameter value or its
relationship with other parameters.
Expression can contain trigonometric and other functions. In particular:
sin(x), the sine of x, x is in radians.
cos(x), the cosine of x, x is in radians.
tan(x), the tangent of x, x is in radians.
sinh(x), the hyperbolic sine of x.
cosh(x), the hyperbolic cosine of x.
tanh(x), the hyperbolic tangent of x.
log(x), the logarithm (base e).
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exp(x), the exponential value of x.
sqrt(x), the square root of x.
abs(x), the absolute value of x.
Description, this is an optional field that may be used to make any annotation about the parameter.
opt button indicates if a parameter is eligible for optimization. It allows temporarily disabling the parameter　
for the　optimizer by clicking　on the box. The color will be turned to red, indicating that the parameter will not
be changed: its value will remain fixed. Clicking again re-enables the parameter and the color will turn back to
green. On the other hand, in cases in which　a parameter is not defined as a numerical value, opt will be
marked as crossed out, meaning that　such parameter will not be considered for direct modification by the
optimizer tool　(but the parameter value may be modified indirectly in optimization steps if its expression
depends on other parameters which are optimized).
The current, previous, delta and initial values of the parameter. Delta value is the difference between the
current and the initial value, not between the current and previous value. The current value can be directly
edited by changing the expression tab, provided that optimization is not running
Goal Functions
The lower part of the window contains the goal functions and constraints. The error function is computed by adding
together all the contributions of the goal functions and constraints.
Each goal function is defined by the following:
Enable/disable checkbox (selected by default) allows the user to disable/enable the goal function by clicking
on it. If disabled, the goal function will be ignored by the optimizer.
Circuit Sxy parameter to be tuned, taken from S-Parameters of the current circuit. By clicking on the button, a
window similar to this one will appear:
The user can choose which part of the Sxy to consider: Module (dB), Phase (Radians) or G.D. (Group Delay).
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Equality or inequality that circuit Sxy parameter should satisfy with respect to goal Sxy parameters. Available
settings are = (equal), <= (lesser or equal) and >= (greater or equal).
= means the goal is to find a curve equal to the goal function
<= means the goal is to find a curve lower or equal than the goal function
>= means the goal is to find a curve higher or equal than the goal function.
Weight is the relative weight of this goal with respect to the other goals and constraints. It can be any number
greater than or equal to zero. The contribution of each goal function to the error function is normalized (i.e.
divided) by the number of points it contains, and multiplied by the weight
Edit This button will open the Optimization Mask window, in which the corresponding mask settings can be
modified.
Mask name This chart allows defining the name of the goal function that will be shown in the results plot while
the Optimizer is running. If the mask is exported to a text file, the file will have this name as well.
Target This chart shows a summary of the target values applied to the mask of the corresponding goal. It can
be modified by editing the goal in the Optimization mask window.
Range This chart shows a summary of the range of frequencies considered by the mask of the corresponding
goal. It can be modified by editing the goal in the Optimization mask window
Num. Points This chart shows the number of points used for the mask of the corresponding goal. It can be
modified by editing the mask in the Optimization mask window.
Discrete/Adaptive These radio buttons are used for indicating if Fest3D will compute the frequency sweep
associated to this goal using the discrete or adaptive algorithm. In case of selecting the adaptive algorithn, the
Config button allows the user to configure the corresponding options, as done in the frequency sweeps
window
Delete button This button removes the corresponding goal function from the Optimizer window
Optimization mask window
When clicking on the Add Goal Function button, or when editing an existing goal by clicking on the corresponding
Edit button, the Optimization mask window will pop up:
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This window allows the user to define/modify a mask of frequency points on which to indicate the desired target
values to be matched according to the Equality or inequality that is defined for the goal. Each mask will define a
frequency sweep in Fest3D circuit which will be used to compute the S-Parameters on the points indicated by the
mask. The average of the square of the differences betweeen the S-Parameters and the target value will be multiplied
by the weight to compute the contribution of this goal function to the error function.
There are two possible ways of creating a mask:
Constant mask (selected by default for a new goal function). This option is the easiest way to create a mask
with a constant target value for a given range of frequencies. The number of points within the range is also
specified. This number of points will be the one used to compute the error function of this goal. By default, this
mask contains a proposed range of frequencies which considers all the Frequency sweeps defined for the
current Fest3D circuit.
Arbitrary mask. This option is used for creating a mask with different target values depending on the
frequency points.
An arbitrary mask can be created in two ways:
1.  By clicking on the Import mask file button, which allows loading an existing data file. The file must be a
text file that contains tabulated data including frequency points and the target values to consider. In
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case that the file contains more than two columns of data (for example, if a Fest3D ouput file is used
as reference for creating a mask), then all the data of the file will be displayed. The user must select
which column will be used as target, either by clicking on the desired column tab, or specifying the
columnn number in the selector shown at the bottom, as shown in the red-marked squares in the
example picture below.
2.  By defining a customized spreadsheet table using the built-in editor of the window:
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With this editor:
You can specify the number of rows of the table by indicating the Number of frequency points
and clicking on Apply. 10 rows are proposed by default.
You can add more rows individually by clilcking on the Insert button. 
You can manually edit the values for frequency and target for each cell.
You can remove multiple rows/columns at once by selecting them and clicking on the Remove
button.
You can create linear progressions (or, as particular case, repetitions of a constant value) as follows:
1.  Type the initial value of the progression in a cell and type the final value in another cell of the
same column.
2.  Select with the mouse all the cells between the initial and final value (remember to also select the
cells containing initial and final value).
3.  Click on the Linearize button.
If you select two columns, Linearize acts on both of theml.
The data of the arbitrary mask can be exported into a text file by clicking on Export mask file button. This
allows reusing the data of a particular mask for example when defining other goal functions, and clicking on
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the Import mask file button.
Finally, the data of the arbitrary mask can also be plotted by clikcing on the Show mask button.
Constraints
The lower part of the window also contains the constraints tab, which typically looks as follows:
Each constraint is defined by the following:
Delete button allows removing the constraint from the window.
Weight is the relative weight of this constraint with respect to the other goals and constraints. It can be any
number greater than or equal to zero.
Enable/disable flag allows disabling the constraint by clicking on the   button: it will change to   indicating
that the constraint will be ignored by the optimizer. Clicking again re-enables the constraint.
Left Formula can refer to all optimization parameters, even the ones whose value is defined by a expression
and disabled ones.
Equality or inequality that left and right expressions should satisfy. Available settings are = (equal), <=
(lesser or equal) and >= (greater or equal).
= means the goal is have left expression equal to right expression
<=means the goal is to have left expression less than or equal to right expression
<=means the goal is to have left expression greater than or equal to right expression
Right Formula can refer to all optimization parameters, even the ones whose value is defined by a expression
and disabled ones.
The contribution of each Constraint to the error function is the square of the difference between left and right
expression, multiplied by the weight. Obviously the contribution is taken to be zero if the equality or inequality is
satisfied.
Technically speaking, the Constraints defined here are not the same concept as the ones used in Constrained
Optimization techniques. In that case, the optimization algorithms handle the constraints separately from the error
function and usually guarantee that the constraints will be satisfied in the final solution. The Constraints used in
Fest3D OPT are soft: optimization algorithms do not need to know about them, since they are already taken into
account by the error function, but no guarantee is made that they will be satisfied.
For this reason, if a Constraint can be expressed as a parameter needing to be equal to a function of the others, it is
more efficient and accurate to use a parameter expression instead of a Constraint.
Algorithms
Fest3D Optimization Algorithm window typically looks as follows
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Fest3D OPT currently supports the following algorithms:
1.  Simplex is the well-known Downhill Simplex Method often found in literature. It performs very well on the
highly non-quadratic error functions of Fest3D. parameters are:
Initial step size the initial size of the Simplex.
2.  Powell is the Powell's Direction Set Method, coupled with Brent's unidimensional minimization. It does not use
gradients. Parameters are:
Initial step size the initial size of steps in Brent's unidimensional minimization.
Allowed Tolerance the relative tolerance of minima found by Brent's unidimensional minimization.
3.  Gradient is the well-known first-order iterative optimization algorithm for finding the minimum of a function.
Gradient is used to find the minimum error by minimizing a cost function.
Initial step size the initial size of steps. In order to find a local minimum, one takes steps proportional
to the negative of the gradient of the function at the current point.
Allowed Tolerance the relative termination tolerance for the cost function.
All algorithms have two common parameters:
Max Iterations the maximum number of iterations. The algorithm will always stop when this number of
iterations is reached (or little after), even if a minimum was not yet found.
Target Error the error function's threshold value. The algorithm will always stop when the error function
becomes smaller than this value (or little after), even if a minimum was not yet found.
Running the OPT from command prompt
It is also possible to execute the OPT from command prompt. The executable name is opt3d.exe on Windows
platform and opt3d on Unix-like platforms, and is located in the directory where Fest3D is installed. Executing the
command opt3d -h (prefixed by Fest3D installation directory if necessary) will show all command-line arguments
and options supported by the OPT, including how to specify EMCE location, input and output files. Please note that
progress messages, including the values of parameters, by default are printed on standard error with priority notice. A
typical invocation looks as follows:
<full-path-to-fest3d/opt3d> --input=<full-path-to-working-directory>/mycircuit.optx --
engine_in=mycircuit.fest3x --out-curr==<full-path-to-working-directory>/mycircuit.out -
-out-prev==<full-path-to-working-directory>/mycircuit.out.prev --engine=<full-path-to-
fest3d>/fest3 -- --nthreads=number-of-cores-to-use
If any of the paths contain spaces, you should add double quotes. e.g: --tmp="C:\path with spaces"
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Before running OPT from command prompt, the user must be aware that the data in the input xml file for OPT (optx)
must be coherent with the data in the xml file of the associated Fest3D circuit (fest3x). This means, that all the
Parameters (named as "Variables" in the xml files) must be coincident in both files, and that each goal function
defined in the optx file (named as "Target" in xml file) uses a label of a frequency sweep which actually exists in
the festx file. Moreover, in the fest3x file those frequency sweeps associated to goal functions must be enabled,
and the rest of existing Frequency sweeps must be disabled. If all these requirements are not matched, the OPT
will throw error messages or will not behave as expected. For this reason, it is prefirable to launch OPT using the
Fest3D Graphical Interface, since in that case all the requirements are ensured automatically.
2.3.4.2 Tolerance Analysis (TOL)
This section describes the structure of Fest3D Tolerance Analysis (TOL), its features and how to configure, interactively
execute and monitor it from the User Interface and from the command prompt.
The TOL section contains the following topics:
Features
Description of TOL features and capabilities.
Using the
TOL
How to configure, interactively execute and monitor the TOL from the User Interface or, in case you
need, from the command prompt.
Features
The Fest3D Tolerance Analysis performs an automatic study of the effects that the deviations of the structure
parameters have on the circuit response. This is useful, for example, for taking into account the mechanical tolerances
of the component dimensions in the manufacturing process. The parameters that have been selected for the analysis
are perturbed randomly around its initial value in successive iterations. It uses a Gaussian probability density function
with a user-defined standard deviation. At the same time, the resulting responses of the circuit for the modified circuit
are calculated and plotted consecutively. This way, the effect of the tolerances can be inspected at a simple glance.
The tool, completely integrated in the GUI, allows the user to:
choose easily the parameters to study.
define the standard deviation for each parameter independently.
manually change the parameters and run the EMCE or TOL with the modified values.
start, monitor, stop, resume the tolerance analysis.
Using the TOL
The Fest3D Tolerance Analysis Window typically looks as follows
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Performing a Tolerance Analysis of a circuit with Fest3D TOL can be divided in three steps:
1.  Choose which parameters to analyze.
In the left side of each parameter there is a button that indicates if the parameter is selected for the tolerance
analysis. Click on it to activate (green color) or deactivate (red color) its corresponding parameter. Only
parameters whose expressions are a number and are used to set a model property, can be chosen to be
optimized. Parameters whose expression are a mathematical expression are not eligible for tolerance analysis.
　By default, all optimizable parameters are deactivated.
.
2.  Define standard deviation for each selected parameter. Open the Tolerance Analysis Window from the
Execute menu or from the corresponding button (
) in the Toolbar. Enter a standard deviation near each
parameter's label. Please bear in mind that in the Tolerance Analysis Window the existing parameters will be
only listed, but they cannot be edited. In order to modify the definition of parameters (names, expressions,
addition/removal of dummy parameters) you can use the Parameters configuration  (
buttons in the Toolbar.
) or Optimizer (
)
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3.  Start, monitor, stop, resume the tolerance analysis. To start the analysis click on the PLAY button (
). The
parameters values, iteration count and error function will be updated in real time. If Auto Plot in the main
window Graphics menu is active, the graphic plot of the circuit analysis results will be updated in real time too
. The analysis stops when the algorithm finds a (possible) minimum, or the error function
reaches the target error, or the maximum number of iterations is reached. You can also stop it in any moment
by clicking on the Stop button (
).
At any moment that tolerance analysis is not running, you can modify the parameters values.  
The upper part of the window contains the parameters to analyze. Each parameter is defined by the following:
Name, the name uniquely identifies the parameter (it is case sensitive). You may give any name you want to
the parameter. You only need to take into consideration that special characters are not allowed, and some key
words are reserved, such as some mathematical functions or Visual Basic keywords.
Expression, allows setting direct values or mathematical expressions which define the parameter value or its
relationship with other parameters.
Expression can contain trigonometric and other functions. In particular:
sin(x), the sine of x, x is in radians.
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cos(x), the cosine of x, x is in radians.
tan(x), the tangent of x, x is in radians.
sinh(x), the hyperbolic　sine of x.
cosh(x), the hyperbolic　cosine of x.
tanh(x), the hyperbolic tangent of x.
log(x), the logarithm (base e).
exp(x), the exponential value of x.
sqrt(x), the square root of x.
abs(x), the absolute value of x.
Description, this is an optional field that may be used to make any annotation about the parameter.
opt button indicates if a parameter is eligible for tolerance analysis. It allows temporarily disabling the
parameter　for the　tolerance by clicking　on the box. The color will be turned to red, indicating that the
parameter will not be changed: its value will remain fixed. Clicking again re-enables the parameter and the
color will turn back to green. On the other hand, in cases in which　a parameter is not defined as a numerical
value, opt will be marked as crossed out, meaning that　such parameter will not be considered for direct
modification by the tolerance tool　(but the parameter value may be modified indirectly in analysis steps if its
expression depends on other parameters which are used in the tolerance anaysis).
The current, previous, delta and initial values of the parameter. Delta value is the difference between the
current and the initial value, not between the current and previous value. The current value of a parameter can
only be edited using either the Parameters configuration  (
The standard deviation for that analysis. By default, every parameter has set a standard deviation of 0.01.
This can be changed individually for every parameter or also can be changed globally with the "Set Common
STDDev" button which can be found at the bottom of the window.
) button in the Toolbar.
) or Optimizer (
The bottom part of the window contains several buttons:
Play button: Starts the tolerance analysis
Stop button: Stops the tolerance analysis
Reset values button: Which will reset the values to the starting ones after a tolerance analysis has been done
% error: Shows the percentage of iterations that have not fullfilled the goal functions' requirements
Max iter: Allows the user to change the maximum number of iterations
Set Common STDDev: Allows the user to change the standard deviation for all the parameters at the same
time
Running the TOL from command prompt
It is also possible to execute the TOL from command prompt. The executable name is opt3d.exe on Windows
platform and opt3d on Unix-like platforms, and is located in the directory where Fest3D is installed (you can view/edit
the installation directory from the Preferences window). Executing the command opt3d -h (prefixed by Fest3D
installation directory if necessary) will show all command-line arguments and options supported by the OPT, including
how to specify EMCE location, input and output files. Please note that progress messages, including the values of
parameters, by default are printed on standard error with priority notice. A typical invocation looks as follows:
opt3d --close-all-fds--engine=<full-path-to-fest3d> --engine-in=mycircuit.fest3 --
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in=mycircuit.opt3 --out=mycircuit.out --log-notice=mycircuit.log --
out_modes=mycircuit.mod --infinity=1000
2.3.5 Synthesis Tools
This section describes the Synthesis Tools integrated into Fest3D and how to use them to synthesize low-pass filters,
band-pass filters, transformers and dual-mode filters.
All synthesis tools have the capability to create:
A Fest3D project
A CST Design Studio project
The Synthesis Tools section contains the following topics:
Introduction
General information, architecture, requirement and integration of the Synthesis Tools.
Low-Pass Filter
The Synthesis Tool to create low-pass filters.
Band-Pass Filter
The Synthesis Tool to create band-pass filters.
Tranformers
The Synthesis Tool to create impedance tranformers.
Dual-mode Filter
The Synthesis Tool to create dual-mode filters.
Introduction
The Synthesis Tools integrated with Fest3D are able to synthesize a variety of millimeter-wave and microwave circuits
from user specifications. A typical use of the Synthesis Tools is to quickly create filters with given band, insertion loss
and number of poles.
Launching the synthesis tools
The synthesis tools can be opened from two locations:
From the CST Studio main page "Modules and Tools". See image below
From the Fest3D main window. Menu "Synthesis".
2.3.5.1 Synthesis Tools: Low-Pass Filter
The waveguide Low-Pass Filter Synthesis Tool (LPF) is an instrument providing and advanced automatic design of
rectangular and coaxial waveguide Chebyschev response low-pass filters.
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LPF automatically determines the physical dimensions of the structure once the specifications have been given. Due to
the consideration of higher modes in the synthesis procedure, no optimization is normally required.
At the end of this help there are some tips to help the users to make the most of this synthesis tool.
LPF can synthesize the following list of lowpass filters:
Rectangular symmetric and asymmetric corrugated lowpass filters with squared corners.
Rectangular symmetric lowpass filters with rounded corners.
Rectangular symmetric and asymmetric iris-coupled lowpass filters with squared corners.
Coaxial lowpass filters.
For all these components, transformers can be attached. In that case, a post-optimization may be required. Fest3D
automatically launches this post-optimization if it has been required during the specification of the lowpass filter
characteristics.
Fig.1: Five-section rectangular waveguide low-pass filter.
In Fig. 1, a Corrugated Rectangular lowpass filter in a symmetric configuration is depicted. The filter shown has an odd
number of sections, in this case N=5, so the input and output ports have the same height. On the other hand, even
degree filters have not the same input and output height.
The GUI has been organized to ease the work of the designer in the process of synthesizing, and if required,
optimizing a lowpass filter. The wizard guides the user and in just 7 steps the filter is fully customized.
1. Project properties
When the Lowpass wizard GUI is launched, the user can select among two options: create a new project or to restore a
previous existing one. Fig.2 shows the Project Management Window. The project is stored in a ".syn" file in which all
data are saved.
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In this tutorial a rectangular low pass filter will be designed and the proper impedance transformers will be attached
in order to match to standard waveguide ports.
Fig.2: Project Management Window.
2. Topology
The second step  shows all the available structures. They are:
1.  Rectangular corrugated.
2.  Rectangular with capacitive iris.
3.  Coaxial.
In this window some other data are also required. These are:
1.  Symmetry
Enable or disable the symmetry in the horizontal plane.
2.  Impedance Transformer (TRF)
In case the Impedance Transformer is selected, the Step 5 will be used to fulfill the TRF. If not selected
Step 5 will be skipped.
3.  Rounded Corners
Rounded corners will be used. The machining radius will be required in Step 4.
4.  Synthesis Model
Starts with inductive element. Given a height for the input port, the next element will have a lower
height.
Starts with capacitive element. Given a height for the input port, the next element will have a larger
height.
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Fig.3: Topology selection.
3. Electrical Specifications
Just after selecting the topology options, the electrical specifications are required. Fig. 4 shows a window in which two
main areas can be distinguished. The one on the top is related to the In-Band electrical specifications and the second
one to the Out-of-Band electrical specifications.
The In-Band specifications require the highest transmission frequency (GHz) and the return loss (dB).
The Out-of-Band can be given in four different ways, an explanatory graph is shown in every case to emphasize what
is the GUI expecting.
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Fig.4: Electrical specifications.
In-Band electrical specifications includes:
Highest transmission frequency (GHz): marked in the graph as the "A" point.
Return loss (dB): Maximum value for the |S11| parameter in the in-band frequency span.
The Out-of-Band electrical specifications can be defined in 4 different ways:
Two out of band frequencies and their corresponding attenuations.
One out of band frequency, its attenuation and the section length.
Maximum attenuation frequency and the maximum attenuation level (Recommended) .
Number of sections and section length.
Due to the length compensation, the final length of each element shall be different (but close) to the one provided by
the user.
4. Geometrical parameters
Once the electrical specifications have been given, important parameters regarding the final dimensions of the
structure have to be given. Fig. 5 shows the window for the rectangular corrugated configuration.
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Fig.5: Geometrical parameters.
In this case, since a rectangular filter is being designed, the wizard requests the width of the filter. As the filter is
homogeneous all the elements will have the same width.
Secondly, one height must be given. These parameters can be specified in two ways and some restrictions to these
parameters apply.
As the filters' height increases some higher modes, which are excited in the large height elements, are not attenuated
enough at the low height elements and propagate through the structure. This causes a severe degradation in the final
response. Although the synthesis technique implements some resources to fix these problems, it is better to avoid the
use of very large heights. By very large heights can be understood values close to the standard waveguide height in
the input port of the filters.
In-Band electrical specifications includes:
By setting the first waveguide height the user can be sure about the filter ports at the end of the synthesis.
Nevertheless, nothing can be known beforehand about the minimum height that the structure will have.
The second option may be interesting when a minimum power handling capability is expected. In this case, it is
useful to set the minimum height in the whole structure.
In case of designing a coaxial filter, the wizard prompts for the external radius (which is constant in the whole filter),
and the internal radius. Analogously to the rectangular filter case, the internal radius can be specified in two ways:
Giving the first internal radius.
Giving the largest internal radius in the filter.
One important option which should not be underestimated is the "Use same input and output ports". This option
forces the filter to have and odd number of sections. Thus, once the order is determined by means of the electrical
specifications, the order is set to the nearest upper odd value.
5. Impedance Matching (optional)
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Only when the option "Attach an Impedance transformer" is selected at Step 2 the following window is prompted by
the wizard after configuring the Geometrical Parameters. As shown in Fig. 6, the input and output Impedance
Matching Networks can be configured.
Both, the input and output transformers require an output height to be fixed. The Return Loss figure should be, at lest,
3 to 5 dB greater than the value used for the filter design. Otherwise, the lowpass response is too degraded.
The number of sections and the centre frequency in each transformer can be specified by means of:
Setting a value for the order.
Indirectly by filling the bandwidth span, given by the Minimum and the Maximum Frequency, in which the
impedance transformer must work.
Fig.6: Impedance transformer window.
6. Simulation parameters
The final step in the synthesis wizard is shown in Fig. 7. At this stage some parameters to set up the Fest3D engine
must be given. The final simulation frequency span and number of points must be specified.
User can also decide whether the synthesis will create:
A Fest3D project. The project will be automatically loaded and simulated in Fest3D.
A CST Design Studio project: The project will be created in CST Design Studio with and associated S-
Parameters task that will be automatically updated.
When selecting Fest3D project, an extra option let the user can enable the post-optimization. By doing so, the GUI will
suggest to reduce the number of points used in the optimization. Two parameters can be optimized combined or
separately. Although the length optimization is much more faster, hence recommended when only filters are being
designed, when an impedance transformer is attached it could be required to optimize both filter sections lengths and
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heights.
The optimization process is launched once the synthesis finishes and will stop once the filter has been successfully
optimized.
Once the design is finished, the structure is automatically opened in the Fest3D canvas or in CST Design Studio and
simulated.
Fig.7: Simulation parameters.
7. Running the synthesis from Command Line/Matlab/Octave
To execute the synthesis from the command line (or using the system() function in Matlab), the user should use the
following command line sequence (keep the argument order).
"$paht_to_LPF_executable/LPF" --adrFEST="$path_to_FEST_executable" --adrWork="$path_to_syn_fyle" --
prjName=#Project_Name_without_.syn_extension
An example will be shown:
Path to the LPF executable. C:\Program Files\Fest3D-2018\bin\64\LPF_2018.exe
Path to the Fest3D executable. C:\Program Files\Fest3D-2018\bin\64\fest3d.exe
Path to the syn file. C:\My LPF Tests\
Project Name. LPFTest.syn. The file name must not contain any spaces.
Pay attention to the presence of the quotation marks which must embrace all the paths which contains spaces.
"C:\Program Files\Fest3D-2018\bin\64\LPF_2018" --adrFEST="C:\Program Files\Fest3D-2018\bin\64\fest3d" --
adrWork="C:\My LPF Tests" --prjName=LPFTest
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8. Design tips
In this section some tips are given to help the user to achieve satisfactory results when using the synthesis tool.
General
When the option "Use same input and output ports" is selected, the obtained filter will have some important
properties.
This option forces the filter to have and odd number of section. Thus, once the order is determined by
means of the electrical specifications, the order is set to the nearest upper odd value.
The obtained filter will be symmetric in the propagation direction.
Due to the symmetry property, both the design and post optimization will take advantage of that and
the required time will be reduced dramatically.
Rectangular corrugated
It has been found that an increment in the height of the filter makes the final response to loose its
equiripple properties due to higher modes effects. This can be solved by reducing the initial section
height. As a beginning point, a height around 2/3 of the standard height is recommended.
Given a height, the asymmetrical geometries always have a worst frequency response than symmetrical
ones. This effect takes place because evanescent modes with lower cut-off frequencies are excited.
In short, any asymmetrical filter has an equivalent behaviour to one of the double height in a
symmetrical geometry.
When synthesizing rounded structures some restrictions apply:
The section length must be big enough to fit the machining radius.
The analysis of rounded structures is slower than its squared counterparts. Thus the optimization
process can be much more slower if the height is included as optimization parameter.
If the obtained response is not equiripple try to decrease the structure height by choosing an smaller
input waveguide height.
Capacitive iris
This topology has some useful properties which can be interesting when the filter input height is very
important. Nevertheless the out of band response, despite having a greater selectivity, is not as good as the
corrugated topology due to the proximity of the second replica.
Coaxial
Due to the TEM properties of this technology, the results which are obtained are excellent in every
configuration.
Impedance Transformers
The synthesis program performs the synthesis of the filter and the impedance transformers in a separate way.
That means that some effects cannot be taken into account at the design time. That is the reason why a post
optimization is normally required. To improve the results and obtain shorter filters follow the following tips:
The matching network requires more sections as the lower adaptation frequency approaches the
waveguide cut-off (fc) frequency. Usually the microwave systems do not use all the frequency up to "fc".
So configure your matching network to match your required span.
Set a return loss figure which is, at least, 3-5 dB greater than the one from the filter. If both elements
have the same value a longer optimization will be required and, perhaps, the desired result will not be
achieved.
References
[1] R. Levy, "Tables of Elements Values for the Distributed Low-Pass Prototype Filter", Transactions on Microwave
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Theory and Techniques, vol. 13, no. 5. pages 519-535, 1965.
[2] R. Cameron, "Microwave Filters for Communication Systems", Wiley, 2007.
[3] Monerris, O.; Soto, P.; et at., "Accurate Circuit Synthesis of Low-Pass Corrugated Waveguide Filters", EuMW, 2010.
2.3.5.2 Synthesis Tools: Band-Pass Filter
The waveguide Bandpass Filter Synthesis Tool (BPF) is an instrument to design waveguide Chebyschev bandpass
filters. BPF is able to design narrow and very wide-band bandpass filters with or without a short optimization.
This synthesis tool is capable to synthesize the following structures:
1.  Inductive iris coupled filters (Figs. 1 a-b)
2.  Metal insert filters (Figs. 1 c-f)
3.  Inductive post filters (Figs. 1 g-j)
Interestingly, all the filters can be homogeneous or inhomogeneous. In other words, the width of the cavities can be
kept constant along the whole filter or not. Inhomogeneity is normally employed to get a better out-of-band
performance.
Furthermore, one or two obstacles can be used in the metal insert and inductive post configuration.
In this tutorial, the BPF tool shall be explained and some advices will be given.
Fig. 1 All the possible geometries that can be sinthesized.
Fig.1.a Homogeneous iris cavity filter.
Fig.1.b Inhomogeneous iris cavity filter.
Fig.1.c One Metal Insert In/homogeneous.
Fig.1.d Two Metal Inserts In/homogeneous.
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Fig.1.e One Metal Insert In/homogeneous.
Fig.1.f Two Metal Inserts In/homogeneous.
1. Project properties
When the BPF wizard GUI is launched, the user can select between two options: to create a new project or to load a
previous existing one. Fig. 2 shows the Project Management Window. All the design files have the extension ".syn". In
this file all the synthesis project data are saved.
2. Topology
Fig. 2: Project Management Window.
Once a project has been selected, the wizard shows the three geometries which can be synthesized.
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Fig. 3.a Inductive Iris.
Fig. 3.b Metal Inserts.
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Fig. 3.c Inductive Posts.
Fig 3. shows this step and allows the user to configure some parameters which depend on the final geometry of the
structure:
Symmetry: This leads to a symmetric filter in the propagation direction. If selected, all the data retrieved in the
following steps take this into account.
Homogeneity: This sets the filter to have constant width or not. In the second case Step 5 lets the user to set
each section width.
Number of obstacles: In the metal inserts and inductive posts cases, the user can configure whether he/she
wishes to place one or two obstacles in each iris.
3. Port parameters
Once the desired topology has been selected, the input and output ports must be chosen. In Fig. 4 a list of available
standard waveguides is shown. Nevertheless, other dimensions can be set manually in case that non-standard
waveguide ports are wished.
In case that the input and output ports are different, the filter must be asymmetric and inhomogeneous. In any other
case only one port can be customized.
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4. Frequency parameters
Fig. 4: Port parameters.
Next, the frequency specifications are required. As depicted in Fig. 5, little information is needed. The purpose of this
step is to determine the order of the filter in terms of the frequency parameters.
In band parameters
Out-of-band parameters
Filter order
The estimate button uses the information gathered in the fields above to calculate the required filter order in order to
meet the specifications. Given that a Chebyshev response is being used, once the data have been filled, the estimate
button can be used.
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5. Resonator parameters
Fig. 5: Frequency parameters.
In this step, the resonators width must be filled. This window is only shown if in Step 2 the user has set the filter to be
inhomogeneous. In that case a table has to be filled with the desired widths of each resonator.
Pay attention that, if the symmetry option has also been selected, the values in the table must be symmetric as well.
When wrong values are filled an error message is shown and it will not be possible to advance to the next step.
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Fig. 6.a: Resonators width.
Fig. 6.b: Table in which the resonator widths must be filled.
6. Iris parameters
Once the previous steps have been followed, the iris dimensions can be configured (Figs. 7a-c). As expected, three
different windows are available, each of them for one topology.
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Fig. 7.a: Inductive Iris.
Fig. 7.b: Metal Inserts.
Fig. 7.c: Inductive Posts.
Each iris has, at least, two parameters, but only one can be used in the design process. The other one must be set in
this step to its final value.
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The next list shows all the parameters of each type of iris.
Inductive iris filters
Width
Thickness
Metal inserts filters
Width
Thickness
Iris thickness
Offset: Only available when two obstacles are placed in each iris. This parameter refers to the gap
between the two metal inserts.
Inductive posts filters
Displacement
Radius
When fixing the radius, these values could be used as first approach
Input waveguide
WR-187
WR-75
WR-34
Radius range
0.8 - 4.5 mm
0.2 - 2.5 mm
0.1 - 1.5 mm
The fixed parameters are set using a table . As before, the fixed parameters in the different irises must be
symmetric in case that the symmetry option has been selected.
Fig. 7.d: Table in which the iris fixed parameters must be filled.
Although the design parameters do not require any configuration, the user can set the maximum and minimum value
which it can take. Doing so, the program will try to achieve a successful synthesis in which the design parameter exists
in the region defined by the user. Those values are introduced in two tables like the one shown in Fig. 7d.
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7. Simulation parameters
The final step in the synthesis wizard is shown in Fig. 8. At this stage some parameters to set up the Fest3D engine
must be given. The final simulation frequency span and number of points must be specified.
User can also decide whether the synthesis will create:
A Fest3D project. The project will be automatically loaded and simulated in Fest3D.
A CST Design Studio project: The project will be created in CST Design Studio with and associated S-
Parameters task that will be automatically updated.
In case of selecting Fest3D project creaton, the user can enable the post-optimization. The optimization is done over
the cavity length and the iris design parameter.
The optimization process is launched automatically once the synthesis finishes and stops once the filter has been
successfully optimized.
Fig. 8: Simulation parameters.
Once the design is finished, the structure is automatically opened in the Fest3D canvas or in CST Design Studio and
simulated.
8. Running the synthesis from Command Line/Matlab/Octave
To execute the synthesis from the command line (or using the system() function in Matlab), the user should use the
following command line sequence (keep the argument order).
"$path_to_BPF_executable/LPF" --adrFEST="$path_to_FEST_executable" --adrWork="$path_to_syn_fyle" --
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prjName=#Project_Name_without_.syn_extension
An example will be shown:
Path to the BPF executable. C:\Program Files\Fest3D\bin\32\BPF.exe
Path to the Fest3D executable. C:\Program Files\Fest3D\bin\32\fest3d.exe
Path to the syn file. C:\My BPF Tests\
Project Name. BPFTest.syn. The file name must not contain any spaces.
"C:\Program Files\Fest3D\bin\32\BPF" --"C:\Program Files\Fest3D\bin\32\fest3d" --"C:\My BPF Tests" --BPFTest
Pay attention to the presence of the quotation marks which must embrace all the paths which contains spaces.
9. Design tips
In this section some tips are given to help the user to achieve satisfactory results when using the synthesis tool.
When a filter is being synthesized, the coupling level required in the input iris is always bigger than the level
required in the central sections. Thus, the fixed parameter in the iris must be set wisely in order not to force the
design parameter into very small or very big values.
When fixing the parameter set them in a way that the coupling level is greater for the input and output
sections and smaller for the middle ones. Doing so all the variable parameters will be much more same sized.
Next a list of tips to increase the coupling is presented in terms of the design parameter.
Window width The coupling increases as the window gets wider.
Window thickness The coupling increases as the window gets narrower.
Metal insert offset A metal insert placed in the middle of the cavity blocks the zone in which the field is
maximum. When two metal inserts are used, a bigger offset achieve a greater coupling level.
Metal insert thickness As this parameter increases much more field is blocked so less coupling level is
achieved.
Post radius A bigger radius implies less coupling level. Use the table provided in Step 6 to choose the
radius wisely.
Posts offset A post placed in the middle blocks much more EM field than the same post placed in a
side. So an offset post always achieve a greater coupling level.
References
[1] G. Matthaei, L. Young, y E.M.T. Jones, Microwave Filters, "Impedance-Matching Networks, and Coupling Structures".
Noorwood, MA: Artech House, 1980.
[2] S.B. Cohn, "Generalized design of band-pass and other filters by computer optimization," in 1974 IEEE MTT-S Int.
Microwave Symp. Dig., 1974, pp. 272-274.
[3] J.D. Rhodes, "A low-pass prototype network for microwave linear phase filters," IEEE Trans. Microwave Theory
Tech., vol. 18, no. 6, pp. 290-301, Jun. 1970.
[4] R. Cameron, "Microwave Filters for Communication Systems", Wiley, 2007.
2.3.5.3 Synthesis Tools: Dual-Mode Filter
The Dual-Mode Filter (DMF) synthesis tool is an instrument to automatically design Dual-Mode Filters. The filter
structure is composed of circular cavities connected between them through rectangular or cross irises. Additionally,
coupling and tuning screws are placed inside each cavity.
This type of filters achieves responses with 2N poles, where N is the number of cavities, due to the two degenerated
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modes inside each cavity. It means that dual-mode filters are smaller (about 2 times shorter) than other classical
configurations. This feature makes them very appropriate for satellite applications, in which the weight and size
reduction of components is a must.
An example of a four-pole dual mode filter structure is shown in Fig. 1.
Fig. 1 Four-pole filter
In this tutorial, the use of the DMF tool is explained and some pieces of advice are provided.
Step 1 - New Project / Open Project
When the DMF wizard GUI is launched, the user can select between two options: to create a new project or to reload a
previous existing one. Fig. 2 shows the Project Management Window. All the design files have the extension ".syn". In
these files the synthesis project data are saved.
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Fig. 2: Project management window.
Step 2 - Filter order, topology, mode and coupling matrix
Once a project has been selected, a window as shown in Fig. 3 appears.
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Fig. 3: General specifications window.
First of all, the filter order must be selected. This tool is capable of synthesizing dual-mode filters of 4-, 5-, 6-, 8-, 10-
or 12- order.
For 6-, 8- and 10- order filters, it is possible to choose between two different topologies: symmetric and asymmetric.
The symmetry considered here is related to the dimensions of the structure. In the symmetric topology, the filter
dimensions will be symmetric with respect to the propagation direction, and all the cavities will be connected through
cross irises. In the asymmetric topology, there is no symmetry in the structure, and some of the cavities are connected
through cross irises and other ones through slot irises.
Next, the resonant mode inside the cavities must be chosen. Modes TE111, TE112, TE113, TE114 and TE115 are
available. The last number of the mode name indicates the number of maximums of electromagnetic field in each
cavity. The higher this number is, the higher is the quality factor but the longer is the filter structure. Besides, the
mode chosen determines the position of the screws, since the screws must be located in a maximum of
electromagnetic field. Therefore, for TE111, TE113 and TE115 modes, screws will be located in the center of the cavity,
but for TE112 and TE114, screws will not be located in the center of the cavity.
Since this tool synthesizes the physical dimensions of the filter from a coupling matrix, the user can choose between
using his/her own matrix or, on the contrary, it is the program itself that calculates it. In case the coupling matrix is
autocalculated by the tool, there is the possibility to choose between calculating the matrix from a doubly or singly
terminated network. A doubly terminated filter network has resistor terminations at both ends, which is indeed the
most common case. In singly terminated filter networks, the source impedance is equal to zero. They are designed to
operate from very high or very low impedance sources and they provide an input admittance response that is very
appropriate for the design of contiguous-channel multiplexers. Note that a singly terminated single network forces an
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asymmetric topology.
Finally, the precision level must be selected. The user can choose between medium, high or very high precision. This
precision level configures the number of modes considered in the structure elements in the design process. So, the
higher the precision is, the more accurate the final design is, but the longer the simulation will be.
Step 3 - Frequency parameters
Next, frequency specifications are required. They must be introduced in a window like the one depicted in Fig. 4.
Fig. 4: Frequency parameters window.
The parameters that must be specified in this step are:
1.  Center frequency of the filter
2.  Bandwidth
3.  Return loss
4.  Number of equalization zeros
5.  Equalization bandwidth or equalization zeros
6.  Transmission zeros
The bandwidth is referred to the frequency band where S11 is under the level specified by the parameter "Return
loss".
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It is possible to include group delay equalization if needed. In some cases, (high order filters) it is possible to choose
the number of equalization zeros. If the number of equalization zeros is increased, the number of transmission zeros
decreases. Therefore, if a great number of equalization zeros is chosen, the group delay response will be very plane,
but the selectivity of the filter will be lower.
If equalization is needed, the user has two possibilities. The first one (Autocalculate zeros) is to introduce the
bandwidth percentage to be equalized (equalization bandwidth) and press "Calculate" so that the tool gives the
optimum equalization zeros. The second one (Manual zeros) is to select the desired position of this equalization
zeros. This tool is only capable to consider symmetric equalization zeros placed in the real axis of the s plane. For
symmetric 8-order filters equalization is only possible with 4 equalization zeros, and for symmetric 12-order filters
equalization is not available.
The number of transmission zeros will depend on the filter order and the number of equalization zeros. For 4-pole,
5-pole or 6-pole filters, there will be a maximum of two symmetrical transmission zeros, for an 8-pole or 10-
pole filters, the response will have a maximum of four transmission zeros (two symmetrical to the other two), and for
12-pole filters, there will be a maximum of six symmetrical transmission zeros (three symmetrical to the other three).
Only the zeros which are over the center frequency must be specified, the symmetrical ones are automatically
obtained.
Once all these parameters are introduced, the "Calculate matrix & Visualize" button must be clicked, and the ideal
response calculated with the information given by the user will be shown. If the theoretical response is correct, you
can proceed to the next step. Otherwise, any parameter can be changed, and the theoretical response visualized
again. Also the calculated coupling matrix is shown and it can be exported to a file from this window.
In case the coupling matrix is defined by the user, the corresponding coupling values in the matrix can be introduced,
or it can be imported form a file. Note that in this case, many of the parameters are already defined by the user-
defined coupling matrix itself, therefore, it is only necessary to indicate the center frequency and the bandwidth of the
filter to be synthesized.
Step 4 - Input/output waveguides and irises
In this step, some geometrical parameters of the filter are configured, which are:
1.  Input/output waveguide ports: There is a list of available standard waveguides. Nevertheless, other dimensions
can be set manually in case that non-standard waveguide ports are wished, by selecting "Non-standard" in the
previous list.
2.  Cavity radius.
3.  Width, thickness, round corner radius and vertical and horizontal offset of the input/output irises.
4.  Width, thickness, external round corner radius and internal round corner radius of the intercavity irises.
In this case, the window is like the one in Fig. 5.
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Fig. 5: Geometrical parameters window.
If the topology chosen has both cross and slot intercavity irises, width and thickness will be the same in both type of
irises, and round corner radius of the slot irises will be the same as the external round corner radius of the cross irises.
Step 5 - Screws
Now, some parameters related to the screws must be configured. The window will have the appearance shown in Fig.
6. The number of cavities depends on the filter order.
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Fig. 6: Screws window.
Screws used in these structures have squared cross section, so screws thickness refers to the square side length.
In practical designs, screws penetration cannot be too short due to mechanical reasons. Therefore, the user can
specify a screws minimum length, so none of them will be shorter than the dimension specified.
Finally, the user can choose the position of the screws, that is, the angle around the circumference of the circular
cavity. Screws in different cavities can be chosen separately, but some considerations must be taken into account:
1.  Vertical screws can be only located in two different positions: top (90º) and bottom (270º).
2.  Horizontal screws can be only located in two different positions: left (0º) and right (180º).
3.  Oblique screws can be only located in four different positions: 45º, 135º, 225º and 315º.
4.  The position of the oblique screws of different cavities is not independent. When two cavities are
interconnected through a slot iris, positions of their oblique screws must differ in 0º or 180º. Alternatively, if
they are connected through cross irises, the right position will vary depending on whether equalization has
been used and the number of equalization zeros employed. Therefore, the positions of the oblique screws
must be modified accordingly to this rules. Tables 1-a and 1-b shows the difference of position between each
pair of cavities depending on the filter order. A difference of position of 90º in the tables means that this
difference can be of +90º or -90º.
Table 1-a. Relative positions of the oblique screws in each pair of cavities when equalization is not used.
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Cavities 2-3
Cavities 3-4
Cavities 4-5
161
Cavities
5-6
Order 4 symmetric
Order 4 asymmetric
Order 5 asymmetric
Order 6 symmetric
Order 6 asymmetric
Order 8 symmetric
Order 8 asymmetric
Order 10 symmetric
Order 10 asymmetric
Order 12 symmetric
Order 12 asymmetric
90º
90º
90º
90º
90º
90º
90º
90º
90º
90º
90º
-
-
-
90º
0º or 180º
90º
0º or 180º
90º
90º
90º
0º or 180º
-
-
-
-
-
90º
90º
90º
90º
90º
90º
-
-
-
-
-
-
-
90º
90º
90º
0º or 180º
-
-
-
-
-
-
-
-
-
90º
90º
Table 1-b. Relative positions of the oblique screws in each pair of cavities when equalization is used.
Cavities 1-2
Cavities 2-3
Cavities 3-4
Cavities 4-5
Cavities
5-6
-
-
-
-
-
-
-
-
-
-
-
-
-
Order 4 symmetric (2 eq.
zeros)
0º or 180º
Order 4 asymmetric (2 eq.
zeros)
0º or 180º
Order 5 asymmetric (2 eq.
zeros)
0º or 180º
-
-
-
Order 6 symmetric (2 eq.
zeros)
Order 6 asymmetric (2 eq.
zeros)
Order 8 symmetric (4 eq.
zeros)
Order 8 asymmetric (2 eq.
zeros)
Order 8 asymmetric (4 eq.
zeros)
Order 10 symmetric (2 eq.
zeros)
Order 10 symmetric (4 eq.
zeros)
0º or 180º
0º or 180º
0º or 180º
0º or 180º
90º
0º or 180º
90º
0º or 180º
0º or 180º
90º
0º or 180º
0º or 180º
0º or 180º
90º
0º or 180º
0º or 180º
90º
0º or 180º
90º
90º
0º or 180º
Copyright 2009-2022 Dassault Systemes Deutschland GmbH.
-
-
-
-
-
-
-
-
-
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Order 10 asymmetric (2 eq.
zeros)
Order 10 asymmetric (4 eq.
zeros)
90º
90º
0º or 180º
90º
0º or 180º
0º or 180º
90º
0º or 180º
-
-
Order 12 asymmetric (2 eq.
zeros)
Order 12 asymmetric (4 eq.
zeros)
0º or 180º
0º or 180º
90º
0º or 180º
90º
0º or 180º
0º or 180º
0º or 180º
0º or 180º
90º
Note that in 4- and 10- order filters, the asymmetric topology only is allowed if a singly terminated filter network is
used. It should also be noted that the 5- order filters always have an asymmetric topology.
Finally, everything is ready to start with the design process of the dual-mode filter.
After clicking "Finish", the design process starts. Once the design is finished, the structure is automatically opened in
the Fest3D canvas and analyzed by the electromagnetic simulator engine.
NOTE: The length of the waveguide ports is adjusted so that the theoretical and simulated phases match.
Step 6 - Exportation type
User can also decide whether the synthesis will create:
A Fest3D project. The project will be automatically loaded and simulated in Fest3D.
A CST Design Studio project: The project will be created in CST Design Studio with and associated S-
Parameters task that will be automatically updated.
Tips and limitations
Accuracy: Tables 2-a to 2-e shows the number of modes used in each element of the filter structure
depending on the precision level chosen.
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 Table 2-a. Number of modes used in input/output waveguides.
Medium precision
High precision
Very high precision
Num. of accessible Modes
Num. of MoM basis functions
Num. of Green's function
terms
10
120
2000
10
200
3000
10
300
6000
Table 2-b. Number of modes used in input/output irises.  
Medium precision
High precision
Very high precision
Num. of accessible Modes
Num. of MoM basis functions
Num. of Green's function
terms
30
120
2000
35
200
3000
45
300
6000
Table 2-c. Number of modes used in circular waveguides.
Medium precision
High precision
Very high precision
Num. of accessible Modes
Num. of MoM basis functions
Num. of Green's function
terms
20
120
2000
20
200
3000
20
300
6000
Table 2-d. Number of modes used in cross/internal irises.
Medium precision
High precision
Very high precision
Num. of accessible Modes
Num. of MoM basis functions
Num. of Green's function
terms
30
120
2000
35
200
3000
45
300
6000
Table 2-e. Number of modes used in screws.
Medium precision
High precision
Very high precision
Num. of accessible Modes
Num. of MoM basis functions
Num. of Green's function
terms
30
120
2000
35
200
3000
45
300
6000
It has been verified that if the filter obtained with the "medium precision" or "high precision" option is synthesized
and then the modes in the "very high precision" option are chosen, the response can be recovered by changing ONLY
the length of the screws. Again, this has been done for some particular designs we have tested. It could be possible
that, in other cases, the response cannot be recovered.
Bandwidth: This design method is focused in dual mode filters with little bandwidth (less than 1% - 1.5%). If a
bandwidth over 1% is specified, it is possible than the results obtained are not good.        
Return Loss: Return loss value must be between 5 dB and 40 dB. Otherwise, an error message will appear.
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Transmission zeros: Obviously, all transmission zeros must be outside the pass-band. Besides, if the
transmission zero value specified is very high, a warning message will appear since it is possible to obtain a
degraded synthesis result.
Equalization zeros:  This tool is only capable to consider symmetric equalization zeros placed in the real axis
of the s plane. For symmetric 8-order filters equalization is only possible with 4 equalization zeros, and for
symmetric 12-order filters equalization is not available.
Input/output waveguide ports: They must be chosen properly. Its cutoff frequency must be under the center
frequency. Apart from this, they cannot be very big, because it could happen that the necessary input/output
coupling is not achieved.        
Cavity radius: This is a critical point, since the quality of the results obtained in the design process strongly
depends on this choice. Because of that, an appropriate cavity radius is automatically calculated from the
center frequency specified in the previous step. However, this is only a rough estimation. It does not mean that
with other cavity radius the algorithm does not work. Therefore, the user can modify it manually. Nevertheless,
it is recommended to choose a value close to the one automatically obtained, and if the radius specified is very
small (cutoff frequency over center frequency of the filter) or very big, an error message will appear. Besides, it
could happen that a spurious mode resonance appears near the pass band, and this is difficult to predict.
When the algorithm detects this effect, an error message is shown. An easy way to correct it is changing the
radius value.
Input/output iris offset: The synthesis method used by this tool assumes that only the vertical mode of the
circular cavity is excited by the input/output iris. Therefore, the offset of the input/output iris cannot be very
big. Otherwise, not only the vertical mode is excited, but also the horizontal mode, and the results obtained will
not be accurate enough.
Screws thickness: The right thickness needed to obtain a good design is related to the wavelength. The bigger
the wavelength is, the bigger the thickness of the screws must be. Table 3 shows some examples of right
dimensions of the screws thickness. They are for guidance only, and it is assumed that the recommended
radius has been chosen.
Table 3. Hints to choose the dimensions of the screw thickness.  
Central frequency (GHz)
Cavity radius (mm)
Screws thickness (mm)
10
12
14
16
35.1
23.4
17.5
14
11.7
10
8.8
2.5
1.7
1.5
Iris thickness: In microwaves band, typical thickness used are between 1-2 mm. If thickness specified is too
big, coupling required will not be achieved.
I/O-iris height and cross arm thickness: In this design method, couplings between input/output waveguides
and cavities are carried out by rectangular irises (a cross iris is composed by two orthogonal rectangular irises).
A rectangular iris allows coupling of modes which are orthogonal to it (for example, a horizontal iris allows
coupling of vertical modes). To achieve that, the big dimension of the rectangle must be much bigger than the
small one, to select only the corresponding mode (horizontal or vertical). Therefore, input/output-iris height
and cross-iris arm thickness cannot be too big, to avoid the coupling of the wrong mode. If this happens, an
error message will be shown, and the corresponding dimension will have to be changed.
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Running the synthesis from Command Line
To execute the synthesis from the command line, the user should use the following command line sequence (KEEP the
argument order).
"$path_to_DMF_executable\DMF" "--$path_to_FEST_executable" "--$path_to_syn_file" "--
#Project_Name_without_.syn_extension" "--$path_to_cache_folder" "--(win for windows and lin for linux)" "--
nthreads=number_of_threads" "--mode=synthesis"
An example is shown:
Path to the DMF executable. C:\Program Files\Fest3D-2018\bin\64\DMF_2018.exe
Path to the Fest3D executable. C:\Program Files\Fest3D-2018\bin\64\fest3d.exe
Path to the .syn file. C:\My DMF Tests\
Project Name. DMFTest.syn.
Cache folder. C:\Documents and Settings\User\My documents\Fest3D_workspace
Operating system. Windows
Number of threads used. 2 
Pay attention to the presence of the quotation marks which must embrace all the paths which contain blank spaces.
"C:\Program Files\Fest3D-2018\bin\64\DMF_2018" "--C:\Program Files\Fest3D-2018\bin\64\fest3d" "--C:\My DMF
Tests" "--DMFTest" "--C:\Documents and Settings\User\My documents\Fest3D_workspace" "--win" "--nthreads=2" "--
mode=synthesis"
It is also possible to obtain the ideal response given by certain specifications. To do that, the procedure is the same as
for the complete synthesis, but substituting "--mode=synthesis" by "--mode=theo". In this case, the output will not be
a .fest3 file, but a .theo file which will contain the S parameters of the ideal (or theoretical) response. This output file
will be saved in the "tmp2018" folder inside the workspace folder.
Based on MATLAB (R) 9.5.0.944444. (c) 1984-2018 The Mathworks Inc.
2.3.5.4 Synthesis Tools: Impedance Transformer
The Impedance Transformer Tool (ITT) is an instrument providing automatic design of rectangular and coaxial
waveguide Chebyschev type multi-section impedance transformers.
ITT automatically determines the physical dimensions of the structure once the specifications have been given. Due to
the consideration of higher modes in the synthesis procedure, no optimization is normally required.
ITT can synthesize the following list of impedance matching networks:
Rectangular symmetric (a) and asymmetric (b) with squared corners.
Rectangular symmetric with rounded corners (c).
Coaxial (d).
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Fig.1: Types of transformers that can be implemented.
The new GUI, available in Fest3D 6.5 and upper, has been organized to ease the work of the designer in the process of
synthesizing, designing and, if required, optimizing the impedance adapter. Current version takes less than 1 minute
from the very first click to the final result. The specifications are given in a 4 step wizard and allows the user to fully
costumize its own design.
1. Project properties
Each time the GUI opens, the user can select to create a new project or restore a previous one. The wizard creates a
.syn file in which all data are stored. Fig. 2 shows the Project Management Window in which a stored project can be
opened or a new one can be created.
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Fig.2: Project Management Window.
In this tutorial the whole process is shown from the very beginning. So a new project option is selected.
2. Topology
The second step  shows all the available structures. They are:
1.  Rectangular 
2.  Coaxial
At this step the user can specify whether the structure must be symmetrical or asymmetrical and, if appropriate, set
the steps to be rounded or squared.
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Fig.3: Topology selection.
3. Electrical and Geometrical parameters
Now the wizard requests the information regarding some configurable dimensions. 
Fig.4: Geometrical parameters.
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In this case, the wizard requests the width of the impedance adapter (which is constant) and the input and output
waveguide height. In case that a rounded corner structure is being designed, the machining radius must be
introduced.
The electrical specificactions which must be filled in are the Return Loss dB and one of the two following options:
1.  Number of elements and center frequency of the impedance adapter.
2.  Frequency range in which the Return Loss specification must be accomplished. This is defined by the minimum
and maximum frequencies. 
4. Simulation parameters
The final step is shown in Fig. 5. At this stage, the wizard allows the user to modify some parameters to setup the
Fest3D engine. It also allows changing the frequency sweep in which the simulation shall be performed.
User can also decide whether the synthesis will create:
A Fest3D project. The project will be automatically loaded and simulated in Fest3D.
A CST Design Studio project: The project will be created in CST Design Studio with and associated S-
Parameters task that will be automatically updated.
In case of selecting Fest3D project, the user can enable the post-optimization. It is possible to optimize the lengths
(recommended), the heights or both at the same time.
Fig.5: Simulation parameters.
Limitations:
Here some limitations of the synthesis tool are described:
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Rounded Corners
The synhtesis tool automatically changes the rounded corners to square when the height difference
between the two waveguides is smaller than the radius diameter.
References
[1] R.S. Elliot, "An Introduction to Guided Waves and Microwave Circuits", Prentice Hall 1993.   
2.3.6 High Power Analysis: Multipactor and Corona.
High Power analysis (Corona and/or Multipactor) can be applied to the EM fields computed by Fest3D by means of
the Spark3D software. The button (
) will automatically launch Spark3D, creating a Spark3D project file that contains
the geometry and EM field results imported from the calculations performed by Fest3D. Alternatively, the same action
can be performed by selecting Execute -> High Power Analysis in the menu bar, or pressing the shortcut key "H".
It is not mandatory to specifically run the EM Field analysis with the button (
) before performing High
Power analysis, and the button (
the existing ones must be updated, the EM fields will be automatically computed in first place before launching
Spark3D. Nevertheless, as also happens for the case of EM Field analysis, it is recommended to configure in first
)  can be pressed directly if desired. If no previous field results are present, or
place the desired settings for EM fields by opening the Configure Field Monitors window with the button  (
) .
Once the Spark3D project is opened, simulation regions, Corona configurations and Multipactor
configurations can be defined and run. For more detailed information about region definitions and Corona and
Multipactor analysis with Spark3D, please consult the Spark3D manual.
Special considerations
Geometry selected for High Power analysis
There are two possible approaches for performing High Power analysis with Fest3D circuits:
1) Working with the complete geometry of the circuit
When there is no previous knowledge of the behaviour of the EM fields of a given circuit, the whole geometry
can be selected in the checkbox "Compute whole circuit" in the Field Monitor configuration window that is
opened with the button (
will contain the EM fields of the complete circuit. These EM fields can be visualized in Spark3D, and the most
relevant areas for a High Power analysis can be spotted. Then, different regions can be defined, in order to run
Corona or Multipactor analysis in those specific areas.
). Using this setting, when pressing the button (
) the resulting Spark3D project
2) Working with partial geometry of the circuit 
When the behaviour of the EM-fields of the circuit under consideration is known in advance, then another
approach consists in selecting in Fest3D only specific elements, before running the High Power analysis. This
can be achieved by doing the following:
Deactivating the checkbox "Compute whole circuit" of the Configure Field Monitors window that is
opened with the button (
Opening the specifications window of the element or elements that compound the areas desired for the
High Power analysis, and selecting them for EM Field analysis.
).
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When pressing the button  (
to Spark3D.
), EM fields shall be computed on those selected elements only, and exported
This second approach is useful for saving computation time for cases of circuits that contain a large number of
elements (for example, a Corona analysis that is desired just in a small portion of a muliplexer with several
channels), or complex elements that could be avoided from EM analysis since their contribution for the total
field response is not relevant for the problem under consideration (for example, a Multipactor analysis that is
desired just for the area of a small rectangular iris in the middle of a circuit that contains cavities with dielectric
resonators).
Partial backward compatibility with previous versions of Fest3D regarding settings for High Power
analysis
In Fest3D versions prior to 2022, the High Power analysis was performed using a dedicated built-in window that
managed the settings and the results for Corona and Multipactor analysis. When a Fest3D project created with an
older version is opened with the current version, most of the settings used in the older version (but not all of
them) shall be adapted:
The elements selected for Corona and/or Multipactor analysis in the older version will be automatically
selected for EM field computations in the current version.
The mesh size value selected for Corona or Multipactor analysis in the older version will be applied to
the general mesh size value in the Configure Field Monitors window in the current version. In case that
both types of analysis were considered, the most restrictive mesh size criterion will be the one to be imported.
Most of the settings defined for Corona and Multipactor analysis in the older version (initial values,
simulation criterions, pressure ranges...) will be translated to equivalent Corona and Multipactor
configurations in the Spark3D project created by Fest3D.
The analysis regions required by Spark3D will NOT be translated from the old version of the Fest3D
project. Specific regions for selecting parts of the imported geometry must be defined by the user in the
Spark3D project created by Fest3D. Those regions must be also associated to the desired Corona or
Multipactor configurations.
2.3.7 Export tools
This section describes the export tools present in Fest3D. There exist 5 different exportations:
Export 3D geometry (closed ports): This option allows exporting the complete device as a single block to a
Standard ACIS Text (SAT) file. Additionally, the existing dielectric volumes will be individually included in the
SAT file as well. The geometry generated by Fest3D considers that all input/output ports are closed, as mere
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walls of the whole circuit.　
Export 3D geometry building blocks (closed ports): This option allows exporting the device  to a Standard
ACIS Text (SAT) file. By using this option, the different elements used to build the device in the Fest3D
schematics will be embedded in the SAT file  as different ACIS bodies. The geometry generated by Fest3D
considers that all input/output ports are closed, as mere walls of the whole circuit.
No information about dielectric objects is given in this option.　Thus, if the user intends to simulate the
exported geometry with another CAD tool, the dielectric parts must be specified manually inside the new
software, as well as the possibility of using them as input/output ports, before performing any analysis.
Export S-Parameters to Touchstone file: Converts the Fest3D output file to TOUCHSTONE format. The
generated file has the same name as the original .fest3 file, but with snp extension.
Export Project to CST MWS®: One may generate a CST Microwave Studio® project from a Fest3D project. To
do this, one may:
Open in Fest3D file that you want to export.
Click on the (
bar. The following window will pop up.
) button in the Tool bar, or go to Export -> Export project to CST MWS in the Menu
You may choose the exportation units to be used in CST MWS®. After selecting the units, a
new window will appear requesting the name and location of the exported project in ".cst"
format. Once both have been chosen, the exportation process will begin.
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 Export Project to CST Design Studio®: One may generate a CST Design Studio® project from a Fest3D
project. Doing this, a ready-to-simulate CST Studio project will be created with a single block component. All
the enabled frequency sweeps of the Fest3D project will appear as different S-Parameter tasks in the CST
Studio project. To do this, one may:
Open the Fest3D file that you want to export.
Click on the (
Menu bar. The following window will pop up, showing some optional export settings:
) button in the Tool bar, or go to Export -> Export project to CST Design Studio in the
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By selecting the option Create 3D Simulation Project, an additional Simulation task will be
included besides the S-Parameter tasks. A Microwave Studio Project will be automatically
created, including the 3D geometry, the materials, the port definitions, the frequency range for
analysis and the field monitors (if any) of the Fest3D project.
By selecting the option Create Optimization Task, an additional Optimization task will be
included besides the S-Parameter tasks. This Optimization task will be configured to use the
parameters imported from the Fest3D project, and will also contain optimization goals
translated from the goal functions that are defined in the Fest3D optimizer. This translation will
be done for all goal functions defined with constant masks.
Despite the fact that the optimization goals of the Optimization task in the Design Studio project
will be defined with the same range of frequencies as the goal functions in Fest3D, the error
function values computed during the optimization process might differ. In Fest3D, the error is
computed at the points specified in the constant mask , whereas in CST Studio the number of
points of the mask is meaningless and the error is obtained with the result curves in the
corresponding total frequency range.
On the other hand, for the case of arbitrary masks used in goal functions in Fest3D project, the
data of the masks will be automatically exported to text files located at the path of the CST
Studio project. As an optional step, the user can choose to take those files into account by
including new optimization goals defined with Template Based Post-Processing results in
the Optimization task , in order to force the S-Parameters response to match the curves
represented by the mask files. A guideline for this process is shown in Tutorial 5.3.
This option will appear selected by default if the Fest3D project contains parameters and goal
functions defined for optimization.
After pressing Ok in the export settings window, a new window will appear requesting the name and
location of the exported project in ".cst" format. Once both have been chosen, the exportation process
will begin.
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2.3.8 CLI
The executable file to launch FEST3D in command-line mode can be found in the installation directory of FEST3D. The file is different depending on
the platform where it is being used:
fest3d.exe for Windows platforms
fest3d for Linux platforms.
The executable can be invoked with different combinations of options. Options can be:
optional (enclosed with square brackets "[ ]" ),
required (shown between parentheses "( )" ) or
mutually exclusive (separated by pipes " | ").
All options are required by default, if not included in brackets "[ ]". However, sometimes options are marked explicitly as required with parentheses
"( )". For example, when they belong to a group of mutually-exclusive or mutually-dependent options.
Together, these elements form valid usage patterns, each starting with Fest3D executable.
Usage patterns
FEST3D has two patterns for different usages in command-line mode:
fest3d.exe --help
fest3d.exe
[ (-Z | -S | -Y) ]
[--action= (runConfig | computeFields | visualization)]                
--input=<full_input_file_path>
--output=<full_ouptput_file_path>
[--licenseServer=<port@ip_address | port@hostname>]
[--nthreads=n]
Copyright 2009-2022 Dassault Systemes Deutschland GmbH.
To show the usage and all comand-line options
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[other options depending on mode]
Options
The table below collects FEST3D command-line options in both long and short forms together with their description. Options with arguments are
followed by "arg" in the table.
Option
--help [-h]
Usage and meaning
prints help usage.
--licenseServer = <port@ip_address |
port@hostname>
Set the address of the license server, typically 27000@localhost for Node-locked License or
27000@ip_address for LAN License. If it is not set, Fest3D will search for a valid license.
ANALYSIS OR EXPORT
--action=<actionType>
define type of action performed by FEST3D application. <actionType> can be:
runConfig
computeFields
exportfile
exportfileblocks
exportcst 
CHARACTERIZATION
-Z
-S
-Y
MANDATORY PARAMETERS FOR ANY TYPE
OF LAUNCH
calculate multi-mode impedance matrix Z
calculate multi-mode scatter matrix S
calculate multi-mode admittance matrix Y
--input=<file>
[--nthreads=<value>]
set .fest3x input file. Must be specified with full path
set number of threads used in the calculation. Although it is optional, it is strongly
recommended to use it. Default value is 1
EXTRA ARGUMENTS
DEPENDING ON SIMULATION
MODE
EXPORTATION
--efile=<file>
--eunits=<type>
path and name of the file where the export will be created
set the type of units to which export the circuit. Types can be meters, mm (default), inches
--esatversion=<value>
indicates the version of ACIS in which the exported SAT file will be written
EXTRA MODIFIERS
CACHE MODIFIERS
--disable_init_lastsimpr
disable use/creation of cache files
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OTHER MODIFIERS
-verbose=<LEVEL>
set mildest severity <LEVEL> that is reported (default: info)
Launching mode examples
S-PARAMETER LAUNCH
FORMAL
LAUNCH
<installation_path/fest3d.exe>
--action=runConfig
--config=Project:1/Model:1/ConfigGroup:1/SparamConfig:1//
--input="<folder_containing_fest3d_file>\<name>.fest3x"
--output="<folder_containing_fest3d_file>\<name>.out
--licenseServer=27000@localhost
--nthreads=<number>
EXAMPLE "C:\Program Files (x86)\CST Studio <version>\FEST3D\fest3d.exe" --action=runConfig --
config=Project:1/Model:1/ConfigGroup:1/SparamConfig:1// --
input="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpas\bandpass.fest3x" --
output=D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpas\bandpass.out --licenseServer=27000@localhost --
nthreads=4
EM-FIELDS LAUNCH
FORMAL
LAUNCH
<installation_path/fest3d.exe>
--action=computeFields
--input="<folder_containing_fest3d_file>\<name>.fest3x"
--licenseServer=27000@localhost
--nthreads=<number>
EXAMPLE "C:\Program Files (x86)\CST Studio <version>\FEST3D\fest3d.exe" --action=computeFields --
input="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpass\bandpass.fest3x" --licenseServer=27000@localhost --
nthreads=4
EXPORTATION TO CAD FILE LAUNCH
FORMAL
LAUNCH
<installation_path/fest3d.exe>
--action=exportfile
--input="<folder_containing_fest3d_file>\<\name>.fest3x"
--licenseServer=27000@localhost
--esatversion=<sat_version>
--efile=<path\sat_filename>.sat
--eunits=<units>
EXAMPLE "C:\Program Files (x86)\CST Studio <version>\FEST3D\fest3d.exe" --action=exportfile --
input="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpass\bandpass.fest3x" --licenseServer=27000@localhost --
esatversion=31.0 --efile="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpass\bandpass.sat" --eunits=mm
EXPORTATION TO CST PROJECT LAUNCH
FORMAL <installation_path/fest3d.exe>
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LAUNCH
--action=exportcst
--input="<folder_containing_fest3d_file>\<\name>.fest3x"
--licenseServer=27000@localhost
--efile=<path\cst_filename>.cst
--eunits=<units>
EXAMPLE "C:\Program Files (x86)\CST Studio <version>\FEST3D\fest3d.exe" --action=exportcst --
input="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpass\bandpass.fest3x" --licenseServer=27000@localhost --
efile="D:\workspace\Examples\Analysis\Rectangular\Bandpass\Bandpass\bandpass_CST.cst" --eunits=mm
OPTIMIZER LAUNCH
FORMAL
LAUNCH
<installation_path/opt3d.exe>
--input="<folder_containing_fest3d_file>\<name>.optx"
--engine_in=<name>.fest3x
--out-curr=<output_current_step>
--out-prev=<output_previous_step>
--engine=<installation_path/fest3d>
--
--licenseServer=27000@localhost
--nthreads=<number>
EXAMPLE "C:\Program Files (x86)\CST Studio <version>\FEST3D\opt3d.exe" --
input="D:\workspace\Examples\Analysis\Circular\Page_URSI_2001\Page_URSI_2001_to_optimize\Page_URSI_2001_to_optimize.optx" --
engine_in=Page_URSI_2001_to_optimize.fest3x --out-
curr="D:\workspace\Examples\Analysis\Circular\Page_URSI_2001\Page_URSI_2001_to_optimize\Page_URSI_2001_to_optimize.out" --
out-
prev="D:\workspace\Examples\Analysis\Circular\Page_URSI_2001\Page_URSI_2001_to_optimize\Page_URSI_2001_to_optimize.out.prev"
--engine="E:\nosave\git\suite_master\INSTALLATION\FEST3D\fest3d" -- --licenseServer=27000@localhost --nthreads=4
2.4 Elements Database
This section describes the components supported by Fest3D, as well as the dialog boxes used to view and edit them.
In Fest3D, the term "element" and its synonim "component" indicates each elementary building block of a circuit. The
elements supported by Fest3D are divided in two classes: waveguides and discontinuities. Waveguides can only be
connected to discontinuities, and vice-versa.
Each element has its own reference system, whose position and orientation depend, firstly, on the type of component
and, ultimately, on the element's location inside the current circuit. On the one hand, discontinuities set the reference
system of each one of their ports. On the other hand, taking into account that the reference systems of the
components connected to each other must match, waveguides' reference system is settled by its counterpart located
in the discontinuities connected to them. However, there is an ambiguity in the determination of elements' coordinate
systems, in general, which is solved by setting the global property reference port 3D. Once we select an I/O port
number for this global property, a reference system is anchored to this I/O waveguide port and the ambiguity of the
whole circuit is solved through the ports' matching between waveguides and discontinuities.
The Elements Database section contains the following topics:
Waveguides
Definition of waveguide, and the list of waveguides supported by Fest3D.
Discontinuities
Definition of discontinuity, and the list of discontinuities supported by Fest3D.
Symmetries
Description of the symmetries, and the list of the available ones for each element.
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2.4.1 Waveguides
This section describes all the waveguides supported by Fest3D, and how they can be used as building blocks to
compose circuits.
The waveguides section contains the following topics:
Definition
What is exactly a Fest3D waveguide, and how it can be used in a circuit.
Waveguides List
All waveguides supported by Fest3D.
Common
Properties
The common properties to all waveguides, their meaning and the dialog box to view/edit
them.
Definition
In Fest3D, a waveguide is an element with uniform cross-section (with a single exception). Waveguides can be either
normal transmission lines, open-ended (I/O port) or closed on a load.
Waveguides can only be connected to one or two discontinuities.
Coordinate System
The coordinate system in a waveguide port is imposed by the one corresponding to the discontinuity port connected
to it. The coordinate system in the other waveguide port will be parallel to the previous one. The next figure shows
this behavior with a rectangular arbitrary waveguide.
Waveguides List
Fest3D supports a large number of different waveguides. In the following, all these waveguides are described and
grouped by their type:
Basic Waveguides
Rectangular
The classic, uniform waveguide with rectangular cross section.
Circular
Coaxial
The classic, uniform waveguide with circular cross section.
The classic, uniform waveguide with an external and an internal circular contours.
Rectangular-Contour Based Waveguides
Here is the list of all waveguides based on an Arbitrary Waveguide with Rectangular-Contour (ARW):
Arbitrary
A uniform waveguide with arbitrary (i.e. defined by the user) cross-section. Supports inner
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Rectangular conductors (and thus TEM modes), strip lines and fin lines. The cross-section contour can be
composed by straight segments, arcs and elliptic arcs. It uses BI-RME method on a Rectangular
reference section.
Coaxial
Square
coaxial
Cross
Draft
A uniform waveguide with a circular inner conductor and with an external conductor either
rectangular or circular. Always has a single TEM mode.
A uniform waveguide with both rectangular inner and external conductors.
A uniform waveguide with two arms of a given width. The extremes of the arms can be rounded.
A uniform rectangular waveguide in which the lateral walls have a triangular shape due to
manufacturing processes.
Elliptic
A uniform waveguide with elliptic cross-section (can be rotated).
Ridge
A uniform waveguide with ridged cross-section.
Slot
A uniform rectangular waveguide with rounded corners.
Truncated
A uniform circular waveguide which has been truncated by horizontal and/or vertical rectangular
segments.
Waffle
A uniform rectangular waveguide with rectangular metallic insertions in the top and/or the bottom
walls. Also called a multi-ridge waveguide.
Ridge-gap
A uniform rectangular waveguide with rectangular metallic insertions symmetrically placed with
respect to the central axis in the top and/or the bottom walls.
The lateral coupling circular waveguide is a dumbbell-shaped element which allows a lateral
rectangular coupling between two circular cavities.
Lateral
coupling
circular
waveguide
Circular-Contour Based Waveguides
Here is the list of all waveguides based on an Arbitrary Waveguide with a Circular Contour (ACW):
Arbitrary
Circular
A uniform waveguide with arbitrary (i.e. defined by the user) cross-section. Implemented as a Circular
waveguide with perturbations. Supports fin lines, but not strip lines or inner conductors (and thus no
TEM modes). The cross-section contour can be composed by straight segments and by arcs belonging
to the unperturbed Circular waveguide. Uses BI-RME method on a Circular reference section.
A uniform waveguide with a elliptic section (axes can have any rotation).
A uniform waveguide with a cross-shaped section.
A uniform waveguide with a "circular with screws" section.
Arbitrary
Circular
with an
Ellipse
Arbitrary
Circular
with a
Cross
Arbitrary
Circular
with
Screws
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Other Waveguides
Here is the list of all waveguides that do not fit in the previous groups:
Radiating
Array
A mathematical representation of an infinite, periodic array of rectangular or circular I/O ports opened
in the free space. Can only be used as I/O Port. It is currently the only Fest3D component with
antenna-like characteristics.
Curved
A waveguide with rectangular cross-section, constant curvature radius and curved either left or right.
There are also techniques to obtain waveguides curved up or down.
An optimized elliptical iris that can be connected only to two circular waveguides.
Circular-
Elliptic
iris
Common Properties
Each waveguide can be used in one of the following three modes (SubType):
Transmission Line. It is the normal type. It has two connections (ports), one at each side, attached to two
discontinuities.
Input/Output port. The waveguide terminates one of its sides with an input/output port. The user has to
define the Port Number, consequently identifying the input/output port, and the order number of the Excited
mode, in the range [1, Number of accessible Modes]. It is also possible to use different order numbers for the
Input mode and Output mode, which must be in the same range.
Termination. The waveguide terminates with an adapted load or short circuit on one of its sides. The user has
to define the reflection coefficient within the range [-1,1]. The waveguide has only one connection, attached to
a discontinuity.
The waveguides have the following common modal parameters which set the accuracy of the computation:
Number of accessible Modes Number of accessible (i.e. connecting, propagating) modes of the waveguide.
Only the accessible modes of a waveguide are assumed to transmit E.M fields (and energy) across the whole
waveguide length. (default: 10)
Number of MoM basis functions Number of modes used in the internal MoM to calculate the discontinuities
attached to the waveguide (default: 30)
Number of Green function terms Number of terms in the frequency-independent (static) part of the Green's
function, which describes the discontinuities attached to the waveguide (default: 300)
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for these properties (stored in the General Specifications window) or the values specified by the user in each
waveguide.
The dialog box of all waveguides contains a Specific tab, where the SubType and some related parameters can be
edited:
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Fest3D waveguides have three common sets of properties: Ports, that shows which discontinuities are attached to the
current waveguide, Material, which contains a basic set of physical material properties, and EM Field, which involves
the resolution of the electromagnetic field calculated for the current waveguide. They typically look as follows:
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The Ports cannot be edited. To change the connections among elements, see the Elements Bar paragraph in the Main
Window section.
By clicking on the Use General Specifications button in the Material or in the EM Field tab, each waveguide can be
configured to either use the default values for these properties (stored in the General Specifications window) or to
per-waveguide user-specified values.
The material parameters are the following (they are also described in the General Specifications window):
Dielectric Permittivity Relative dielectric constant of the dielectric homogeneously filling the waveguide
(default: 1.0 i.e. vacuum)
Dielectric Permeability Relative dielectric constant of the dielectric homogeneously filling the waveguide
(default: 1.0 i.e vacuum)
Dielectric Conductivity Intrinsic conductivity of the dielectric homogeneously filling the waveguide, in S/m
(default: 0.0)
Metal Resistivity Intrinsic resistivity of the metallic walls of the waveguide, in Ohm · m (default: 0.0)
2.4.1.1 Basic Waveguides
2.4.1.1.1 Rectangular Waveguide
This section describes the Rectangular waveguide and how to use it, as well as its features and limitations.
The Rectangular waveguide section contains the following topics:
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Definition
Limitations
Errors
What is exactly a Rectangular waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Rectangular How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Rectangular waveguide is a uniform waveguide with rectangular cross section, as shown in the following figure:
Limitations
The Rectangular waveguide has no limitations.
Errors
The Rectangular waveguide should never produce errors.
Using the Rectangular
The dialog box of the Rectangular waveguide is quite minimal, yet it is the standard base for the dialog boxes of all
other Waveguides.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
A (mm) the waveguide width
B (mm) the waveguide height
L (mm) the waveguide length
Additionally, in order to fill the A and B parameters, one can choose between a set of standard rectangular
waveguives by clicking in the box of Use Standard Waveguide.
In order to perform either Multipactor Analysis or Corona Analysis in such a waveguide just click in the
corresponding box.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
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Hints
The length of this waveguide can be zero.
2.4.1.1.2 Circular Waveguide
This section describes the Circular waveguide and how to use it, as well as its features and limitations.
The Circular waveguide section contains the following topics:
Definition
What is exactly a Circular waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Circular
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Circular waveguide is a uniform waveguide with circular cross section, as shown in the following figure:
Limitations
The modes of the Circular waveguides are pre-computed. The maximum number of supported modes is
approximately 160000.
In case that "all-cylindrical" symmetry is used, this basically means that NO more than 795 terms of the green function
can be used. However, this number should be more than enough to reach convergence and it is not a real limitation.
In case that TEM symmetry is used, this basically means that NO more than 200 terms of the green function can be
used. However, this number should be more than enough to reach convergence and it is not a real limitation.
Errors
If the user specifies more than approximately 160000 modes (the maximum supported), an error is produced and the
simulation stops. The Circular waveguide produces no other errors.
Using the Circular
The dialog box of the Circular waveguide is the following:
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
R (mm) the waveguide radius
L (mm) the waveguide length
The user can choose standard circular waveguides by clicking the corresponding box and selecting one of the
waveguide numbers.
In order to perform either Multipactor Analysis or Corona Analysis in such a waveguide just click in the
corresponding box.
The first mode of the circular waveguide is chosen as the one with vertical polarization.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
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Hints
The length of this waveguide can be zero. This is sometimes useful if the direct coupling between two
waveguides is not available in Fest3D.
2.4.1.1.3 Coaxial waveguide
This section describes the circular coaxial waveguide and how to use it, as well as its features and limitations.
The coaxial waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an circular coaxial waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the circular coaxial
waveguide
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The coaxial waveguide is a uniform waveguide with circular cross section, as shown in the following figure:
Limitations
The direct coupling of this element to the circular waveguide can be done only in the case that the circuit has TEM
symmetry. Circuits with such a symmetry should begin and finish with coaxial waveguides, no offsets should be
present and the circuit can be only composed by coaxial and circular elements.
Errors
In the case of coaxial-circular connections, only the discontinuities showed in the following picture can be directly
computed with a step.
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Other cases should be tackled by using an intermediate zero length circular waveguide of the same radius than the
outer bigger radius of the attached waveguides.
The coaxial waveguide produces no other errors.
Using the coaxial
The coaxial waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes.
The following picture shows a typical Element Properties dialog box for the coaxial waveguide.
The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
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Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The number of basis functions for the coaxial waveguide is automatically given as a function of the number of terms
of Green's function terms:
TEM symmetry: the number of basis functions is two times Number of Green's function terms. The maximum
number is set to 150 since this provides around 45000 modes.
Without symmetry: the number of basis functions is three times the square root of the Number of Green's
function terms. IMPORTANT: If a large amount of accessible modes is desired, and the number of Green's
funcions is not high enough, a warning message will appear inidicating the recommended number of Green's
functions for computing the high modes with a certain accuracy. If this requirement is not fulfilled, numerical
instabilities may occur in the simulation.
The following parameters can be edited:
L (mm): waveguide length.
Outer Radius (mm): radius of the outer circular.
Inner Radius (mm): radius of the inner circular.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Material tab allows customizing the physical material properties for the current waveguide, as described in the
Waveguides Common Properties section.
Hints
When the symmetry TEM is active, it is recommended to reduce a lot the number of Green's function terms.
Values around 20 or even below of this number could already provide convergent results.
2.4.1.2 Arbitrary Rectangular Waveguides
2.4.1.2.1 Arbitrary Rectangular (ARW)
This section describes the Arbitrary Rectangular waveguide and how to use it, as well as its features and limitations.
The Arbitrary Rectangular waveguide section contains the following topics:
Definition
Limitations
Errors
Using the Arbitrary
Rectangular
What is exactly an Arbitrary Rectangular waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
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The Arbitrary Rectangular waveguide computes the modal chart of any waveguide with an arbitrary cross section
defined by a combination of linear, circular and elliptical arcs, which must be included in a fictitious, bigger
rectangular waveguide (reference box).
The reference box is a fictitious rectangular waveguide that surrounds the contour of the Arbitrary Rectangular
waveguide and is needed by the mathematical theory used by this element (BI-RME Method).
The cross-section of this element can be composed by one or more contours, which define its geometry. Each
contour can be defined by means of straight, circular and elliptical arcs, as well as of any possible combination
between these three kinds of segments.
The user must define only the portions of the arbitrary contour that not coincide with the surrounding rectangular
box. In the following picture the contour of the arbitrary waveguide divides the reference box into an internal area S
and a complementary area.
The cross-section to be analyzed can have multiple inner contours, such as the ones shown in the following picture,
which defines the internal areas S,S1,S2,S3. In this case the user must be careful, since there are four regions (or areas)
that the program can use to perform the analysis. Only one region of interest (S1, S2, S3 or S) must be indicated for
modal analysis purposes.
The Arbitrary Rectangular waveguide supports TEM modes when the arbitrary contour has inner conductor(s). The
number of TEM modes present in an Arbitrary Rectangular waveguide is equal to the number of inner conductors.
Important: The hollow section of the arbitrary waveguide is defined by the "X" point present in the mesh editor/file.
Limitations
The Arbitrary Rectangular waveguide has some limitations and caveats you should be aware of.
3D Visualization
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This element can be only visualized in 3D by making use of the 3D Viewer which is accessible from the
main Window top menu bar.
Connections to other elements
The Arbitrary Rectangular waveguide can only be connected to Step or N-Step. It is possible to connect the
remaining ports of those Steps and N-Steps to Rectangular, Circular, Arbitrary Rectangular, (or derived, as
Coaxial and Elliptic) waveguides. If the connected waveguides have the same reference box as this element and
their X,Y offsets and rotation are zero, a specialized routine is used to compute the coupling integral, which is
faster and more accurate than the general case.
Invalid contours
A contour cannot exceed the rectangular surrounding box. Contours cannot touch or intersect one another but
can touch the external reference box. Contours cannot contain invalid parameters:
the radius of a circular portion must be grater than zero
the minor semi-axis of an elliptical portion must be lesser than the major semi-axis and greater
than zero
only one region of interest of the cross-section can be specified (this is handled automatically by
Fest3D)
If a contour defined by the user is invalid, the program generates a fatal error and stops the simulation.
Tangent contours
Each contour can take any shape, and it can be therefore also tangent or incident to the external box as in the
pictures below. Some precautions should be taken in this case. If a circular or elliptical arc is tangent to the
external rectangular box in points different to the starting and ending points of the arc, this will not be
detected by the program. For this reason, the user must split or rearrange the arcs so that only the starting
and/or ending points of the arc are tangent to the rectangular box. Furthermore, in this case some errors may
happen. Such errors must be adequately treated as discussed in convergence failed paragraph below.
Very big or very small cross-section areas (>95% or <30% of the reference box area)
If the contour of the arbitrary structure nearly coincides with the rectangular surrounding waveguide, the
program may produce the error no points to test E.M. fields explained below.
In the opposite case, if the cross-section defines a very small area (<30%), the method will need a big number
of resonant modes to generate the same number of valid modes for the arbitrarily shaped waveguide. In such a
case, the user should use a smaller reference box, or an extremely high number of modes for the rectangular
box (the latter solution highly increases consumed memory and computational time of simulation.
Low accuracy at extremely low frequencies (<0.1 GHz)
If an Arbitrary Rectangular waveguide with inner conductor(s) and thus TEM modes is used to simulate a circuit
at extremely low frequencies (<0.1 GHz), the results produced will be very probably inaccurate. In such case,
the user should increase only the number of reference box modes and the number of Green function terms.
This problem has two correlated causes:
1.  The Integral Equation method shows numeric instabilities at extremely low frequencies and fails at
exactly zero frequency.
2.  The coupling integrals corresponding to the possible connections between the Arbitrary Rectangular
modes (in particular the TEM modes) and the connected waveguides modes are computed numerically
and are thus not analitically exact. This numeric error enhances the above numeric instabilities resulting
in low accuracy.
The proposed solution (increase only the number of reference box modes and the number of Green function
terms) produces more accurate coupling integrals and thus solves the problem for the used frequency range.
Be aware that, by going further down in frequency range, the problem will re-appear.
The accuracy vs. speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Arbitrary Rectangular waveguide can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
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error in subroutine GEIG/EIG: convergence failed in lapack for solving TE/TM eigenvalue problem
This error may be produced when the arbitrary contour is tangent to the reference box as shown in the picture
above. In this case, the user should either reduce the number of modes of the reference box or use a bigger
reference box.
Error: no points to test the E.M. fields
This error may be produced if the contour of the arbitrary structure nearly coincides with the rectangular
surrounding box. In this case, you can increase the number of modes or use a bigger reference box.
Error: not enough arbitrary modes generated
If the number of generated modes is less than required, the program generates this warning message. The
program automatically reduces the number of basis functions to go ahead in the simulation. If no convergence
is reached, the user must start a new simulation specifying more reference box modes.
Error: LTM Matrix is not positive definite. Please, try to increase the number of reference box modes.
This error can occur if the geometry is tricky. For instance, if a small arc is employed. To solve the problem, you
can try to increase the number of reference box modes until the error disappears.
Using the Arbitrary Rectangular
The Arbitrary Rectangular waveguide is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes and can view and edit the arbitrary shape using the Arbitrary Shape Editor.
The following picture shows a typical Element Properties dialog box for the Arbitrary Rectangular Waveguide.
The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
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The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the
arbitrary cross-section. By default the number of reference box modes is 0, which means that it will be
autocomputed
A (mm): the reference box width.
B (mm): the reference box height.
L (mm): the waveguide length.
MESH File: file containing the arbitrary cross-section. The Edit button opens the Arbitrary Shape Editor
allowing the user to view/edit it.
The Material and EM Field tabs allow customizing, respectively, the physical material properties and the
electromagnetic resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or
arbitrary waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence
problems can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of
reference box modes in order to have enough precision is done.
If unexpected results are obtained, verify that the "x" in the arbitrary shape editor is within the region of
interest.
2.4.1.2.2 Coaxial waveguide
This section describes the Coaxial waveguide and how to use it, as well as its features and limitations.
The Coaxial waveguide section contains the following topics:
Definition
What is exactly a Coaxial waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Coaxial
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Coaxial waveguide is a uniform, coaxial waveguide with a circular inner conductor and either a circular or a
rectangular outer conductor.
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The Coaxial waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
If the Coaxial waveguide outer conductor is circular, the inner and outer circular conductors must have the same axis.
If the Coaxial waveguide outer conductor is rectangular, it must coincide with the reference box.
The Coaxial waveguide supports TEM modes. Actually, it always has a single TEM mode.
Limitations
The Coaxial waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Coaxial waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Coaxial
The Coaxial waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Coaxial waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
A of reference box (mm): reference box width.
B of reference box (mm): reference box height.
Outer Conductor Shape: either rectangular or circular
Inner Radius (mm): radius of the inner circular conductor.
L (mm): waveguide length.
Center X offset (mm): horizontal offset of the inner conductor center, relative to the reference box center.
Center Y offset (mm): vertical offset of the inner conductor center, relative to the reference box center.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
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Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.3 Cross waveguide
This section describes the cross waveguide and how to use it, as well as its features and limitations.
The cross waveguide section contains the following topics:
Definition
What is exactly a cross waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the cross
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Cross waveguide is a uniform waveguide with two arms of a given width. The extremes of the arms can be
rounded. The following figure shows the element:
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The Cross waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
Limitations
The Cross waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The cross waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Cross waveguide
The Cross waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by clicking the plot
button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the cross waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box(mm): reference box width.
Bbox reference box(mm): reference box height.
A (if 0, A=Abox)(mm): length of horizntal arm.
B (if 0, B=Bbox)(mm): length of vertical arm.
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A1 (mm): width of horizontal arm.
L (mm): waveguide length.
B1 (mm): width of vertical arm.
R (mm): radius of the arm extreme corners.
Rint (mm): internal radius of the arm corners.
X0 Offset (mm): horizontal offset of the cross waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the cross waveguide center, relative to the reference box center.
Alpha (degrees): rotation of the cross waveguide w.r.t the reference rectangular box.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.4 Draft waveguide
This section describes the draft waveguide and how to use it, as well as its features and limitations.
The draft waveguide section contains the following topics:
Definition
What is exactly a draft waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the draft
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Draft waveguide is a rectangular waveguide in which the lateral walls have a triangular shape due to
manufacturing processes. The following figure shows the element:
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The Draft waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the draft section of the
real waveguide.
Limitations
The Draft waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The draft waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Draft waveguide
The Draft waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by clicking the plot
button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the draft waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box(mm): reference box width.
Bbox reference box(mm): reference box height.
A (if 0, A=Abox)(mm): width of draft waveguide.
B (if 0, B=Bbox)(mm): height of draft waveguide.
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L (mm): waveguide length.
R (mm): radius of the draft waveguide corners .
Beta (degrees): angle of the draft waveguide .
X0 Offset (mm): horizontal offset of the draft waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the draft waveguide center, relative to the reference box center.
Alpha (degrees): rotation of the draft waveguide w.r.t the reference rectangular box.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.5 Elliptic waveguide
This section describes the Elliptic waveguide and how to use it, as well as its features and limitations.
The Elliptic waveguide section contains the following topics:
Definition
What is exactly an Elliptic waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Elliptic
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Elliptic waveguide is a uniform waveguide with elliptic cross-section as shown in the following legend.
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The Elliptic waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
Limitations
The Elliptic waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Elliptic waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Elliptic
The Elliptic waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Elliptic waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
A of reference box (mm): reference box width.
B of reference box (mm): reference box height.
A, Major Axis (mm): ellipse major (horizontal) axis.
B, Minor Axis (mm): ellipse minor (vertical) axis.
L (mm): waveguide length.
Center X offset (mm): horizontal offset of the ellipse center, relative to the reference box center.
Center Y offset (mm): vertical offset of the ellipse center, relative to the reference box center.
Rotation (degrees): rotation angle of the ellipse, counterclockwise.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
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resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.6 Ridge waveguide
This section describes the Ridge waveguide and how to use it, as well as its features and limitations.
The ridge waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly a Ridge waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Ridge waveguide How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Ridge waveguide is a uniform rectangular waveguide with one or two (double ridge) rectangular metal insets in
the top and/or in the bottom of the rectangular housing. The following figure shows the element:
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The Ridge waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
Limitations
The Ridge waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Ridge waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Ridge waveguide
The Ridge waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by clicking the plot
button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the Ridge waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
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Abox reference box(mm): reference box width.
Bbox reference box(mm): reference box height.
A (if 0, A=Abox) (mm): width of the ridge waveguide.
B (if 0, B=Bbox) (mm): height of the ridge waveguide.
L (mm): waveguide length.
A1 (mm): width of the top ridge inset.
B1 (mm): height of the top ridge inset.
A2 (mm): width of the bottom ridge inset.
B2 (mm): height of the bottom ridge inset.
Rext (mm): radius of external corners
Rint (mm): radius of internal corners
X0 Offset (mm): horizontal offset of the ridge waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the ridge waveguide center, relative to the reference box center.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.7 Lateral coupling circular waveguide
This section describes the lateral coupling circular waveguide and how to use it, as well as its features and limitations.
The lateral coupling circular waveguide section contains the following topics:
Definition
What is exactly a lateral coupling circular waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the ridge-gap
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The lateral coupling circular waveguide is a dumbbell-shaped element which allows a lateral rectangular coupling
between two circular cavities. The following figure shows the element:
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The lateral coupling circular waveguide is a special case of the more general element Arbitrary Rectangular, and thus
also uses the concept of reference box: a fictitious rectangular waveguide which must completely include the ridge-
gap section of the real waveguide.
Limitations
The lateral coupling circular waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The lateral coupling circular waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the lateral coupling circular waveguide
The lateral coupling circular waveguide is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor
by clicking the plot button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the lateral coupling circular waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box (mm): reference box width.
Bbox reference box (mm): reference box height.
Radius (mm): radius of the connected cylindrical cavities.
Iris height (mm): Iris width/height.
Thickness (mm): distance between circular cavities (measured as seen in the legend).
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L (mm): waveguide length.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.8 Ridge-gap waveguide
This section describes the ridge-gap waveguide and how to use it, as well as its features and limitations.
The ridge-gap waveguide section contains the following topics:
Definition
What is exactly a ridge-gap waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the ridge-gap
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Ridge-gap waveguide is a uniform rectangular waveguide with rectangular metallic insertions in the top and/or
the bottom walls. Also called a multi-ridge waveguide. The following figure shows the element:
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The Ridge-gap waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the ridge-gap section of
the real waveguide.
Limitations
The Ridge-gap waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The ridge-gap waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Ridge-gap waveguide
The Ridge-gap waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by
clicking the plot button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the ridge-gap waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
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Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box (mm): reference box width.
Bbox reference box (mm): reference box height.
A (if 0, A=Abox)(mm): width of ridge-gap waveguide.
B (if 0, B=Bbox)(mm): height of ridge-gap waveguide.
L (mm): waveguide length.
N: number of teeth in the top ridge-gap section. It must be an even number.
Upper Teeth Width (mm): teeth width.
Upper Teeth Height (mm): teeth height.
Upper Main Separation (mm): distance from the center of the waveguide to the first teeth.
M: number of teeth in the bottom ridge-gap section. It must be an even number.
Lower Teeth Width (mm): teeth width.
Lower Teeth Height (mm): teeth height.
Lower Main Separation (mm): distance from the side teeth to the lateral wall. It can be zero.
X0 Offset (mm): horizontal offset of the ridge-gap waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the ridge-gap waveguide center, relative to the reference box center.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.9 Square coaxial waveguide
This section describes the Square coaxial waveguide and how to use it, as well as its features and limitations.
The Square coaxial waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an Square coaxial waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Square coaxial How to create, edit and use this element from Fest3D.
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Hints
Non-trivial properties of this element.
Definition
The Coaxial waveguide is a uniform, coaxial waveguide with both rectangular inner and outer conductors.
The Coaxial waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
The Square coaxial waveguide supports TEM modes. Actually, it always has a single TEM mode.
Limitations
The Square coaxial waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Square coaxial waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Square Coaxial
The Square coaxial waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Square Coaxial waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box (mm): reference box width.
Bbox reference box (mm): reference box height.
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A (if 0, A=Abox) (mm): width of the external conductor.
B (if 0, B=Bbox) (mm): height of the external conductor.
Offset X (mm): horizontal offset of the square coaxial waveguide center, relative to the reference box center.
Offset Y (mm): Vertical offset of the square coaxial waveguide with respect to the reference box.
L (mm): waveguide length.
Bar parameters:
A bar (mm): width of the inner conductor
B bar (mm): height of the inner conductor
Offset X bar (mm): horizontal offset of the inner conductor center, relative to the reference box center.
Offset Y bar (mm): vertical offset of the inner conductor center, relative to the reference box center.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.10 Slot waveguide
This section describes the slot waveguide and how to use it, as well as its features and limitations.
The slot waveguide section contains the following topics:
Definition
What is exactly a slot waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the slot
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Slot waveguide is a uniform rectangular waveguide with rounded corners. The following figure shows the
element:
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The Slot waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
Limitations
The Slot waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The slot waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Slot waveguide
The Slot waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by clicking the plot
button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the slot waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box(mm): reference box width.
Bbox reference box(mm): reference box height.
A (if 0, A=Abox)(mm): width of the slot waveguide.
B (if 0, B=Bbox)(mm): height of the slot waveguide.
R (mm): radius of the corners.
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L (mm): waveguide length.
X0 Offset (mm): horizontal offset of the slot waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the slot waveguide center, relative to the reference box center.
Alpha (degrees): rotation of the slot waveguide w.r.t the reference rectangular box.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.11 Truncated waveguide
This section describes the truncated waveguide and how to use it, as well as its features and limitations.
The truncated waveguide section contains the following topics:
Definition
What is exactly a truncated waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the truncated
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Truncated waveguide is a uniform circular waveguide which has been truncated by an horizontal and/or vertical
rectangular segments. The following figure shows the element:
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The Truncated waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the cross section of the
real waveguide.
Limitations
The Truncated waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The truncated waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Truncated waveguide
The Truncated waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by
clicking the plot button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the truncated waveguide.
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The EnableD/DisableD button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box(mm): reference box width.
Bbox reference box(mm): reference box height.
A (if 0, A=2R)(mm): width of the truncated waveguide.
B (mm): height of the truncated waveguide.
R (mm): radius of the circular waveguide.
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L (mm) the waveguide length.
X0 Offset (mm): horizontal offset of the truncated waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the truncated waveguide center, relative to the reference box center.
Alpha (degrees): rotation of the truncated waveguide w.r.t the reference rectangular box.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.2.12 Waffle waveguide
This section describes the waffle waveguide and how to use it, as well as its features and limitations.
The waffle waveguide section contains the following topics:
Definition
What is exactly a waffle waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the waffle
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Waffle waveguide is a uniform rectangular waveguide with rectangular metallic insertions in the top and/or the
bottom walls. Also called a multi-ridge waveguide. The following figure shows the element:
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The Waffle waveguide is a special case of the more general element Arbitrary Rectangular, and thus also uses the
concept of reference box: a fictitious rectangular waveguide which must completely include the waffle section of the
real waveguide.
Limitations
The Waffle waveguide has the same limitations and caveats as the Arbitrary Rectangular waveguide.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The waffle waveguide can produce the same errors as the Arbitrary Rectangular waveguide.
Using the Waffle waveguide
The Waffle waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes. It is also possible to view the arbitrary shape using the Arbitrary Shape Editor by clicking the plot
button located at the end of the Specific tab.
The following picture shows a typical Element Properties dialog box for the waffle waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Number of box modes: number of modes in the reference box used to generate the modes of the arbitrary
cross-section. By default the number of reference box modes is 0, which means that it will be autocomputed.
Abox reference box (mm): reference box width.
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Bbox reference box (mm): reference box height.
A (if 0, A=Abox)(mm): width of waffle waveguide.
B (if 0, B=Bbox)(mm): height of waffle waveguide.
L (mm): waveguide length.
N: number of teeth in the top waffle section.
A1 (mm): distance from the side teeth to the lateral wall. It can be zero if you want teeth to be touching the
borders. It can be negative in order to achieve lateral teeth with smaller dimensions than the rest of the teeth.
B1 (mm): teeth height.
C1 (mm): teeth width.
M: number of teeth in the bottom waffle section.
A2 (mm): distance from the side teeth to the lateral wall. It can be zero if you want teeth to be touching the
borders. It can be negative in order to achieve lateral teeth with smaller dimensions than the rest of the teeth.
B2 (mm): teeth height.
C2 (mm): teeth width.
X0 Offset (mm): horizontal offset of the waffle waveguide center, relative to the reference box center.
Y0 Offset (mm): vertical offset of the waffle waveguide center, relative to the reference box center.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
NOTE: Using A1 or B1 < 0 leads to waffle waveguides like this example:
Hints
It is always recommended to use a reference box of the same size as the surrounding rectangular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
2.4.1.3 Arbitrary Circular Waveguides
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2.4.1.3.1 Circular Arbitrary (ACW)
This section describes the Arbitrary Circular waveguide and how to use it, as well as its features and limitations.
The Arbitrary Circular waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an Arbitrary Circular waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Arbitrary Circular How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Arbitrary Circular waveguide computes the modal chart of any waveguide with an arbitrary cross section defined
by a combination of linear, circular and elliptical arcs, which must be included in a fictitious, bigger circular waveguide
(reference cavity).
The reference cavity is a fictitious circular waveguide that surrounds the contour of the Arbitary Circular waveguide
and is needed by the mathematical theory used by this element (BI-RME Method).
The cross-section of this element can be composed by one or more contours, which define its geometry. Each
contour can be defined by means of straight, circular and elliptical arcs, as well as of any possible combination
between these three kinds of segments.
The user must define only the portions of the arbitrary contour that do not coincide with the surrounding circular
reference cavity. In the following pictures the contours divide the reference cavity into an internal area S, which is the
cross section of the arbitrary waveguide, and a complementary area. The cross section S is assumed to be embedded
entirely in the circular reference cavity.
The cross-section to be analyzed can have multiple inner contours, such as the ones shown in the following picture,
which defines the internal areas S,S1,S2,S3. In this case the user must be careful, since there are four regions (or areas)
that the program can use to perform the analysis. Only one region of interest (S1, S2, S3 or S) must be indicated for
modal analysis purposes.
Examples of possible geometries are shown below. The contours supported by the Arbitrary Circular waveguide can
be divided into four types:
1.  closed over the cavity: a contour with two contact points placed on the external reference cavity, as in the
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following figure
2.  closed: a closed contour not touching the external cavity, as the following figure shows
3.  stripline: a stripline consists of a narrow metal strip placed between two metallic ground planes. This element
supports the modal analysis of encapsulated strip lines, as the one included in the following figure
4.  finline: a finline is an encapsulated slotline. This element supports the analysis of finlines if the dielectric
substrate of the finline and the dielectric waveguide material are the same, as shown in the following figure
where eight finlines are used
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Important: The hollow section of the arbitrary waveguide is defined by the "X" point present in the mesh editor/file.
Limitations
The Arbitrary Circular waveguide has some limitations and caveats you should be aware of:
connections to other elements
The Arbitrary Circular waveguide can only be connected to Step or N-Step. It is possible to connect the
remaining ports of those Steps and N-Steps to Rectangular, Circular, Arbitrary Circular (and derived, such as
ACW with Screws, ACW with an Ellipse and ACW with a Cross) or Arbitrary Rectangular, (and derived, such as
Coaxial and Elliptic) waveguides. If the connected waveguides have the same reference box as this element and
their X,Y offsets and rotation are zero, a specialized routine is used to compute the coupling integral, which is
faster and more accurate than the general case.
invalid contours
A contour cannot exceed the circular reference cavity. Contours cannot touch or intersect one another but can
touch the external reference box. Contours cannot contain invalid parameters:
the radius of a circular portion must be grater than zero
the minor semiaxis of an elliptical portion must be lesser than the major semiaxis and greater than zero
only one offset, rotation and region of interest of the cross-section can be specified (this is handled
automatically by Fest3D)
If a contour defined by the user is invalid, the program generates a fatal error and stops the simulation.    
tangent contours
Each contour can take any shape, and it can be therefore also tangent or incident to the external box as in the
pictures below. Some precautions should be taken in this case. If elliptical arc is tangent to the external circular
box in points different to the starting and ending points of the arc, this will not be detected by the program.
For this reason, the user must split or rearrange the arcs so that only the starting and/or ending points of the
arc are tangent to the circular box. Furthermore, in this case some errors may happen. Such errors must be
adequately treated as discussed in the LTM Matrix is not positive definite paragraph below.
very big or very small cross-section areas (>95% or <30% of the reference box area)
If the contour of the arbitrary structure nearly coincides with the circular surrounding waveguide, the program
may produce the error no points to test E.M. fields explained below.
In the opposite case, if the cross-section defines a very small area (<30%), the method will need a big number
of resonant modes to generate the same number of valid modes for the arbitrarily shaped waveguide. In such a
case, the user should use a smaller reference box, or an extremely high number of modes for the circular box
(the latter solution highly increases consumed memory and computational time of simulation. This case should
be avoided if possible.
The accuracy vs speed tradeoffs of this element are also treated in a subsection of Tutorial 3: Accuracy or Speed?
Errors
The Arbitrary Circular waveguide can produce the following errors under certain circumstances. Each error and their
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possible solutions or workarounds are explained as follows:
error: not enough arbitrary modes generated
This error message means that the algorithm could not compute enough modes in the waveguide of arbitrary
cross section. In this case, the number of modes of the reference circular box must be increased. The numerical
effort (used memory and computational time) increases with the previous number of modes, thus care must be
taken when increasing this parameter. Alternatively, the number of accessible modes in the waveguide may be
reduced.
error: no points to test the E.M. fields
This error may be produced if the contour of the arbitrary structure nearly coincides with the circular
surrounding box. In this case, you have to increase the number of modes or use a bigger circular box.
error: LTM Matrix is not positive definite.
This error can occur if the geometry is tricky, specially when there are tangent contours involved. You can take
several actions in order to solve this problem:
Increase the number of box modes: if the source of the problem is the numerical convergence of the
method, this action might solve it.
Change the dimension of the reference box: this action is specially useful if the structure is touching the
box, for instance, where tangent contours are involved. A slightly bigger box might be able to solve the
structure correctly.
Using the Arbitrary Circular
The Arbitrary Circular waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes and can view and edit the arbitrary shape using the Arbitrary Shape Editor.
The following figures show a typical Element Properties dialog box for the Arbitrary Circular Waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited in the Specific page:
Number circular box modes: number of modes in the reference box used to generate the modes of the
arbitrary cross-section. By default the number of reference box modes is 0, which means that it will be
autocomputed.
Rbox (reference box)(mm): reference circular cavity radius.
L (mm): waveguide length.
MESH File: file containing the arbitrary cross-section. The Edit button opens the Arbitrary Shape Editor
allowing the user to view/edit it.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
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Hints
The length of this waveguide can be zero.
It is always recommended to use a reference box of the same size as the surrounding circular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
If strange results are obtained, verify that the "x" in the arbitrary shape editor is within the region of interest.
2.4.1.3.2 ACW with an Ellipse
This section describes the Arbitrary Circular with an Ellipse waveguide and how to use it, as well as its features and
limitations.
The Arbitrary Circular with an Ellipse waveguide section contains the following topics:
Definition
Limitations
Errors
Using the Arbitrary Circular with an
Ellipse
What is exactly an Arbitrary Circular with an Ellipse waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or
workarounds to them.
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Arbitrary Circular with an Ellipse element is an elliptic waveguide. It is a special case of the more general element
Arbitrary Circular, where the arbitrary cross section is an ellipse, as shown in the following figure:
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The Arbitrary Circular with an Ellipse waveguide can only be connected to Step or N-Step discontinuities and there are
also limitations related to the connection of this element to those Step or N-Step. See the Arbitrary Circular
waveguide for further details.
Limitations
The Arbitrary Circular with an Ellipse waveguide has the same limitations and caveats as the Arbitrary Circular element
it is derived from.
Errors
The Arbitrary Circular with an Ellipse waveguide can produce the same errors as the Arbitrary Circular waveguide. It
can also produce errors if an invalid geometry is specified.
Using the Arbitrary Circular with an Ellipse
The Arbitrary Circular with an Ellipse waveguide is completely integrated into Fest3D. The user can create, view and
edit this element properties using dialog boxes.
The following figure shows a typical Element Properties dialog box for the Arbitrary Circular with an Ellipse waveguide:
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited in the Specific page:
Number circular box modes: number of modes in the reference box used to generate the modes of the
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arbitrary cross-section. By default the number of reference box modes is 0, which means that it will be
autocomputed.
Rbox (reference box) (mm): reference circular cavity radius.
A, Major SemiAxis (mm): ellipse major semiaxis length.
B, Minor SemiAxis (mm): ellipse minor semiaxis length.
L (mm): waveguide length.
Center X offset (mm): ellipse horizontal offset from the center of the reference cavity.
Center Y offset (mm): ellipse vertical offset from the center of the reference cavity.
Rotation (degrees): ellipse rotation angle.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is recommended to use this element when the ellipse waveguide is connected to circular waveguides. If
connected to rectangular waveguides, it is better to use the ellipse waveguide done with the arbitrary
rectangular contour.
The length of this waveguide can be zero.
It is always recommended to use a reference box of the same size as the surrounding circular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
If strange results are obtained, verify that the "x" in the arbitrary shape editor is within the region of interest.
2.4.1.3.3 ACW with a Cross
This section describes the Arbitrary Circular with a Cross waveguide and how to use it, as well as its features and
limitations.
The Arbitrary Circular with a Cross waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an Arbitrary Circular with a Cross waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds
to them.
Using the Arbitrary Circular with a
Cross
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Arbitrary Circular with a Cross element is a cross-shaped waveguide. It is a special case of the more general
element Arbitrary Circular, where the arbitrary cross section is always a polygonally approximated cross, as shown in
the following figure:
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The Arbitrary Circular with a Cross waveguide can only be connected to Step or N-Step discontinuities and there are
also limitations related to the connection of this element to those Step or N-Step. See the Arbitrary Circular
waveguide for further details.
Limitations
The Arbitrary Circular with a Cross waveguide has the same limitations and caveats as the Arbitrary Circular element it
is derived from.
Errors
The Arbitrary Circular with a Cross waveguide can produce the same errors as the Arbitrary Circular waveguide. It can
also produce errors if an invalid geometry is specified.
Using the Arbitrary Circular with a Cross
The Arbitrary Circular with a Cross waveguide is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes. It is also possible to view and edit the arbitrary shape, as shown in the
right figure below, using the Arbitrary Shape Editor by clicking the plot button located at the end of the Specific tab.
The following left figure shows a typical Element Properties dialog box for the Arbitrary Circular with a Cross
waveguide:
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited in the Specific page:
Number circular box modes: number of modes in the reference box, used to generate the modes of the
arbitrary section. By default the number of reference box modes is 0, which means that it will be
autocomputed.
Rbox (reference box)(mm): reference circular cavity radius.
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A arm length (mm): length of the horizontal arm.
B arm length (mm): length of the vertical arm.
L (mm): waveguide length.
A1 arm thickness (mm): thickness of the vertical arm.
B1 arm thickness (mm): thickness of the horizontal arm.
R (mm): radius of the arm external corners.
Rint (mm): radius of the arm internal corners
X0 offset (mm): cross horizontal offset from the center of the reference cavity.
Y0 offset (mm): cross vertical offset from the center of the reference cavity.
Alpha (degrees): cross rotation angle.
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints
It is recommended to use this element when the cross waveguide is connected to circular waveguides. If
connected to rectangular waveguides, it is better to use the cross waveguide done with the arbitrary
rectangular contour.
The length of this waveguide can be zero.
It is always recommended to use a reference box of the same size as the surrounding circular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
If strange results are obtained, verify that the "x" in the arbitrary shape editor is within the region of interest.
2.4.1.3.4 ACW with Screws
This section describes the Arbitrary Circular with Screws waveguide and how to use it, as well as its features and
limitations.
The Arbitrary Circular with Screws waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an Arbitrary Circular with Screws waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds
to them.
Using the Arbitrary Circular with
Screws
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Arbitrary Circular with Screws element is a ridged waveguide. It is a special case of the more general element
Arbitrary Circular, where the arbitrary cross section is a ridged waveguide, as shown in the following figure:
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The Arbitrary Circular with Screws waveguide can only be connected to Step or N-Step discontinuities and there are
also limitations related to the connection of this element to those Step or N-Step. See the Arbitrary Circular
waveguide for further details.
Limitations
The Arbitrary Circular with Screws waveguide has the same limitations and caveats as the Arbitrary Circular element it
is derived from.
Errors
The Arbitrary Circular with Screws waveguide can produce the same errors as the Arbitrary Circular waveguide. It can
also produce errors if an invalid geometry is specified.
Using the Arbitrary Circular with Screws
The Arbitrary Circular with Screws waveguide is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes.
The following left figure shows a typical Element Properties dialog box for the Arbitrary Circular with Screws
waveguide, while the right figure shows the screws properties dialog box:
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited in the Specific page:
Number circular box modes: number of modes in the reference box used to generate the modes of the
arbitrary cross-section. By default the number of reference box modes is 0, which means that it will be
autocomputed.
Rbox (reference box) (mm): reference circular cavity radius.
L (mm): waveguide length. The Arbitrary Circular with Screws waveguide is a ridged waveguide, so L (mm) is
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also the depth of the screws.
The following parameters can be edited for each screw in the Screws page:
Phase of screw (deg): angular location of the screw, counterclockwise.
Length of screw: screw length (height).
Thickness of screw: screw thickness (width).
Material and EM Field tabs allow customizing, respectively, the physical material properties and the electromagnetic
resolution for the current waveguide, as described in the Waveguides Common Properties section.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Hints   
The length of this waveguide can be zero.
It is always recommended to use a reference box of the same size as the surrounding circular or arbitrary
waveguides.
When connected to a waveguide with dimensions different from the box ones, some convergence problems
can arise: it is recommended to increase the precision of the computation.
If the number of reference box modes is set to "0", an attempt to calculate the required number of reference
box modes in order to have enough precision is done.
If strange results are obtained, verify that the "x" in the arbitrary shape editor is within the region of interest.
2.4.1.4 Other Waveguides
2.4.1.4.1 Curved waveguide
This section describes the Curved waveguide and how to use it, as well as its features and limitations.
The Curved waveguide section contains the following topics:
Definition
What is exactly a Curved waveguide.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Curved
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Curved waveguide is a non-uniform waveguide with rectangular cross section (in the X-Y plane) and curved either
left or right (in the Z direction), as shown in the following figure:
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The geometrical parameters shown in the above figure are:
A (mm): x-dimension of the rectangular transverse section of the curved waveguide (this direction defines the
plane of curvature).
B (mm): y-dimension of the rectangular transverse section of the curved waveguide.
Mean radius (mm): Mean curvature radius of the curved waveguide (range: R > A/2).
Curvature angle (degrees): Curvature angle (range: 0 < PHI < 360).
Curvature direction: Values can be left or right.
Furthermore, the analysis of a Curved waveguide requires the following numeric parameters:
Number of TE basis functions: Maximum value for the y-axis modal index for TE-to-Y modes (Typical value=25)
Number of TM basis functions: Maximum value for the y-axis modal index for TM-to-Y modes (Typical
value=25)
Max TE Y-direction Modal Index: Number of expansion basis functions in the v variable used to solve the TE-to-
Y modes (Typical value=25)
Max TM Y-direction Modal Index: Number of expansion basis functions in the v variable used to solve the TM-
to-Y modes (Typical value=25)
Limitations
The Curved waveguide has some limitations and caveats you should be aware of:
connections to other elements
The Curved waveguide can only be connected to Step. Furthermore, both X,Y offsets and rotation of those
Steps must be zero on all ports and can be connected to Rectangular waveguides whose cross section (A,B)
coincides with the cross section of this element.
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invalid parameters
The geometrical parameters of the Curved waveguide must satisfy the following constraints:
A > 0
B > 0
R < A/2
0° < PHI < 360°
The numerical parameters must satisfy the following constraints:
Number of Green function terms < NbfTM · NmaxTM + NbfTE · NmaxTE
low accuracy at extreme geometries (R -> A/2)
If a Curved waveguide has very small mean curvature radius (close to A/2), the results will be probably
inaccurate. Then you should increase the number of basis functions used to solve the TE and TM modes.
using as Input/Output port
Usually the curved waveguide will not be used as an I/O port. However if you use it as an I/O port you must
pay attention to the modes that are excited in it. This is due to the fact that in the Curved waveguide the
modes are frequency dependent and are sorted for each frequency point. In this way, the order of the modes
in the curved waveguide can change from one frequency point to the other.
up or down curvature direction
A single Curved waveguide can only turn left or right. It is anyway possible to get a Curved waveguide turning
up or down in the following way:
create a curved waveguide with right or left curvature connected to two rectangular waveguides.
rotate by 90 or -90 degrees a rectangular waveguide connected to the curved one for which we want to
obtain the up or down curvature.
This process can be observed in the following diagram: let's start with a structure with two curved waveguides
forming a U-configuration (i.e. curved in the same direction) as in the following figure
then edit the step [3] and set the rotation (phi) to 90 or -90 degrees.
In this way there is a 90 or -90 degrees rotation between the reference frame of the left half of the circuit and
the reference frame of the right half.
This means the second curved waveguide will become turned up or down in the global reference frame.
Of course, you must be careful with the geometry of the structure, so check that you are satisfying all
constraints.
In particular, A and B of all the waveguides in the left half must be equal to, respectively, B and A of all the
waveguides in the right half:
Aleft = Bright   and  Bleft = Aright
Errors
The Curved waveguide can produce errors only if invalid parameters are specified.
Using the Curved
The Curved waveguide is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Curved Waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
A (mm): cross-section width.
B (mm): cross-section height.
Mean radius (mm): mean curvature radius.
Curvature angle (degrees): curvature angle.
Curvature direction: Left or Right.
Number of TE basis functions: maximum value for the y-axis modal index for TE-to-Y modes (Typical
value=25)
Number of TM basis functions: maximum value for the y-axis modal index for TM-to-Y modes (Typical
value=25)
Max TE Y-direction Modal index: number of expansion basis functions in the v variable used to solve the TE-
to-Y modes (Typical value=25)
Max TM Y-direction Modal index: number of expansion basis functions in the v variable used to solve the
TM-to-Y modes (Typical value=25)
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Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Material tab allow customizing the physical material properties for the current waveguide, as described in the
Waveguides Common Properties section.
2.4.1.4.2 Circular-Elliptic Iris
This section describes the Circular Elliptic Iris waveguide and how to use it, as well as its features and limitations.
The Circular Elliptic Iris waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly an Circular Elliptic Iris waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Circular Elliptic
Iris
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Circular Elliptic Iris waveguide is a uniform waveguide with elliptic cross-section.
Limitations
This element can be only used when inserted between two circular waveguides. The circular waveguides must be
larger than the elliptic iris.
The number of modes must accomplish a relation with respect to the number of green function terms:
4* Modes*Modes > Number of green function terms
Errors
No errors are reported.
Using the Circular Elliptic Iris
The Circular Elliptic Iris waveguide is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Circular Elliptic Iris waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option allows defining the waveguide subtype and related parameters, as described in the Waveguides
Common Properties section.
By clicking on the Use General Specifications button, each waveguide can be configured to use either the default
values for the modal parameters (stored in the General Specifications window) or the values specified by the user in
each waveguide.
The following parameters can be edited:
Elliptical basis functions: Number of basis functions (one dimension) to expand each elliptical mode.
A (mm): Major semiaxis.
B (mm): Minor semiaxis.
L (mm): waveguide length.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Material tab allow customizing the physical material properties for the current waveguide, as described in the
Waveguides Common Properties section.
Hints
In order to rotate this element, use the rotation property of the steps attached to it.
Normally, a value of 10-20 in the number of Elliptical basis functions should be enough for precision. A value
larger than 25 should be never required for convergence. The computational time of this element strongly
depends on this parameter.
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2.4.1.4.3 Radiating Array
This section describes the Radiating Array waveguide and how to use it, as well as its features and limitations.
The Radiating Array waveguide section contains the following topics:
Definition
Limitations
Errors
What is exactly a Radiating Array waveguide.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Radiating Array How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Radiating Array waveguide simulates an infinite array of open-ended waveguides arranged in a doubly periodic
grid on a flat surface, as shown in the following figures:
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A Radiating Array is an infinite, periodic array of waveguides, i.e. the array elements are placed in a double periodic
lattice and they are fed with the same amplitude, but with a phase constant that will change progressively from one
element to the next one.
This linear phase taper will excite a radiated beam in the direction defined by the angles (θ, φ).
Under these periodic conditions, the original problem can be reduced to the characterization of only one period of
the structure, which is called the Unit Cell .
The Unit Cell consists of the rectangular or circular waveguide and a fictitious waveguide, named Phase Shift Wall
waveguide (PSWW).
The PSWW represents the free space under the periodic conditions dictated by the array.
The modes used in the Phase Shift Wall waveguide are derived using the periodicity of the array and applying
Floquet's theorem [1].
For an exhaustive theoretical discussion of the problem the reader can make reference to [1].
[1] N. Amitay, V. Galindo, C. Wu. Theory and Analysis of Phased Array Antennas. Wiley-Interscience, 1972.
The geometrical parameters shown in the figures above are:
Angle α of the grid (degrees): the waveguides are arranged on a periodic grid to form the infinite array.
Allowed range: 0° < α ≤ 90°.
The grid can be either rectangular (α=90°) or triangular (α < 90°).
Width A of the array periodic cell (mm): the horizontal distance between two consecutive periodic cells.
Height B of the array periodic cell (mm): the vertical distance between two consecutive periodic cells.
The area A · B should be greater or equal than the one of the single waveguides forming the array.
Scanning angle θ (degrees): angle that defines the direction of the main beam radiated by the array.
Allowed range: -90° ≤ θ ≤ 90°.
Scanning angle φ (degrees): angle that defines the direction of the main beam radiated by the array.
Allowed range: 0° ≤ φ ≤ 180°.
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Limitations
The Radiating Array waveguide has some limitations and caveats you should be aware of.
connections to other elements
The Radiating Array waveguide can only be connected to a Step. Furthermore, that Step must have zero X,Y
offsets and Rotation can be connected to Rectangular or Circular waveguides whose cross section (A,B) does
not exceed the cross section of this element.
feeding waveguide below cut-off frequency
if the waveguide connected to the radiating array is below cut-off frequency and has a length such that no
power propagates across it, the antenna does not work. The user should be aware of this and avoid this case.
low accuracy at extreme parameters values
if the elevation angle θ is chosen exactly equal to 90° or -90°, the program might have, in some cases,
instabilities. The problem can be fixed by simply taking θ smaller than 90° degrees by a few tens of degree (i.e.
89.9° or 89.8°). This has no impact on the simulation, considering that θ=±90 corresponds exactly to the plane
of the array (not important in most of the cases) and anyway the possibility to evaluate the S-parameters up to
89.9° is sufficient to compute the relevant response of the array.
spurious lobes in the radiation pattern
another aspect is the presence of grating lobes (spurious lobes in the radiation pattern) which depends on the
inter-element distance (unit cell dimension).
angular sweeps (θ, φ)
instead of the normal frequency sweep, the user can perform an angle (θ or φ) sweep. In this case, having fixed
the frequency, the S parameters will be given as a function of the direction of the radiated beam.
Errors
The Radiating Array waveguide can produce errors only in the case that invalid parameters are specified.
Using the Radiating Array
The Radiating Array waveguide is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Radiating Array waveguide.
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The Enabled/Disabled button allows enabling and disabling this element, as described in the Main Window Edit
menu.
The SubType option is disabled in this element, since Radiating Arrays can only be Input/Output Ports.
Ports tab shows the discontinuities connected to this waveguide, as described in the Waveguides Common Properties
section.
Material tab allow customizing the physical material properties for the current waveguide, as described in the
Waveguides Common Properties section.
The following parameters can be edited:
A (mm): unit-cell width.
B (mm): unit-cell height.
Grid angle array (α, degrees): angle of the grid array.
The remaining properties, Scanning angle θ (degrees) and Scanning angle φ (degrees) are global circuit
parameters and can be edited in the General Specification Window.
Hints
No hints
2.4.2 Discontinuities
This section describes all the discontinuities supported by Fest3D, and how they can be used as building blocks to
compose a circuit.
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The discontinuities section contains the following topics:
Definition
What is exactly a Fest3D discontinuity, and how it can be used in a circuit.
Discontinuities List
All discontinuities supported by Fest3D.
Definition
In Fest3D, a discontinuity is an element describing either a cavity or a surface where one or more waveguides can be
attached. Discontinuities often have non-uniform cross-section and non-trivial 3D geometries.
Discontinuities can be only connected to waveguides.
Coordinate System
In general, the coordinate system in a port of a discontinuity is predefined for each type of discontinuity. The
discontinuities enforce the coordinate systems of the adjacent waveguides. On the other hand, in some elements such
as Step, 2D Iris and so on, the position of the coordinate system in each port has a similar behavior as the one of its
counterpart defined in waveguides, that is, it is imposed by the previous waveguide. For these elements it is important
to distinguish the coordinate system defined to expand the electromagnetic field from the coordinate system used to
define the geometry of the device. This last coordinate system is always defined at port 1 pointing the x unitary vector
to the left when looking towards the element. Read the documentation of each type of discontinuity to recover
specific information.
Discontinuities List
Unless explicitly stated, each discontinuity can be connected to an unlimited number of waveguides.
Fest3D supports the following discontinuities:
BASIC DISCONTINUITIES
Step
N-Step
N-Port User Defined
1-Port User Defined
Lumped element
A zero-thickness surface connecting two waveguides (actually a particular
case of N-Step).
A zero-thickness surface connecting two or more waveguides.
An element of possibly unknown geometry, solely represented by its multi-
mode S, Z or Y matrix. Fest3D can produce S, Z, or Y matrices suitable to be
used for this element, but they can also be imported from or exported to
other E.M. simulation tools.
A monopole, solely represented by its multi-mode S, Z or Y matrix. Fest3D
can produce S, Z, or Y matrices suitable to be used for this element, but they
can also be imported from other E.M. simulation tools. It is used to evaluate
its incoming complex amplitudes (impressed modes)
An element of possibly unknown geometry, where the user specifies the
multi-mode Z matrix. Used to create, among others, shunt elements and
transmission lines.
Coupling Matrix element
An element of possibly unknown geometry, where the user specifies the
Coupling Matrix. It represents a N-order multicoupled network.
Touchstone element
An element of possibly unknown geometry, solely represented by a
Touchstone file. It represents the Scattering parameters data of a N-port
network.
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Rounded corner iris 3D
An iris with rounded corners in 3D.
JUNCTIONS
C-Junction
T-Junction
Y-Junction
Y-Junction (60º)
2D OMT
2D compensated tee
BENDS
Stepped bend
Mitered bend
2D Curved
A cubic (hence the name) or parallelepiped cavity. Each of the six surfaces can
be connected to zero, one or more Rectangular waveguides. Each connected
waveguide can have different x,y offsets and rotation.
A cubic or parallelepiped cavity, connected to three Rectangular waveguides
and exactly corresponding to their T-shape intersection. T-Junction can be
either on the horizontal plane (H-plane) or on the vertical plane (E-plane). It is
based on the C-Junction.
A discontinuity with planar 'Y' shape. It is based on the Arbitrary shape
(constant width/height) and has the same configurations and limitations. It
must be connected to three Rectangular waveguides.
The 2D OMT, based on the Arbitrary shape , represents an OMT among three
Rectangular waveguides. Additional posts (rectangular metal insertions and
screws) can be considered inside the OMT as well
A discontinuity with planar 'T' shape with a metal insertion used to
compensation. It is based on the Arbitrary shape (constant width/height) and
has the same configurations and limitations. It must be connected to three
Rectangular waveguides.
The Stepped Bend discontinuity is a special derivation of a common bend
shape between two rectangular waveguides, in which the non-shared corner
of the bend is substituted by steps. It is based on the Arbitrary shape
(constant width/height) and has the same configurations and limitations.
The Mitered Bend discontinuity is a special derivation of a common bend
shape between two rectangular waveguides (ports 1 and 2), in which the non-
shared corner of the bend is substituted by a mitered corner. It is based on
the Arbitrary shape (constant width/height) and has the same configurations
and limitations.
The 2D Curved discontinuity based on the Arbitrary shape (constant
width/height) , represents a curved bend between two rectangular
waveguides
CONST WIDTH/HEIGHT
Arbitrary shape (constant
width/height)
A discontinuity with planar arbitrary shape. It can be used in two
configurations: constant height or constant width.
Waveguide step with N metal
insets
Waveguide step with N screws
A discontinuity with a planar shape which represents a waveguide with N
metal inserts. It is based on the Arbitrary shape (constant width/height) and
has the same configurations and limitations. It must be connected to two
Rectangular waveguides.
A discontinuity with a planar shape that represents a waveguide with N
screws. It is based on the Arbitrary shape (constant width/height) and has the
same configurations and limitations. It must be connected to two Rectangular
waveguides.
Waveguide step with rounded
A discontinuity with a planar shape which represents a step between two
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corners
Rounded corner iris
waveguides. It is based on the Arbitrary shape (constant width/height) and
has the same configurations and limitations. It must be connected to two
Rectangular waveguides.
The Rounded corner iris discontinuity, based on the Arbitrary shape element,
represents an iris in either constant width or height, like the one sketched in
the figure below.
2D Rounded short
The 2D Rounded short, based on the Arbitrary shape , represents a one port
short waveguide. 
COAXIAL CAVITY LIBRARY
Cavity with posts
A cubic or parallelepiped cavity, containing one or more posts.
Straight feed cavity
Mushroom feed cavity
A cubic or parallelepiped cavity with a straight feed. It is based on the Cavity
with posts and has the same configurations and limitations.
A cubic or parallelepiped cavity with a mushroom feed. It is based on the
Cavity with posts and has the same configurations and limitations.
Straight contact feed cavity
A cubic or parallelepiped cavity with a straight contact feed. It is based on the
Cavity with posts and has the same configurations and limitations.
S-Shape contact feed cavity
A cubic or parallelepiped cavity with a S-shape contact feed. It is based on the
Cavity with posts and has the same configurations and limitations.
Loop feed cavity
Magnetic feed cavity
A discontinuity with a loop feed. It is based on the Cavity with posts and has
the same configurations and limitations.
A cubic or parallelepiped cavity with a magnetic feed. It is based on the Cavity
with posts and has the same configurations and limitations.
Top contact feed cavity
A cubic or parallelepiped cavity with a top contact feed. It is based on the
Cavity with posts and has the same configurations and limitations.
General cavity
A cubic or parallelepiped cavity which allows multiple coaxial and rectangular
excitations. It is based on the Cavity with posts and has the same
configurations and limitations.
HELICAL RESONATORS
Contact feed to helical resonator
Helical resonator
CST SOLVER LIBRARY
General rectangular cavity
A cubic or parallelepiped cavity with a straight feed that contacts a helical
resonator. It is based on the Cavity with posts and has the same
configurations and limitations.
A cubic or parallelepiped cavity that contains one or more resonators of
helical shape. It is based on the Cavity with posts and has the same
configurations and limitations.
A cubic or parallelepiped cavity which allows multiple coaxial, circular and
rectangular excitations. It can contain different types of posts of PEC or
dielectric material.
General cylindrical cavity
A cylindrical cavity which allows multiple coaxial, circular and rectangular
excitations. It can contain different types of posts of PEC or dielectric material.
Lateral couplings to cylindrical
cavity
A cavity defined by two circular waveguides that is excited by lateral ports,
which can be circular or rectangular.
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Circular to Rectangular T-Junction A cavity defined by two circular waveguides that is excited by a lateral port
Circular T-Junction
Ridge T-Junction
Coaxial T-Junction
which is a rectangular waveguide. It is based on the Lateral couplings to
cylindrical cavity and has the same configurations and limitations.
A cavity defined by two circular waveguides that is excited by a lateral port
which is also a circular waveguide. It is based on the Lateral couplings to
cylindrical cavity and has the same configurations and limitations.
A cavity defined by two ridge waveguides that is excited by an orthogonal
port which is also a ridge waveguide.
A cavity defined by two coaxial waveguides that is excited by a lateral port
which is also a coaxial waveguide. It is based on the Lateral couplings to
cylindrical cavity and has the same configurations and limitations.
2.4.2.1 Basic Discontinuities
2.4.2.1.1 Step
This section describes the Step discontinuity and how to use it, as well as its features and limitations.
The Step discontinuity section contains the following topics:
Definition
What is exactly an Step discontinuity.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Step
How to create, edit and use this element from Fest3D.
Definition
The Step discontinuity is a zero-thickness surface used to attach two waveguides. It has two ports, each one
representing a waveguide. It is a special case of the more general element N-Step.
One of the attached waveguides must be the big one i.e. its cross section must contain the cross section of the other
(small) waveguide. The coordinate system of Step discontinuity is right-handed and is located at port 1 as shown in
the picture below, where the waveguide represented by port 1 is highlighted in red.
The waveguide that is represented by port 2 can be rotated and traslated with respect to the waveguide represented
by port 1, as shown in the following figure (small waveguide is port 2 , and the big waveguide is port 1, the big
waveguide is in first plane and small waveguide is in second plane):
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Traslation is defined by offsets in x- and y-axis of Step discontinuity coordinate system, while rotation is defined by an
angle applied around z-axis in clockwise direction. In order to define the values for these parameters it is important to
know how Fest3D places circuit elements in their corresponding spatial position. When building a circuit, Fest3D
locates each element according to a global reference system which is right-handed and settled in the input port of the
circuit. To do so Fest3D concatenates traslations and rotations which are defined by the user in the local reference
system of certain elements. The user must be aware of transformations previously applied to a certain element in
order to properly define offsets and rotation angle in the local reference system of the current element. Depending on
previous movements, the local reference system of the element may be transformed with respect to the global
reference system.
For example, if there has been a rotation and/or a traslation before the current Step, the user must take into account
that the local reference system of the Step is rotated and/or traslated with respect to the global reference system.
Thus, when defining the values of offsets and rotation angle of the current Step, their definition must be done with
respect to the transformed local reference system.
The easiest way to properly define traslations and rotation of Step discontinuity is by connecting its port 1 to a
waveguide that whenever possible has not been previously moved. This way, the local reference system of the Step is
not transformed with respect the global coordinate system and the offsets and rotation angle will be easily defined.
The following example illustrates this fact.
How to define rotation and traslations through Step discontinuity
Consider a circuit with three waveguides connected by two Steps, where the input port of the circuit is located at
waveguide 1:
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We want to obtain a structure where:
waveguides 1 and 2 are aligned with z-axis of global coordinate system and 
waveguide 3 is rotated 45º and traslated 2 mm in X and Y directions with respect to the global reference
system of the circuit.
To do so, Step 1 must rotate and traslate waveguide 3 with respect to waveguide 1 in order to locate it in the proper
spatial position and Step 2 must undo that transformation, so that waveguide 2 remains aligned with waveguide 1
.
Option 1
The easiest way to define the values of offsets and rotation angle of Steps 1 and 2 is the following one:
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Steps 1 and 2 connect their port 1 to waveguides 1 and 2 respectively, which means that their local reference systems
are located in these waveguides. As waveguides 1 and 2 are not rotated nor traslated in x- and y-axis with respect to
the global reference system of the circuit, local reference systems of Step 1 and 2 are not transformed.
 Values of X and Y offsets and rotation angle of Steps 1 and 2 locate waveguide 3 in the same spatial position,
although being defined in different coordinate systems, which are shown in the following pictures:
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Option 2
We consider now an alternative way of connecting circuit elements to obtain the same structure as before. We just
change the way Step 2 is connected: we connect port 1 of Step 2 to waveguide 3. Step 1 changes the position of
waveguide 3 and so the local coordinate system of Step 2, which is located in waveguide 3. 
In the structure we want to obtain waveguides 1 and 2 are aligned, so we have to undo the transformation carried out
by Step 1 through Step 2. In order to define the offsets and rotation of Step 2, we must take into account that its local
coordinate system is also modified with respect the global coordinate system. In this case it is advisable to work
with matrix representation. 
Traslations in x- and y-axis and rotations around z-axis can be defined by the following affine transformation matrix:
cos [α]
sin [α]
-sin [α]
cos [α]
 For the particular transformations carried out by Step 1, the matrix takes the form:
A =
cos [45]
sin [45]
-sin [45]
cos [45]
In order to know the specific movements that undo these tranfomations, we must compute the inverse of matrix A:
A -1 =
0.707107
0.707107
0.707107
-0.707107
-2.82843
 which corresponds to a rotation of 45º around z-axis and a traslation of -2.82843 in x-axis. These values define Step 2
parameters:
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 If we do not consider that the local reference system of Step 2 is transformed by the modifications done to
waveguide 3 and define offsets and rotation of Step 2 to undo the transformations introduced by Step 1 with the
following values:
we will obtain a structure which is not what we expected. As shown in the picture below, waveguides 1 and 2 are not
aligned with the z-axis.
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Please refer to the N-Step element for further details and examples, remembering that a Step is simply an N-Step with
exactly 1 small waveguide.
Errors
The Step discontinuity can produce the following errors under certain circumstances. For each error, the possible
solutions or workarounds are explained.
error: unsupported coupling integral
You connected an unsupported combination of waveguides to the Step. A possible solution is to include
between the two waveguides, a waveguide of zero length which coupling integrals with the two surrounding
waveguides are known. Of course, this can lead to convergence problems.
Using the Step
The Step discontinuity is completely integrated into Fest3D. The user can create, view and edit this element properties
using dialog boxes.
The following figure show a typical Element Properties dialog box for the Step discontinuity:
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
For the second port of the Step, the following port parameters can be edited:
X Offset (mm) the X coordinate of the port 2 waveguide center, relative to the port 1 waveguide.
Y Offset (mm) the Y coordinate of the port 2 waveguide center, relative to the port 1 waveguide.
Rotation (degrees) the rotation of the port 2 waveguide, relative to the port 1 waveguide.
2.4.2.1.2 N-Step
This section describes the N-Step discontinuity and how to use it, as well as its features and limitations.
The N-Step discontinuity section contains the following topics:
Definition
What is exactly an N-Step discontinuity.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the N-Step
How to create, edit and use this element from Fest3D.
Definition
The N-Step discontinuity is a zero-thickness surface used to attach two or more waveguides.
One of the attached waveguides must be the big one i.e. its cross section must contain all the cross sections of the
other (small) waveguides.
The N-Step has as many ports as the number of attached waveguides. Ports are used to connect elements together.
In this case, each waveguide is attached to a different port of the N-Step.
The big waveguide must be attached to port 1 of the N-Step. The small waveguides must be attached to ports
number 2 and higher of the N-Step.
Each small waveguide can be rotated and translated with respect to the big waveguide, as shown in the following
figure, where the z axis is pointing outwards the screen:
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The coordinate system imposed at any port of the N-Step by the previous waveguide is rotated and translated to the
others ports.
The cross sections of the small waveguides must not intersect and must be completely contained in the cross section
of the big waveguide.
For example, the following figure shows an admissible combination:
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Errors
The N-Step discontinuity can produce the following errors under certain circumstances. For each error, the possible
solutions or workarounds are explained.
error: unsupported coupling integral
You connected an unsupported combination of waveguides to the N-Step. The only solution is to change the
circuit and avoid that combination.
Using the N-Step
The N-Step discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following figures show a typical Element Properties dialog box for the N-Step discontinuity:
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
For each port of the N-Step attached to a small waveguide (i.e. all ports except the first), the following port
parameters can be edited:
X Offset (mm) the X coordinate of the small waveguide center, relative to the big waveguide.
Y Offset (mm) the Y coordinate of the small waveguide center, relative to the big waveguide.
Rotation (degrees) the rotation of the small waveguide, relative to the big waveguide.
2.4.2.1.3 N-Port User Defined
This section describes the N-Port User Defined discontinuity and how to use it, as well as its features and limitations.
The N-Port User Defined discontinuity section contains the following topics:
Definition
Limitations
Errors
Using the N-Port User
Defined
Definition
What is exactly a N-Port User Defined discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
How to create, edit and use this element from Fest3D.
The N-Port User Defined discontinuity is a general-purpose element, whose electromagnetic characteristics are
completely configurable by specifying its S, Z or Y matrices. The S, Z or Y matrices can be obtained using the Compute
Z Matrix feature of Fest3D on another circuit, or can be imported from any other software that can produce them. This
allows reducing a whole circuit to a single element, reusable in more complex circuits.
The N-Port User Defined element has many ports as specified in the S, Z or Y matrix. Each port must be connected to
a waveguide (also see Limitations below).
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Limitations
The N-Port User Defined discontinuity has some limitations and caveats you should be aware of.
Frequency points
The same frequency points used for the computation of the exported matrix must be used by the circuit
containing an N-Port User Defined discontinuity.
Errors
The User Defined discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
Sorry, the element User Defined number n was defined with different symmetries from what is defined
in the circuit
You connected the User Defined in a circuit with different symmetries. Solution: use the same symmetries.
Sorry, in the element User Defined n the relative electric permittivity of port p does not match with the
relative electric permittivity of the circuit where it is connected to
You connected to the User Defined a waveguide filled with a different dielectric material from what is specified
in the S, Z or Y matrix file. Solution: use the same dielectric material for that port.
Sorry, in the element User Defined n the relative electric permeability of port p do not match with the
relative electric permeability of the circuit where it is connected to
You connected to the User Defined a waveguide filled with a different dielectric material from what is specified
in the S, Z or Y matrix file. Solution: use the same dielectric material for that port.
Sorry, in the element User Defined n the conductivity of port p do not match with the conductivity of
the circuit where it is connected to
You connected to the User Defined a waveguide with different conductivity from what is specified in the S, Z or
Y matrix file. Solution: use the same conductivity for that port.
Sorry, in the element User Defined the waveguide type of port does not match with the waveguide type
of circuit where it is connected to. In the element User Defined n geometrical dimensions i of port p do
not match with the circuit
You connected to the User Defined a waveguide with different dimensions from what is specified in the S, Z or
Y matrix file. Solution: use the same dimensions for that port.
In the element User Defined the number of frequency points in the input file mismatch the number of
frequency points in the circuit
Solution: use the same number of frequency points.
In the element User Defined n the frequency points in the input file mismatch the frequency points in
the circuit
Solution: use the same frequency points.
Sorry, in the element User Defined n the number of modes does not agree with the number of
accessible modes in wg. x
Solution: use the same number of modes.
Sorry, in the element User Defined the mode number k does not agree with its corresponding mode in
wg. x
Solution: use the same mode expansion.
Using the N-Port User Defined
The N-Port User Defined discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following figure shows a typical Element Properties dialog box for the N-Port User Defined discontinuity:
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The name and path of the file can be either entered directly (hit the Enter key when done) or chosen with the help of
an Open File dialog. The frequency and parameters ranges contained in the file are automatically read and shown in
the dialog box.
2.4.2.1.4 1-Port User Defined
This section describes the 1-Port User Defined discontinuity and how to use it, as well as its features and limitations.
The 1-Port User Defined discontinuity section contains the following topics:
What is exactly a 1-Port User Defined discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
How to create, edit and use this element from Fest3D.
Definition
Limitations
Errors
Using the 1-Port User
Defined
Definition
The 1-Port User Defined discontinuity is a general-purpose element of one port, whose electromagnetic
characteristics are completely configurable by specifying its S, Z or Y matrices. The S, Z or Y matrices can be obtained
using the Compute Z Matrix feature of Fest3D on another one port circuit, or can be imported from any other
software that can produce them.
Limitations
The 1-Port User Defined discontinuity has some limitations and caveats you should be aware of.
Frequency points
The same frequency points used for the computation of the exported matrix must be used by the circuit
containing an 1-Port User Defined discontinuity.
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Errors
The 1-Port User Defined discontinuity can produce the following errors under certain circumstances. For each error,
the possible solutions or workarounds are explained.
Sorry, the element 1-Port User Defined number n was defined with different symmetries from what is
defined in the circuit
You connected the 1-Port User Defined in a circuit with different symmetries. Solution: use the same
symmetries.
Sorry, in the element 1-Port User Defined n the relative electric permittivity of port 1 do not match with
the relative electric permittivity of the circuit where it is connected to
You connected to the 1-Port User Defined a waveguide filled with a different dielectric material from what is
specified in the S, Z or Y matrix file. Solution: use the same dielectric material for that port.
Sorry, in the element 1-Port User Defined n the relative electric permeability of port 1 do not match
with the relative electric permeability of the circuit where it is connected to
You connected to the 1-Port User Defined a waveguide filled with a different dielectric material from what is
specified in the S, Z or Y matrix file. Solution: use the same dielectric material for that port.
Sorry, in the element 1-Port User Defined n the conductivity of port 1 do not match with the
conductivity of the circuit where it is connected to
You connected to the 1-Port User Defined a waveguide with different conductivity from what is specified in the
S, Z or Y matrix file. Solution: use the same conductivity for that port.
Sorry, in the element 1-Port User Defined the waveguide type of port does not match with the
waveguide type of circuit where it is connected to. In the element 1-Port User Defined n geometrical
dimensions i of port 1 does not match with the circuit
You connected to the 1-Port User Defined a waveguide with different dimensions from what is specified in the
S, Z or Y matrix file. Solution: use the same dimensions for that port.
In the element 1-Port User Defined the number of frequency points in the input file mismatch the
number of frequency points in the circuit
Solution: use the same number of frequency points.
In the element 1-Port User Defined n the frequency points in the input file mismatch the frequency
points in the circuit
Solution: use the same frequency points.
Sorry, in the element 1-Port User Defined n the number of modes does not agree with the number of
accessible modes in wg. x
Solution: use the same number of modes.
Sorry, in the element 1-Port User Defined the mode number k does not agree with its corresponding
mode in wg. x
Solution: use the same mode expansion.
Using the 1-Port User Defined
The 1-Port User Defined discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following figure shows a typical Element Properties dialog box for the 1-Port User Defined discontinuity:
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The name and path of the file can be either entered directly (hit the Enter key when done) or chosen with the help of
an Open File dialog. The frequency and parameters ranges contained in the file are automatically read and shown in
the dialog box.
2.4.2.1.5 Lumped
This section describes the Lumped discontinuity and how to use it, as well as its features and limitations.
The Lumped discontinuity section contains the following topics:
Definition
What is exactly a Lumped discontinuity.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Lumped
How to create, edit and use this element from Fest3D.
Definition
The Lumped discontinuity is configured by specifying its Z matrix. The Z matrix can be completely specified by the
user, or some predefined parametrization can be used: currently supported cases are shunt elements, transmission
lines and lossless transmission lines.
The Lumped element must have exactly two ports, connected to two identical waveguides (except for their lengths).
It is even possible to Optimize the parameters used to specify the Z matrix of this element.
Limitations
The Lumped discontinuity has some limitations and caveats you should be aware of:
no geometry and electromagnetic validation
It is up to the user to guarantee that this element is connected correctly. The Lumped element performs no
geometry or electromagnetic validation against the waveguides it is connected to. It only checks that the two
waveguides it is connected to are identical (possibly except for their lengths).
no em field can be computed on this element
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Errors
The Lumped discontinuity should not produce errors.
Using the Lumped
The Lumped discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes, as the one shown below:
The Element Properties dialog box for the Lumped discontinuity allows the user to create impedance matrices for the
following circuit-like components:
Inverter
Parallel impedance
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T configuration impedances
Π (Greek PI) configuration impedances
Each impedance can be defined as a parallel of one or more of the following basic circuit-like components:
a constant, real resistance (R)
a pure inductance (L)
a pure capacity (C)
If the value of a resistance, inductance or capacity is set to zero (respectively 0 Ohm, 0 nanoHenry or 0 nanoFarad to
be exact), then such component is assumed not to be present. This allows the following combinations of components
in parallel: RLC, RL, RC, LC, R, L, C.
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
2.4.2.1.6 Coupling Matrix
This section describes the Coupling Matrix discontinuity and how to use it, as well as its features and limitations.
The Coupling Matrix discontinuity section contains the following topics:
Definition
Limitations
Errors
What is exactly a Coupling Matrix discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Coupling Matrix How to create, edit and use this element from Fest3D.
Definition
The Coupling Matrix (CM) discontinuity represents a generalized multicoupled network through an N x N matrix
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where N is the number of resonators (the degree or order) of the filter and the elements of the matrix are the
coupling between each of the resonators. Since the source and load terminations for the Coupling Matrix element are
nonzero, the value of the input/output couplings appears in the N x N matrix by adding an extra row top and bottom
and an extra column on left and right creating an N+2 x N+2 matrix. In addition, the center frequency and the
bandwidth of the bandpass are required.
The Coupling Matrix element has exactly two ports.
It is even possible to Optimize the Coupling Matrix elements in order to obtain the desired frequency response.
Limitations
The Coupling Matrix discontinuity has some limitations and caveats you should be aware of:
no geometry and electromagnetic validation
It is up to the user to guarantee that this element is connected correctly. The Coupling Matrix element
performs no geometry or electromagnetic validation against the waveguides it is connected to. However,
despite the fact that there is no real geometry for the Coulpling Matrix element, it is depicted on the 3D
visualization as a box with a cross section corresponding to the connected waveguides and length lambda/4 (at
Coupling Matrix element center frequency).
no EM field can be computed on this element
use of the number of accessible modes
Since the Coupling Matrix element simulation is a circuit calculation, the element does not use internally the
number of modes to calculate the frequency response. This makes irrelevant how many accessible modes are
using the waveguides to which the element is connected (Please, note that the number of the accessible
modes of each waveguide connected to the Coupling Matrix element must be the same). In order to
denormalize the source and load impedances of the Coupling Matrix element, all the accessible modes used in
each of the waveguides to which Coupling Matrix element is connected are taking into account.
Errors
The Coupling Matrix discontinuity can produce the following errors under certain circumstances:
The factorization has been completed, but the factor U is exactly singular, so the solution could not be
computed. The coupling matrix set is singular, that is, the determinant of the matrix is zero.
Using the Coupling Matrix
The Coupling Matrix discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes, as the one shown below:
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The Element Properties dialog box for the Coupling Matrix discontinuity allows the user to create coupling matrices
with the following parameters:
Filter Order: number of resonators of the filter (max. 20).
Center frequency (GHz).
Bandwidth (GHz).
Matrix: table with the value of the couplings between resonators. Note that source and load terminations are
always included. Since the Coupling Matrix represents a passive and reciprocal network, the matrix is
symmetrical about its principal diagonal.
Import matrix: the coupling values of the matrix can be set by importing a TXT file.
Export matrix: the coupling values of the matrix can be exported to a TXT file.
Visualize: computes and visualizes the Scattering parameters from the Coupling Matrix, the center
frequency and the bandwidth. The terminations (source and load) are normalized to unity.
Export S-Param: the Scattering parametres are exported as a Fest3D .out file.
It is allowed visualizing the S-Parameters calculated from the Coupling Matrix element. The frequency response is
calculated independently of the waveguides connected to the element by normalizing the source and load
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terminations to unity impedance. Export S-Param button allows exporting the frequency response to a Fest3D .OUT
file.
Each coupling value of the Coupling Matrix can be optimized by doing a right click on the corresponding cell.
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
2.4.2.1.7 Touchstone
This section describes the Touchstone discontinuity and how to use it, as well as its features and limitations.
The Touchstone discontinuity section contains the following topics:
Definition
Limitations
Errors
What is exactly a Touchstone discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Touchstone How to create, edit and use this element from Fest3D.
Definition
The Touchstone discontinuity is a general-purpose element, whose electromagnetic characteristics are
completely specified by loading a Touchstone® file (also known as SnP file), which is an ASCII text file used for
documenting a N-port network parameter data. The Touchstone discontinutiy only allows Version 1.0
Touchstone® files (".ts" Version 2.0 extension is not allowed).
Limitations
The Touchstone discontinuity has some limitations and caveats you should be aware of:
no geometry and electromagnetic validation
It is up to the user to guarantee that this element is connected correctly. The Touchstone element performs no
geometry or electromagnetic validation against the waveguides it is connected to. However, despite the fact
that there is no real geometry for the Touchstone element, it is depicted on the 3D visualization:
2-port network: as a rectangular box with a cross section corresponding to the connected waveguides
and length lambda/4 (at Touchstone file first frequency).
N-port network (N>2): as a circular box where the ports are located around it at equidistant distance.
The size of the box depends on the number of ports of the network.
no EM field can be computed on this element
use of the number of accessible modes
Although the Touchstone discontinuity allows connections with waveguides with any number of accessible
modes, the characteristic impedances of the ports connected to the element only take into account the first
accessible mode to calculate the frequency response (Please, note that the number of the accessible modes
of each waveguide connected to the Touchstone element must be the same).
simulation frequency range
The simulation frequency range of the whole circuit must be contained within the frequency range specified in
the Touchstone element.
Noise parameters are not allowed
The noise data of linear active devices will be omitted if they exist in the Touchstone® file.
Errors
The Touchstone discontinuity can produce the following errors under certain circumstances related to the loading of
the Touchstone® file:
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Error loading the option line in touchstone file. The allowed values for the frequency units are: GHz, MHz, KHz
and Hz.
Error loading the option line in touchstone file. Only Scattering parameters (S) are allowed.
Error loading the option line in touchstone file. The allowed values for the format data are: RI for real-
imaginary, MA for magnitude-angle and DB for dB-angle (dB=20*log10|magnitude|).
Error loading the option line in touchstone file. The reference resistance to which the parameters are
normalized must be a positive number in Ohms. Zero value will consider the parameters as not renormalized.
Error loading the option line in touchstone file. The option line must be formatted as follows: # <frequency
unit> <parameter> <format> R <n>.
Error loading the option line in touchstone file. Option parameters not found in touchstone file.
Using the Touchstone
The Touchstone discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes, as the one shown below:
The following figure shows a typical Element Properties dialog box for the Touchstone discontinuity:
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The name and path of the file can be either entered directly (hit the Enter key when done) or chosen with the help of
an Open File dialog.
2.4.2.1.8 Rounded corner iris 3D
This section describes the Rounded corner iris 3D discontinuity and how to use it, as well as its features and
limitations.
The Rounded corner iris 3D discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Rounded corner iris 3D discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Rounded corner iris
3D
How to create, edit and use this element from Fest3D.
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Definition
The Rounded corner iris discontinuity represents an iris with rounded corners which are built in the H- or E-plane. Top
and side views for both planes are sketched in the figures below.
Basic geometrical scheme of side view for E-plane
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Basic geometrical scheme of side view for H-plane
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Basic geometrical scheme of top view for H-plane
Basic geometrical scheme of top view for E-plane
The Rounded corner iris 3D discontinuity is an extension of the rounded corner iris (2D), which allows geometries not
purely inductive or capacitive.
Limitations
This element has some limitations and caveats you should be aware of:
High memory consumption using parallelization in circuits with many irises
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different irises in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.  
Errors
The Rounded corner iris 3D discontinuity can produce the following errors under certain circumstances. For each error,
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the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver BI-RME 3D RWG
The maximum frequency introduced is under the cut-off frequency of the cavity that contains the 3D iris, used
by the Solver BI-RME 3D RWG. Provided that the dimensions of the iris and the ports are correct, the solution is
to increase the value of this maximum frequency. It is recommended to set it to a value two or three times the
maximum frequency of the desired analysis band.        
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce the mesh size
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry. It is advisable to check if the geometry can be visualized with the 3D viewer. If this is
the case, then the problem is related to the meshing algorithms, due to the same reasons explained for the
previous error related to failure of the 3D mesh.        
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded. Besides,
this problem can appear when performing simulations with several cores, due to the higher memory
requirements of this feature. Reducing the number of processors is necessary to successfully perform the
simulation.
Using the Rounded corner iris discontinuity
The Rounded corner iris discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes and can view it in the 3D viewer.
Connections to other elements This element must be connected to two Rectangular waveguides (one for each port).
The following picture shows a typical Element Properties dialog box for the Rounded corner iris discontinuity.
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Specific properties of the Rounded corner iris 3D
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
R (mm/inches): Radius of the external corners.
Ai (mm/inches): Width dimension of the iris (X axis).
Bi (mm/inches): Height dimension of the iris (Y axis).
Li (mm/inches): The length of the iris (Z axis).
Iris offset X (mm/inches): The offset of the iris in the x-axis direction, relative to the reference box center.
Iris offset Y (mm/inches): The offset of the iris in the y-axis direction, relative to the reference box center.
Mesh size (mm/inches): This value specifies the size of the triangles which are used for meshing the geometry
of this element (iris walls and rounded corners) during the simulation. The user should change this mesh size
for each particular case, taking into account the maximum and minimum dimensions employed. The smaller
the mesh size, the finest the internal meshing, which will lead to more accurate results, but it will also slow
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down the simulation time. Also, very small values may produce memory allocation problems, due to large size
of matrices involved with the meshing.
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (air by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (air by default).
Select type of geometry (E-plane or H-plane): To select whether the round corners of the iris are build in the
E or the H plane  .
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
The particular geometry of this element is analyzed using the electromagnetic Solver BI-RME 3D RWG. This Solver
considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface currents of the posts. This Solver
requires that the geometry is meshed with triangular patches onto which the RWG basis functions are defined.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figures below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element. For the case of the second port tab, X and Y offsets
can be set. These offsets are defined with respect to the port 1 as depicted in the legend figures (parameters
p2_off_x and p2_off_y).
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Port 1 properties of the Rounded corner iris 3D
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Port 2 properties of the Rounded corner iris 3D
Important considerations about the ports
If two rectangular waveguides of the same section are used, the internal solver performs an analytical treatment to the
ports. In other cases, if one of the port sections is bigger than the other, an internal mesh of the smaller port
section is required by the BI-RME 3D RWG electromagnetic Solver. For this case, the optional parameter Mesh
size port must be set , which specifies the size of the triangles that are used for the port meshing.
It is important to remark that the correct choice of this parameter is critical for the accuracy of the electromagnetic
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analysis. The mesh density employed for the port must be increased for large numbers of accessible modes of the
rectangular waveguide, in order to maintain the accuracy of the method. As a consequence, a large number of
accessible modes in the waveguide port will require a higher computational cost.
In order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing this way Fest3D to automatically choose an adequate value as a default. The automatic criterion employed
obeys the following rules:
If 30 or less accessible modes are employed in the rectangular waveguide, the triangle size is chosen as 1/5 of
the minimum dimension (a,b) of the waveguide.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
If a large amount of accessible modes is desired for the smaller waveguide port, it is necessary to take into
account that very fine meshes will be created using the automatic criterion, slowing down the simulation time
and increasing the memory consumption. Thus, it is not recommended to employ a high number of accessible
modes unless it is mandatory. If this is the case, one way to deal with the mentioned drawback is to set
manually the mesh size value for those cases, using the value that is shown in the element information as a
reference. Tests with larger values can be performed in order to find a tradeoff between convergence,
accuracy and computational cost.
Finally, it is important to remind again that the Mesh size port value is only necessary for the cases of different
port sections connected to this element, and only applies to the smaller port section. Values set to the larger
port or to any of the ports if both sections are equal, will not take any effect during simulation.
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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Specific properties of the Rounded corner iris 3D EM Field
2.4.2.2 Junctions library
The Junctions library contains the following discontinuities:
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Cubic Junction
T-Junction
Y-Junction (60 deg)
Y-Junction general with N screws
2D OMT
2D Compensated Tee
2.4.2.2.1 Cubic Junction
This section describes the C-Junction discontinuity and how to use it, as well as its features and limitations.
The C-Junction discontinuity section contains the following topics:
Definition
What is exactly a C-Junction discontinuity.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the C-Junction
How to create, edit and use this element from Fest3D.
Definition
The C-Junction discontinuity is a cubic or parellelepiped cavity. Each surface of the cavity can be connected to zero or
one rectangular waveguide.
The dimensions of the C-Junction are taken from the adjacent waveguides. As a maximum, the total number of
waveguides connected to the C-Junction is six.
This type of discontinuity enforces a fixed position of the coordinate system in each port. The next figure shows this
distribution.
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Limitations
The C-Junction can be connected only to rectangular waveguides. Two rectangular connected waveguides with
common sides must have the same dimensions on that sides.
The dimensions a, b and c of the C-Junction can not be left undefined so at least two rectangular waveguides
have to be connect to the discontinuity.
The waveguides located in opposite C-junction faces must have the same number of accessible modes.
EM Fields can not be computed on this element
Errors
The C-Junction discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
error: unsupported coupling integral
You connected a non-Rectangular waveguide to the C-Junction. The only solution is to change the circuit and
include a zero-length rectangular waveguide between the C-junction and the connected waveguide.
error: inconsistent geometry
You did not connected enough rectangular waveguide to the C-Junction in order to be able to extract the a, b
and c dimensions. Or you connected rectangular waveguides whose dimensions can not match in a C-Junction.
The first problem can be solved connecting 2 or more waveguides (depending on the position in the C-
Junction). The solution of the second problem is to change the circuit and include a zero-length rectangular
waveguide between the C-junction and the connected waveguide.
Using the C-Junction
The C-Junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following figures show a typical Element Properties dialog box for the C-Junction discontinuity:
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following C-Junction parameters can be edited:
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Modes Front-Back: number of modes used for Front-Back coupling.
Modes Left-Right: number of modes used for Left-Right coupling.
Modes Top-Bottom: number of modes used for Top-Bottom coupling.
These number of modes must be higher than the corresponding number of accessible modes of the adjacent
waveguides. Setting this value to 0 the number of modes taken will be equal to the corresponding number of
accessible modes.
In the lower part of the window, the number of ports are defined and the situation of each port in the C-junction is
given: front, back, right, left, top and bottom.
2.4.2.2.2 T-Junction
This section describes the T-Junction discontinuity and how to use it, as well as its features and limitations.
The T-Junction discontinuity section contains the following topics:
Definition
Limitations
What is exactly a T-Junction discontinuity.
What are the limitations you should be aware of.
Using the T-Junction
How to create, edit and use this element from Fest3D.
Definition
The T-Junction discontinuity is a parallelepiped cavity connected to three Rectangular waveguides, forming a T-like
shape. It is a special case of the more general element C-Junction. The dimensions of the parallelepiped cavity are
determined as the intersection of the connected Rectangular waveguides.
Please refer to the C-Junction element for further details and examples, remembering that a T-Junction is a special
case of it.
Limitations
The T-Junction discontinuity has the same limitations and caveats as the C-Junction.
Using the T-Junction
The T-Junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following figures show a typical Element Properties dialog box for the T-Junction discontinuity:
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
In the lower part of the window, the number of ports are defined and the situation of each port in the C-junction is
given: front, back, right, left, top and bottom.
2.4.2.2.3 Y-junction General with N screws
This section describes the General Y-junction with N screws discontinuity and how to use it, as well as its features and
limitations.
The General Y-junction with N screws discontinuity section contains the following topics:
Definition
What is exactly a General Y-junction with N screws discontinuity.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the Y-junction
How to create, edit and use this element from Fest3D.
Hints
Non-trivial features of the Y-junction.
Definition
The General Y-junction with N screws discontinuity, based on the Arbitrary shape , represents a generalized Y-junction
among three Rectangular waveguides. Additional posts (rectangular metal insertions and screws) can be considered
inside the Y-junction as well. This element is a template that lets you to specify the geometry of the circuit defining a
reduced number of parameters, without using the Arbitrary Shape Editor.
For these reasons many of the limitations and remarks of the Arbitrary shape element apply to this element as well.
The only difference comes from the definition of the coordinate system on each of the three ports.
The user can specify the geometry as shown in the following figure:
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The user must specify the lengths L12, L13, L2 and L3, and the angles 2 and 3 (in degrees). All lengths and widths must
be positive. Angles can be positive, negative or zero.
Examples:
A symmetric (120°) Y-junction requires α2 = α3 = 60°
A T-junction with port 1 and port 2 on the same waveguide requires α2 = 0°, α3 = 90°
A T-junction with port 2 and port 3 on the same waveguide requires α2 = α3 = 90°
Limitations
This element has the same limitations and caveats as the Arbitrary shape it is derived from.
In addition to this, the user should be aware that only some of the most common errors (negative lengths or port
widths) are detected and suitable error messages are issued. In general, it is up to the user to ensure that the
geometry is valid.
Errors
The Y-junction discontinuity can produce the same errors as the Arbitrary shape it is derived from.
Using the Y-junction (general) with N screws
The Y-junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Rounded corner iris discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L12: Distance from port 1 to the point where port 2 branch starts.
L13: Distance from port 1 to the point where port 3 branch starts.
L2: Length of port 2 branch.
L3: Length of port 3 branch.
Angle 2: Angle between port 2 and port 1.
Angle 3: Angle between port 3 and port 1.
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
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is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers three ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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Another part of the specifications of this element is the General posts tab, as shown in the figure below. Here,
additional posts (full constant width/height) can be inserted in the geometry if desired, by pressing the Add
button. Two post shapes can be selected:
Rectangular metal insertions. The parameters of these insertions are the same as the ones defined in the
Waveguide step with N metal inserts discontinuities.
Screws. The parameters of these insertions are the same as the ones described in the Waveguide step with N
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screws discontinuities.
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
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calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Hints
If the two angles of the arms are set to 90 degrees, a T junction is created.
The electromagnetic Solver will perform more efficient analysis for small values of lengths of the different
branches. Larger ports can be easily considered by increasing the length of the respective waveguides attached
to this element.
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2.4.2.2.4 Y-Junction (60 deg)
Definition
The Y-junction (60 degrees) discontinuity is based on the General Y-junction with N screws discontinuity, and has the
same characteristics and limitations. The only considerations to be taken is that the angles of the arms are fixed to
60 degrees and that no screws can be positioned inside of the Y-junction.
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Please refer to General Y-junction with N screws discontinuity to get more information.
2.4.2.2.5 2D OMT
This section describes the 2D OMT discontinuity and how to use it, as well as its features and limitations.
The 2D OMT section contains the following topics:
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Definition
What is exactly a 2D OMT.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the 2D OMT
How to create, edit and use this element from Fest3D.
Hints
Non-trivial features of the 2D OMT.
Definition
The 2D OMT, based on the Arbitrary shape, represents an OMT among three Rectangular waveguides. Additional
posts (rectangular metal insertions and screws) can be considered inside the OMT as well. This element is a template
that lets you to specify the geometry of the circuit defining a reduced number of parameters, without using the
Arbitrary Shape Editor.
For these reasons many of the limitations and remarks of the Arbitrary shape element apply to this element as well.
The only difference comes from the definition of the coordinate system on each of the three ports.
The user can specify the geometry as shown in the following figure:
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The user must specify the lengths dn and ln for every step. Additionally port lengths lp1, lp2 and lp3 can be set.
A radius for every edge of steps can be set. Lp1, Lp2 and Lp3 and radius can be zero. Offset can be positive, negative
or zero. Rest of dimensions must be positive.
Limitations
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This element has the same limitations and caveats as the Arbitrary shape it is derived from.
In addition to this, the user should be aware that only some of the most common errors (negative lengths or port
widths) are detected and suitable error messages are issued. In general, it is up to the user to ensure that the
geometry is valid.
Errors
The 2D OMT discontinuity can produce the same errors as the Arbitrary shape it is derived from.
Using the 2D OMT
The 2D OMT discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the 2D OMT.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Number of steps:  (1 by default). For each step, a specific tab will appear, in which two parameters are set:
li (mm/inches): Distance l of each step (shown in the legend).
di (mm/inches): Distance d of each step (shown in the legend).
Lp1 (mm/inches): Distance from port 1 to the point where port 2 branch starts. It can be zero.
Lp2 (mm/inches): Distance from port 2 to the point where port 1 branch starts. It can be zero.
Lp3 (mm/inches): Distance from port 3 to the point where port 1 branch starts. It can be zero.
P3 Offset (mm/inches): Offset of the port 3 respect to the center of that wall.
R:  Optional rounding radius used in the external corners (shown in the legend).
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers three ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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Another part of the specifications of this element is the General posts tab, as shown in the figure below. Here,
additional posts (full constant width/height) can be inserted in the geometry if desired, by pressing the Add
button. Two post shapes can be selected:
Rectangular metal insertions. The parameters of these insertions are the same as the ones defined in the
Waveguide step with N metal inserts discontinuities.
Screws. The parameters of these insertions are the same as the ones described in the Waveguide step with N
screws discontinuities.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
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allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Hints
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The electromagnetic Solver will perform more efficient analysis for small values of lengths of the different
branches. Larger ports can be easily considered by increasing the length of the respective waveguides attached
to this element.
2.4.2.2.6 2D Compensated Tee
This section describes the 2D Compensated Tee discontinuity and how to use it, as well as its features and limitations.
The 2D compensated Tee section contains the following topics:
Definition
Limitations
Errors
What is exactly a 2D Compensated Tee.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the 2D Compensated
tee
How to create, edit and use this element from Fest3D.
Hints
Non-trivial features of the 2D Compensated Tee.
Definition
The 2D Compensated Tee, based on the Arbitrary shape, represents a T-junction among three Rectangular
waveguides. Additional posts (rectangular metal insertions and screws) can be considered inside the T-junction as
well. This element is a template that lets you to specify the geometry of the circuit defining a reduced number of
parameters, without using the Arbitrary Shape Editor.
For these reasons many of the limitations and remarks of the Arbitrary shapeelement apply to this element as well.
The only difference comes from the definition of the coordinate system on each of the three ports.
The user can specify the geometry as shown in the following figure:
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The user must specify the lengths Lp1, Lp2, Lp3 and the dimensions of the insertion Wi, Li, Ri, Re, Rp and its offset.
Lp1, Lp2 and Lp3 and radius can be zero. Offset can be positive, negative or zero. Rest of dimensions must be positive.
Limitations
This element has the same limitations and caveats as the Arbitrary shapeit is derived from.
In addition to this, the user should be aware that only some of the most common errors (negative lengths or port
widths) are detected and suitable error messages are issued. In general, it is up to the user to ensure that the
geometry is valid.
Errors
The 2D Compensated Tee discontinuity can produce the same errors as the Arbitrary shapeit is derived from.
Using the 2D compensated Tee
The 2D Compensated Tee discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the 2D Compensated Tee discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Lp1: Distance from port 1 to the point where port 2 branch starts. It can be zero.
Lp2: Distance from port 2 to the point where port 1 branch starts. It can be zero.
Lp3: Distance from port 3 to the point where port 1 branch starts. It can be zero.
Offset: Offset of the insert from the mid point of port 1.
Wi: Width of metal insert.
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Li: Length of metal insert.
Re: Base radius of the insert. It can be 0. 
Ri: Top radius of the insert. It can be 0.
Rp: Radius of the port1. It can be 0.
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers three ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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Another part of the specifications of this element is the General posts tab, as shown in the figure below. Here,
additional posts (full constant width/height) can be inserted in the geometry if desired, by pressing the Add
button. Two post shapes can be selected:
Rectangular metal insertions. The parameters of these insertions are the same as the ones defined in the
Waveguide step with N metal inserts discontinuities.
Screws. The parameters of these insertions are the same as the ones described in the Waveguide step with N
screws discontinuities.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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Hints
The electromagnetic Solver will perform more efficient analysis for small values of lengths of the different
branches. Larger ports can be easily considered by increasing the length of the respective waveguides attached
to this element.
2.4.2.3 Bends
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2.4.2.3.1 Stepped Bend
This section describes the Stepped Bend discontinuity and how to use it, as well as its features and limitations.
The Stepped Bend discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Stepped Bend discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Stepped Bend How to create, edit and use this element from Fest3D.
Definition
The Stepped Bend discontinuity based on the Arbitrary shape (constant width/height) , represents a special bend
shape between two rectangular waveguides (ports 1 and 2), in which the non-shared corner of the bend is made out
of steps. An optional rounding radius can be considered for defining the stepped geometry, as shown in the figure
below.
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Using the Stepped Bend discontinuity
The Stepped Bend discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes and can view it in the 3D viewer.
The following picture shows a typical Element Properties dialog box for the Stepped Bend discontinuity.
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
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The following parameters can be edited:
R (mm/inches): Optional rounding radius used in the external corners (shown in the legend).
Length port 1 (mm/inches): Piece of length of the port 1 (shown in the legend).
Length port 2 (mm/inches): Piece of length of the port 2 (shown in the legend).
Number of steps (1 by default). For each step, a specific tab will appear, in which two parameters are set:
li (mm/inches): Distance l of each step (shown in the legend).
di (mm/inches): Distance d of each step (shown in the legend).
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Bend direction: This direction of the turn of the bend from port 1.  It can be set as "Right", "Left", ""Up" or
"Down". Depending on this parameter, the geometry will be automatically set as  Constant width or Constant
height. 
Max Frequency (0 = auto) (GHz): the highest frequency for the analysis of the component. In most cases
it can be set to “auto”, which means that this value is taken automatically as the double of the maximum
frequency analyzed in the circuit. A modification of the maximum simulated frequency can result in a change of
the S parameters. It could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. 
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
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calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Limitations
This element has the same limitations and caveats as the Arbitrary shape discontinuity.
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Errors
This element can produce the same errors as the Arbitrary shape. 
Hints
Better convergence is achieved if non-zero values of Length of port 1 and 2 are used (typically 1/10 of the size
of each respective port).
2.4.2.3.2 Mitered Bend
This section describes the Mitered Bend discontinuity and how to use it, as well as its features and limitations.
The Mitered Bend discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Mitered Bend discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Mitered Bend How to create, edit and use this element from Fest3D.
Definition
The Mitered Bend discontinuity based on the Arbitrary shape (constant width/height) , represents a special bend
shape between two rectangular waveguides (ports 1 and 2), in which the non-shared corner of the bend is a mitered
corner, which may have an additional intermediate point(depending on the parameters' values L1' and L2' given by
the user). An additional rounding radius can be also considered. Geometry examples are shown in the figure below.
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Using the Mitered Bend discontinuity
The Mitered Bend discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes and can view it in the 3D viewer.
The following picture shows a typical Element Properties dialog box for the Mitered Bend discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L1 (mm/inches): Distance defined from port 2 to the mitered corner (shown in the legend).
L2 (mm/inches): Distance defined from port 1 to the mittered corner (shown in the legend).
L1' (mm/inches): Distance defined from L1 to the position of an optional intermediate point in the mitered
corner (shown in the legend).
L2 '(mm/inches): Distance defined from L2 to the position of an optional intermediate point in the mitered
corner (shown in the legend).
Length port 1 (mm/inches): Piece of length of the port 1 (shown in the legend).
Length port 2 (mm/inches): Piece of length of the port 21 (shown in the legend).
R (mm/inches): Optional rounding radius used in the external corners (shown in the legend).
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Bend direction: This direction of the turn of the bend from port 1.  It can be set as "Right", "Left", ""Up" or
"Down". Depending on this parameter, the geometry will be automatically set as  Constant width or Constant
height. 
Max Frequency (0 = auto) (GHz): the highest frequency for the analysis of the component. In most cases
it can be set to “auto”, which means that this value is taken automatically as the double of the maximum
frequency analyzed in the circuit. A modification of the maximum simulated frequency can result in a change of
the S parameters. It could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. 
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
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to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Limitations
This element has the same limitations and caveats as the Arbitrary shape discontinuity.
Errors
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This element can produce the same errors as the Arbitrary shape.
Hints
Better convergence is achieved if non-zero values of Length of port 1 and 2 are used (typically 1/10 of the size
of each respective port).
2.4.2.3.3 2D Curved
This section describes the 2D Curved discontinuity and how to use it, as well as its features and limitations.
The 2D Curved discontinuity section contains the following topics:
Definition
What exactly is a 2D Curved discontinuity.
Limitations
What are the limitations you should be aware of.
Errors
The possible errors produced by this element, and solutions or workarounds to them.
Using the 2D Curved How to create, edit and use this element from Fest3D.
Definition
The 2D Curved discontinuity based on the Arbitrary shape (constant width/height) , represents a curved bend shape
between two rectangular waveguides (ports 1 and 2). The user can specify the geometry as shown in the following
figure:
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Limitations
This element has the same limitations and caveats as the Arbitrary shape it is derived from.
In addition to this, the user should be aware that only some of the most common errors (negative angle
or different port sizes) are detected and suitable error messages are issued. In general, it is up to the user to ensure
that the geometry is valid.
Errors
The 2D Curved discontinuity can produce the same errors as the Arbitrary shape it is derived from.
Using the 2D Curved discontinuity
The 2D Curved discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes and can view it in the 3D viewer.
The following picture shows a typical Element Properties dialog box for the 2D Curved discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
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Angle (degrees): Curvature angle (range: 0 < angle< 360)
Mean radius (mm/inches): Mean radius of the curve
Curvature direction: This direction of the turn of the bend from port 1.  It can be set as "Right", "Left", ""Up" or
"Down". Depending on this parameter, the geometry will be automatically set as  Constant width or Constant
height. 
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
 Please note that input and output waveguides must have same dimensions when being connected through this
element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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Hints
For Curvature Angle > 90 degrees, it is recommended to split the bend into multiple sub-bends (connected by
zero-length waveguides) to improve performance
For Mean Radius > A, it is recommended to split the bend into multiple sub-bends (connected by zero-length
waveguides) to improve performance.
2.4.2.4 Const width/height discontinuities
2.4.2.4.1 Arbitrary shape
This section describes the Arbitrary shape (constant width/height) discontinuity and how to use it, as well as its
features and limitations. The Const width/height arbitrary shape discontinuity section contains the following topics:
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Definition
Limitations
Errors
Using the Arbitrary shape (constant
width/height)
Definition
What is exactly a Arbitrary shape (constant width/height) discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or
workarounds to them.
How to create, edit and use this element from Fest3D.
The Arbitrary shape (constant width/height) discontinuity represents a microwave circuit that is constant along a
certain direction, but is otherwise arbitrary in the normal plane. It is employed to model rectangular waveguide
junctions where all the waveguides have the same width (parameter 'A') or height (parameter 'B'). In addition, the
centre of these waveguides must be contained in the same plane (perpendicular to the constant direction) as shown
in the following figures.
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In order to geometrically define a Arbitrary shape (constant width/height) discontinuity, one must describe the
arbitrary 2D contour of the component and the position of the ports. Additionally, the user must define whether the
2D contour is extruded in the direction of the width (A) or height (B) of the connected waveguides by choosing the
appropriate "Constant height" or "Constant width" radio button.
The contour of the Arbitrary shape (constant width/height) discontinuity is described in a .mesh file that can be
generated and modified using the Arbitrary Shape Editor integrated in Fest3D. It contains a collection of straight
segments, circular and/or elliptical arcs that define a closed path (open contours are not supported).  Multiple
contours are allowed, representing elements that are multiply-connected (ie. having one or more "holes"). However,
this contours cannot intersect or be mutually tangent. Furthermore, an internal contour cannot be placed within
another internal contour .
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The ports of the structure can be defined as the interfaces between the discontinuity and each of the connected
Rectangular waveguides. There is no limit in the number of ports that an Arbitrary shape (constant width/height)
discontinuity can support. To define their position, the segments that define the intersection between the plane
containing the arbitrary section and the transversal plane of each connected waveguide must be marked as ports in
the Arbitrary Shape Editor.
Each port has its own fixed coordinate system, and the waveguide that is connected to such port adopts the same
coordinate system. In the previous figures, the two examples of  the constant-height and constant-width components
included each port coordinate system as a reference. For other structures, the procedure to determine unambiguously
the orientation of the coordinate system for each port can be described as follows:
Starting from the 2D arbitrary contour, define the vectors tangent to the contour at the ports (t) in a
counter-clockwise sense and the normal vectors (n) pointing inwards.
From t and n, vector u can be found as u = t X n
The constant dimension of the ports will be aligned with u , meaning that for constant-height
discontinuities u = y and for constant-width discontinuities u = x.
Knowing one of the waveguide transversal components u, the other that remains unknown v (ie. v = x for
constant-height discontinuities and v = y for constant-width components), can be found following this
rule:
For port #1: v = t 
which implies that the waveguide  direction points inwards (ie. from the waveguide towards the
discontinuity).
Otherwise,  v = -t
which implies that the waveguide  direction points outwards (ie. from the discontinuity towards
the waveguide).
Regarding the parameters of the electromagnetic Solver based in the BI-RME 2D method that analyzes this
component, the user must fix a maximum frequency value as well. The maximum frequency value is related to the
higher resonant mode considered within the discontinuity when all the ports are short-circuited.
A material different from vacuum can be chosen to fill the discontinuity. In such a case, the dielectric properties
(relative dielectric permittivity and permeability) of this material must be specified.
Although this element typically represents an E-plane or H-plane component, the discontinuity accepts any
rectangular waveguide mode as excitation. Consequently, it can be regarded as a full-wave element. However, if this
element is indeed used within an E-plane or H-plane circuit, it is advised to select the general "All-capacitive" or "All-
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inductive" symmetry option in the specifications of the circuit. The use of the appropriate symmetry will speed up
considerably the analysis of the discontinuity since less modes are computed.
Limitations
The Const width/height discontinuity has some limitations and caveats you should be aware of.
Connections to other elements
This element can only be connected to Rectangular waveguides (one for each port). The width and height of
the ports of this element must be equal to the dimensions of the Rectangular waveguides attached to the
component.
No full check for valid geometry
The code performs only a limited (incomplete) geometry validation. It is the user's responsibility to ensure the
specified geometry is valid.
Invalid geometries
Examples of invalid contours are:
open contours
intersecting or tangent contours
contours internal to other internal contours
cross-section profile with <1 ports
ports defined on arcs rather than on segments
Low accuracy in some cases
Defining two adjacent segments as ports should be avoided (for instance, bends). Instead, it is advised to
include a portion of the access rectangular waveguide in the 2D section.
Some loss in accuracy should be expected if the contour includes very thin regions or internal contours very
close to the boundary or to other internal contours, as shown in the following figures.
If you cannot avoid these cases, you are recommended to set a high value of Max Frequency .
Slow convergence in some cases
The simulation of some geometries, including the ones explained in low accuracy in some cases above, may
require some extra user effort to reach convergence. In particular, the default auto setting of Max Frequency
parameter explained below, may not be enough to reach convergence. In these cases, the Convergence Study
must be performed including the Max Frequency parameter with all other numeric accuracy parameters and
tuning all of them manually.
Errors
The Const width/height arbitrary shape discontinuity can produce the following errors under certain circumstances.
For each error, the possible solutions or workarounds are explained.
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Invalid geometry
The geometry is invalid. The problem will be specified together with the probable causes. Usually it is sufficient
to adjust the profile definition using the Arbitrary Shape Editor to fix the problem.
LTM matrix is not positive definite
This error can occur if the geometry is tricky. For instance, if a small arc is employed. To solve the problem, you
can try to increase the Max Frequency until the error disappears.
Not enough arbitrary modes generated
If the number of generated modes is less than 3, the simulation pops up a message and it is stopped. To solve
this, the user must start a new simulation specifying a larger Max Frequency.
Using the Arbitrary shape (constant width/height)
The Arbitrary shape (constant width/height) discontinuity is completely integrated into Fest3D. The user can create,
view and edit this element properties using dialog boxes and the Arbitrary Shape Editor.
The following pictures show a typical Element Properties dialog box for the Arbitrary shape (constant width/height):
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
MESH File: the file containing the arbitrary shape cross-section (profile) for this element
Edit button: The Edit button opens the Arbitrary Shape Editor allowing the user to view/edit the mesh file.
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Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. The number of ports that have been defined in the
MESH file appear automatically in this tab. For each port, a specification tab is shown. A waveguide must be
selected from the Attached waveguide list, which will be filled with the connections already associated to this
element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
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to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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2.4.2.4.2 Waveguide step with N Metal inserts
This section describes the Waveguide step with N metal inserts discontinuity and how to use it, as well as its features
and limitations.
The Waveguide step with N metal inserts section contains the following topics:
Definition
Limitations
Errors
Using the Waveguide step with N metal
inserts
What is exactly a Waveguide step with N metal inserts.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or
workarounds to them.
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Waveguide step with N metal inserts, based on the Arbitrary shape element, represents a waveguide with N
rectangular metal inserts of rectangular shape like the one sketched in the figure below. This element must have
constant height or width.
Square case
Non-square case
Limitations
This element has the same limitations as the Arbitrary shape element.
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Errors
This element has the same limitations as the Arbitrary shape element.  
Using the Waveguide step with N metal inserts
The Waveguide step with N metal inserts is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes and can view it in the 3D viewer.
Connections to other elements: This element must be connected to two Rectangular waveguides (one for each
port). The width and height of step ports will be equal to the dimensions of the Rectangular waveguides attached to
the element.
The following picture shows a typical Element Properties dialog box for the Waveguide step with N metal inserts.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
Regarding the geometry of this element, there are some particular parameters to define depending on the geometry
of the contour (squared or non-squared):
SQUARE CASE
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L (mm/inches): The length of the waveguide with metal insert.
NON-SQUARE CASE
L1 (mm/inches): The length of the waveguide with metal inserts connected to port 1.
L2 (mm/inches): The length of the waveguide with metal inserts connected to port 2.
OFFSET (mm/inches): The offset between port 1 and port 2 is positive towards the right (when looking from
port 1).
Ri (mm/inches): Radius of the internal corners.
Re (mm/inches): Radius of the external corners.
Besides, the following general parameters can be also edited:
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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Another part of the specifications of this element is the Metal inserts tab, as shown in the figure below.
Here, rectangular metal insertions (full constant width/height) can be set. One metal insertion is considered by default,
ready to be defined. Additional insertions can be included in the geometry if desired, by pressing the Add button. 
For each metal insert, the following parameters can be edited:
Thickness (mm/inches): Width of the metal insert
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Length (mm/inches): Length of the metal insert
Offset (mm/inches): Offset in X or Y axis respect to the center of the geometry. In case of X offset, it has a
positive value if you move the metal insert to the right (as seen from port 1).
Displacement (mm/inches): Z displacement respect to the center of the geometry. Here, positive Z
displacement means to move the metal insert away from port 1.
Angle (degrees): A rotation angle that is defined counter-clockwise when looking from port 1. 
Any of the particular metal insert can be removed by pressing the Delete post button.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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Hints
This element can be replaced by the N-step in many situations. Using the N-step with inductive/capacitive
symmetries in the circuit will speed up the simulation in the frequency-independent part but it may slow down
the simulation in the frequency-dependent part. Implementing a circuit with the metal insert element and with
the N-step can help to verify if the simulation result is accurate since these elements are based on completely
different numerical techniques.
The electromagnetic Solver will perform more efficient analysis for small values of L/L1/L2. Larger ports can be
easily achieved by increasing the length of the respective waveguides attached to this element.
2.4.2.4.3 Waveguide step with N Screws
This section describes the Waveguide step with N metal inserts Discontinuities and how to use it, as well as its features
and limitations.
The Waveguide step with N metal inserts section contains the following topics:
Definition
Limitations
Errors
What is exactly a Waveguide step with N Screws.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds
to them.
Using the 2D Discontinuity with
screws
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Waveguide step with N metal inserts, based on the Arbitrary shape element, represents a waveguide with N metal
inserts of circular shape (screws) like the one sketched in the figure below. This element must have constant its height
or its width.
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Square case
Non-square case
Limitations
This element has the same limitations as the Arbitrary shape element.  
Errors
This element has the same limitations as the Arbitrary shape element.  
Using the Waveguide step with N screws
The 2D Discontinuity with screws is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes and can view it in the 3D viewer.
Connections to other elements: This element must be connected to two Rectangular waveguides (one for each
port). The width and height of step ports will be equal to the dimensions of the Rectangular waveguides attached to
the element.
The following picture shows a typical Element Properties dialog box for the Waveguide step with N Screws.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
Regarding the geometry of this element, there are some particular parameters to define depending on the geometry
of the contour (squared or non-squared):
SQUARE CASE
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L (mm/inches): The length of the waveguide with metal insert.
NON-SQUARE CASE
L1 (mm/inches): The length of the waveguide with screws connected to port 1.
L2 (mm/inches): The length of the waveguide with screws connected to port 2.
OFFSET (mm/inches): The offset between port 1 and port 2 is positive towards the right (when looking from
port 1).
Ri (mm/inches): Radius of the internal corners.
Re (mm/inches): Radius of the external corners.
Besides, the following general parameters can be also edited:
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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Another part of the specifications of this element is the Screws tab, as shown in the figure below. Here, circular metal
insertions (full constant width/height) can be set. One screw is considered by default, ready to be defined. Additional
screws can be included in the geometry if desired, by pressing the Add button. 
For each screw, the following parameters can be edited:
Radius (mm/inches): Radius of the screw
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Offset (mm/inches): Offset in X or Y axis respect to the center of the geometry. In case of X offset, it has a
positive value if you move the screw to the right (as seen from port 1).
Z displacement (mm/inches): Z displacement respect to the center of the geometry. Here, positive Z
displacement means to move the post away from port 1.
Any screw can be removed by pressing the Delete post button.
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
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allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Hints
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The electromagnetic Solver will perform more efficient analysis for small values of L/L1/L2. Larger ports can be
easily achieved by increasing the length of the respective waveguides attached to this element.
2.4.2.4.4 Waveguide Step with rounded corners
This section describes the Waveguide step with rounded corners discontinuity and how to use it, as well as its features
and limitations.
It contains the following topics:
Definition
Limitations
Errors
What is exactly a Waveguide step with rounded corners discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Half iris rounded How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
Definition
The Waveguide step with rounded corners discontinuity, based on the Arbitrary shape element, represents a transition
between two rectangular waveguides of different height or width (only one can be different at the same time)
including rounded corners.
The Waveguide step with rounded corners discontinuity is a special case of the more general element named
Arbitrary shape .
Limitations
This element has the same limitations as the Arbitrary shape element.
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Errors
This element has the same limitations as the Arbitrary shape element.   
Using the waveguide step with rounded corners discontinuity
The Waveguide step with rounded corners discontinuity is completely integrated into Fest3D. The user can create,
view and edit this element properties using dialog boxes and can view it in the 3D viewer.
The following picture shows a typical Element Properties dialog box for the Half iris rounded discontinuity.
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L1 (mm/inches): The length of the waveguide piece connected to port 1.
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L2 (mm/inches): The length of the waveguide piece connected to port 2.
Li (mm/inches): The length of the iris.
Ai (mm/inches): Dimension of the iris. In the constant width case, it is the height and in the constant height
case it is the width.
Offset (mm/inches): The offset of the iris, from port 1 to port 2 is positive towards the right.
Ri (mm/inches): Radius of the internal corners.
Re (mm/inches): Radius of the external corners.
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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2.4.2.4.5 Rounded corner iris
This section describes the Rounded corner iris discontinuity and how to use it, as well as its features and limitations.
The Rounded corner iris discontinuity section contains the following topics:
Definition
Limitations
Errors
What is exactly a Rounded corner iris discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Rounded corner
iris
How to create, edit and use this element from Fest3D.
Hints
Non-trivial properties of this element.
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Definition
The Rounded corner iris discontinuity, based on the Arbitrary shape element, represents an iris in either constant
width or height, like the one sketched in the figure below.
The Rounded corner iris discontinuity is a special case of the more general element named Arbitrary shape .
Limitations
This element has the same limitations as the Arbitrary shape element. 
Errors
This element has the same limitations as the Arbitrary shape element. 
Using the Rounded corner iris discontinuity
The Rounded corner iris discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes and can view it in the 3D viewer.
Connections to other elements: This element must be connected to two Rectangular waveguides (one for each
port). The width and height dimensions of this element are equal to the dimensions of the Rectangular waveguides
attached to the component.
The following picture shows a typical Element Properties dialog box for the Rounded corner iris discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L1 (mm/inches): The length of the waveguide piece connected to port 1.
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L2 (mm/inches): The length of the waveguide piece connected to port 2.
Li (mm/inches): The length of the iris.
Ai (mm/inches): Dimension of the iris. In the constant width case, it is the height and in the constant height
case it is the width.
Offset (mm/inches): The offset of the iris, from port 1 to port 2 is positive towards the right.
Ri (mm/inches): Radius of the internal corners.
Re (mm/inches): Radius of the external corners.
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers two ports. For each
port, a specification tab is shown. A waveguide must be selected from the Attached waveguide list, which will be
filled with the connections already associated to this element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
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2.4.2.4.6 2D Rounded short
This section describes the 2D Rounded short discontinuity and how to use it, as well as its features and limitations.
The 2D Rounded short section contains the following topics:
Definition
Limitations
Errors
What is exactly a 2D Rounded short.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the 2D Rounded
Short
How to create, edit and use this element from Fest3D.
Hints
Non-trivial features of the 2D Rounded short.
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Definition
The 2D Rounded short, based on the Arbitrary shape , represents a one port short waveguide. This element is a
template that lets you to specify the geometry of the circuit defining a reduced number of parameters, without using
the Arbitrary Shape Editor.
For these reasons many of the limitations and remarks of the Arbitrary shape element apply to this element as well.
The user can specify the geometry as shown in the following figure:
The user must specify the length L and radius R. Neither R or L can be 0.
Limitations
This element has the same limitations and caveats as the Arbitrary shape it is derived from.
Errors
The 2D Rounded short discontinuity can produce the same errors as the Arbitrary shape it is derived from.
Using the 2D Rounded short
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The 2D Rounded short discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following picture shows a typical Element Properties dialog box for the Rounded corner iris discontinuity.
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L: Length of the short.
R: Radius of the short.
Dielectric Permittivity: the relative dielectric permittivity of the homogeneous medium filling this element (1.0
is vacuum).
Dielectric Permeability: the relative dielectric permeability of the homogeneous medium filling this element
(1.0 is vacuum).
Select type of geometry: Here the geometry can be specified to be Constant width or Constant height.
Maximum frequency (GHz): the highest frequency for the analysis of the component. By default, it is set
to 0.0, which means that this value is taken automatically as the double of the maximum frequency analyzed in
the circuit. A modification of the maximum simulated frequency can result in a change of the S parameters. It
could also slow down the simulation unnecessarily.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the discontinuity are
configured in the Ports tab, as shown in the figure below. This discontinuity always considers one port. For that
port, a waveguide must be selected from the Attached waveguide list, which will be filled with the connections
already associated to this element.
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
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particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Hints
The electromagnetic Solver will perform more efficient analysis for small values of L. Larger ports can be
easily achieved by increasing the length of the respective waveguides attached to this element.
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2.4.2.5 Coaxial cavity library
The Coaxial cavity library contains the following discontinuities:
Cavity with posts
Straight feed cavity
Mushroom feed cavity
Straight contact feed cavity
S-Shape contact feed cavity
Loop feed cavity
Magnetic feed cavity
Top contact feed cavity
General cavity
2.4.2.5.1 Cavity with posts
This section describes the Cavity with posts discontinuity and how to use it, as well as its features and limitations.
The Cavity with posts discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Cavity with posts discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Cavity with posts How to create, edit and use this element from Fest3D.
Definition
The Cavity with posts discontinuity represents a rectangular cavity with resonant posts and/or tuning screws of various
shapes, whose geometrical parameters and position are specified by the user. The posts can be positioned at any of
the 6 different surfaces of the rectangular cavity . Input/Output rectangular ports can also be
placed on the walls. For performing the analysis, two different electromagnetic Solver types based on the BI-RME 3D
method can be selected .
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Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications, several different shapes can be considered for the posts, which are shown in
figure B. By default, any post will be placed at the center of the bottom surface. The user can change this surface, and
specify an offset with respect to the center. For rectangular-shaped posts, a rotation angle can be also applied, taking
into account the main reference system defined in figure A (examples are depicted in figure C for the different
surfaces of the cavity).
Figure B: Different post types considered for this cavity
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Figure C: Offset conventions for posts
Limitations
The Cavity with posts discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular waveguides.
Port does not match capacitive posts
If the Solver BI-RME 3D Cylindrical is selected for analysis , this element can not
be used for capacitive or inductive posts. The height of the post has to be always smaller than the cavity width
or height. Nevertheless, if the design requires the presence of purely inductive or capacitive posts without
approximations, it is also possible to perform the analysis by changing the Solver to BI-RME 3D RWG (further
information addressed at the element specifications), despite a slow-down in the simulation time.
As another alternative, if you plan to simulate a purely capacitive or inductive structure with posts, it is a better
idea to use the Constant width/height arbitrary shape discontinuity element inside Fest3D.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
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connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
Collisions between ports and/or posts
The electromagnetic Solvers based on the BI-RME 3D method do not support intersection between
ports, or geometrical collisions between ports and posts. The software will detect this kind of situations and
return an error message. On the other hand, the detection of collision between posts is handled differently
depending on the Solver. For the case of BI-RME 3D Cylindrical, post collision is not supported, and the
software will consider it as an error. On the contrary, for the Solver BI-RME 3D RWG, post collision is
allowed and the software will alert of this situation as a warning.
High memory consumption using parallelization in circuits with many cavities using the Solver BI-RME
3D RWG
If the Solver BI-RME 3D RWG is selected and small values of mesh sizes are specified (for high accuracy or
convergence tests), then very large meshes and dense matrices are required in the simulation, consuming an
important amount of RAM. Once the meshing of the element is performed, the information window will show
an estimation of the maximum total memory that will be used during calculations. Besides, the software will
automatically detect if the memory requirements are greater than the RAM memory available in the system,
and will stop the simulation if necessary. If there are several different cavities in the circuit, and multicore
simulation is desired, it is important to take into account that these RAM requirements are increased,
and a slowdown in the computer performance might be encountered. For those cases, it is recommended to
employ a lower number of processors, which may allow successfully completing a simulation that cannot be
performed using more cores due to memory limitation problems. If reducing the number of processors the
memory problems still persist, it is advisable to increase the mesh size values (reduce precision) of the posts or
rounded corners in the cavity (explained in the specifications section below) for performing the simulation.
Errors
The Cavity with posts discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR while performing simulation. Error while building mesh. Please try to reduce mesh size
value(s)
This error occurs when there is a problem building the internal meshing of the posts needed by this element,
when the Solver BI-RME 3D Cylindrical is selected. This problem usually appears when using posts of
mushroom or hollow type, if the mesh size value specified by the user is not adequate for the dimensions of
the post. The values used for mesh size must be reduced in order to avoid this error.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
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If the Solver BI-RME 3D RWG is chosen, this element requires to create a 3D mesh for the whole cavity
together with the posts, from which the surface meshing of metallic objects is extracted. If this error appears, it
means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D mesh is necessary to
compute data employed for the EM fields calculations. For this reason, the simulation is forbidden if the 3D
mesh is not available. This situation may happen if a wrong geometry has been specified (e.g., posts colliding
with each other). The dimensions and offsets of the posts should be revised, and verified with the 3D viewer in
order to detect any possible geometrical problems. If the geometry is correct, another source for this error is
that very small air gaps are present in the cavity, which can not be dealt by the 3D meshing algorithm for the
given mesh sizes. Reducing their values might be the solution for a correct 3D mesh generation. If the problem
persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh when the Solver BI-RME 3D RWG is selected.
This can occur if there are failures while generating the geometry of the cavity. It is advisable to check if the
geometry can be visualized with the 3D viewer. If this is the case, then the problem is related to the meshing
algorithms, due to the same reasons explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Cavity with posts
The Cavity with posts discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Cavity with posts:
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Figure D: Specific properties of the Cavity with posts
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
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between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired. Finally, it is important to bear in mind that for
performing simulation with rounded corner cavities, it is necessary to use the Solver BI-RME 3D RWG.
Solver type. The geometry of this element can be analyzed by selecting one of two available Solvers based in
the BI-RME 3D method implemented inside Fest3D:
BI-RME 3D Cylindrical: This Solver considers specialized high order cylindrical basis functions for
modelling the surface currents of the posts. It is selected by default, since the posts are generally of
cylindrical shape in most cases. The functions of this Solver offer a very fast performance, but have some
limitations, as they cannot be used for analysis of purely inductive posts (as mentioned above in the
limitations section), electromagnetic field computation or analysis of cavities with rounded corners
and/or non-cylindrical shapes.
BI-RME 3D RWG: This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the
surface currents of the posts. This Solver requires that the geometry is meshed with triangular patches
onto which the RWG basis functions are defined. Thus, this Solver is more general and can be employed
to analyze any kind of geometrical problem, although as a drawback it requires a higher computational
cost in order to properly model the behaviour of rounded shapes.
Maximum Frequency (GHz): This parameter is required for any of the two BI-RME 3D Solvers, and specifies
the maximum value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. For performing this analysis, it is necessary to choose the Solver BI-RME 3D RWG
for the simulation. Otherwise, a warning message will be shown to the user.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab.
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element.
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Figure E: Port properties of the Cavity with posts
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
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Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
The offsets and the mesh size of the port only make sense if a rectangular waveguide smaller than the cavity
surface dimensions is considered. The mesh density employed for the port must be increased for large numbers of
accessible modes of the rectangular waveguide, in order to maintain the accuracy of the method. As a consequence, a
large number of accessible modes in the waveguide port will require a higher computational cost.
In order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing this way Fest3D to automatically choose an adequate value as a default. The automatic criterion employed
obeys the following rules:
If 30 or less accessible modes are employed in the rectangular waveguide, the triangle size is chosen as 1/5 of
the minimum dimension (a,b) of the waveguide.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and mesh size) have no meaning, and the internal electromagnetic Solver employs
analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for the mesh discretization of the rectangular port. The user can take this value as
reference in order to manually increase it for speeding up calculations, or decreasing it if more precision is desired,
taking into account the memory limitations.
Another important part of the specifications of this element is the General Posts tab. Here, the different posts/tuning
screws desired for the geometry are defined. By default, a Cylindrical post is already considered, ready to be defined.
More posts can be inserted by selecting the post shape from the available list and pressing the Add button. It is
important to mention that if draft angle, rectangular or helical shapes are selected, simulation is only allowed
if the Solver BI-RME 3D RWG is selected.
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Figure F: General Posts properties of the Cavity with posts
For each post, the user can edit the specifications for the position, dimensions, mesh size and offsets of the post.
Any of the posts can be discarded by pressing the Delete post button on each tab. Depending on the shape of the
post, a specific legend with the definition of the geometrical parameters is automatically shown at the right side of the
window. Legends with the offset definitions and the other types of post shapes are also displayed for reference.
Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
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Figure G: Additional window for definition of roundings on a post.
The mesh size parameter indicates the density of the mesh of the associated geometry, employed by
the electromagnetic Solver. The user should change this mesh size for each particular case, taking into account the
maximum and minimum dimensions employed. The smaller the mesh size, the finest the internal meshing, which will
lead to more accurate results, but it will also slow down the simulation time. Also, very small values may produce
memory allocation problems, due to large size of the matrices involved.
The definition of this value depends on the basis functions of the selected Solver type:
For the high order cylindrical basis functions of the BI-RME 3D Cylindrical Solver, indicates the size of the
linear segments used for surface discretization.
For the triangular RWG basis functions of the BI-RME 3D RWG Solver, indicates the size of the 2D triangles
used for the surface meshing.
The user has to bear in mind that the convergence speed of the two types of basis functions is different, and
the use of the same value of mesh size might not be adequate for the both types of Solvers at the same time.
Generally, convergent results are achieved faster with the BI-RME 3D Cylindrical Solver, and smaller values will
be required for the BI-RME 3D RWG for obtaining similar accuracy. On the other hand, if very small values are
already used in the cylindrical function case, the change to RWG basis functions must be done with care, since
very large mesh densities might be produced.
The electromagnetic fields of this discontinuity can be computed and visualized. With this purpose, The EM Field tab
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allows to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of the
air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can be
chosen the same as specified in the general properties of the field computation, or can be specified for the particular
element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
For performing EM fields computations, it is mandatory to use the Solver BI-RME 3D RWG in the simulation.
Figure H: EM Field properties of the Cavity with posts
For general field visualizations, the mesh size value specified for the cavity will produce a uniform mesh density along
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the whole air volume inside the cavity. Nevertheless, for performing High Power analysis inside cavities with cylindrical
posts, it is important to employ a detailed resolution around the areas with maximum field values, in order to ensure
convergent results in the Corona and Multipactor algorithms for breakdown power detection. If a uniform mesh
criteria is employed for the whole volume air region inside the cavity, very dense meshes are created in order to
preserve a high resolution in the desired areas, which may require a remarkable time for mesh generation and
specially for calculations. Also, memory overflows may occur in the Corona algorithm if a very large amount of
tetrahedra is considered.
In order to help avoiding these problems, Fest3D performs an automatic refinement procedure around the areas of
maximum field, which are the surroundings of the metallic posts. Thus, field details are taken into account without
forcing a high resolution in the empty air regions (which may occupy most part of the cavity).
Taking as reference value the mesh size specified for the High Power algorithm (Corona or Multipactor), the
refinement procedure is applied following the scheme shown in Figure I. Considering a general cylindrical post (it can
be any of the defined shapes in Figure B), a General Refinement Area is defined around the geometrical center of the
post, consisting in a fictitious box defined in terms of the post radius. Inside this General Area, the original mesh size is
reduced by a factor 2. This means that the resolution of the fields computed inside the region is exactly the double of
the one employed in the air far from the post, according to the original value specified.
As the strongest field variations in the posts are always located at the cap of the cylindrical shape, a Cap Refinement
Area is also defined using a second box centered in the middle of the cylinder tape. The box width and height are the
same as the defined for the box of the General Area. Inside this Cap Area, the original mesh size is reduced in a factor
8. Besides, the height of this Area is also defined in terms of the mesh size specified. This definition ensures that,
independently of the value of the mesh size for the rest of the cavity, the Cap Region will always consider a higher
resolution for the field computations in this critical area, with at least 2 triangles defined around the tape in the
direction of the cylinder axis.
As final comments, the simplified scheme of Figure I only shows the case of a cylinder whose base is placed on the
bottom wall of the cavity, but the procedure is equally applied to all the posts that appear in the cavity, independently
of their orientation. Finally, this refinement procedure is also applied to the Export Fields to Spark 3D option, since the
goal of this exportation is to perform a High Power analysis as well. For this case, the mesh size associated to this tab
of the properties will be the one used for the refinement reference.
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Figure I. Scheme of the automatic refinement applied to the air meshing for field computations using High Power
analysis. MS is the mesh size specified by the user for Corona, Multipactor, or general field exportation.
2.4.2.5.2 Straight feed cavity
This section describes the Straight feed cavity discontinuity and how to use it, as well as its features and limitations.
The Straight feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Straight feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Straight feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The Straight feed cavity discontinuity consists in a rectangular cavity which is excited using a straight coaxial probe.
The cavity dimensions, the local reference system, and the different surface names are depicted in figure A, and are
the same as in the Cavity with posts. The geometrical parameters and positions of the probe are shown in figure B and
can be specified by the user. Besides this main excitation block, rectangular ports and additional
resonant posts/tuning screws can be considered at any of the cavity walls. For performing the analysis, two different
electromagnetic Solver types based on the BI-RME 3D method can be selected .
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
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Regarding the geometrical specifications of the excitation probe, a schematic picture of a common practical case is
shown in figure B, including the names of the relevant dimensions to be specified by the user.
Figure B: Basic geometrical scheme of the excitation block
Limitations
The Straight feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides.
Analysis of inductive or capacitive posts
If the Solver BI-RME 3D Cylindrical is selected for analysis , this element can not
be used for capacitive or inductive posts. The height of the post has to be always smaller than the cavity width
or height. Nevertheless, if the design requires the presence of purely inductive or capacitive posts, it is a better
idea to use the Constant width/height arbitrary shape discontinuity element inside Fest3D.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
Collisions between ports and/or posts
The electromagnetic Solvers based on the BI-RME 3D method do not support intersection between
ports, or geometrical collisions between ports and posts. The software will detect this kind of situations and
return an error message. On the other hand, the detection of collision between posts is handled differently
depending on the Solver. For the case of BI-RME 3D Cylindrical, post collision is not supported, and the
software will consider it as an error. On the contrary, for the Solver BI-RME 3D RWG, post collision is
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allowed and the software will alert of this situation as a warning.
High memory consumption using parallelization in circuits with many cavities using the Solver BI-RME
3D RWG
If the Solver BI-RME 3D RWG is selected and small values of mesh sizes are specified (for high accuracy or
convergence tests), then very large meshes and dense matrices are required in the simulation, consuming an
important amount of RAM. Once the meshing of the element is performed, the information window will show
an estimation of the maximum total memory that will be used during calculations. Besides, the software will
automatically detect if the memory requirements are greater than the RAM memory available in the system,
and will stop the simulation if necessary. If there are several different cavities in the circuit, and multicore
simulation is desired, it is important to take into account that these RAM requirements are increased,
and a slowdown in the computer performance might be encountered. For those cases, it is recommended to
employ a lower number of processors, which may allow successfully completing a simulation that cannot be
performed using more cores due to memory limitation problems. If reducing the number of processors the
memory problems still persist, it is advisable to increase the mesh size values (reduce precision) of the posts or
rounded corners in the cavity (explained in the specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The Straight feed cavity discontinuity can produce the following errors under certain circumstances. For each error, the
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possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR while performing simulation. Error while building mesh. Please try to reduce mesh size
value(s)
This error occurs when there is a problem building the internal meshing of the posts needed by this element,
when the Solver BI-RME 3D Cylindrical is selected. This problem usually appears when using posts of
mushroom or hollow type, if the mesh size value specified by the user is not adequate for the dimensions of
the post. The values used for mesh size must be reduced in order to avoid this error.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If the Solver BI-RME 3D RWG is chosen, this element requires to create a 3D mesh for the whole cavity
together with the posts, from which the surface meshing of metallic objects is extracted. If this error appears, it
means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D mesh is necessary to
compute data employed for the EM fields calculations. For this reason, the simulation is forbidden if the 3D
mesh is not available. This situation may happen if a wrong geometry has been specified (e.g., posts colliding
with each other). The dimensions and offsets of the posts should be revised, and verified with the 3D viewer in
order to detect any possible geometrical problems. If the geometry is correct, another source for this error is
that very small air gaps are present in the cavity, which can not be dealt by the 3D meshing algorithm for the
given mesh sizes. Reducing their values might be the solution for a correct 3D mesh generation. If the problem
persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh when the Solver BI-RME 3D RWG is selected.
This can occur if there are failures while generating the geometry of the cavity. It is advisable to check if the
geometry can be visualized with the 3D viewer. If this is the case, then the problem is related to the meshing
algorithms, due to the same reasons explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
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if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Straight feed cavity
The Straight feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the General cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired. Finally, it is important to bear in mind that for
performing simulation with rounded corner cavities, it is necessary to use the Solver BI-RME 3D RWG.
Solver type. The geometry of this element can be analyzed by selecting one of two available Solvers based in
the BI-RME 3D method implemented inside Fest3D:
BI-RME 3D Cylindrical: This Solver considers specialized high order cylindrical basis functions for
modelling the surface currents of the posts. It is selected by default, since the posts are generally of
cylindrical shape in most cases. The functions of this Solver offer a very fast performance, but have some
limitations, as they cannot be used for analysis of purely inductive posts (as mentioned above in the
limitations section), electromagnetic field computation or analysis of cavities with rounded corners
and/or non-cylindrical shapes.
BI-RME 3D RWG: This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the
surface currents of the posts. This Solver requires that the geometry is meshed with triangular patches
onto which the RWG basis functions are defined. Thus, this Solver is more general and can be employed
to analyze any kind of geometrical problem, although as a drawback it requires a higher computational
cost in order to properly model the behaviour of rounded shapes.
Maximum Frequency (GHz): This parameter is required for any of the two BI-RME 3D Solvers, and specifies
the maximum value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. For performing this analysis, it is necessary to choose the Solver BI-RME 3D RWG
for the simulation. Otherwise, a warning message will be shown to the user.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
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For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Magnetic probe is allowed.
By default, the first port tab will be already assigned to the Coaxial waveguide that is required before opening the
specifications window, as shown in Figure E. Also the probe will be automatically displayed and ready to be
configured. The rest of the ports will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to
define a different order for the ports, so that the Coaxial port is not the first one.
Regarding the specific parameters of the Straight probe, the following parameters can be edited:
Lprobe (mm/inches): The length of the probe .
Rprobe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section. 
Mesh size probe (mm/inches): Controls the value of the mesh size for this probe. 
The mesh size parameter indicates the density of the mesh of the associated geometry, employed by
the electromagnetic Solver. The user should change this mesh size for each particular case, taking into account the
maximum and minimum dimensions employed. The smaller the mesh size, the finest the internal meshing, which will
lead to more accurate results, but it will also slow down the simulation time. Also, very small values may produce
memory allocation problems, due to large size of the matrices involved.
The definition of this value depends on the basis functions of the selected Solver type:
For the high order cylindrical basis functions of the BI-RME 3D Cylindrical Solver, indicates the size of the
linear segments used for surface discretization.
For the triangular RWG basis functions of the BI-RME 3D RWG Solver, indicates the size of the 2D triangles
used for the surface meshing.
The user has to bear in mind that the convergence speed of the two types of basis functions is different, and
the use of the same value of mesh size might not be adequate for the both types of Solvers at the same time.
Generally, convergent results are achieved faster with the BI-RME 3D Cylindrical Solver, and smaller values will
be required for the BI-RME 3D RWG for obtaining similar accuracy. On the other hand, if very small values are
already used in the cylindrical function case, the change to RWG basis functions must be done with care, since
very large mesh densities might be produced.
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Figure E: Port properties of the Straight feed cavity, case of a coaxial port
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Figure F: Port properties of the Straight feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
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Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Straight feed cavity
The electromagnetic fields of this discontinuity can be computed and visualized. With this purpose, The EM Field tab
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allows to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of the
air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can be
chosen the same as specified in the general properties of the field computation, or can be specified for the particular
element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
For performing EM fields computations, it is mandatory to use the Solver BI-RME 3D RWG in the simulation.
Figure H: EM Field properties of the Straight feed cavity
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In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.3 Mushroom feed cavity
This section describes the Mushroom feed cavity discontinuity and how to use it, as well as its features and limitations.
The Mushroom feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Mushroom feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Mushroom feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The Mushroom feed cavity discontinuity consists in a rectangular cavity which is excited using a coaxial probe with
two cylindrical sections (mushroom shape). The cavity dimensions, the local reference system, and the different
surface names are depicted in figure A, and are the same as in the Cavity with posts. The geometrical parameters and
positions of the probe are shown in figure B and can be specified by the user. Besides this main excitation block,
rectangular ports and additional resonant posts/tuning screws can be considered at any of the cavity walls. For
performing the analysis, two different electromagnetic Solver types based on the BI-RME 3D method can be selected
.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
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Regarding the geometrical specifications, a schematic picture of a common practical case is shown in figure B,
including the names of the relevant dimensions to be specified by the user.
Figure B: Basic geometrical scheme of the excitation block
Limitations
The Mushroom feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides.
Analysis of inductive or capacitive posts
If the Solver BI-RME 3D Cylindrical is selected for analysis , this element can not
be used for capacitive or inductive posts. The height of the post has to be always smaller than the cavity width
or height. Nevertheless, if the design requires the presence of purely inductive or capacitive posts, it is a better
idea to use the Constant width/height arbitrary shape discontinuity element inside Fest3D.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
Collisions between ports and/or posts
The electromagnetic Solvers based on the BI-RME 3D method do not support intersection between
ports, or geometrical collisions between ports and posts. The software will detect this kind of situations and
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return an error message. On the other hand, the detection of collision between posts is handled differently
depending on the Solver. For the case of BI-RME 3D Cylindrical, post collision is not supported, and the
software will consider it as an error. On the contrary, for the Solver BI-RME 3D RWG, post collision is
allowed and the software will alert of this situation as a warning.
High memory consumption using parallelization in circuits with many cavities using the Solver BI-RME
3D RWG
If the Solver BI-RME 3D RWG is selected and small values of mesh sizes are specified (for high accuracy or
convergence tests), then very large meshes and dense matrices are required in the simulation, consuming an
important amount of RAM. Once the meshing of the element is performed, the information window will show
an estimation of the maximum total memory that will be used during calculations. Besides, the software will
automatically detect if the memory requirements are greater than the RAM memory available in the system,
and will stop the simulation if necessary. If there are several different cavities in the circuit, and multicore
simulation is desired, it is important to take into account that these RAM requirements are increased,
and a slowdown in the computer performance might be encountered. For those cases, it is recommended to
employ a lower number of processors, which may allow successfully completing a simulation that cannot be
performed using more cores due to memory limitation problems. If reducing the number of processors the
memory problems still persist, it is advisable to increase the mesh size values (reduce precision) of the posts or
rounded corners in the cavity (explained in the specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
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Errors
The Mushroom feed cavity discontinuity can produce the following errors under certain circumstances. For each error,
the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR while performing simulation. Error while building mesh. Please try to reduce mesh size
value(s)
This error occurs when there is a problem building the internal meshing of the posts needed by this element,
when the Solver BI-RME 3D Cylindrical is selected. This problem usually appears when using posts of
mushroom or hollow type, if the mesh size value specified by the user is not adequate for the dimensions of
the post. The values used for mesh size must be reduced in order to avoid this error.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If the Solver BI-RME 3D RWG is chosen, this element requires to create a 3D mesh for the whole cavity
together with the posts, from which the surface meshing of metallic objects is extracted. If this error appears, it
means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D mesh is necessary to
compute data employed for the EM fields calculations. For this reason, the simulation is forbidden if the 3D
mesh is not available. This situation may happen if a wrong geometry has been specified (e.g., posts colliding
with each other). The dimensions and offsets of the posts should be revised, and verified with the 3D viewer in
order to detect any possible geometrical problems. If the geometry is correct, another source for this error is
that very small air gaps are present in the cavity, which can not be dealt by the 3D meshing algorithm for the
given mesh sizes. Reducing their values might be the solution for a correct 3D mesh generation. If the problem
persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh when the Solver BI-RME 3D RWG is selected.
This can occur if there are failures while generating the geometry of the cavity. It is advisable to check if the
geometry can be visualized with the 3D viewer. If this is the case, then the problem is related to the meshing
algorithms, due to the same reasons explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
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reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Mushroom feed cavity
The Mushroom feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the General cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
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Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired. Finally, it is important to bear in mind that for
performing simulation with rounded corner cavities, it is necessary to use the Solver BI-RME 3D RWG.
Solver type. The geometry of this element can be analyzed by selecting one of two available Solvers based in
the BI-RME 3D method implemented inside Fest3D:
BI-RME 3D Cylindrical: This Solver considers specialized high order cylindrical basis functions for
modelling the surface currents of the posts. It is selected by default, since the posts are generally of
cylindrical shape in most cases. The functions of this Solver offer a very fast performance, but have some
limitations, as they cannot be used for analysis of purely inductive posts (as mentioned above in the
limitations section), electromagnetic field computation or analysis of cavities with rounded corners
and/or non-cylindrical shapes.
BI-RME 3D RWG: This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the
surface currents of the posts. This Solver requires that the geometry is meshed with triangular patches
onto which the RWG basis functions are defined. Thus, this Solver is more general and can be employed
to analyze any kind of geometrical problem, although as a drawback it requires a higher computational
cost in order to properly model the behaviour of rounded shapes.
Maximum Frequency (GHz): This parameter is required for any of the two BI-RME 3D Solvers, and specifies
the maximum value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. For performing this analysis, it is necessary to choose the Solver BI-RME 3D RWG
for the simulation. Otherwise, a warning message will be shown to the user.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Magnetic probe is allowed.
By default, the first port tab will be already assigned to the Coaxial waveguide that is required before opening the
specifications window, as shown in Figure E. Also the probe will be automatically displayed and ready to be
configured. The rest of the ports will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to
define a different order for the ports, so that the Coaxial port is not the first one.
Regarding the specific parameters of the Mushroom probe, the following parameters can be edited:
L1 (mm/inches): Length of the first cylindrical section of the probe .
R probe (mm/inches): The radius of the first cylindrical section of the probe . If it is set to zero,
the default value of the inner conductor of the coaxial waveguide used as the port will be
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considered. The electromagnetic Solver does not directly support values larger than this inner radius, but
smaller values are also allowed for simulations. Nevertheless, it is possible to perform simulations with larger
radius for the probe, by applying the strategy described in the limitations section.
L2 (mm/inches): Length of the second cylindrical section of the probe .
R2 (mm/inches): Radius of the second cylindrical section of the probe .
Mesh size probe (mm/inches): Controls the value of the mesh size for this probe. 
The mesh size parameter indicates the density of the mesh of the associated geometry, employed by
the electromagnetic Solver. The user should change this mesh size for each particular case, taking into account the
maximum and minimum dimensions employed. The smaller the mesh size, the finest the internal meshing, which will
lead to more accurate results, but it will also slow down the simulation time. Also, very small values may produce
memory allocation problems, due to large size of the matrices involved.
The definition of this value depends on the basis functions of the selected Solver type:
For the high order cylindrical basis functions of the BI-RME 3D Cylindrical Solver, indicates the size of the
linear segments used for surface discretization.
For the triangular RWG basis functions of the BI-RME 3D RWG Solver, indicates the size of the 2D triangles
used for the surface meshing.
The user has to bear in mind that the convergence speed of the two types of basis functions is different, and
the use of the same value of mesh size might not be adequate for the both types of Solvers at the same time.
Generally, convergent results are achieved faster with the BI-RME 3D Cylindrical Solver, and smaller values will
be required for the BI-RME 3D RWG for obtaining similar accuracy. On the other hand, if very small values are
already used in the cylindrical function case, the change to RWG basis functions must be done with care, since
very large mesh densities might be produced.
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Figure E: Port properties of the Mushroom feed cavity, case of a coaxial port
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Figure F: Port properties of the Mushroom feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
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Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Mushroom feed cavity
The electromagnetic fields of this discontinuity can be computed and visualized. With this purpose, The EM Field tab
allows to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of the
air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can be
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chosen the same as specified in the general properties of the field computation, or can be specified for the particular
element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
For performing EM fields computations, it is mandatory to use the Solver BI-RME 3D RWG in the simulation.
Figure H: EM Field properties of the Mushroom feed cavity
In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
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2.4.2.5.4 Straight contact feed cavity
This section describes the Straight contact feed cavity discontinuity and how to use it, as well as its features and
limitations.
The Straight contact feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Straight contact feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds
to them.
Using the Straight contact feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The Straight contact feed cavity discontinuity consists in a rectangular waveguide section which is excited using a
straight coaxial probe which feeds a post that is attached to any of the cavity walls orthogonal to the coaxial. The
cavity dimensions, the local reference system, and the different surface names are depicted in figure A, and are the
same as in the Cavity with Posts. The geometrical parameters and positions of the probe and the contact post are
shown in figure B and can be specified by the user. Besides this main excitation block (probe together with contact
post), rectangular ports and additional resonant posts/tuning screws can be considered at any of the cavity walls. For
performing the analysis, an electromagnetic Solver based on the BI-RME 3D method with RWG basis functions is
employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications of the excitation probe, a schematic picture of a common practical case with
the contact post attached to the bottom surface is shown in figure B, including the names of the relevant dimensions
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to be specified by the user.
Figure B: Basic geometrical scheme of the straight contact probe
Limitations
The Straight contact feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
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dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The Straight contact feed cavity discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
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solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Straight contact feed cavity
The Straight contact feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the Straight contact feed cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
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Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Straight contact probe is
allowed. For this probe, the shape of the required contact post can be chosen as well from the Type of contact post
list (a view of the different allowed contact posts is also shown at the right side of the window). By default, the first
port tab will be already assigned to the Coaxial waveguide that is required before opening the specifications window,
as shown in Figure E. Also the probe will be automatically displayed and ready to be configured. The rest of the ports
will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to define a different order for the
ports, so that the coaxial port is not the first one.
Regarding the specific parameters of the Straight contact probe, the following parameters can be edited:
L post (mm/inches): The distance between the contact post and the coaxial port .
R probe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section.
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
Below these probe parameters, the contact post parameters are also displayed. Depending on the shape of the post
selected, the legend at the right will show the geometrical parameters that can be edited for the particular geometry
.
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Figure E: Port properties of the Straight contact feed cavity, case of a coaxial port
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Figure F: Port properties of the Straight contact feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
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Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Straight contact feed cavity
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the Straight contact feed cavity
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In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.5 S-Shape contact feed cavity
This section describes the S-Shape contact feed cavity discontinuity and how to use it, as well as its features and
limitations.
The S-Shape contact feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a S-Shape contact feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds
to them.
Using the S-Shape contact feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The S-Shape contact feed cavity discontinuity consists in a rectangular cavity which is excited using a S-shaped coaxial
probe which feeds a post that is attached to any of the cavity walls orthogonal to the coaxial. The cavity dimensions,
the local reference system, and the different surface names are depicted in figure A, and are the same as in the Cavity
with Posts. The geometrical parameters and positions of the probe and the contact post are shown in figure B and can
be specified by the user. Besides this main excitation block (probe together with contact post), rectangular ports and
additional resonant posts/tuning screws can be considered at any of the cavity walls. For performing the analysis, an
electromagnetic Solver based on the BI-RME 3D method with RWG basis functions is employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
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Regarding the geometrical specifications, a schematic picture of a common practical case with the contact post
attached to the bottom surface is shown in figure B, including the names of the relevant dimensions to be specified by
the user. The rest of the geometrical parameters needed for building the probe are auto calculated.
Figure B: Basic geometrical scheme of the excitation block
Limitations
The S-Shape contact feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
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dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The S-Shape contact feed cavity discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
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solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the S-Shape contact feed cavity
The S-Shape contact feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the S-Shape contact feed cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
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Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Straight contact probe is
allowed. For this probe, the shape of the required contact post can be chosen as well from the Type of contact post
list (a view of the different allowed contact posts is also shown at the right side of the window). By default, the first
port tab will be already assigned to the Coaxial waveguide that is required before opening the specifications window,
as shown in Figure E. Also the probe will be automatically displayed and ready to be configured. The rest of the ports
will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to define a different order for the
ports, so that the coaxial port is not the first one.
Regarding the specific parameters of the Top contact probe, the following parameters can be edited:
L post (mm/inches): The distance between the contact post and the coaxial port .
L1 (mm/inches): The length of the straight part of the S shape that starts from the coaxial port .
L2 (mm/inches): The length of the straight part of the S shape that contacts the post .
R probe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section. 
H contact (mm/inches): The height at which the probe contacts the post .
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
Below these probe parameters, the contact post parameters are also displayed. Depending on the shape of the post
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selected, the legend at the right will show the geometrical parameters that can be edited for the particular geometry
. 
Figure E: Port properties of the S-Shape contact feed cavity, case of a coaxial port
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Figure F: Port properties of the S-Shape contact feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
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Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the S-Shape contact feed cavity
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
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allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the S-Shape contact feed cavity
In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
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automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.6 Loop feed cavity
This section describes the Loop feed cavity discontinuity and how to use it, as well as its features and limitations.
The Loop feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Loop feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Loop feed cavity How to create, edit and use this element from Fest3D.
Definition
The Loop feed cavity consists in a rectangular cavity which is excited using a loop coaxial probe. The cavity
dimensions, the local reference system, and the different surface names are depicted in figure A, and are the same as
in the Cavity with posts. The geometrical parameters and positions of the probe are shown in figure B and can be
specified by the user. Besides this main excitation block, rectangular ports and additional resonant posts/tuning
screws can be considered at any of the cavity walls. For performing the analysis, an electromagnetic Solver based on
the BI-RME 3D method with RWG basis functions is employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications of the excitation probe, a schematic picture of a common practical case is
shown in figure B, including the names of the relevant dimensions to be specified by the user. The rest of the
geometrical parameters needed to build the probe are auto calculated. A rotation angle for the loop is also
considered, whose definitions depending on the surface of the probe are also shown in the figure.
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Figure B: Basic geometrical scheme of the maneic loop probe
Limitations
The Loop feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
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many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
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Errors
The Loop feed cavity discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
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Using the Loop feed cavity
The Loop feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
Figure D: Specific properties of the General cavity
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Magnetic probe is allowed.
By default, the first port tab will be already assigned to the Coaxial waveguide that is required before opening the
specifications window, as shown in Figure E. Also the probe will be automatically displayed and ready to be
configured. The rest of the ports will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to
define a different order for the ports, so that the Coaxial port is not the first one.
Regarding the specific parameters of the Magnetic loop probe, the following parameters can be edited:
Lloop (mm/inches): Penetration length of the loop inside the cavity .
Dloop (mm/inches): Distance between input and output of the loop in the corresponding  surface wall . 
Rprobe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
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simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section.
L1 (mm/inches): The length of the input straight segment of the probe .
L2 (mm/inches): The length of output straight segment of the probe .
Angle (degrees): Loop rotation angle .
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
Figure E: Port properties of the Loop feed cavity, case of a coaxial port
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Figure F: Port properties of the Loop feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
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Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Loop feed cavity
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the Loop feed cavity
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In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.7 Magnetic feed cavity
This section describes the Magnetic Feed discontinuity and how to use it, as well as its features and limitations.
The Magnetic feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Magnetic Feed discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Magnetic feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The Magnetic feed cavity discontinuity consists in a rectangular cavity which is excited using a coaxial
probe that contacts one of the four neighbor surfaces of the input surface. The cavity dimensions, the local reference
system, and the different surface names are depicted in figure A, and are the same as in the Cavity with posts. The
geometrical parameters and positions of the probe are shown in figure B and can be specified by the user. Besides
this main excitation block, rectangular ports and additional resonant posts/tuning screws can be considered at any of
the cavity walls. For performing the analysis, an electromagnetic Solver based on the BI-RME 3D method with RWG
basis functions is employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
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Regarding the geometrical specifications of the excitation probe, a schematic picture of a common practical case is
shown in figure B, including the names of the relevant dimensions to be specified by the user. The rest of the
geometrical parameters needed for building the probe are auto calculated.
Figure B: Basic geometrical scheme of the magnetic probe 
Limitations
The Magnetic feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
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greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The Magnetic feed cavity discontinuity can produce the following errors under certain circumstances. For each error,
the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
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FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Magnetic feed cavity
The Magnetic feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the General cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
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Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Magnetic probe is allowed.
By default, the first port tab will be already assigned to the Coaxial waveguide that is required before opening the
specifications window, as shown in Figure E. Also the probe will be automatically displayed and ready to be
configured. The rest of the ports will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to
define a different order for the ports, so that the Coaxial port is not the first one.
Regarding the specific parameters of the Magnetic probe, the following parameters can be edited:
Lcontact (mm/inches): Distance from the excitation surface to the contact point of the Contact surface. 
Lprobe (mm/inches): Length of the straight segment of the probe . 
Rprobe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section.
Alpha (degrees): Probe rotation angle . By default this angle is 90 degrees, but smaller and larger
angles can also be employed. The software will automatically validate if the selected angle is appropriate for
building this kind of geometry for the rest of parameters specified. 
Contact surface: Surface contacted by the probe (figure B).
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
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Figure E: Port properties of the Magnetic feed cavity, case of a coaxial port
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Figure F: Port properties of the Magnetic feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
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Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Magnetic feed cavity
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the Magnetic feed cavity
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In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.8 Top contact feed cavity
This section describes the Top contact feed cavity discontinuity and how to use it, as well as its features and
limitations.
The Top contact feed cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Top contact feed cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Top contact feed
cavity
How to create, edit and use this element from Fest3D.
Definition
The Top contact feed cavity discontinuity consists in a rectangular cavity which is excited using a coaxial probe that
feeds a cylindrical post, which is contacted from its top. The cavity dimensions, the local reference system, and the
different surface names are depicted in figure A, and are the same as in the Cavity with posts. The geometrical
parameters and positions of the probe are shown in figure B and can be specified by the user. Besides this main
excitation block (probe together with contact post), rectangular ports and additional resonant posts/tuning screws can
be considered at any of the cavity walls. For performing the analysis, an electromagnetic Solver based on the BI-RME
3D method with RWG basis functions is employed.
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Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications, a schematic picture of a common practical case is shown in figure B,
including the names of the relevant dimensions to be specified by the user. The rest of the geometrical parameters
needed for building the probe are auto calculated.
Figure B: Basic geometrical scheme of the excitation block
Limitations
The Top contact feed cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
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If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The Top contact feed cavity discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
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dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Top contact feed cavity
The Top contact feed cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Magnetic Feed:
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Figure D: Specific properties of the Top contact feed cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
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Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Straight contact probe is
allowed. For this probe, the shape of the required contact post can be chosen as well from the Type of contact post
list (a view of the different allowed contact posts is also shown at the right side of the window). By default, the first
port tab will be already assigned to the Coaxial waveguide that is required before opening the specifications window,
as shown in Figure E. Also the probe will be automatically displayed and ready to be configured. The rest of the ports
will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to define a different order for the
ports, so that the coaxial port is not the first one.
Regarding the specific parameters of the Top contact probe, the following parameters can be edited:
R probe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section. 
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
Below these probe parameters, the contact post parameters are also displayed. Depending on the shape of the post
selected, the legend at the right will show the geometrical parameters that can be edited for the particular geometry
.
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Figure E: Port properties of the Top contact feed cavity, case of a coaxial port
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Figure F: Port properties of the Top contact feed cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
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Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
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Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
Figure G: General Posts properties of the Top contact feed cavity
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The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the Top contact feed cavity
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In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.5.9 General cavity
This section describes the General cavity discontinuity and how to use it, as well as its features and limitations.
The General cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a General Cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the General cavity How to create, edit and use this element from Fest3D.
Definition
The General cavity consists in a rectangular cavity which supports multiple coaxial and rectangular excitation ports
placed at any of its six surface walls, as well as additional resonant posts/tuning screws. The cavity dimensions, the
local reference system, and the different surface names are depicted in figure A.
For performing the analysis, two different electromagnetic Solver types based on the BI-RME 3D method can be
selected .
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
When considering a coaxial port, different types of probe geometries can be selected by the user. All the possible
probe types are included in figure B. For more details on the parameters of each probe, the different specific elements
of the Coaxial library can be consulted.
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Figure B: Different types of probes that can be used in this element with a coaxial waveguide port.
Limitations
The Straight Probe discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides.
Analysis of inductive or capacitive posts
If the Solver BI-RME 3D Cylindrical is selected for analysis , this element can not
be used for capacitive or inductive posts. The height of the post has to be always smaller than the cavity width
or height. Nevertheless, if the design requires the presence of purely inductive or capacitive posts, it is a better
idea to use the Constant width/height arbitrary shape discontinuity element inside Fest3D.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
Collisions between ports and/or posts
The electromagnetic Solvers based on the BI-RME 3D method do not support intersection between
ports, or geometrical collisions between ports and posts. The software will detect this kind of situations and
return an error message. On the other hand, the detection of collision between posts is handled differently
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depending on the Solver. For the case of BI-RME 3D Cylindrical, post collision is not supported, and the
software will consider it as an error. On the contrary, for the Solver BI-RME 3D RWG, post collision is
allowed and the software will alert of this situation as a warning.
High memory consumption using parallelization in circuits with many cavities using the Solver BI-RME
3D RWG
If the Solver BI-RME 3D RWG is selected and small values of mesh sizes are specified (for high accuracy or
convergence tests), then very large meshes and dense matrices are required in the simulation, consuming an
important amount of RAM. Once the meshing of the element is performed, the information window will show
an estimation of the maximum total memory that will be used during calculations. Besides, the software will
automatically detect if the memory requirements are greater than the RAM memory available in the system,
and will stop the simulation if necessary. If there are several different cavities in the circuit, and multicore
simulation is desired, it is important to take into account that these RAM requirements are increased,
and a slowdown in the computer performance might be encountered. For those cases, it is recommended to
employ a lower number of processors, which may allow successfully completing a simulation that cannot be
performed using more cores due to memory limitation problems. If reducing the number of processors the
memory problems still persist, it is advisable to increase the mesh size values (reduce precision) of the posts or
rounded corners in the cavity (explained in the specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
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The Straight probe discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR while performing simulation. Error while building mesh. Please try to reduce mesh size
value(s)
This error occurs when there is a problem building the internal meshing of the posts needed by this element,
when the Solver BI-RME 3D Cylindrical is selected. This problem usually appears when using posts of
mushroom or hollow type, if the mesh size value specified by the user is not adequate for the dimensions of
the post. The values used for mesh size must be reduced in order to avoid this error.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If the Solver BI-RME 3D RWG is chosen, this element requires to create a 3D mesh for the whole cavity
together with the posts, from which the surface meshing of metallic objects is extracted. If this error appears, it
means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D mesh is necessary to
compute data employed for the EM fields calculations. For this reason, the simulation is forbidden if the 3D
mesh is not available. This situation may happen if a wrong geometry has been specified (e.g., posts colliding
with each other). The dimensions and offsets of the posts should be revised, and verified with the 3D viewer in
order to detect any possible geometrical problems. If the geometry is correct, another source for this error is
that very small air gaps are present in the cavity, which can not be dealt by the 3D meshing algorithm for the
given mesh sizes. Reducing their values might be the solution for a correct 3D mesh generation. If the problem
persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh when the Solver BI-RME 3D RWG is selected.
This can occur if there are failures while generating the geometry of the cavity. It is advisable to check if the
geometry can be visualized with the 3D viewer. If this is the case, then the problem is related to the meshing
algorithms, due to the same reasons explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
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Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the General cavity
The General cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the General Cavity:
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Figure D: Specific properties of the General cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
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Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired. Finally, it is important to bear in mind that for
performing simulation with rounded corner cavities, it is necessary to use the Solver BI-RME 3D RWG.
Solver type. The geometry of this element can be analyzed by selecting one of two available Solvers based in
the BI-RME 3D method implemented inside Fest3D:
BI-RME 3D Cylindrical: This Solver considers specialized high order cylindrical basis functions for
modelling the surface currents of the posts. It is selected by default, since the posts are generally of
cylindrical shape in most cases. The functions of this Solver offer a very fast performance, but have some
limitations, as they cannot be used for analysis of purely inductive posts (as mentioned above in the
limitations section), electromagnetic field computation or analysis of cavities with rounded corners
and/or non-cylindrical shapes.
BI-RME 3D RWG: This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the
surface currents of the posts. This Solver requires that the geometry is meshed with triangular patches
onto which the RWG basis functions are defined. Thus, this Solver is more general and can be employed
to analyze any kind of geometrical problem, although as a drawback it requires a higher computational
cost in order to properly model the behaviour of rounded shapes.
Maximum Frequency (GHz): This parameter is required for any of the two BI-RME 3D Solvers, and specifies
the maximum value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity. For performing this analysis, it is necessary to choose the Solver BI-RME 3D RWG
for the simulation. Otherwise, a warning message will be shown to the user.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. The types of available probes are shown in the right
side of the window, as depicted in Figure E. Once selected, the geometrical parameters of the specific probe as well as
the contact post (if required for the chosen geometry) can be also edited. For detailed description of each probe
parameter, please consult the different particular elements of the Coaxial library. A example of specific probe is
included as a second Coaxial port in Figure F. Another example case of port chosen as a Rectangular waveguide is also
included in figure G.
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Figure E: Port properties of the General cavity, case of a coaxial port
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Figure F: Port properties of the General cavity, case of a second coaxial port with a Mushroom probe
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Figure G: Port properties of the General cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
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Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. It is important to mention that if
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draft angle, rectangular or helical shapes are selected, simulation is only allowed if the Solver BI-RME 3D RWG
is selected. The post parameters and the different shapes allowed are the same as explained in the Cavity with posts
discontinuity.
Figure H: General Posts properties of the General cavity
The electromagnetic fields of this discontinuity can be computed and visualized. With this purpose, The EM Field tab
allows to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of the
air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can be
chosen the same as specified in the general properties of the field computation, or can be specified for the particular
element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
For performing EM fields computations, it is mandatory to use the Solver BI-RME 3D RWG in the simulation.
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Figure I: EM Field properties of the General cavity
In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
2.4.2.6 Helical resonators library
The Helical resonators library contains the following discontinuities:
Helical resonator
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Contact feed to helical resonator
2.4.2.6.1 Helical resonator
This section describes the Helical resonator discontinuity and how to use it, as well as its features and limitations.
The Helical resonator discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Helical resonator discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Helical resonator How to create, edit and use this element from Fest3D.
Definition
The Helical resonator discontinuity represents a rectangular cavity with a resonator of helical shape that can
be positioned at any of the 6 different surfaces of the rectangular cavity . Together with the main
resonator, more helices as well as other types of resonant posts/tuning screws can be included in the cavity. Besides,
input/output rectangular ports can also be placed on the walls. For performing the analysis, an electromagnetic Solver
based on the BI-RME 3D method with RWG basis functions is employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications, the parameters of the helical shape are shown in figure B. By default, the
helix and the rest of additional posts will be placed at the center of the bottom surface. The user can change this
surface, and specify an offset between the center of the surface and the center of the helix. Examples of offsets for
different post shapes are depicted in figure C for the different surfaces of the cavity, taking into account the main
reference system defined in figure A.
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Figure B: Definition of the parameters that describe the helical resonator
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Figure C: Offset conventions for posts
Limitations
The Helical resonator discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular waveguides.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
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greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Errors
The Helical resonator discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.  
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
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reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Helical resonator
The Helical resonator discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Helical resonator:
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Figure D: Specific properties of the Helical resonator
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
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B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab.
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element.
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Figure E: Port properties of the Helical resonator
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
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Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
The offsets and the mesh size of the port only make sense if a rectangular waveguide smaller than the cavity
surface dimensions is considered. The mesh density employed for the port must be increased for large numbers of
accessible modes of the rectangular waveguide, in order to maintain the accuracy of the method. As a consequence, a
large number of accessible modes in the waveguide port will require a higher computational cost.
In order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing this way Fest3D to automatically choose an adequate value as a default. The automatic criterion employed
obeys the following rules:
If 30 or less accessible modes are employed in the rectangular waveguide, the triangle size is chosen as 1/5 of
the minimum dimension (a,b) of the waveguide.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and mesh size) have no meaning, and the internal electromagnetic Solver employs
analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for the mesh discretization of the rectangular port. The user can take this value as
reference in order to manually increase it for speeding up calculations, or decreasing it if more precision is desired,
taking into account the memory limitations.
Another important part of the specifications of this element is the General Posts tab. By default, a helical resonator
post is already considered, ready to be defined . The legend with the different parameters of the
resonator is also included at the right side of the window for reference.  Additionally, more posts/tuning screws can be
inserted by selecting the post shape from the available list and pressing the Add button. The post parameters and
the different shapes allowed are the same as explained in the Cavity with posts discontinuity.
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Figure F: General Posts properties of the Helical resonator
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
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calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure G: EM Field properties of the Helical resonator
In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure for the additional posts different from the helical shapes, which is the same
as the one explained in the Cavity with posts discontinuity.
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2.4.2.6.2 Contact feed to helical resonator
This section describes the Contact feed to helical resonator discontinuity and how to use it, as well as its features and
limitations.
The Contact feed to helical resonator discontinuity section contains the following topics:
What exactly is a Contact feed to helical resonator discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or
workarounds to them.
How to create, edit and use this element from Fest3D.
Definition
Limitations
Errors
Using the Contact feed to helical
resonator
Definition
The Contact feed to helical resonator discontinuity consists in a rectangular waveguide section which is excited using
a straight coaxial probe which feeds a helical resonator that is attached to any of the cavity walls orthogonal to the
coaxial. The cavity dimensions, the local reference system, and the different surface names are depicted in figure A,
and are the same as in the Cavity with Posts. The geometrical parameters and positions of the probe and the contact
post are shown in figure B and can be specified by the user. Besides this main excitation block (probe together with
contact helix), rectangular ports and additional resonant posts/tuning screws can be considered at any of the cavity
walls. For performing the analysis, an electromagnetic Solver based on the BI-RME 3D method with RWG basis
functions is employed.
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
Regarding the geometrical specifications of the excitation probe, a schematic picture of a common practical case with
the contact helix attached to the bottom surface is shown in figure B, including the names of the relevant dimensions
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to be specified by the user.
Figure B: Basic geometrical scheme of the straight contact probe
Limitations
The Contact feed to helical resonator discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Rectangular or Coaxial waveguides. Although there is no limitation in
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the number of rectangular ports, only one coaxial port is allowed per cavity. For a more general design
including different coaxial waveguides as excitations of a single cavity, the General cavity element can be used
instead.
Maximum number of posts
There is no theoretical limit to the number of posts. Anyway, using a large number of posts in a single element
may significantly slow down the simulation.
If you want to design a circuit with several posts (combline filter, for example), in theory you have two options:
a long cavity with a lot of posts
many cascaded cavities
In general, the most efficient approach is to use a segmentation strategy to divide the cavity into small blocks
connected by plain waveguide sections. In any case, also the “single cavity" analysis works fine (but may require
higher computational time), provided that the limitations in posts dimensions are fulfilled. Take into account
that if the same cavity with post/s is repeated in the circuit, the static part is solved only once thanks to the
internal arrangement of Fest3D in those cases.
High memory consumption using parallelization in circuits with many cavities
If small values of mesh sizes are specified (for high accuracy or convergence tests), then very large meshes and
dense matrices are required in the simulation, consuming an important amount of RAM. Once the meshing of
the element is performed, the information window will show an estimation of the maximum total memory that
will be used during calculations. Besides, the software will automatically detect if the memory requirements are
greater than the RAM memory available in the system, and will stop the simulation if necessary. If there are
several different cavities in the circuit, and multicore simulation is desired, it is important to take into
account that these RAM requirements are increased, and a slowdown in the computer performance might
be encountered. For those cases, it is recommended to employ a lower number of processors, which may allow
successfully completing a simulation that cannot be performed using more cores due to memory limitation
problems. If reducing the number of processors the memory problems still persist, it is advisable to increase
the mesh size values (reduce precision) of the posts or rounded corners in the cavity (explained in the
specifications section below) for performing the simulation.
Use of probe radius larger than the inner radius of the coaxial.
The electromagnetic BI-RME 3D Solver used by this element does not directly allow modeling an excitation
probe contacting a coaxial port with a smaller inner radius. Anyway, it is possible to simulate this kind of
structures, by employing the strategy shown in the schematic below (figure C). By means of a Step
discontinuity, an additional auxiliary coaxial with zero length can be inserted between the real coaxial
waveguide and the Straight probe discontinuity, in which the radius desired for the probe can be set. This
auxiliary coaxial can be connected to the Straight probe and solved by the inner kernel. The Step will take into
account the differences between the two coaxials by computing the appropiate coupling integrals. On the
other hand, it is important to bear in mind that if a radius value smaller than the inner of coaxial is required for
the probe, there is no need to employ this strategy since this situation is directly supported by the Solver.
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Figure C: Schematic example for using a probe with a radius larger the inner radius of the coaxial waveguide port.
Errors
The Contact feed to helical resonator discontinuity can produce the following errors under certain circumstances. For
each error, the possible solutions or workarounds are explained.
FATAL ERROR. Not even a single resonant mode can be obtained for this cavity. Please change the
cavity dimensions or increase the Maximum Frequency of the Solver (Solver Name)
The maximum frequency introduced is under the cut-off frequency of the cavity delimited by the specified
dimensions . Provided that these dimensions are correct, the
solution is to increase the value of this maximum frequency. It is recommended to set it to a value two or three
times the maximum frequency of the desired analysis band.
FATAL ERROR while performing simulation. (Error of some kind). Re-check the geometry, or try to
reduce mesh size(s) value(s)
The eigenvalue problem can not be solved due to problems with the building of the matrices. This error can be
produced by an illegal position of the posts not detected by Fest3D. Another source for errors in the
eigenvalue problem is that the meshing of some of the post surfaces is not accurate enough. If the positions of
the posts are correct, the mesh sizes should be reduced, specially if the dimensions of radii or lengths are small.
FATAL ERROR. No 3D mesh detected. Please re-check the geometry, or try to reduce mesh size of the
post(s)
If this error appears, it means that the meshing algorithm was able to create a 2D mesh, but not a 3D. This 3D
mesh is necessary to compute data employed for the EM fields calculations. For this reason, the simulation is
forbidden if the 3D mesh is not available. This situation may happen if a wrong geometry has been specified
(e.g., posts colliding with each other). The dimensions and offsets of the posts should be revised, and verified
with the 3D viewer in order to detect any possible geometrical problems. If the geometry is correct, another
source for this error is that very small air gaps are present in the cavity, which can not be dealt by the 3D
meshing algorithm for the given mesh sizes. Reducing their values might be the solution for a correct 3D mesh
generation. If the problem persists, the user can ask for support on his specific geometry.
Error building mesh file
This error occurs when there is some problem building the mesh. This can occur if there are failures while
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generating the geometry of the cavity. It is advisable to check if the geometry can be visualized with the 3D
viewer. If this is the case, then the problem is related to the meshing algorithms, due to the same reasons
explained for the previous error related to failure of the 3D mesh.
FATAL ERROR, mesh file not found
This message will appear if the meshing needed by the internal routines is not found. This error is usually
related to the building mesh error explained before, and should not appear in the case of a correct mesh
generation.
LAPACK error: some error message
The admittance matrix is not invertible at the simulated frequency point. This can only happen during the
frequency loop. This error is very unusual and it can be produced if a simulated frequency point is too close to
a pole. In this case the problem can be solved by slightly changing the frequency points.
cmalloc() failed: Out of memory!:
This happens when too much memory is required to solve the system. It is recommended, in this case, to
reduce the Maximum Frequency value, and/or increase the mesh size values.
Simulation error (no further explanation):
This error is also related with memory limitations, and may occur if too much precision is demanded, specially
if the Solver BI-RME 3D RWG is selected. Besides, this problem can appear when performing simulations
with several cores, due to the higher memory requirements of this feature. Reducing the number of
processors is necessary to successfully perform the simulation.
Using the Contact feed to helical resonator
The Contact feed to helical resonator discontinuity is completely integrated into Fest3D. The user can create, view and
edit this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Contact feed to helical
resonator:
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Figure D: Specific properties of the Contact feed to helical resonator
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
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A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities), as
well as the value of the mesh size used for meshing these rounded corners inside the electromagnetic solver. If
the value is set to zero, an automatic value depending on the cavity dimensions and the radii values will be
used. The information screen will show during simulation the value employed for this mesh, which can be
controlled here in order to demand more accuracy if desired.
Solver type. The particular geometry of this element can only be analyzed using the electromagnetic Solver
BI-RME 3D RWG. This Solver considers Rao-Wilton-Glisson (RWG) basis functions for modelling the surface
currents of the posts. This Solver requires that the geometry is meshed with triangular patches onto which the
RWG basis functions are defined.
Maximum Frequency (GHz): This parameter is required for the BI-RME 3D Solver, and specifies the maximum
value of the frequencies of the resonant modes of the cavity to be computed during the analysis.
To conclude with the specific properties tab, two checkboxes allow the user to perform Multipactor and Corona
analysis of this discontinuity.  
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must selected from the Type of probe list. For this element, only the Straight contact
helix probe is allowed. For this probe, the shape of the required contact post can be chosen as well from the Type of
contact post list (a view of the different allowed contact posts is also shown at the right side of the window). By
default, the first port tab will be already assigned to the Coaxial waveguide that is required before opening the
specifications window, as shown in Figure E. Also the probe will be automatically displayed and ready to be
configured. The rest of the ports will be configured rectangular waveguides (Figure F). Nevertheless, it is possible to
define a different order for the ports, so that the coaxial port is not the first one.
Regarding the specific parameters of the Straight contact helix probe, the following parameters can be edited:
Num. turn contact: The number of the helix turn at which the contact with the coaxial probe is performed.
This value will determine automatically the height of the coaxial port.
R probe (mm/inches): The radius of the probe . If it is set to zero, the default value of the
inner conductor of the coaxial waveguide used as the port will be considered. The electromagnetic Solver
does not directly support values larger than this inner radius, but smaller values are also allowed for
simulations. Nevertheless, it is possible to perform simulations with larger radius for the probe, by applying the
strategy described in the limitations section.
L Helix(mm/inches): The distance between the contact helix and the coaxial port .
Angle from base(degrees): The angle from the base of the helix to the straight probe . This
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parameter can vary between 0 and 360 degrees for the specified turn of the helix at which the contact is
performed.
Mesh size probe (mm/inches): This parameter indicates the typical length that will be used for the triangular
mesh employed by this discontinuity for modeling the coaxial probe.
Below these probe parameters, the parameters of the contact helix are also displayed. These parameters are also
defined in figure B included in the legend at the right of the window.
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Figure E: Port properties of the Contact feed to helical resonator, case of a coaxial port
Figure F: Port properties of the Contact feed to helical resonator, case of a rectangular port
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Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and C, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Mesh size port (mm/inches): The mesh size of each port of the element can be edited. This value is the typical
size of the triangles used for meshing the geometry of the port. It is important to remark that the correct
choice of the mesh size of the port is critical for the accuracy of the electromagnetic analysis. There are
some particularities to bear in mind regarding this parameter, as detailed below.
The particular port tab is removed by pressing the Delete port button. 
Considerations for coaxial ports
When considering a Coaxial waveguide as a port, the mesh density must be increased for large numbers of
accessible modes of the coaxial waveguide in order to maintain the accuracy of the method. As a consequence,
a large number of accessible modes in the coaxial waveguide will require a higher computational cost. This
drawback might be avoided in most of the practical situations, since a large number of modes is not necessary
for a coaxial waveguide in common applications (generally, less than 20 modes will suffice).
Thus, in order to help the user to take into account these considerations, it is recommended to set this value to zero,
allowing Fest3D to automatically choose an adequate value as a default. The automatic criterion employed obeys the
following rules:
If 30 or less accessible modes are employed in the coaxial waveguide, the triangle size is chosen as 1/5 of the
difference between the external and internal radius of the coaxial.
If the number of coaxial modes is between 30 and 45, the triangle size is chosen as 0.2 times the cut-
off wavelength associated to the largest mode number desired in the coaxial.
If 45 or more modes are employed for the coaxial, the triangle size is chosen as 0.1 times the cut-off
wavelength associated to the largest mode number desired in the coaxial.
Considerations for rectangular ports
On the other hand, when the waveguide port is chosen to be a Rectangular waveguide, the offsets and the
mesh size of the port only make sense if the waveguide port is smaller than the dimensions of the
corresponding cavity surface. For this case, the port will be discretized in a similar way as the coaxial port,
requiring a meshing which can be controlled by the mesh size port parameter or be let to zero and use the
automatic criterion depending on modes explained above. The only difference regarding this mesh criteria
with respect to the coaxial port case is that the geometrical criterion employed for 30 or less modes considers
1/5 of the minimum of the dimensions (a,b) of the rectangular waveguide.
Nevertheless, in a common usage of this element, the rectangular ports will have the same dimensions as the
corresponding cavity surfaces delimited by the cavity dimensions A,B,L specified. In those cases, these
parameters (offsets and characteristic length) have no meaning, and the internal electromagnetic solver
employs analytical expressions for dealing with these ports, which require much less computational effort.
For this reason, it is recommended to build a circuit using waveguides with the same dimensions as the
cavities wherever it is possible, employing Step discontinuities if different size of waveguides is desired
between cavities. A warning message will appear in order to alert the user to have this situation in mind if
smaller ports are selected. Nevertheless, there might be some cases in which the connection of smaller
rectangular ports will be mandatory, such as when rounded corners are used in the cavity.
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As a final comment, the information window will show, for each discontinuity of this kind, the exact value of the mesh
size that is being employed for each port that requires meshing, as well as the number of triangles generated. The
user can take this mesh size value as reference in order to manually increase it for speeding up calculations (for very
small number of modes, the automatic criterion based on the port geometry can be relaxed without remarkable loss
of accuracy), or decreasing it if more precision is desired, taking into account the memory limitations.
Another part of the specifications of this element is the General posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button. The post parameters and the
different shapes allowed are the same as explained in the Cavity with posts discontinuity.
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Figure G: General Posts properties of the Contact feed to helical resonator
The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab
allows one to specify a mesh size value associated to the maximum size of the tetrahedra employed in the meshing of
the air volume region inside the cavity. An explanation figure of the parameter is also shown in the tab. This value can
be chosen as the same as specified in the general properties of the field computation, or can be specified for the
particular element. A small value will give a more detailed resolution of the fields, but will require a longer time for the
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calculations. On the other hand, very large values will lead to a poor resolution in the visualization. It is recommended
to manually set a tradeoff value taking into account the dimensions of the cavity under consideration.
Figure H: EM Field properties of the Contact feed to helical resonator
In addition, it is also important to mention that, for performing High Power analysis, Fest3D performs an
automatic refinement procedure, which is the same as the one explained in the Cavity with posts discontinuity.
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2.4.2.7 CST solver library
The CST solver library contains the following discontinuities:
General rectangular cavity
General cylindrical cavity
Lateral couplings to cylindrical cavity
Circular to Rectangular T-Junction
Circular T-junction
Ridge T-junction
Coaxial T-junction
Square coaxial T-junction
General bend
2.4.2.7.1 General rectangular cavity
This section describes the General rectangular cavity discontinuity and how to use it, as well as its features and
limitations.
The General rectangular cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a General rectangular cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the General rectangular
cavity
How to create, edit and use this element from Fest3D.
Definition
The General rectangular cavity consists in a rectangular cavity which supports multiple waveguide excitation ports of
any shape (Basic and Rectangular/Circular contour based waveguides), as well as additional resonant posts/tuning
screws, which can be configured to be Perfect Electric Conductor (PEC), or dielectric. The cavity dimensions, the local
reference system, and the different surface names are depicted in figure A.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package.
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Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
For positioning the ports and the posts in the cavity, the user can select any of the six surface walls on which the
geometry will be placed, and specify offset values which will translate the local reference system of each post or
port with respect to the wall center. Additionaly, rotation angles can also be applied around the local axes (u, v,
w) defined for each post or port. The definitions of the local systems and the sign conventions for each case are
shown in figure B.
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Figure B: Offset conventions for ports and posts placed on the cavity walls
On the other hand, for the posts there is also the possibility of selecting surface "None", which means that the
base of the post will not be attached to any of the surface walls, and can be freely positioned with respect to the
local reference system defined at the center of the cavity as shown in figure C. The offset values will modify the
position of the reference system (u, v, w) defined at the center of the base of each post. Rotation angles can also
be applied around each one of the 3 post's local axes (u, v, w), in order to modify the default orientation if desired.
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Figure C: Free positioning of the post with respect to the local reference system of the cavity
When considering a coaxial waveguide port, different types of probe geometries can be selected by the user. All the
possible probe types are included in figure D. When selected in the Ports tab, a specific legend will be shown with the
definition of the geometrical parameters of each probe.
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Figure D: Different types of probes that can be used in this element with a coaxial waveguide port.
Regarding the posts, several different shapes can be considered, which are shown in figure E. By default, any post will
be automatically placed at the center of the bottom surface.
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Figure E: Different post types considered for this cavity
Limitations
The General rectangular cavity discontinuity has some limitations and caveats you should be aware of:
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
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number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Collisions between ports and/or posts
The electromagnetic Solver does not support intersection between ports, or geometrical collisions
between ports and posts. The software will detect this kind of situations and return an error message.
On the other hand, collision between posts is possible. Depending on the type of material used for the posts,
the situation will be handled differently:
If all posts are of PEC material, they will be fused and considered as one object.
If there is volume intersection between posts of PEC and dielectric materials, the metallic part of
the intersection will prevail (the intersection volume inside the dielectric will be filled with PEC).
If there is collision between two posts of dielectric materials, one of the two geometries will
prevail over the other in the intersection volume. The criterion for choosing the prevailing geometry
will be the largest value of the product of the relative permittivity and permeability parameters of
the material associated to each post.
Errors
The General rectangular cavity discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the General rectangular cavity
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The General rectangular cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the General rectangular
cavity:
Figure F: Specific properties of the General rectangular cavity
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
A (mm/inches): The cavity width .
B (mm/inches): The cavity height .
L (mm/inches): The cavity length .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Cavity corner radius. Optional rounded corners can be set for building the cavity. The user can choose
between not using rounded corners (by default), or selecting one of the three different configurations defined
in the legend included in the tab. For any of these cases, the values of the 4 different radii can be edited (it is
worth mentioning that some of the radii values can be zero allowing the user to build half-rounded cavities.
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allows the user to apply mesh refinements in order to speed up the convergence when the
geometry contains cylindrical-shaped excitation probes or posts of PEC material. These refinements consists in the
addition of a virtual box that covers a volume zone surrounding the cap of each post or probe. A generic 2D
scheme with the definition of the refinement box is shown in the following figure.
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Definition of the virtual refinement box applied to cylindrical probes and PEC posts inside the cavity
The mesh volume inside this box is controlled by means of the input refinement factor value. The mesh size
used inside the box is selected as the most restrictive value of the two following criteria:
Criterion 1: mesh size = (smallest wavelength used in the analysis / cells per wavelength) / refinement factor
Criterion 2: mesh size = (maximum perimeter * normal tolerance / 360) / refinement factor
Besides the refinements of the posts, other refinements are considered for cases of ports containing straight
corners associated to inner vertices of the geometry around which the EM-fields will be typically highly-valued.
These refinements are defined as virtual square boxes centered around each inner straight corner as shown in the
schematic figure below.
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Definition of the virtual refinement boxes applied to inner straight corners of a port
The size of each box will be computed as 0.1 times the maximum length of the two edges connected by the
asssociated vertex. The volume of these boxes will be extended along the complete length of the port.
As in the case of the refinements for the posts, the mesh volume inside these boxes will be controlled by means of the
input refinement factor value. The base value of the mesh size will be the one determined by the application of the
Cells per min. mode wavelength parameter defined in the specifications of each port.
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
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consequence.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must be selected from the Type of probe list. The types of available probes are shown in the
right side of the window, as depicted in Figure G. Once selected, the geometrical parameters of the selected probe
can be also edited. A legend will be shown indicating the definition of the specific parameters of the probe. A example
of specific probe is included as a second Coaxial port in Figure I. Another example case of port chosen as a
Rectangular waveguide is also included in figure I.
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Figure G: Port properties of the General rectangular cavity, case of a coaxial port
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Figure H: Port properties of the General rectangular cavity, case of a second coaxial port with a Mushroom probe
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Figure I: Port properties of the General rectangular cavity, case of a rectangular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
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Port length (mm/inches): Indicates a separation distance value from the cross section of the waveguide to the
cavity. It is recommended to use values greater than zero whenever is possible, in order to reduce the
number of accessible modes required to obtain convergent results. Besides, it is also important to take into
account that when there are non-zero values for rotation angles in the port, the definition of the port
length will change. Examples of different cases are shown in figure J. 
Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the rectangular cavity .
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and B, conventions are:
Surface Front: Only X and Y offsets can be edited (Z offset will be fixed to 0)
Surface Back: Only X and Y offsets can be edited (Z offset will be fixed to C)
Surface Right: Only Y and Z offsets can be edited (X offset will be fixed to A/2)
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to B/2)
Surface Left: Only Y and Z offsets can be edited (X offset will be fixed to -A/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -B/2)
Rotation angles: These angles will rotate around each one of the local axes of the reference system defined at
the center of the cross section of the port:
Rotation around W axis: This will be the rotation angle around the axis oriented in the propagation
direction of the port (orthogonal to axis U and V)
Rotation around V axis: This will be the rotation angle around the vertical axis of the port's cross
section. Before applying rotations, this axis will be coincident with one of the local axes defined on each
cavity wall:
For surfaces Front, Back, Right and Left: V axis will be coincident with the local Y axis of the
wall 
For surfaces Top and Bottom: V axis will be coincident with the local Z axis of the wall 
Rotation around U axis: This will be the rotation angle around the horizontal axis of the port's cross
section. Before applying rotations, this axis will be coincident with one of the local axes defined on each
cavity wall:
For surfaces Front, Back, Top and Bottom: U axis will be coincident with the local X axis of
the wall 
For surfaces Right and Left: U axis will be coincident with the local Z axis of the wall 
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
The particular port tab is removed by pressing the Delete port button.
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Figure J: Definitions for port length and blend radius parameters
Considerations for the ports
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes of the waveguide ports for a fixed mesh. Besides, the discretization of the port surfaces will
adapt to the number of accessible modes depending on the value of  the parameter Cells per min. mode
wavelength chosen for each port , which means that the overall 3D mesh
used by the FEM Solver will be more dense and the computational effort will also increase again as well. Therefore in
order to avoid very large simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of
accessible modes in the ports of this discontinuity unless they are indeed mandatory for the convergence of
the structure.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button.
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Figure K: General Posts properties of the General rectangular cavity
For each post, the user can edit the specifications for the dimensions of the post. Regarding the positioning, the
surface wall of the cavity, offsets and rotation angles can be edited in the same way as done with the Ports tab,
following the conventions of figures B and C. Depending on the shape of the post, a specific legend with the
definition of the geometrical parameters is automatically shown at the right side of the window. Legends with the
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offset definitions and the other types of post shapes are also displayed for reference.
Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
Additional window for definition of roundings on a post.
The Material of the post can be also selected. The user can choose between PEC and Lossless dielectric for each one
of the post. In case of selecting lossless dielectric material, the corresponding relative permittivity and permeability
parameters can be edited.
Finally, any of the posts can be discarded by pressing the Delete post button on each tab.
2.4.2.7.2 General cylindrical cavity
This section describes the General cylindrical cavity discontinuity and how to use it, as well as its features and
limitations.
The General cylindrical cavity discontinuity section contains the following topics:
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Definition
Limitations
Errors
What exactly is a General cylindrical cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the General cylindrical
cavity
How to create, edit and use this element from Fest3D.
Definition
The General cylindrical cavity consists in a cylindrical cavity which supports multiple waveguide excitation ports of any
shape (Basic and Rectangular/Circular contour based waveguides), as well as additional resonant posts/tuning screws,
which can be configured to be Perfect Electric Conductor (PEC), or dielectric. The cavity dimensions, the local reference
system, and the different surface names are depicted in figure A.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package. 
Figure A: Cavity dimensions, surface names and the local reference coordinate system employed
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For positioning the ports and the posts in the cavity, the user can select any of the surface walls on which the
geometry will be placed, and specify offset values which will translate the local reference system of each post or
port with respect to the wall center. Additionaly, rotation angles can also be applied around the local axes (u, v,
w) defined for each post or port. The definitions of the local systems and the sign conventions for each case are
shown in figure B.
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Figure B: Offset conventions for ports and posts placed on the cavity walls
On the other hand, for the posts there is also the possibility of selecting surface "None", which means that the
base of the post will not be attached to any of the surface walls, and can be freely positioned with respect to the
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local reference system defined at the center of the cavity as shown in figure C. The offset values will modify the
position of the reference system (u, v, w) defined at the center of the base of each post. Rotation angles can also
be applied around each one of the 3 post's local axes (u, v, w), in order to modify the default orientation if desired.
Figure C: Free positioning of the post with respect to the local reference system of the cavity
When considering a coaxial waveguide port, different types of probe geometries can be selected by the user. All the
possible probe types are included in figure D. When selected in the Ports tab, a specific legend will be shown with the
definition of the geometrical parameters of each probe.
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Figure D: Different types of probes that can be used in this element with a coaxial waveguide port.
Regarding the posts, several different shapes can be considered, which are shown in figure E. By default, any post will
be automatically placed at the center of the bottom surface.
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Figure E: Different post types considered for this cavity
Limitations
The General cylindrical cavity discontinuity has some limitations and caveats you should be aware of:
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
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number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Collisions between ports and/or posts
The electromagnetic Solver does not support intersection between ports, or geometrical collisions
between ports and posts. The software will detect this kind of situations and return an error message.
On the other hand, collision between posts is possible. Depending on the type of material used for the posts,
the situation will be handled differently:
If all posts are of PEC material, they will be fused and considered as one object.
If there is volume intersection between posts of PEC and dielectric materials, the metallic part of
the intersection will prevail (the intersection volume inside the dielectric will be filled with PEC).
If there is collision between two posts of dielectric materials, one of the two geometries will
prevail over the other in the intersection volume. The criterion for choosing the prevailing geometry
will be the largest value of the product of the relative permittivity and permeability parameters of
the material associated to each post.
Errors
The General cylindrical cavity discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the General cylindrical cavity
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The General cylindrical cavity discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the General cylindrical
cavity:
Figure F: Specific properties of the General cylindrical cavity
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The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Radius (mm/inches): The cavity radius.
Height (mm/inches): The cavity height .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allows the user to apply mesh refinements in order to speed up the convergence when the
geometry contains cylindrical-shaped excitation probes or posts of PEC material. These refinements consists in the
addition of a virtual box that covers a volume zone surrounding the cap of each post or probe. A generic 2D
scheme with the definition of the refinement box is shown in the following figure.
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Definition of the virtual refinement box applied to cylindrical probes and PEC posts inside the cavity
The mesh volume inside this box is controlled by means of the input refinement factor value. The mesh size
used inside the box is selected as the most restrictive value of the two following criteria:
Criterion 1: mesh size = (smallest wavelength used in the analysis / cells per wavelength) / refinement factor
Criterion 2: mesh size = (maximum perimeter * normal tolerance / 360) / refinement factor
Besides the refinements of the posts, other refinements are considered for cases of ports containing straight
corners associated to inner vertices of the geometry around which the EM-fields will be typically highly-valued.
These refinements are defined as virtual square boxes centered around each inner straight corner as shown in the
schematic figure below.
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Definition of the virtual refinement boxes applied to inner straight corners of a port
The size of each box will be computed as 0.1 times the maximum length of the two edges connected by the
asssociated vertex. The volume of these boxes will be extended along the complete length of the port.
As in the case of the refinements for the posts, the mesh volume inside these boxes will be controlled by means of the
input refinement factor value. The base value of the mesh size will be the one determined by the application of the
Cells per min. mode wavelength parameter defined in the specifications of each port.
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
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consequence.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
For each port, a specification tab will appear. In first place, a waveguide must be selected from the Attached
waveguide list, which will be filled with the connections already associated to this element. If the waveguide is of
Coaxial type, a probe must be selected from the Type of probe list. The types of available probes are shown in the
right side of the window, as depicted in Figure H. Once selected, the geometrical parameters of the selected probe
can be also edited. A legend will be shown indicating the definition of the specific parameters of the probe. A example
of specific probe is included as a second Coaxial port in Figure I. Another example case of port chosen as a Circular
waveguide is also included in figure I.
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Figure G: Port properties of the General cylindrical cavity, case of a coaxial port
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Figure H: Port properties of the General cylindrical cavity, case of a second coaxial port with a S probe
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Figure I: Port properties of the General cylindrical cavity, case of a circular port
Additionally, for each port tab the following general information can be edited:
Surface: Specifies the surface of the cavity that is assigned to the port. This surface can be chosen in a menu
that obeys the names shown in figure A.
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Port length (mm/inches): Indicates a separation distance value from the cross section of the waveguide to the
cavity. It is recommended to use values greater than zero whenever is possible, in order to reduce the
number of accessible modes required to obtain convergent results. Besides, it is also important to take into
account that when there are non-zero values for rotation angles in the port, the definition of the port
length will change. Examples of different cases are shown in figure J. 
Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the cylindrical cavity .
Offsets: Depending on the cavity surface chosen for placing the port, the coherent directions for offsets will be
displayed for each case. Following figures A and B, conventions are:
Surface Top: Only X and Z offsets can be edited (Y offset will be fixed to Height/2)
Surface Bottom: Only X and Z offsets can be edited (Y offset will be fixed to -Height/2)
Surface Lateral: Only Y offset can be edited.
Position angle (degrees): Specifies an angle value for rotating the lateral port around the height axis of the
local reference system of the cavity (Y axis), measured from the positive Z axis of this reference system . This value applies only for the cases in which surface Lateral is selected.
Rotation angles: These angles will rotate around each one of the local axes which are used to place the port
on each cavity wall:
Rotation around W axis (degrees): This will be the rotation angle around the axis oriented in the
propagation direction of the port (orthogonal to axis U and V)
Rotation around V axis (degrees): This will be the rotation angle around the vertical axis of the port's
cross section. Before applying rotations, this axis will be coincident with one of the local axes defined on
each cavity wall:
For surface Lateral, V axis will be the local Y axis of the cavity 
For surfaces Top and Bottom, V axis will be the local Z axis of the wall 
Rotation around U axis (degrees): This will be the rotation angle around the horizontal axis of the
port's cross section. Before applying rotations, this axis will be coincident with one of the local axes
defined on each cavity wall:
For surface Lateral, U axis will be the local X axis of the cavity 
For surfaces Top and Bottom, U axis be the local X axis of the wall 
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
The particular port tab is removed by pressing the Delete port button.
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Figure J: Definitions for port length and blend radius parameters
Considerations for the ports
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes of the waveguide ports for a fixed mesh. Besides, the discretization of the port surfaces will
adapt to the number of accessible modes depending on the value of  the parameter Cells per min. mode
wavelength chosen for each port , which means that the overall 3D mesh
used by the FEM Solver will be more dense and the computational effort will also increase again as well. Therefore in
order to avoid very large simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of
accessible modes in the ports of this discontinuity unless they are indeed mandatory for the convergence of
the structure.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button.
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Figure K: General Posts properties of the General cylindrical cavity
For each post, the user can edit the specifications for the dimensions of the post. Regarding the positioning, the
surface wall of the cavity, offsets and rotation angles can be edited in the same way as done with the Ports tab,
following the conventions of figures B and C. Depending on the shape of the post, a specific legend with the
definition of the geometrical parameters is automatically shown at the right side of the window. Legends with the
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offset definitions and the other types of post shapes are also displayed for reference.
Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
Additional window for definition of roundings on a post.
The Material of the post can be also selected. The user can choose between PEC and Lossless dielectric for each one
of the post. In case of selecting lossless dielectric material, the corresponding relative permittivity and permeability
parameters can be edited.
Finally, any of the posts can be discarded by pressing the Delete post button on each tab.
2.4.2.7.3 Lateral couplings to cylindrical cavity
This section describes the Lateral couplings to cylindrical cavity discontinuity and how to use it, as well as its features
and limitations.
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The Lateral couplings to cylindrical cavity discontinuity section contains the following topics:
Definition
Limitations
Errors
Using the Lateral couplings to
cylindrical cavity
Definition
What exactly is a Lateral couplings to cylindrical cavity discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or
workarounds to them.
How to create, edit and use this element from Fest3D.
The Lateral couplings to cylindrical cavity discontinuity consists in a cylindrical cavity whose radius is defined by two
circular ports (namely ports 1 and 2). The length of the cavity is provided by the user. Additionally, lateral ports can
access the cavity (at least one). The cavity dimensions, the local reference system and the definition of the geometrical
parameters of the ports are shown in figures A and B.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package.
Figure A: Cavity dimensions and local reference coordinate system employed
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Figure B: Definitions and geometrical parameters used for the ports
Limitations
The Lateral couplings to cylindrical cavity discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Circular or Rectangular waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
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The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Lateral couplings to cylindrical cavity discontinuity can produce the following errors under certain circumstances.
For each error, the possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the Lateral couplings to cylindrical cavity
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The Lateral couplings to cylindrical cavity discontinuity is completely integrated into Fest3D. The user can create, view
and edit this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Lateral couplings to
cylindrical cavity:
Figure C: Specific properties of the Lateral couplings to cylindrical cavity
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
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Length (mm/inches): The length of the circular cavity .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The ports of this element can be inserted in two ways:
By performing connections with waveguides before opening the element properties. These connections will be
automatically detected as new ports.
By pressing the Add port button (a connection with a waveguide will be required later before completing the
circuit).
The first two ports are expected to be Circular waveguides which are used to define the cavity radius according to
figure A. The rest of the ports tabs belong to lateral exitations.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
Besides, for each one of the lateral port tabs the following information can be edited:
Position angle (Degrees): Specifies an angle value for rotating the lateral port along the propagation direction
(Z axis) when observing the cavity from the perspective of Port 1 .
Rotation angle (Degrees): Specifies an angle value for rotating the lateral port along X axis when observing
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the cavity in side view . This parameter is only editable for the case of Rectangular waveguide
ports.
Offset Z (mm/inches): Indicates an optional displacement value in the propagation direction (Z axis) with
respect the center of the cavity .
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
waveguide port to the circular cavity . It is recommended to use values greater than zero in
order to obtain more stable and convergent results.
Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the circular cavity .
The particular port tab is removed by pressing the Delete port button.
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Figure D: Port properties of the Lateral couplings to cylindrical cavity, case of one of the fixed ports (1 and 2)
Figure E: Port properties of the Lateral couplings to cylindrical cavity, case of a lateral port
Considerations for the ports
The first two ports are always forced to be two Circular waveguides with equal radius, and each lateral ports can
be either a Circular or a Rectangular waveguide. The dimensions of the cross section of each port will be taken from
the specifications of the corresponding waveguide element, and will be checked together with the geometric
specifications of this discontinuity in order to warn the user if any inconsistency is found (for example, lateral port
greater than the cavity length, etc).
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It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
2.4.2.7.4 Circular to Rectangular T-Junction
This section describes the Circular to Rectangular T-Junction discontinuity and how to use it, as well as its features and
limitations.
The Circular to Rectangular T-Junction discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Circular to Rectangular T-Junction discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the General cavity How to create, edit and use this element from Fest3D.
Definition
The Circular to Rectangular T-Junction discontinuity consists in a cylindrical cavity whose radius is defined by two
circular ports (namely ports 1 and 2) which is accesed by a lateral port of rectangular shape (port 3). The length of the
cavity is provided by the user. The cavity dimensions, the local reference system and the definition of the geometrical
parameters of the ports are shown in figures A and B.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package.
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Figure A: Cavity dimensions and local reference coordinate system employed
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Figure B: Definitions and geometrical parameters used for the ports
Limitations
The Circular to Rectangular T-Junction discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Circular or Rectangular waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
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The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Circular to Rectangular T-Junction discontinuity can produce the following errors under certain circumstances. For
each error, the possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
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Using the Circular to Rectangular T-Junction
The Circular to Rectangular T-Junction discontinuity is completely integrated into Fest3D. The user can create, view
and edit this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Lateral couplings to
cylindrical cavity:
Figure C: Specific properties of the Circular to Rectangular T-Junction
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
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The following parameters can be edited:
Length (mm/inches): The length of the circular cavity .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The first two ports must be Circular waveguides which are used to define the cavity radius according to figure A. The
rest of the ports tabs belong to lateral exitations.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
Besides, for the third port tab the following information can be edited:
Position angle (Degrees): Specifies an angle value for rotating the lateral port along the propagation direction
(Z axis) when observing the cavity from the perspective of Port 1 .
Rotation angle (Degrees): Specifies an angle value for rotating the lateral port along X axis when observing
the cavity in side view .
Offset Z (mm/inches): Indicates an optional displacement value in the propagation direction (Z axis) with
respect the center of the cavity .
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
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waveguide port to the circular cavity . It is recommended to use values greater than zero in
order to obtain more stable and convergent results.
Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the circular cavity .
Figure D: Port properties of the Circular to Rectangular T-Junction, case of one of the fixed ports (1 and 2)
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Figure E: Port properties of the Circular to Rectangular T-Junction, case of third port
Considerations for the ports
The first two ports are always forced to be two Circular waveguides with equal radius The dimensions of the
cross section of each port will be taken from the specifications of the corresponding waveguide element, and will be
checked together with the geometric specifications of this discontinuity in order to warn the user if any inconsistency
is found (for example, lateral port greater than the cavity length, etc).
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
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, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
2.4.2.7.5 Circular T-Junction
This section describes the Circular T-Junction discontinuity and how to use it, as well as its features and limitations.
The Circular T-Junction discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Circular T-Junction discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the General cavity How to create, edit and use this element from Fest3D.
Definition
The Circular T-Junction discontinuity consists in a cylindrical cavity whose radius is defined by two circular ports
(namely ports 1 and 2) which is accesed by a lateral port of circular shape (port 3). The length of the cavity is provided
by the user. The cavity dimensions, the local reference system and the definition of the geometrical parameters of the
ports are shown in figures A and B.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package.
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Figure A: Cavity dimensions and local reference coordinate system employed
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Figure B: Definitions and geometrical parameters used for the ports
Limitations
The Circular T-Junction discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Circular waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
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and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Circular T-Junction discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
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Using the Circular T-Junction
The Circular T-Junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Lateral couplings to
cylindrical cavity:
Figure C: Specific properties of the Circular T-Junction
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
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The following parameters can be edited:
Length (mm/inches): The length of the circular cavity .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The first two ports must be Circular waveguides which are used to define the cavity radius according to figure A. The
rest of the ports tabs belong to lateral exitations.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
Besides, for the third port tab the following information can be edited:
Position angle (Degrees): Specifies an angle value for rotating the lateral port along the propagation direction
(Z axis) when observing the cavity from the perspective of Port 1 .
Offset Z (mm/inches): Indicates an optional displacement value in the propagation direction (Z axis) with
respect the center of the cavity .
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
waveguide port to the circular cavity . It is recommended to use values greater than zero in
order to obtain more stable and convergent results.
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Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the circular cavity .
Figure D: Port properties of the Circular T-Junction , case of one of the fixed ports (1 and 2)
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Figure E: Port properties of the Circular T-Junction , case of third port
Considerations for the ports
The first two ports are always forced to be two Circular waveguides with equal radius The dimensions of the
cross section of each port will be taken from the specifications of the corresponding waveguide element, and will be
checked together with the geometric specifications of this discontinuity in order to warn the user if any inconsistency
is found (for example, lateral port greater than the cavity length, etc).
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
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, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
2.4.2.7.6 Ridge T-Junction
This section describes the Ridge T-junction discontinuity and how to use it, as well as its features and limitations.
The Ridge T-junction discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Ridge T-junction discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the Ridge T-junction How to create, edit and use this element from Fest3D.
Definition
The Ridge T-junction discontinuity consists in a ridge cavity defined by two Ridge waveguide ports (namely ports 1
and 2) which is accesed by another orthogonal Ridge waveguide port (port 3). The definition of the geometrical
parameters of the ports are shown in figure A.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package.
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Figure A: Definition of the Ridge T-junction
 Additionally, this T-junction allows the insertion of posts. Several different shapes can be considered, which are
shown in figure B.
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Figure B: Different post types considered for this cavity
By default, the posts will be placed along the surface Bottom, which refers to the bottom surface of a
rectangular cavity defined by the limits of the 3 ridge ports. The definitions of the local systems and the sign
conventions are shown in figure C.
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Figure C: Offset conventions for posts placed on the surface Conductor
On the other hand, for the posts there is also the possibility of selecting surface "None", which means that the
base of the post will not be attached to any wall, and can be freely positioned with respect to the local reference
system defined at the center of the rectangular cavity defined by the limits of the ports  as shown in figure
D. The offset values will modify the position of the reference system (u, v, w) defined at the center of the base of
each post. Rotation angles can also be applied around each one of the 3 post's local axes (u, v, w), in order to
modify the default orientation if desired.
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Figure D: Free positioning of the post with respect to the local reference system of the main ridge cavity
Limitations
The Ridge T-junction discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Ridge waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
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565
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Ridge T-junction discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the Ridge T-junction
The Ridge T-junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Ridge T-junction:
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Figure E: Specific properties of the Ridge T-junction
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Direction from port 1 to port 3: Specifies the direction of the turn defined from the port 1 to the port 3. It
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can be Right or Left.
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allows the user to apply mesh refinements in order to speed up the convergence when the
geometry contains cylindrical-shaped excitation probes or posts of PEC material. These refinements consists in the
addition of a virtual box that covers a volume zone surrounding the cap of each post or probe. A generic 2D
scheme with the definition of the refinement box is shown in the following figure.
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Definition of the virtual refinement box applied to cylindrical probes and PEC posts inside the cavity
The mesh volume inside this box is controlled by means of the input refinement factor value. The mesh size
used inside the box is selected as the most restrictive value of the two following criteria:
Criterion 1: mesh size = (smallest wavelength used in the analysis / cells per wavelength) / refinement factor
Criterion 2: mesh size = (maximum perimeter * normal tolerance / 360) / refinement factor
Besides the refinements of the posts, other refinements are considered for cases of ports containing straight
corners associated to inner vertices of the geometry around which the EM-fields will be typically highly-valued.
These refinements are defined as virtual square boxes centered around each inner straight corner as shown in the
schematic figure below.
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Definition of the virtual refinement boxes applied to inner straight corners of a port
The size of each box will be computed as 0.1 times the maximum length of the two edges connected by the
asssociated vertex. The volume of these boxes will be extended along the complete length of the port.
As in the case of the refinements for the posts, the mesh volume inside these boxes will be controlled by means of the
input refinement factor value. The base value of the mesh size will be the one determined by the application of the
Cells per min. mode wavelength parameter defined in the specifications of each port.
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
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consequence.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The first two ports must be two identical Ridge waveguides which are used to define the main ridge cavity. The third
port corresponds to the lateral ridge exitation.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
waveguide port towards the junction .
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation).
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Figure F: Port properties of the Ridge T-junction
Considerations for the ports
The first two ports are always forced to be two Ridge waveguides with identical dimensions. The dimensions
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of the cross section of each port will be taken from the specifications of the corresponding waveguide element, and
will be checked together with the geometric specifications of this discontinuity in order to warn the user if any
inconsistency is found (for example, height of port 3 greater than height of port 1, etc).
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button.
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Figure G: General Posts properties of the Ridge T-junction
For each post, the user can edit the specifications for the dimensions of the post. Regarding the positioning, the
surface wall of the cavity, offsets and rotation angles can be edited in the same way as done with the Ports tab,
following the conventions of figures C and D. Depending on the shape of the post, a specific legend with the
definition of the geometrical parameters is automatically shown at the right side of the window. Legends with the
offset definitions and the other types of post shapes are also displayed for reference.
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Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
Additional window for definition of roundings on a post.
The Material of the post can be also selected. The user can choose between PEC and Lossless dielectric for each one
of the post. In case of selecting lossless dielectric material, the corresponding relative permittivity and permeability
parameters can be edited.
Finally, any of the posts can be discarded by pressing the Delete post button on each tab.
2.4.2.7.7 Coaxial T-Junction
This section describes the Coaxial T-junction discontinuity and how to use it, as well as its features and limitations.
The Coaxial T-junction discontinuity section contains the following topics:
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What exactly is a Coaxial T-junction discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
How to create, edit and use this element from Fest3D.
Definition
Limitations
Errors
Using the Coaxial T-
junction
Definition
The Coaxial T-junction discontinuity consists in a cylindrical coaxial cavity whose radii is defined by two circular coaxial
ports (namely ports 1 and 2) which is accesed by a lateral port of circular coaxial shape (port 3). The length of the
cavity is provided by the user. The cavity dimensions, the local reference system and the definition of the geometrical
parameters of the ports are shown in figures A and B.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package. 
Figure A: Definition of the Coaxial T-Junction
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Figure B: Definitions and geometrical parameters used for the ports
Additionally, this T-junction allows the insertion of posts. Several different shapes can be considered, which are shown
in figure C.
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Figure C: Different post types considered for this cavity
By default, the posts will be placed along the surface named as Conductor, which refers to the cylindrical surface that
corresponds to the outer conductor of the main coaxial cavity defined by the ports 1 and 2. The definitions of the
local systems and the sign conventions are shown in figure D.
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Figure D: Offset conventions for posts placed on the surface Conductor
On the other hand, for the posts there is also the possibility of selecting surface "None", which means that the
base of the post will not be attached to any wall, and can be freely positioned with respect to the local reference
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system defined at the center of the coaxial cavity as shown in figure E. The offset values will modify the position of
the reference system (u, v, w) defined at the center of the base of each post. Rotation angles can also be
applied around each one of the 3 post's local axes (u, v, w), in order to modify the default orientation if desired.
Figure E: Free positioning of the post with respect to the local reference system of the coaxial cavity
Limitations
The Coaxial T-junction discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Coaxial waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
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Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Coaxial T-junction discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
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Using the Coaxial T-junction
The Coaxial T-junction discontinuity is completely integrated into Fest3D. The user can create, view and edit this
element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Coaxial T-junction:
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Figure F: Specific properties of the Coaxial T-junction
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Length (mm/inches): The length of the main coaxial cavity .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allowsthe user to apply mesh refinements in order to speed up the convergence when the
geometry contains cylindrical-shaped excitation probes or posts of PEC material. These refinements consists in the
addition of a virtual box that covers a volume zone surrounding the cap of each post or probe. A generic 2D
scheme with the definition of the refinement box is shown in figure G.
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Definition of the virtual refinement box applied to cylindrical probes and PEC posts inside the cavity
The mesh volume inside this box is controlled by means of the input refinement factor value. The mesh size
used inside the box is selected as the most restrictive value of the two following criteria:
Criterion 1: mesh size = (smallest wavelength used in the analysis / cells per wavelength) / refinement factor
Criterion 2: mesh size = (maximum perimeter * normal tolerance / 360) / refinement factor
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
consequence.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab.
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The first two ports must be two identical Coaxial waveguides which are used to define the coaxial cavity. The third
port corresponds to the lateral coaxial exitation.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
Besides, for the third port tab the following information can be edited:
Position angle (Degrees): Specifies an angle value for rotating the lateral port along the propagation direction
(Z axis) when observing the cavity from the perspective of Port 1 .
Offset Z (mm/inches): Indicates an optional displacement value in the propagation direction (Z axis) with
respect the center of the cavity .
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
waveguide port to the circular cavity . It is recommended to use values greater than zero in
order to obtain more stable and convergent results.
Blend radius (mm/inches): Specifies an optional value of a radius used for blending the edges of the cross
section of the waveguide port which are in contact with the circular cavity .
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Figure H: Port properties of the Coaxial T-junction, case of one of the fixed ports (1 and 2)
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Figure I: Port properties of the Coaxial T-junction, case of third port
Considerations for the ports
The first two ports are always forced to be two Coaxial waveguides with equal outer and inner radii. The
dimensions of the cross section of each port will be taken from the specifications of the corresponding waveguide
element, and will be checked together with the geometric specifications of this discontinuity in order to warn the user
if any inconsistency is found (for example, lateral port greater than the cavity length, etc).
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It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button.
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Figure J: General Posts properties of the Coaxial T-junction
For each post, the user can edit the specifications for the dimensions of the post. Regarding the positioning, the
surface wall of the cavity, offsets and rotation angles can be edited in the same way as done with the Ports tab,
following the conventions of figures D and E. Depending on the shape of the post, a specific legend with the
definition of the geometrical parameters is automatically shown at the right side of the window. Legends with the
offset definitions and the other types of post shapes are also displayed for reference.
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Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
Additional window for definition of roundings on a post.
The Material of the post can be also selected. The user can choose between PEC and Lossless dielectric for each one
of the post. In case of selecting lossless dielectric material, the corresponding relative permittivity and permeability
parameters can be edited.
Finally, any of the posts can be discarded by pressing the Delete post button on each tab.
2.4.2.7.8 Square coaxial T-Junction
This section describes the Square coaxial T-junction discontinuity and how to use it, as well as its features and
limitations.
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The Square coaxial T-junction discontinuity section contains the following topics:
Definition
Limitations
Errors
What exactly is a Square coaxial T-junction discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to
them.
Using the Square coaxial T-
junction
How to create, edit and use this element from Fest3D.
Definition
The Square coaxial T-junction discontinuity consists in a cavity defined by two Square coaxial waveguide ports
(namely ports 1 and 2) which is accesed by another orthogonal Square coaxial waveguide port (port 3). The definition
of the geometrical parameters of the ports are shown in figure A.
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package. 
Figure A: Definition of the Square coaxial T-junction
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 Additionally, this T-junction allows the insertion of posts. Several different shapes can be considered, which are
shown in figure B.
Figure B: Different post types considered for this cavity
By default, the posts will be placed along the surface Bottom, which refers to the bottom surface of a
rectangular cavity defined by the limits of the 3 ports. The definitions of the local systems and the sign
conventions are shown in figure C.
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Figure C: Offset conventions for posts placed on the surface Conductor
On the other hand, for the posts there is also the possibility of selecting surface "None", which means that the
base of the post will not be attached to any wall, and can be freely positioned with respect to the local reference
system defined at the center of the rectangular cavity defined by the limits of the ports  as shown in figure
D. The offset values will modify the position of the reference system (u, v, w) defined at the center of the base of
each post. Rotation angles can also be applied around each one of the 3 post's local axes (u, v, w), in order to
modify the default orientation if desired.
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Figure D: Free positioning of the post with respect to the local reference system of the main coaxial cavity
Limitations
The Square coaxial T-junction discontinuity has some limitations and caveats you should be aware of:
Connections to other elements
This element can only be connected to Square coaxial waveguides.
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
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been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The Square coaxial T-junction discontinuity can produce the following errors under certain circumstances. For each
error, the possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the Square coaxial T-junction
The Square coaxial T-junction discontinuity is completely integrated into Fest3D. The user can create, view and edit
this element properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Square coaxial T-
junction:
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Figure E: Specific properties of the Square coaxial T-junction
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
Direction from port 1 to port 3: Specifies the direction of the turn defined from the port 1 to the port 3. It
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can be Right, Left, Top or Bottom.
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allows the user to apply mesh refinements in order to speed up the convergence when the
geometry contains cylindrical-shaped excitation probes or posts of PEC material. These refinements consists in the
addition of a virtual box that covers a volume zone surrounding the cap of each post or probe. A generic 2D
scheme with the definition of the refinement box is shown in the following figure.
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Definition of the virtual refinement box applied to cylindrical probes and PEC posts inside the cavity
The mesh volume inside this box is controlled by means of the input refinement factor value. The mesh size
used inside the box is selected as the most restrictive value of the two following criteria:
Criterion 1: mesh size = (smallest wavelength used in the analysis / cells per wavelength) / refinement factor
Criterion 2: mesh size = (maximum perimeter * normal tolerance / 360) / refinement factor
Besides the refinements of the posts, other refinements are considered for cases of ports containing straight
corners associated to inner vertices of the geometry around which the EM-fields will be typically highly-valued.
These refinements are defined as virtual square boxes centered around each inner straight corner as shown in the
schematic figure below.
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Definition of the virtual refinement boxes applied to inner straight corners of a port
The size of each box will be computed as 0.1 times the maximum length of the two edges connected by the
asssociated vertex. The volume of these boxes will be extended along the complete length of the port.
As in the case of the refinements for the posts, the mesh volume inside these boxes will be controlled by means of the
input refinement factor value. The base value of the mesh size will be the one determined by the application of the
Cells per min. mode wavelength parameter defined in the specifications of each port.
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
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consequence.
Continuing with the description of the Element Properties, the different excitation ports of the cavity are defined in
the Ports tab. 
The first two ports must be two identical Square coaxial waveguides which are used to define the main cavity. The
third port corresponds to the lateral exitation.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Port length (mm/inches): Indicates a separation distance value measured from the cross section of the
waveguide port towards the junction .
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation).
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Figure F: Port properties of the Square coaxial T-junction
Considerations for the ports
The first two ports are always forced to be two Square coaxial waveguides with identical dimensions. The
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dimensions of the cross section of each port will be taken from the specifications of the corresponding waveguide
element, and will be checked together with the geometric specifications of this discontinuity in order to warn the user
if any inconsistency is found (for example, height of port 3 greater than height of port 1, etc).
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
Another part of the specifications of this element is the General Posts tab. Here, additional resonant posts/tuning
screws can be inserted in the geometry if desired, by pressing the Add button.
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Figure G: General Posts properties of the Square coaxial T-junction
For each post, the user can edit the specifications for the dimensions of the post. Regarding the positioning, the
surface wall of the cavity, offsets and rotation angles can be edited in the same way as done with the Ports tab,
following the conventions of figures C and D. Depending on the shape of the post, a specific legend with the
definition of the geometrical parameters is automatically shown at the right side of the window. Legends with the
offset definitions and the other types of post shapes are also displayed for reference.
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Additionally, most of the post shapes admit the definition of roundings of the cap (and the base as well for the case
of rectangular shapes). By pressing the Round the post cap/base button, a new window will appear on which the
different types of roundings available for the particular post shape can be set. The post will indicate if any cap or
base rounding has been previously activated.
Additional window for definition of roundings on a post.
The Material of the post can be also selected. The user can choose between PEC and Lossless dielectric for each one
of the post. In case of selecting lossless dielectric material, the corresponding relative permittivity and permeability
parameters can be edited.
Finally, any of the posts can be discarded by pressing the Delete post button on each tab.
2.4.2.7.9 General bend
This section describes the General bend discontinuity and how to use it, as well as its features and limitations.
The General bend discontinuity section contains the following topics:
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Definition
Limitations
Errors
What exactly is a General bend discontinuity.
What are the limitations you should be aware of.
The possible errors produced by this element, and solutions or workarounds to them.
Using the General bend How to create, edit and use this element from Fest3D.
Definition
The General bend discontinuity consists in a bend delimited by two identical waveguide ports of any shape (Basic and
Rectangular/Circular contour based waveguides). The bend geometry is defined with an angle between the two ports,
the straight lengths desired for each port and an optional curvature radius. Besides, another angle parameter indicates
a rotation around the input Z axis (propagation) considering a reference system placed at the center of the first
port. These geometrical parameters are shown in figures A, B and C. With these parameters, a general bend can be
built in the 3D space, which is not limited to pure inductive/capacitive geometries. 
For performing the analysis, a Finite Element Method (FEM) Solver is employed in order to compute the General
Admittance Matrix (GAM) of the discontinuity. More specifically, this FEM Solver works in Frequency Domain using a
Reduced Order Model (MOR). This Solver is provided by the CST Studio Suite® software package. 
Figure A: Definition of the geometry of the General bend. Case with curvature radius.
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Figure B: Definition of the geometry of the General bend. Case without curvature radius.
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Figure C: Definition of the rotation angle around Z axis for the General bend.
Limitations
The General bend discontinuity has some limitations and caveats you should be aware of:
Software requirements
This element requires the employment of the High Frequency Solver of CST Studio Suite® software,
which is included in the installation package together with Fest3D. The program will automatically detect if
there is a valid license for the usage of this Solver. If not, this element will not be available in the
Palette, and previously created circuits that contain this element will not simulate.
Definition of frequency points for the Solver
The particular FEM Solver employed for analysis in CST Studio Suite® requires a single range of frequencies
and a number of samples that will be uniformly distributed within the range. In order to provide these data,
Fest3D will consider the actual frequency points of all the active frequency sweeps defined for analysis,
as well as the sweeps defined for optimization (according to the Frequency Specifications). The maximum
and minimum values will be the limits of the range used by the FEM Solver, and the minimum frequency
step considering the frequencies of all sweeps will be the one used for obtaining the number of samples
of an equivalent uniform distribution. After computations, the results for the actual frequency points defined
in Fest3D will be obtained by linear interpolation (the commited error is assumed to be small enough for
practical applications).
Nevertheless, depending on the different frequency ranges defined for a Fest3D circuit, it may occur that the
number of points obtained for the equivalent uniform distribution is very large. Since this number affects
the computational effort of the Solver, a maximum value has been considered. If this maximum value has
been reached, a warning message will be shown, indicating the limitation in the number of frequency
samples and the maximum error (frequency deviation) that will be commited. The user should decide is
this error is acceptable for the particular application, and modify the Frequency Specifications (reduce the
number of sweeps, change the frequency points) in order to solve the problem.
Partial parallelization features
If several discontinuities of this type are present in the same circuit, their respective simulations will be
performed one by one regardless of the number of cores specified by the user for the Fest3D simulation.
Nevertheless, multi-core capabilities can be used internally by the FEM Solver in each one of the elements. The
performance of the FEM Solver computations will depend on the maximum number of allowed cores,
according to the specific license agreement for the CST Studio Suite® software installed in the machine.
Errors
The General bend discontinuity can produce the following errors under certain circumstances. For each error, the
possible solutions or workarounds are explained.
License error while starting CST Studio Suite: A valid license file could not be detected for  CST Studio
Suite® software. Please contact support in order to get a valid license file for the software.
Error(s) while running CST solver: This message appears if one or more errors have been detected during
simulation of the CST Solver. The different error descriptions give details of each particular problem. In most
cases, the errors will be related to inconsistencies found in the computation of the port modes or in the mesh
generation. Another source of errors might be lack of memory in the system if very dense meshes are used.
Modifying the number of accessible modes for the ports and/or the mesh parameters (for ports and for the
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solver) might solve the problems.
Error while exporting matrix results of CST solver: This error appears if there were problems in the
exportation process of data. This might happen for example if the disk runs out of physical space. The user
must bear in mind that the simulations of the FEM solver might require a large amount of disk space, specially
if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the Fest3D input file is
located has enough free space and re-run the simulation.
Error while exporting modal fields results of CST solver:  This error appears if there were problems in the
exportation process of data related to port modal fields. This might happen for example if the disk runs out of
physical space. The user must bear in mind that the simulations of the FEM solver might require a large amount
of disk space, specially if very dense meshes are used (e.g. several GBytes). Make sure that the disk in which the
Fest3D input file is located has enough free space and re-run the simulation.
Using the General bend
The General bend discontinuity is completely integrated into Fest3D. The user can create, view and edit this element
properties using dialog boxes.
The following pictures show the Specific tab of a typical Element Properties dialog box for the Coaxial T-junction:
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Figure D: Specific properties of the General bend
The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu.
The following parameters can be edited:
L1 (mm/inches): Straight length measured from the center of port 1 .
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L2 (mm/inches): Straight length measured from the center of port 2 .
R (mm/inches): Optional curvature radius for the bend geometry .
Angle (Deg): Angle defined between the ports 1 and 2 .
Rotation around Z in (Deg): Rotation angle around the propagation axis of the port 1 .
Dielectric permittivity (relative) : Relative permittivity of the medium inside the cavity (vacuum by default).
Dielectric permeability (relative) : Relative permeability of the medium inside the cavity (vacuum by default).
Besides, the tetrahedral meshing employed by the FEM Solver can be controlled by means of 3 parameters defined in
the same way as done in the CST Studio Suite® software:
Cells per wavelength: This parameter controls the upper limit to the cell size with respect to the smallest
wavelength used in the analysis range (which corresponds to the maximum frequency value set in the
Frequency Specifications for the Fest3D circuit). Increasing this number leads to a higher accuracy, but also
increases the total computation time. The default value is 10, providing a good compromise between the
calculation time and the achievable accuracy for most practical cases.
Smooth mesh with equilibrate ratio: This option controls the mesh smoothing in order to improve quality of
the generated mesh. It represents the maximum ratio between the lengths of two adjacent edges. The closer to
1, the smoother the resulting mesh will be. The default value is 1.2.
Normal tolerance (Deg): This parameter controls the discretization of curved edges and surfaces. Normal
tolerance is the angle in degrees between model edge or face normals at two adjacent mesh vertices. The
default value is 22.5, which forces to use approximately 16 points along circular contours. Lower values of
normal tolerance will lead to smoother discretization of curved surfaces.
Additionally, this element allows the user to apply mesh refinements for cases of ports containing straight
corners associated to inner vertices of the geometry around which the EM-fields will be typically highly-valued.
These refinements are defined as virtual square boxes centered around each inner straight corner as shown in the
schematic figure below.
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Definition of the virtual refinement boxes applied to inner straight corners of a port
The size of each box will be computed as 0.1 times the maximum length of the two edges connected by the
asssociated vertex. The volume of these boxes will be extended along the complete length of the port.
As in the case of the refinements for the posts, the mesh volume inside these boxes will be controlled by means of the
input refinement factor value. The base value of the mesh size will be the one determined by the application of the
Cells per min. mode wavelength parameter defined in the specifications of each port.
The use of these refinement boxes can be enabled (by default) or disabled by clicking on the Enable refinements
checkbox. In most practical cases it is recommended to enable the use of refinements. Otherwise, the general mesh
parameters (specially normal tolerance and cells per wavelength) must be adjusted to be more restrictive in order
for the Solver to obtain good accuracy for the EM-fields inside the cavity and/or the resonant frequencies of the posts.
This will produce a denser mesh for the volume of the whole element, and higher computational times as a
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611
consequence.
Continuing with the description of the Element Properties, the two excitation ports of the cavity are defined in the
Ports tab. 
The two ports must be two identical waveguides. They can be either Basic waveguides (rectangular, circular,
coaxial), or Rectangular/Circular contour based waveguides.
For each port, a specification tab will appear. There are two basic fields which can be edited for any of the ports:
In first place, a waveguide must be selected from the Attached waveguide list, which will be filled with the
connections already associated to this element.
Cells per min. mode wavelength: This parameter controls the cell size with respect to the minimum
wavelength considering all the accessible modes used in the waveguide associated to the port. The choice of
this parameter is very important in order to ensure acceptable convergence for the solution of all the
port modes. Small values may lead to simulation warnings and/or errors and unstable results depending
on the number of accessible modes.  The default value is 5, which offers a good compromise between
simulation time and good discretization for solving all the accessible modes of the port. Larger values of
this parameter will force to use finer discretization of the port surface, increasing the overall meshing of the 3D
structure and the simulation time as a consequence. It is also worth mentioning that this parameter may take
no effect in the overall meshing for the cases where the general mesh parameters used for the FEM Solver are
restrictive enough for the structure under analysis (this will depend on the values of the mesh parameters, the
geometry dimensions and the frequency range used in the simulation)
Fest3D User Manual
612
Figure E: Port properties of the General bend
Considerations for the ports
It is important to take into account that the computational effort of the FEM Solver increases with the number of
accessible modes for a fixed mesh. Besides, the discretization of the port surfaces will adapt to the number of
accessible modes depending on the value of  the parameter Cells per min. mode wavelength chosen for each port
Fest3D User Manual
613
, which means that the overall 3D mesh used by the FEM Solver will be
more dense and the computational effort will also increase again as well. Therefore in order to avoid very large
simulation times IT IS STRONGLY RECOMMENDED not to use large numbers of accessible modes in the ports of
this discontinuity unless they are indeed mandatory for the convergence of the structure.
2.4.3 Allowed Symmetries
Global symmetries can be configured from the general specifications window. An element can implement a
symmetry or allow a symmetry without implementing it. The second case means that a circuit containing the
element can activate such a symmetry, but the element itself does not incorporate the symmetries in its calculations.
The symmetries are specified for the entire circuit, but in order to be valid, all elements in the circuit must implement
or allow such a symmetry.
Allowed Symmetries
The following table lists the symmetries allowed by the various elements within the circuit. This does not necessarily
mean that the symmetries are taken into account in the element, but just that the circuit formed by those elements
support such symmetries. In case that more than one symmetry is specified simultaneously in a circuit, the elements
must allow them all.
Rectangular
Circular
Coaxial
Arbitrary Rectangular,
Coaxial, Elliptic, Ridge, Slot,
Truncated, Waffle, Cross,
Draft, Coaxial square, Lateral
coupling circ wg, Ridge-gap
Circular Arbitrary,
Arbitrary Circular with an Ellipse,
Arbitrary Circular with a Cross,
Arbitrary Circular with Screws ,
Circular Elliptic iris
Radiating Array
Curved
Step
N-Step (if N-Step has only
2 ports, use the Step row above)
C-Junction (if C-Junction is
planar, use T-Junction row
below)
T-Junction
All-Inductive All-Capacitive X symmetry Y symmetry
yes
no
no
no
yes
no
no
no
yes
yes
no
yes
yes
yes
no
yes
All-
Cylindrical
TEM
no
yes
no
no
no
yes
yes
no
no
no
no
no
no
no
no
yes
yes
yes
no
yes
no
no
yes
yes
no
yes
no
no
yes
yes
no
no
yes
yes
yes
no
no
no
yes
no
no
no
yes
no
no
no
yes
yes
no
no
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614
All-Inductive All-Capacitive X symmetry Y symmetry
All-
Cylindrical
TEM
Rounded corner iris 3D
Bends library
Coaxial library
Helical resonator library
Constant width/height library
CST Solver library
no
yes
yes
yes
yes
no
no
yes
yes
yes
yes
no
yes
no
yes
yes
yes
no
yes
no
yes
yes
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
Implemented Symmetries
The following table lists the implemented symmetries by the various kind of elements. This means that these elements
exploit such symmetries.
Rectangular
Circular
Coaxial
Arbitrary Rectangular,
Coaxial, Elliptic, Ridge, Slot,
Truncated, Waffle, Cross,
Draft, Coaxial square, Lateral
coupling circ wg, Ridge-gap
Arbitrary Circular,
Arbitrary Circular with an Ellipse,
Arbitrary Circular with a Cross,
Arbitrary Circular with Screws,
Circular Elliptic iris
Radiating Array
Curved
Step
N-Step (if N-Step has only
2 ports, use the Step row above)
C-Junction (if C-Junction is
planar,
use T-Junction row below)
T-Junction
Rounded corner iris 3D
Bends library
Coaxial library
All-Inductive All-Capacitive X symmetry Y symmetry
yes
no
no
no
yes
no
no
no
yes
yes
no
yes
yes
yes
no
yes
All-
Cylindrical
TEM
no
yes
no
no
no
yes
yes
no
no
no
no
no
no
no
no
yes
yes
yes
no
no
no
yes
no
no
no
yes
yes
no
no
no
yes
no
no
no
yes
yes
no
no
no
no
no
no
yes
yes
yes
no
no
no
no
no
no
no
yes
no
no
no
yes
no
no
no
no
no
no
no
no
no
no
no
Fest3D User Manual
All-Inductive All-Capacitive X symmetry Y symmetry
Helical resonator library
Constant width/height library
CST Solver library
no
yes
no
no
yes
no
no
yes
no
no
yes
no
615
All-
Cylindrical
TEM
no
no
no
no
no
no
2.5 Legal Notices
Please refer to <installation folder>\Licenses to find the Legal notices web page. Typically this is placed in C:\Program
files (x86)\CST Studio <version>\Licenses
Fest3D User Manual
616
Index
1-Port User Defined,  268-270
2D Compensated Tee,  307-313
2D Curved,  325-330
2D OMT,  298-307
2D Rounded short,  363-368
3D Viewer,  82-86
ACW with a Cross,  236-239
ACW with an Ellipse,  233-236
ACW with Screws,  239-243
Adaptive Frequency Sampling Method,  93-97
Allowed Symmetries,  613-615
Analysis,  91
Arbitrary Rectangular (ARW),  190-194
Arbitrary shape,  330-339
Cavity with posts,  369-382
Circular Arbitrary (ACW),  227-233
Circular T-Junction ,  552-560
Circular to Rectangular T-Junction ,  544-552
Circular Waveguide,  186-188
Circular-Elliptic Iris,  247-248
CLI,  175-178
Coaxial cavity library,  369
Coaxial T-Junction ,  574-589
Coaxial waveguide,  188-190 ,  194-197
Compare Results tool,  89-91
Contact feed to helical resonator,  486-499
Convergence Study,  117
Coupling Matrix,  272-275
Cross waveguide,  197-200
CST solver library,  499
Cubic Junction,  287-289
Curved waveguide,  243-247
Design,  120
Discontinuities,  252-256
Draft waveguide,  200-203
ElectroMagnetic Computational Engine (EMCE),  91-93
Elements bar,  76
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617
Elements Database,  178
Elliptic waveguide,  203-206
EM Field Analysis,  112-117
Engineering tools,  98-112
Export tools,  171-175
Fest3D Introduction,  5-8
Fest3D Manual,  69-71
Fest3D Online Help,  5
Fest3D Parallelization,  117-120
Fest3D Tutorial,  8
Fest3D User Manual,  0
Frequency Specifications,  76-79
General bend,  603-613
General cavity,  462-474
General cylindrical cavity,  517-536
General rectangular cavity,  499-517
Graphical User Interface (GUI),  71
Helical resonator,  475-486
Helical resonators library,  474-475
High Power Analysis: Multipactor and Corona.,  170-171
Junctions library,  286-287
Lateral coupling circular waveguide,  209-212
Lateral couplings to cylindrical cavity,  536-544
Legal Notices,  615
Loop feed cavity,  429-440
Lumped,  270-272
Magnetic feed cavity,  440-451
Mitered Bend,  319-325
Mushroom feed cavity,  394-407
N-Port User Defined,  266-268
N-Step,  263-266
Optimizer (OPT),  120-130
Parameters configuration,  87-89
Radiating Array,  248-252
Rectangular Waveguide,  183-186
Requirements ,  71
Ridge T-Junction ,  560-574
Ridge waveguide,  206-209
Ridge-gap waveguide,  212-215
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618
Rounded corner iris,  358-363
Rounded corner iris 3D,  276-286
Slot waveguide,  218-221
Square coaxial T-Junction ,  589-603
Square coaxial waveguide,  215-218
S-Shape contact feed cavity,  418-429
Step,  256-263
Stepped Bend,  314-319
Straight contact feed cavity,  407-418
Straight feed cavity,  382-394
Synthesis Tools,  134
Synthesis Tools: Band-Pass Filter,  143-153
Synthesis Tools: Dual-Mode Filter,  153-165
Synthesis Tools: Impedance Transformer,  165-170
Synthesis Tools: Low-Pass Filter,  134-143
The General Specifications Window,  79-82
The Main Window,  71-76
The Preferences Window,  86-87
T-Junction,  289-290
Tolerance Analysis (TOL),  130-134
Top contact feed cavity,  451-462
Touchstone,  275-276
Truncated waveguide,  221-224
Tutorial 1: The First Circuit,  8-15
Tutorial 2. Running the Simulation,  15-19
Tutorial 3. Accuracy or speed?,  19-22
Tutorial 4. Arbitrary Shape Editor,  22-28
Tutorial 5. Optimizer,  28
Tutorial 5.1. Optimizer: setup,  28-39
Tutorial 5.2. Optimizer: run,  39-42
Tutorial 5.3. Optimizer: export to CST Studio,  42-57
Tutorial 6: Electromagnetic field Analysis,  57-65
Tutorial 7: High Power Analysis ,  65-69
Waffle waveguide,  224-227
Waveguide step with N Metal inserts,  339-347
Waveguide step with N Screws,  347-354
Waveguide Step with rounded corners,  354-358
Waveguides,  179-183
Fest3D User Manual
619
Y-Junction (60 deg),  297-298
Y-junction General with N screws,  290-296

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software described in this document is furnished under a license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a 
retrieval system, or transmitted in any form or any means electronic 
or mechanical, including photocopying and recording, for any 
purpose other than the purchaser’s personal use without the written 
permission of Dassault Systèmes. 
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CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
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PARTICLE  STUDIO,  CST  Studio  Suite,  EM  Studio,  EMC  Studio, 
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Dassault  Systèmes  or  its  subsidiaries  trademarks  is  subject  to  their 
express written approval. 
the  3DSDS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries. 
3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome  to  CST  Studio  Suite®,  the  powerful  and  easy-to-use  electromagnetic  field 
simulation software. This program combines a user-friendly interface with unsurpassed 
simulation performance. CST Studio Suite contains a variety of solvers for carrying out 
Thermal  and Mechanical  Simulation. They  are  all grouped  as  a  specific  Thermal  and 
Mechanical Module, also known as CST MPhysics® Studio. 
Please  refer  to  the  CST  Studio  Suite  -  Getting  Started  manual  first.  The  following 
explanations  assume  that  you  have  already  installed  the  software  and  familiarized 
yourself with the basic concepts of the user interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite - Getting Started manual. 
2.  Work  through  this  document  carefully.  It  provides  all  the  basic  information 
necessary to understand the advanced documentation. 
3.  Look  at  the  examples  provided  in  the  Component  Library  (File:  Component 
Library   Examples).  Especially  the  examples  which  are  tagged  as  Tutorial 
provide detailed information of a specific simulation workflow. Press the Help 
button  of  the  individual  component to get to  the  help  page  of  this  component. 
Please note that all these examples are designed to give you a basic insight into 
a particular application domain. Real-world applications are typically much more 
complex and harder to understand if you are not familiar with the basic concepts. 
4.  Start with your own first example. Choose a reasonably simple example which 
will allow you to quickly become familiar with the software. 
5.  After you have worked through your first example, contact technical support for 
hints  on  possible  improvements  to  achieve  even  more  efficient  usage  of  the 
software. 
What is CST MPhysics Studio? 
CST  MPhysics  Studio is  a  software  package  from  the  CST  Studio  Suite  family  which 
allows  thermal  and  mechanical  simulations.  It  simplifies  the  process  of  defining  the 
structure by providing a powerful solid modeling front end, which is based on the ACIS 
modeling kernel. Strong graphic feedback simplifies the definition of your device even 
further. After the component has been modeled, a fully automatic meshing procedure is 
applied before a simulation engine is started. 
A key feature of CST MPhysics Studio is its tight integration with the other CST Studio 
products. This allows an easy to use workflow for coupled EM-Multiphysics simulations. 
A further outstanding feature is the full parameterization of the structure modeler, which 
enables the use of variables in the definition of your component. In combination with the 
built-in  optimizer  and  parameter  sweep  tools,  CST  MPhysics  Studio  is  capable  of 
analyzing and designing thermal and mechanical aspects of devices. 
Who Uses CST MPhysics Studio? 
Anyone who needs to investigate thermal and mechanical aspects of electromagnetic 
devices. Of course it is also possible to use the product standalone, but the full set of 
capabilities  deploys  when  coupling  the  thermal  and  mechanical  simulators  with  other 
products from the CST Studio Suite family such as CST Microwave Studio®, CST Design
CST MPhysics Studio Key Features 
The following list gives you an overview of the CST MPhysics Studio main features. Note 
that  not  all  of  these features may  be  available  to you  because  of  license  restrictions. 
Contact a sales office for more information. 
General 
  Native  graphical  user  interface  based  on  Windows  10,  Windows  Server  2016 
and Windows Server 2019. 
  The structure can be viewed either as a 3D model or as a schematic. The latter 
allows for easy coupling of thermal simulation parameters with circuit simulation. 
  Various independent types of solver strategies (based on hexahedral as well as 
tetrahedral meshes) allow accurate simulations with a high level of performance 
for a wide range of multi-physical applications. 
  For  specific  solvers  highly  advanced  numerical  techniques  offer  features  like 
Perfect Boundary Approximation® (PBA) for hexahedral grids and curved and 
higher order elements for tetrahedral meshes. 
Structure Modeling 
  Advanced  ACIS-based,  parametric  solid  modeling  front  end  with  excellent 
structure visualization  
  Feature-based hybrid modeler allows quick structural changes 
  Import  of  3D  CAD  data  from  ACIS®  SAT/SAB,  CATIA®,  SOLIDWORKS®, 
Autodesk Inventor, IGES, VDA-FS, STEP, PTC Creo, Siemens NX, Parasolid, 
Solid Edge, CoventorWare, Mecadtron, NASTRAN, STL or OBJ files 
  Import of 2D CAD data by DXF, GDSII and Gerber RS274X, RS274D files 
  Import of EDA data from design flows including Cadence Allegro® / APD® / 
SiP®, Mentor Graphics HyperLynx®, Zuken CR-5000® / CR-8000®, IPC-2581 
and ODB++® (e.g. Altium Designer, Mentor Graphics Expedition / PADS / 
Boardstation®, CADSTAR®, Visula®) 
  Import of PCB designs originating from CST PCB Studio® 
  Import of 2D and 3D sub models 
  Import of Agilent ADS® layouts 
  Import of Sonnet® EM models 
  Import of a visible human model dataset or other voxel datasets 
  Export  of  CAD  data  to  ACIS  SAT/SAB,  IGES,  STEP,  NASTRAN,  STL,  DXF, 
GDSII, Gerber or POV files 
  Parameterization for imported CAD files 
  Material database 
  Structure templates for simplified problem setup 
Mechanics Solver 
  Temperature dependent Young’s modulus 
  Displacement boundary condition 
  Traction boundary condition 
  Thermal expansion 
  Neo-Hookean material model for simulation of large deformations 
  Various stress plots: von Mises, hydrostatic and tensor components 
  Strain plots including visualization of the volumetric strain 
  Nonlinear solver computes the Green-Lagrange and the Almansi-strain as well 
as the 2nd Piola-Kirchhoff and Cauchy stress tensors 
  Displacement plot including visualization of deformed mesh 
  Import of force densities from EM-solvers
Thermal Steady State Solver 
  Isotropic and anisotropic material properties 
  Bioheat material properties  
  Nonlinear material properties (Bioheat properties and thermal conductivity) 
  Thermal contact resistance 
  Moving media 
  Convection for human voxel models 
  Heat transfer by conduction in volumes 
  Heat transfer by convection and radiation through surfaces 
  Sources:  fixed  and  floating  temperatures,  heat  sources,  eddy  current  and 
stationary current loss fields, volume/surface power loss distributions in dielectric 
or lossy metal materials imported from CST Microwave Studio, CST EM Studio 
or CST PCB Studio, crashed particle loss distribution from CST Particle Studio 
  Adiabatic / fixed or floating temperature / open boundary conditions 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Thermal conductance matrix calculation 
  Equivalent Circuit EMS/MPS/DS Co-Simulation for linear problems 
Thermal Transient Solver 
  Isotropic and anisotropic material properties 
  Bioheat material properties  
  Nonlinear material properties (Bioheat properties, thermal conductivity and heat 
capacity) 
  Thermal contact resistance 
  Moving media 
  Convection for human voxel models 
  Heat transfer by conduction in volumes 
  Heat transfer by convection and radiation through surfaces 
  Sources: fixed, initial and floating temperatures, heat sources, eddy current and 
stationary current loss fields, volume/surface power loss distributions in dielectric 
or lossy metal materials imported from CST Microwave Studio, CST EM Studio 
or CST PCB Studio, crashed particle loss distribution from CST Particle Studio 
  Adiabatic / fixed or floating temperature / open boundary conditions 
  Low or high order time integration method, constant or adaptive time step width 
  Network distributed computing for remote calculations 
  Calculation of CEM43°C thermal dose in biological tissuesConjugate Heat Transfer Solver 
  Transient and steady-state solver for incompressible laminar or turbulent flows 
  Conjugate heat transfer between solids and fluids 
  Temperature dependent material properties (thermal conductivity, heat capacity 
and dynamic viscosity) 
  Multi-fluid support for liquid cooling simulations  
  Boussinesq approximation for buoyancy force in flows 
  Surface-to-surface radiation with automatic calculation of view factors 
  Opening: velocity- and pressure-based inlets and outlets  
  Walls: slip/no slip, isothermal and adiabatic  
  Internal inlet and outlets  
  Internal heat sources 
  External heat sources imported from CST Microwave Studio or CST EM Studio  
  Axial/Centrifugal fan model support 
  Planar and volume flow resistance model support
  Two-resistor/Delphi component model support  
  Thermal contact properties: resistance, capacitance 
  Thermal surface properties: surface emissivity and heat transfer coefficient 
  Heat pipes support 
  Thermoelectric coolers (TEC) based on the Peltier effect 
  ECXML file format import 
  Full GPU acceleration support 
SAM (System and Assembly Modeling) 
  3D representations for individual components 
  Automatic project creation by assembling the schematic’s elements into a full 3D 
representation 
  Manage project variations derived from one common 3D geometry setup 
  Coupled  Multiphysics  simulations  by  using  different  combinations  of  coupled 
circuit/EM/thermal/mechanical projects 
Visualization and Secondary Result Calculation 
  Online visualization of intermediate 1D results during simulation 
  Import and visualization of external xy-data 
  Copy / paste of xy-datasets 
  Fast access to parametric data via interactive tuning sliders 
  Automatic saving of parametric 1D results 
  Multiple 1D result view support 
  Various  2D  and  3D  field  visualization  options  for  thermal  fields,  heat  flow 
densities, displacement fields, stress fields, etc. 
  Animation of field distributions 
  Display and integration of 2D and 3D fields along arbitrary curves 
  Integration of 3D fields across arbitrary faces 
  Hierarchical  result  templates  for  automated  extraction  and  visualization  of 
arbitrary results from various simulation runs. These data can also be used for 
the definition of optimization goals. 
Result Export 
  Export of result data such as fields, curves, etc. as ASCII files 
  Export screen shots of result field plots 
Automation 
  Powerful  VBA  (Visual  Basic for  Applications)  compatible macro  language  with 
editor and macro debugger 
  OLE  automation  for  seamless  integration  into  the  Windows  environment 
(Microsoft  Office®,  MATLAB®,  AutoCAD®,  MathCAD®,  Windows  Scripting
About This Manual 
This manual is primarily designed to enable a quick start of CST MPhysics Studio. It is 
not intended to be a complete reference guide to all the available features but will give 
you an overview of key concepts. Understanding these concepts will allow you to learn 
how to use the software efficiently with the help of the online documentation. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the Ctrl key while pressing the S key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the 
command.  
Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item. 
  Example: View: Visibility  Wire Frame (Ctrl+W) 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support
Chapter 2 – Simulation Workflows 
This chapter contains two workflow examples demonstrating the basic features of CST 
MPhysics Studio. In the first example, a very simple structural mechanics model of an 
accelerometer is created. This workflow describes in detail, how to generate a model 
geometry,  assign  material  properties  and  sources,  generate  a  mesh  and  run  the 
simulation. Besides, the visualization and interpretation of structural mechanics results 
are discussed. 
The  second  example  describes  the  detailed  workflow  for  setting  up  uni-  and  bi-
directional EM-Thermal coupled simulations. In the uni-directionally coupled simulation, 
a high frequency electromagnetic solver calculates the ohmic losses in the walls of an 
HF-filter  which  are  imported  by  the  Conjugate  Heat  Transfer  (CHT)  solver.  Then  the 
CHT solver conducts a thermal analysis to get the temperature distributions in the filter 
and its surroundings. In the bi-directionally coupled simulation, the EM solver and the 
CHT solver exchange not only ohmic losses but also the temperature field, i.e., the high 
frequency EM solver can import the temperature field calculated by the CHT solver to  
update its temperature-dependent EM properties of its materials.   
Studying  these  examples  carefully  will  help  to  become  familiar  with  many  standard 
operations that are important when performing simulations with CST MPhysics Studio. 
In  the  subsequent  chapters  some  remarks  concerning  the  extended  features  of  the 
solvers omitted in the tutorial part of this documentation can be found. 
The following explanations describe the “long” way to open a particular dialog box or to 
launch a particular command. Whenever available, the corresponding Ribbon item will 
be  displayed  next  to  the  command  description.  Because  of  the  limited  space  in  this 
manual,  the  shortest  way  to  activate  a  particular  command  (i.e.  by  either  pressing  a 
shortcut key or by activating the command from the context menu) is omitted. You should 
regularly open the context menu to check available commands for the currently active 
mode. 
Simulation Workflow: Structural Mechanics 
In  this  example  you  will  model  a  simple  accelerometer.  At  first,  the  geometry  of  the 
structure  will  be  created,  and  material  properties  will  be  defined.  Then,  boundary 
conditions will be specified and the solver will be configured and started. Finally, it will 
be shown how the solution results should be interpreted. 
The Structure 
The following  picture  demonstrates  the  spatial  structure  of  a simple accelerometer.  It 
consists of two fixed flat conductors with a potential difference applied, and a movable 
conductor between them.1 
3
If the system moves with acceleration, the inertial force pushes the movable conductor 
towards one of the fixed ones. The potential difference, e.g., between the conductors 2 
and 3 changes proportionally. 
Create a New Project 
After starting CST Studio Suite, please select Thermal and Mechanics from the list of 
installed modules: 
After a new CST MPhysics Studio project is created, you can switch the problem type 
to Mechanics by selecting Home: Edit  Problem Type  Mechanics 
. 
Open the QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
you can open this assistant by selecting QuickStart Guide from the dropdown list of the 
Help button 
 in the upper right corner. 
The following dialog box should now be positioned in the upper right corner of the main view:The red arrow always indicates the next step necessary for your problem definition. You do 
not need to process the steps in this order, but we recommend that you follow this guide at 
the beginning in order to ensure all necessary steps have been completed. 
Look at the dialog box as you follow the various steps in this example. You may close the 
assistant at any time. Even if you re-open the window later, it will always indicate the next 
required step.
If you are unsure of how to access a certain operation, click on the corresponding line. The 
Quick Start Guide will then either run an animation showing the location of the related menu 
entry or open the corresponding help page. 
Define the Units 
By default, m is selected as the dimensions unit. Please change this setting by selecting 
Home: Settings  Units 
. In the Units dialog, please select mm for dimensions: 
Model the Structure 
The first step is to create a brick. 
1.  Select the brick creation tool from the main menu: Modeling: Shapes  Brick 
2.  Press the Escape key in order to open the dialog box. 
3.  Fill up the brick size fields as it is shown in the table below. 
Xmin 
Ymin 
Zmin 
-10  Xmax 
-1  Ymax 
0  Zmax 
6 
1 
0.05 
4.  In order to select the material, click on the corresponding combo box and select 
Copper  (annealed).  This  material  is  predefined  for  CST  MPhysics  Studio 
projects.5.  Now click the OK button. A new brick has been created:
1.  Let us explore the material properties of the newly created object. Open the Materials 
folder in the Navigation Tree and double-click the item Copper (annealed). 
The  dialog  box  Material  Parameters:  Copper  (annealed)  appears  where  various
In this tab you can change the mechanical properties of the selected material. These 
are the three most important mechanical properties: 
  Young's modulus defines the stiffness of the isotropic elastic material. It is normally 
measured in GPa, or kN/mm2. The typical values vary between 0.01 GPa (rubber) 
and over 1000 GPa (diamond). It is important to know the value of this material 
parameter very well, since it has a large influence on the accuracy of the solution. 
  Poisson's ratio defines the scale of the transverse contraction of a longitudinally 
stretched body. This parameter can vary between -1 and 0.5, whereas most of the 
materials are characterized by a positive Poisson's ratio. 
  Thermal expansion coefficient is the strain of a body if its temperature changes by 
1 K. This value is utilized to compute strain induced by an external temperature 
field. 
2.  Now press Cancel and start creating a new brick (Modeling: Shapes  Brick 
) with 
the following size (please do not press OK yet):  
Xmin 
Ymin 
Zmin 
-6  Xmax 
-1  Ymax 
0.05  Zmax 
6 
1 
0.7 
3.  In order to change the material for the new solid, select [Load from Material Library…] 
in the Material combo box. The dialog box Load from Material Library appears. Select 
the material Steel-1010 and press the button Load.4.  Now  press  the  button OK  in the  Brick  dialog  box.  A  new  brick consisting  of  Steel-
1010 is created.
5.  By selecting Modeling: Picks  Picks (S) 
 activate the general pick tool to pick two 
edges of the second brick, as shown in the picture below: 
6.  Select Modeling: Tools  Blend  Chamfer Edges 
 in order to chamfer the selected 
edges.  Enter  the  chamfer  width  of  0.65,  and  keep  the  default  angle  of  45°  in  the 
appearing dialog box and click the OK button. 
7.  Again, open the Brick dialog and enter the following values: 
Xmin 
Ymin 
Zmin 
6.3  Xmax 
-1  Ymax 
0  Zmax 
7.5 
1 
0.7 
For the new brick a new material should be created. Select [New Material…] in the 
Material combo box. The New Material Parameters dialog is shown. In the General
After that, switch to the Mechanics tab in this dialog, select Normal for material 
Type, set the Young’s modulus to 2 GPa and the Poisson’s ratio to 0.4. 
Confirm your settings with OK. 
8.  Pick and chamfer one of the upper edges with the chamfer width of 0.7, and keep the 
) in order to obtain 
default angle of 45° (Modeling: Tools  Blend  Chamfer Edges
9.  Create the following bricks: 
  One of Plastic with the following size: 
Xmin 
Ymin 
Zmin 
7  Xmax 
-1  Ymax 
0.7  Zmax 
  Another one of Plastic with the following size: 
Xmin 
Ymin 
Zmin 
-10  Xmax 
-1  Ymax 
0.05  Zmax 
7.5 
1 
1.5 
-9 
1 
1.5 
  The last one made of Copper (annealed) with the following dimensions: 
Xmin 
Ymin 
Zmin 
-10  Xmax 
-1  Ymax 
1.5  Zmax 
7.5 
1 
1.6 
   The result should be as shown in the following picture:10. 
In  Navigation  Tree  to  the  left  of  the  main  document  window,  open  the  item 
Components  and  select  component1.  Afterwards  activate  Modeling:  Tools   
Transform 
.
11. 
In the dialog Transform Selected Object select the operation Mirror, check the 
boxes Copy and Unite and set the mirror plane normal to 0, 0, 1, as shown in the 
following picture. If necessary, uncheck Shape Center for the Mirror plane normal: 
12. 
Click OK button. Now the geometric structure setup is complete:Traction and Displacement Boundaries 
After the spatial structure has been built, the next step is to define the displacement and 
traction boundaries. Displacement boundaries refer to the surfaces of the model which 
have been shifted by a certain distance in a certain direction. To fix a surface at its initial 
position it is also possible to set the displacement values to zero. 
Traction  boundaries  are the  surfaces  where  a certain  pressure  is  applied  in  a  certain 
direction.  Both  displacements  and  tractions  are  defined  as  vectors  in  the  Cartesian 
coordinate system. 
In the present example let us fix the both sides of the model and apply a pressure to the 
middle electrode, which would mimic the influence of inertial forces during acceleration. 
The following steps must be performed:
1.  Press the toolbar button Simulation: Boundaries  Displacement Boundary 
2.  Select the side faces of the model, as shown in the picture below (you have to select 
. 
five faces at x-min and 3 faces at x-max): 
After pressing the Return key, the dialog box Define Displacement Boundary will appear: 
3.  Keep the zero values for all the components of the displacement vector and press 
the OK button. Now the sides of the model are fixed in space. 
4.  Press the toolbar button Simulation: Boundaries  Traction Boundary 
5.  Double-click the upper surface of the third electrode: 
.After pressing the Return key, the dialog box Define Traction Boundary will appear:
6.  Put the value of -2e-6 GPa as the Z-coordinate of the traction vector. This means that 
the  pressure  of  2 kPa  is  applied  towards the  negative direction  of the  Z-axis.  This 
pressure would roughly correspond to the acceleration of 17*g, or 170 m/s2, into the 
positive Z-direction. 
Mesh Settings 
The structural mechanics solver is quite sensitive to the quality of discretization. In order 
to obtain reliable results, the default mesh density needs to be increased. To do this, 
press the toolbar button Simulation: Mesh  Global Properties 
In the Mesh Properties – Tetrahedral dialog, change the Cells per max model box edge 
setting for Model to 20: 
.This will increase the density of generated mesh. In order to check the resulting mesh, 
you may press the Update button: 
Press the OK button to accept the changes and close the window.
Start the Simulation 
Finally, after all the settings have been made, it is time to start the mechanical solver. 
Press the toolbar button Simulation: Solver  Setup Solver 
. The structural mechanics 
solver parameter dialog box appears. Note that Adaptive mesh refinement is activated 
in  order  to  refine  the  mesh  automatically  at  critical  points.  Click  on  Properties…  and 
increase the Maximum Number of passes to 10 for this example. 
You can click the Help button in order to learn more about the controls in this dialog box. 
For now, the default settings are good enough, so just click the Start button. After the 
calculation has been started, you can control the execution of the solver in the Progress 
and Messages windows. 
Analyze the Solution of the Tetrahedral Solver 
After  the  mechanical  solver  finishes  the  computation,  several  items  appear  in  the 
Navigation Tree.The directory NT: 1D Results  Adaptive Meshing contains information on the adaptive 
mesh refinement performed by the solver. Here you can inspect the number of cells in 
the mesh for each iteration step, time used by the solver to generate the solution, as 
well as the relative error of the solution. For example, in the picture below you can see 
the  number  of  degrees  of  freedom  in  the  solution  for  each  step  of  mesh  refinement. 
Please note that the exact values may be slightly on different systems.
The directory 2D/3D Results contains the distributions of displacement, strain and stress 
within  the  solution  domain.  If  a  temperature  distribution  has  been  imported  from  the 
thermal solver, it will be mapped to the tetrahedral mesh and will be available for display 
here as well. 
A click on the item NT: 2D/3D Results  Displacement displays a deformation plot of 
the body deformation.Here the original shape of the model is shown semi-transparently whereas the scalar 
plot of absolute displacement is shown on the solid deformed shape. 
Select Arrows from the plot type pull-down menu in 2D/3D Plot: Plot Properties to display 
a vector plot of the body deformation, as shown in the following picture.
Selecting Contour from the plot type pull-down menu displays a scalar plot and enables 
the  vector  component  pull-down  menu  in  the  2D/3D  Plot  ribbon,  which  contains  the 
following items: X, Y, Z, Abs, Normal, Tangential. 
  Click on X, Y or Z to display the corresponding component of the displacement vector. 
The example below demonstrates the displacement of the solution domain in the Z-
direction. 
  The  item  Abs  demonstrates  the  distribution  of  the  absolute  value  of  displacement 
within the solution domain. 
  The  items  Normal  and  Tangential  demonstrate  the  length  of  the  corresponding 
projection of displacement vector onto each body surface. 
Navigation Tree item NT: 2D/3D Results  Strain contains the following sub-items: 
  Directory Components contains the components XX, YY, ZZ, XY, XZ and YZ of the 
strain tensor. 
  Sub-item  Volumetric  displays  the  distribution  of the  volumetric  strain  in  the  model, 
which means the relative volume change in each node of the solution domain. The 
negative values mean contraction, whereas the positive values mean expansion.Finally, Navigation Tree item NT: 2D/3D Results  Stress contains the following entries: 
  Directory Components contains the components XX, YY, ZZ, XY, XZ and YZ of the 
stress tensor. 
  The  tree-entry  Von  Mises  displays  the  distribution  of  von  Mises  stress  within  the 
solution domain. If this stress at some location is higher than the yield strength of the 
corresponding material, plastic deformation takes place in this location. Von Mises 
stress is always positive.
  The  tree-entry  Hydrostatic  displays  the  hydrostatic  stress  distribution,  reproducing 
the change of the volume in the stressed body. The negative values mean contraction 
forces. 
  The tree-entry First Principal Stress displays the distribution of the largest eigenvalue 
of  the  stress  tensor  in the  solution  domain.  The  first  principal  stress  is  the  largest 
tension applied at the given point. 
Another  useful  feature  is  the  visualization  of  computation  results  on  a  cutting  plane. 
Select 2D/3D Plot: Sectional View  Fields on Plane 
 from the toolbar to enter this 
mode. By default, the cutting plane is perpendicular to the X-axis. Its orientation can be 
modified from the toolbar by changing the 2D/3D Plot: Sectional View  Normal setting. 
Also the position of the cutting plane can be changed in this way. 
In the following picture the distribution of the absolute value of displacement vector is 
shown on the cutting plane perpendicular to the Y-axis.Vector fields can be visualized on a cutting plane in the same manner. Just select the 
Arrow  plot  type  in  the  2D/3D  Plot  ribbon  (of  course,  for  a  plot  with  vector  data  like 
Displacement). In this case the Fields on Plane mode stays activated. 
Summary 
This example should have given you an overview of the key concepts of CST MPhysics 
Studio. Now you should have a basic idea of how to do the following: 
1.  Model the structures by using the solid modeler; 
2.  Define and modify various material parameters; 
3.  Assign displacement and traction boundaries;
4.  Start the structural mechanics solver; 
5.  Explore the results of adaptive mesh refinement; 
6.  Visualize various distributions delivered by the mechanical solver; 
7.  Visualize the deformation of the mesh and scale it. 
If you are familiar with all these topics, you have a very good starting point for further 
improving your usage of CST MPhysics Studio. 
For more information on a particular topic, we recommend you browse through the online 
 button in the upper right corner. If you 
help system which can be opened via the Help 
have any further questions or remarks, do not hesitate to contact your technical support 
team. We also  strongly recommend  that  you  participate  in  one  of  our  special  training 
classes held regularly at a location near you. Ask your support center for details. 
Simulation Workflow: Coupled EM-CHT Simulation 
Coupled simulations are the main application field for CST MPhysics Studio. The new 
parametric  multi-physics  workflow  simplifies  the  management  of  coupled  simulation 
projects, which share the same model geometry (called the Master Model). Changes in 
the Master Model are directly transferred to the subprojects. In addition, this workflow 
supports the definition of global parameters, which are shared between the subprojects, 
as well as the usage of parameter sweeps or optimization sequences. 
Two  types  of EM-CHT  couplings  are  supported, i.e.,  uni-directional  and  stationary  bi-
directional couplings. In a uni-directional EM-CHT coupling the EM solver first solves the 
electromagnetic fields and the resultant thermal losses.  The CHT solver then imports 
those losses as heat sources and performs a thermal analysis to obtain the temperature 
field  in  the  computational  domain.  Currently,  the  EM  solvers  which  can  be  uni-
directionally coupled with the CHT solver include the HF frequency domain solver, HF 
transient  solver,  LF  frequency  domain  solvers  (Fullwave,  Eletroquasistatic  and 
Magnetoquasistatic), 
and 
domain 
LF 
Magnetoquasistatic), and Stationary Current solver. 
(Eletroquasistatic 
solvers 
time 
A stationary bi-directional EM-CHT coupling not only allows the CHT solver to import the 
thermal losses obtained from an EM solver but also allows the EM solver to import the 
temperature field calculated by the CHT solver. The bi-directional coupling can find its 
application  involving  material  whose  EM  properties  are  dependent  on  temperature.  
Currently, the EM solvers which can be coupled with the CHT solver in  stationary bi-
directions include the HF frequency domain solver, HF transient solver, LF frequency 
domain solver (Magnetoquasistatic), and Stationary Current solver. 
The  typical  workflow  for  setting  up  a  uni-directional  EM-CHT  coupled  project  is  first 
demonstrated. The simulated device consists of a filter placed on a horizontal support 
and  surrounded  by  air.  The  HF  frequency  domain  solver  is  first  used  to  perform  a 
frequency domain analysis of the filter.  The ohmic losses from the filter will be obtained 
along with the electromagnetic fields. Physically, the ohmic losses will be transformed 
into heat and result in the increase of the filter’s temperature. The corresponding thermal 
analysis is conducted by using the CHT solver which imports the ohmic losses as heat 
sources and computes the temperature distribution in the filter with the cooling effect of 
the surrounding air being considered.   
The workflow for setting up a stationary bi-directional EM-CHT coupled project shares a 
lot with its counterpart for the uni-directional coupling and, therefore, only the difference 
will be described.
Uni-Directional EM-CHT Link Set-up 
Please open the project “Combline Filter Draft” located in the Component Library. To 
access  the  example,  please  select  the  File  tab,  then  select  Component  Library,  type 
“Combline” into the search field on the top right and press Enter: 
To open the project you have to download a copy first, by clicking on the Download 
symbol. Once this is done you are ready to open the example by clicking on the Open 
Project symbol. 
Start  the  automatic  creation  of  a  coupled  electromagnetic/thermal  computation  by 
selecting  Home:  Simulation   Simulation  Project 
   EM-Thermal  Coupling   Uni-
directional.
The EM simulation project is named EM1 and will be performed by the frequency domain 
solver of MWS. Select High Frequency as Project type and Frequency Domain as Solver 
type. All the settings from the master model can be inherited by selecting its schematic 
block as the reference model. 
After you click the OK button, the dialog box below appears to create the second part of 
the EM-Thermal link:In the dialog box, the project type Thermal & Mechanics is already chosen. So you only 
need to select the thermal solver type Conjugate Heat Transfer and rename the project 
to CHT.  Once you are done, press the OK button. The EM and thermal simulation tasks 
whose names are EM1 and CHT, respectively, will be created and added to the Tasks 
folder in the Navigation Tree in the Schematic view sequentially.
Loss Import 
In  the  next  step,  you  are  invited  to  define  the  frequency  at  which  the  thermal  losses 
should be computed and exported. The losses directly exported by the EM solver are by 
default calculated for an input peak power of 1W. The simulated device however may 
be operated at a different input power therefore the exported losses must be rescaled 
proportionally.  For  an  operational  input  power  of  100W,  assign  the  value  100  to  the 
Scaling factor for losses entry: 
Click OK. The corresponding monitors and field imports are configured automatically in 
both  simulation  projects.  Now  you  may  switch  to  the  thermal  project  (select  the  CHT 
project  tab  in  the  main  view)  and  configure  additional  material  properties,  necessary 
thermal sources, boundary conditions and calculation parameters. 
In the navigation tree a field source called EM1 (named after the name of the EM 
project of the EM-Thermal link) has been automatically added and configured. Edit it to 
reconfigure it if necessary. The exclamation mark indicates that losses are missing 
because the EM1 simulation has not yet been performed.Background and Boundary Conditions 
To take into account the effect of natural convection it is necessary to create some space 
around the device (Simulation: Settings  Background 
) so that the airflow induced 
by heated device can be simulated:
Some of the materials contained in the original model are missing thermal properties. In 
order  for  the  CHT  solver  to  work  properly,  the  density,  heat  capacity  and  thermal 
conductivity of the background and of all the solids must be defined (>0). In addition, the 
dynamic  viscosity  of  the  background  material  must  be  specified.  To  include  the 
contribution  of  radiation  from  a  solid,  the  emissivity  has  to  be  specified  as  well.  By 
default, radiation calculation is not activated but can be enabled in the solver parameter 
dialog . 
The background material properties (Simulation: Settings  Background 
) need to be 
copied from the material “Air”. To do this click on the Properties… button and then on 
the Copy Properties from Material… button in the General tab of the material dialog.
Note: solids made of material PEC will be automatically replaced in the solver by the 
material Copper (annealed). 
Make sure that the material named “MWSSCHEM1/dielectric” has the following thermal
Please check the material named “MWSSCHEM1/brass” in the same manner:    31
Open Simulation: Settings  Boundaries 
respect to the YZ plane and set-up the YZ symmetry boundary condition:  
 to exploit the symmetry of the model withAssuming the device is positioned horizontally, the horizontal support is modeled as an 
adiabatic wall while the other sides of the computational domain are set to open:
Mesh Settings 
  CFD) 
Please change the mesh type to CFD (Simulation: Mesh  Global Properties
and open the mesh properties dialog. Adjust the Minimum cell setting to a fraction of 40 
for the maximum cell in the model.Solver Parameters 
Please change the default temperature unit to Celsius in the project Units dialog (Home: 
Settings  Units 
) to have the results presented in Celsius later.
Then open the solver parameter dialog (Simulation: Solver  Setup Solver 
). Activate 
the  Gravity  check  box  to  simulate  the  effect  of  natural  convection.  Switch  off  the 
Turbulence  model  check  box.  Adjust  the  Ambient  temperature  unit  to  Celcius  and 
specify the ambient conditions of 20°C.  
If  Radiation  is  turned  on,  the  radiation  temperature  can  be  used  as  reference 
temperature when the contribution of open boundary conditions to radiation is taken into 
account.. Please note that we perform this simulation without radiation in order to reduce 
the computation time for this tutorial.Open the CHT Solver Special Settings dialog by pressing the button Specials… and limit 
the Number of iterations to a maximum of 80 in order to shorten the otherwise lengthy 
simulation  time.  Please  note  that  the  results  obtained  after  80  iterations  are  not  fully 
converged.  If  more  accurate  results  are  desired  change  the  number  of  iterations  to 
automatic calculation (i.e. switch off the Maximum checkbox). With current settings, the 
overall simulation time should be less than 20 minutes.
Apply all settings with the OK or Apply buttons before closing the CHT Solver Special 
Settings and Conjugate Heat Transfer Solver Parameters dialog box. 
Coupled Run 
Switch back to schematic of the master project (first tab) and therein to the Schematic 
view (select the appropriate tab at the bottom of the main view). Press the button Home: 
Simulation  Update 
. At first, the EM calculation will be started. Next, the losses will 
be  computed.  Finally,  these  losses  will  be  imported  into  the  thermal  project,  and  the 
thermal calculation will be performed.  
Alternatively, right click on NT: Tasks  Coupled EM-Thermal1 and Update the task.A  progress  bar  will  appear  in  the  progress  window  which will  update  you  on  the  task 
progress.  You  can  activate  this  window  by  selecting  View:  Window    Windows   
Progress  Window.  Information  text  regarding  the  simulation  will  appear  above  the 
progress bar. The most important stages are listed below for the CHT solver: 
1.  Updating tasks: 1of 1: the selected task includes the previously created EM and 
CHT simulation. 
2.  …. the EM simulation is performed….
3.  CHT solver: Surface mesh generation: the solid surfaces are triangulated.  
4.  CHT solver: Octree grid generation: the CFD mesh is constructed by using the 
solid surface triangulations.  
5.  CHT solver: Importing surface/volume losses: the losses from the EM simulation 
are imported and mapped into the CFD mesh.  
6.  CHT solver: Upgrade grid: inactive cells are removed from the CFD mesh.  
7.  CHT solver: Iterations: the simulation is performed. 
Simulation Results  
Once the EM simulation has been completed please leave the schematic and return to 
the  CHT  simulation.  Follow  the  progresses  of  the  CHT  simulation  by  looking  at  the 
convergence  monitors  in  the  NT:  1D  Results   Convergence  monitors   Equation 
residuals and NT: 1D Results  Convergence monitors  Equation balances. 
The simulation completes 80 iterations before stopping. The following dialog box pops 
up  because  the  simulation  has  not  fully  converged  (i.e.  several  convergence  criteria 
have not been met due to the low maximum number of iterations):
To visualize the loss imported from the EM simulation, select NT: 2D/3D Results  Heat 
source densities and a cut plane, for instance X=0. Please note that the losses can only 
be  visualized  on  cut  planes  (check  ribbon  2D/3D  Plot:  Sectional  View   Fields  on 
Plane). Observe that the losses are the highest on the walls of the coaxial feeds and of 
the cylinders. 
Once the simulation has stopped, visualize in the same cut plane the temperature by 
selecting NT: 2D/3D Results  Temperature.The temperature increases are the highest where the losses are also the highest. The 
air in contact with the walls of the filter heats up and carries the heat away which cools 
down the filter. One can observe that the simulation has not converged to a steady-state 
solution in the whole domain because the heat carried by the air flow has not yet reached 
the  top  boundary  of  the  computational  domain.  Still,  the  simulation  has  enough 
progressed to show a correct temperature distribution inside the filter. 
The CHT solver takes into account the air cooling effect by simultaneously calculating 
the  heat  transfer  in  the  fluid  and  solid  domains  and  the  air  flow  caused  by  the 
temperature gradients and gravity. This key feature differentiates the CHT solver from 
the  thermal  solvers  which  do  not  solve for  the  air  flow  and  thus  can  simulate  neither 
natural nor forced convection.
The air flow can be visualized by selecting NT: 2D/3D Results  Velocity 
The velocity vector plot shows the air circulating inside the filter as well as the heated 
air ascending and being replaced by air at ambient temperature. 
Stationary Bi-Directional EM-CHT Link Set-up  
The typical workflow for setting up a stationary bi-directional EM-CHT coupled project is 
almost identical to that for setting up a uni-directional coupled one.  The difference is 
only in the first set-up step which is shown below.  For the demonstration purpose, the 
project “Combline Filter Draft” is adopted here again.  
Start  the  automatic  creation  of  a  coupled  electromagnetic/thermal  computation  by 
selecting  Home:  Simulation    Simulation  Project 
    EM-Thermal  Coupling   
Stationary Bi-directional. The dialog boxes for creating the EM and CHT simulation projects are the same as those 
in setting up the uni-directional coupling:
However, after both the EM and thermal simulation projects are created and before the 
loss import dialog appears, a dialog box which is unique to the bi-directional coupling 
will pop up. It asks for the number of iterations between the EM and the thermal tasks: 
After you input your desired number and press OK, the above dialog box will disappear 
and a loss import dialog will pop up. From now on, the set-up process is identical to the 
previous workflow for uni-directional couplings. 
Note that the bi-directional EM-Thermal coupling is generally used for the cases where 
the  EM  properties  of  material  are  temperature  dependent.    Project  “Combline  Filter 
Draft”  is  adopted  here  just  for  demonstration  of  the  workflow.  The  properties  of  its 
materials are not dependent on temperature.  Special attention also needs to be paid to
the  bi-directional  coupling  between  the  HF  frequency  domain  solver  and  the  thermal 
solvers.    After  both  the  HF  frequency  domain  solver  and  the  CHT  sub-projects  are 
created, “Rebuild simulation projects” in the property of “Sequence” in Schematic view 
should  be  checked  to  ensure  all  frequency  samples  are  re-calculated  by  the  HF
Chapter 3 – Solver Overview 
Solvers and Sources 
Various  simulation  types  differ  in the  definition  of  materials,  boundary  conditions  and 
sources.  The  way  to  define  materials  in  CST  MPhysics  Studio  is  quite  similar  for  all 
solvers, whereas there are larger differences in the definition of sources and boundary 
conditions. For this reason, an overview of the sources, loads and boundaries for each 
solver are explained below. 
Mechanical Solver: 
  Displacement boundary: Simulation: Boundaries  Displacement Boundary 
  Traction boundary: Simulation: Boundaries  Traction Boundary 
  External temperature and/or force distribution: 
Simulation: Sources  Field Import 
Thermal and Conjugate Heat Transfer Solvers: 
  Fixed temperature: Simulation: Sources and Loads  Temperature Source 
  Heat source: Simulation: Sources and Loads  Heat Source 
  Thermal 
from  an  electromagnetic  or  particle 
losses 
simulation:Simulation: Sources and Loads  Thermal Losses 
  Thermal  contact  resistance:  Simulation:  Sources  and  Loads    Contact 
Properties 
  Convection and radiation at surfaces: Simulation: Sources and Loads  Thermal 
 
Surface 
Initial temperature distribution for a transient calculation: 
Simulation: Sources  Field Import 
Conjugate Heat Transfer Solver: 
  Fan: Simulation: Interior Boundaries  Fan 
  Thermoelectric cooler (TEC): Simulation: Sources and Loads  Thermoelectric 
Cooler 
  Heat Pipe: Simulation: Sources and Loads  Heat Pipe 
  Two-resistor  component  model:  Simulation:  Sources  and  Loads    Compact 
Thermal Model  Two-resistor 
  Delphi component model: Simulation: Sources and Loads  Compact Thermal 
Model  Delphi 
  Fluid Domains: Simulation: Interior Boundaries  Fluid Domain 
Interior boundaries: Simulation: Interior Boundaries  Lid 
 
Initial conditions  Initial Temperature on Solid and Initial Condition on Fluid 
 
Domain
 and Opening 
  ECXML: Simulation: Imports  ECXML 
Mechanical Solver 
The mechanical solver is a tetrahedral based solver for structural mechanic problems. 
Its main application is computing deformations driven by thermal expansion and external 
forces.  The  deformation  results  can  be  used  for  a  subsequent  High  Frequency 
Electromagnetic analysis with the tetrahedral based frequency domain solvers from CST 
Microwave Studio.  
Refer to  the  chapter  Simulation Workflow for  a description of  the  basic features. The 
import of temperature and force density distributions is described in the section Workflow 
for Coupled Simulations.
Thermal and Conjugate Heat Transfer Solvers 
CST MPhysics Studio includes a thermal and a conjugate heat transfer (CHT) solver. 
The thermal solver is optimized to simulate thermal conduction in the steady state and 
transient regime  and supports  hexahedral  and  tetrahedral grids. The  CHT solver  is  a 
CFD based heat transfer solver capable of solving thermal conduction, convection and 
radiation simultaneously in the steady state and transient regime. The main applications 
of these solvers include solving steady state or transient temperature problems resulting 
from various types of losses. Both solvers are also well suited to compute standalone 
thermal  problems.  The  following  sub-sections  will  demonstrate  the  most  important 
aspects of a thermal simulation with CST MPhysics Studio. 
Background Material 
The first step for setting up a thermal simulation is to define the units for temperature 
and  dimension,  like  it  has  been  described  in  the  chapter  Simulation  Workflow. 
Afterwards an appropriate background material should be selected. Open the material 
background properties dialog box by selecting Modeling: Materials  Background 
:For thermal problems, the background material is set to Air (thermal conductivity: 0.026 
WK-1m-1,  heat  capacity:  1.005kJK-1kg-1,  density:  1.204  kg/m3  and  dynamic  viscosity: 
1.84e-5  Pa.s  at  normal  conditions).  These  settings  may  be  changed  by  selecting the 
Material  type  (Normal  is  advisable  in  most  cases),  afterwards  opening  the  material 
dialog box by pressing Properties... and select the Thermal property page:
The easiest way to assign the necessary values is to copy the properties from an existing 
material in the material library. Press the Copy Properties from Material… button in the 
General tab, select [Load from Material Library…] in the Copy Properties from Material 
dialog box:Now choose the desired material from the material list. 
Material Properties 
The  material  parameters  for  a  thermal  problem  can  be  defined  inside  the  material 
parameters dialog box: Modeling: Materials  New/Edit  New Material 
. Select the 
Thermal tab.  
It is necessary to specify a thermal conductivity to perform a thermal or conjugate 
heat transfer simulation. In the Thermal tab please specify a thermal conductivity for 
your material in W K-1 m-1 in case a Normal or Anisotropic thermal material Type has 
been selected. If a temperature dependent thermal conductivity, heat capacity and/or 
blood flow coefficient should be taken into account, activate the checkbox Nonlinear and 
define the material curve by entering the corresponding dialog box via Properties…
If you select a PTC (Perfect Thermal Conductor) type, an infinite thermal conductivity is 
assumed. A body with PTC material assigned always has a uniform temperature. 
Please note that the conjugate heat transfer solver replaces PTC with copper. 
For  transient  thermal  problems    and  the  conjugate  heat 
transfer  solver  the  heat  capacity  and  the  material  density  must  be  specified.  These 
parameters determine how much energy per Kelvin is stored in a certain amount of mass 
or volume:Specify the material emissivity when radiation is enabled in a conjugate heat transfer 
simulation. 
The  field  Thermal  expansion  coefficient  is  available  only  if  the  CHT  solver  type  is 
selected. It allows to enter the volumetric coefficient of thermal expansion in [1e-6 / k]. 
The thermal expansion coefficient describes how the volume of a fluid changes with a 
change in temperature and must be set when natural convection is simulated i.e. when 
the gravity is defined and the fluid flow is simulated. If the value is zero the solver applies 
the  ideal  gas  law  to  calculate  the  thermal  expansion  coefficient  as  the  inverse  of  the 
ambient temperature. This law is not valid for liquids therefore it is important to set the 
thermal expansion coefficient when a liquid is simulated and gravity is defined. 
Because  the  thermal  diffusivity  plays  an  important  role  for  the  transient  simulation 
process,  it  is  shown  here  as  well.  The  diffusivity  can  be  calculated  from  the  thermal 
conductivity, the heat capacity and the material density as follows:
, 
where  
: Diffusivity [m² / s] 
k: Thermal conductivity [W / K  /m] 
: Density [kg / m³] 
cP: Specific heat capacity [J / K / kg] 
Nonlinear heat capacity can be used for simulation of material phase change in transient 
computations.  This  can  be  achieved  by  a  local  increase  of  heat  capacity  for  a  small 
interval of temperatures. For more information on simulation of phase changes, please 
refer to the online help. 
For simulations which involve biological materials, heating mechanisms of living tissue 
can be taken into account . In addition, it is possible to 
define a convection coefficient for surface materials of human voxel models (typically: 
skin). 
The  Flow  Resistance  material  parameter  is  only  supported  by  the  conjugate  heat 
transfer solver. It is used to model the fluid flow behavior across a screen without having 
to mesh the screen geometry.  
A flow going through a sheet with a planar flow resistance experiences a pressure drop 
which can be expressed as follows: 
,  
is the dimensionless loss coefficient, 
where
velocity.  
is the sheet local normal and 
 the flow 
A flow going through a volume resistance experiences a pressure gradient which can 
be written as follows: 
, 
where 
is the loss coefficient tensor per unit length and 
is a velocity component in 
the global coordinate system (X,Y,Z).    
The loss coefficient tensor is defined with respect to a local coordinate system (U’,V’,W’) 
and transformed into a 3x3 tensor in the global coordinate system.  
A Flow Resistance assigned to a surface uses the specifications of the sheet properties 
group whereas a Flow Resistance assigned to a solid uses the specifications of the solid
Boundary Conditions 
The  boundary  conditions  for  the  thermal  and  conjugate  heat  transfer  solver  can  be 
defined  in  the  Thermal  Boundaries  tab  of  the  Boundary  Conditions  dialog  box 
(Simulation: Settings  Boundaries 
) 
For Steady State and Transient Thermal Solvers:
For “isothermal” and “open” boundaries the temperature settings may be assigned by 
pressing the corresponding button […]. This button opens the dialog Boundary Settings, 
in which the temperature value can further be configured, for example, by assigning of 
a fixed or floating temperature. By default, the option Unset is selected, which means 
the boundary is considered as a PTC surface without sources assigned. 
For the "open" boundary condition, it is assumed that the temperature approaches the 
predefined value with increasing distance from the structure. Apply this type of boundary 
condition if thermal conduction through the surrounding background material plays an 
important role for your problem. In order to consider thermal convection effects on the 
structure, Thermal surface properties  should be used. 
When  no  heat  flow  leaves  the  computational  domain  through  a  boundary,  use  the 
"adiabatic" boundary condition. In case the conductive heat flow of an open structure 
can be neglected, you can use these boundary conditions instead of “open” boundary 
conditions (if radiation or convection effects dominate).  
The  "isothermal"  boundary  condition  forces  the  temperature  to  be  constant  at  this 
boundary. As a consequence, the tangential component of the heat flow density is forced 
to be zero here.  
The following table shows an overview, where T is the temperature and Q is the heat 
flux density:Isothermal 
Adiabatic 
Open 
Temperature (T) 
T = const (fixed or floating) 
d T / dN = 0 
Lim R→∞ (T) = const (fixed or 
floating) 
Heat Flow (Q) 
Q tangential = 0 
Q normal = 0 
The  picture  below  illustrates  an  example  of  how  thermal  fields  are  influenced  by  the 
different boundary types. It shows a metal sphere at a constant temperature, which is 
surrounded by a material with constant thermal conductivity.
For Conjugate Heat Transfer Solver: 
The conjugate heat transfer solver supports similar types of boundary conditions. It is 
however  important  to  note  that  it  interprets  these  boundary  conditions  differently,  in 
particular for the case of open boundaries.   User input for isothermal walls:  temperature, emissivity and friction (no-slip/slip) at the 
boundary wall. The reference temperature used for radiation is the wall temperature.   
User  input  for  adiabatic  walls:  friction  at  the  boundary  wall  (no  heat  exchange,  zero 
emissivity). 
User  input  for  symmetrical  boundaries:  none  (no  friction,  no  heat  exchange,  zero 
emissivity). 
User  input  for  open  boundaries:  flow  temperature,  flow  velocity  or  flow  gauge 
pressure. An open boundary allows flow to enter and leave the domain, which could be 
used to model the flow and thermal behavior of an inlet or of an outlet specified by a 
pressure gauge or a velocity. If the flow temperature is unknown, which is the case for 
outlets or if the flow direction is unknown set the temperature to unset. 
The emissivity is set to 1. The reference temperature used for radiation is the radiation 
temperature defined in solver parameter dialog.
Imports/Sources and Loads 
The thermal and conjugate heat transfer solvers can handle several types of sources or 
loss mechanisms, which are listed below: 
Temperature Source 
This source is available via Simulation: Sources and Loads  Temperature Source 
. 
This source type can be assigned to a surface of an object with PTC material properties 
or any other material with non-zero thermal conductivity. For the transient thermal solver 
an  initial  temperature  source  can  be  defined,  which  is  taken  into  account  only  for 
generation  of  the  initial  temperature  distribution  and  ignored  during  the  transient 
solution. 
Heat Source 
This source is available via Simulation: Sources and Loads  Heat Source 
When assigned to a solid with a non-zero thermal conductivity source and that is neither 
PTC nor PEC it defines the thermal power evenly released within the solid. The user 
may define the total power released within the solid (Total) or the volume heat density 
(Density).When assigned to a solid that is either PTC or PEC it defines the total heat flow 
coming from the solid surface. Therefore, a heat source with zero heat flow and a 
floating temperature are identical.
Thermal Loss Distribution 
This source is available via Simulation: Imports  Thermal Losses 
. Thermal losses 
can occur inside materials with finite conductivity, on surfaces of good conductors, inside 
dispersive  materials  or  at  materials  where  particles  hit  the  surface.  These  loss 
distributions can be imported and used as thermal sources inside thermally conductive 
materials. If previously calculated loss distributions are present, you can edit setting by 
reopening the dialog box (Simulation: Imports  Thermal Losses 
).It is possible to choose source fields from the same project or from an external project. 
The following table shows a list of loss types and which solver from the CST Studio Suite 
can create these losses.  
Type of loss 
Ohmic  (electric  vol. 
losses) 
Created by 
Transient  Solver  (
Eigenmode Solver (
PIC Solver (
),  Frequency  Domain  Solver  (
), LF-Solver (
), J-Static Solver (
), IR-Drop Solver (
), Wakefield Solver (
Lossy  metal  (surface 
losses) 
Transient  Solver  (
Eigenmode  Solver  (
) 
Wakefield Solver (
),  Frequency  Domain  Solver  (
),  PIC  Solver  (
),  LF-Solver  (
), 
), 
) 
), 
), 
Dispersive 
(electric 
and  magnetic  vol. 
losses) 
Transient Solver (
Solver (
), Wakefield Solver (
) 
), Frequency Domain Solver (
), PIC 
Crashed particles 
Tracking Solver (
), PIC Solver (
)
For further details, refer to the online help. 
Thermal Surface Properties 
Thermal surface properties are available via Simulation: Sources and Loads  Thermal 
Surface 
. 
Thermal  surface  properties  can  be  assigned  to  surfaces  of  thermally  conductive 
materials. A thermal surface property definition describes the radiation and convection 
losses from a surface:The  Emissivity 
radiation capability of the selected surface 
  is  a  dimensionless  constant  between  0  and  1  which  describes  the 
, 
 stands for the radiated power, 
whereas 
for the reference temperature, which can be equal to ambient or user-defined, 
Stefan-Boltzmann  constant  and 
 for the 
  for  the  area  for  the  selected  surfaces.  An 
 for the surface temperature, 
 =  0 means that the surface does not lose thermal power by radiation. 
emissivity value 
A value of 1 means that the thermal power emitted by the surface equals to that of a 
black body at the same temperature. 
The Convective heat transfer coefficient 
fluid and the surface of conductive materials: 
 describes convection processes between a
denotes  the  power, 
where 
reference temperature in the fluid and 
  the  solid  surface  temperature, 
  the 
 the area for the selected surfaces. 
The thermal surface properties dialog includes additional options for the conjugate heat 
transfer solver. The emissivity of the solid defined by the emissivity of its material can 
be overwritten by a surface emissivity for the assigned surface. In addition, the local fluid 
temperature can be used as the reference temperature when convection is prescribed 
by a heat transfer coefficient.Fan (not supported by Thermal solver) 
Fans are available via Simulation: Sources and Loads  Fan 
. They are defined by 
their entry and exit faces. The entry and exit faces must belong to the same lump of the 
same solid. They can be either assigned both to the same surface if the fan is planar or 
translated from each other. Note that a planar (infinitely thin) fan can only be created on 
an outer boundary and can’t be created in the interior domain. A non-planar (thick) fan 
can be created either on the outer boundaries or in the interior domain. 
The fan behavior can be specified as follows:
The fan characteristics (i.e. fan curve, volume flow rate or stagnation pressure) are given 
for a quoted speed. The fan however can be operated at a different speed. The derating 
factor is the ratio of operating speed and quoted speed and is a dimensionless value 
between 0 and 1. If the derating factor is 0.8, the operating speed will be 80% of the 
quoted  speed  and  the  fan  characteristics  and  the  dissipated  heat  will  be  adjusted 
accordingly.  The  flow  temperature  can  be  controlled  either  by  specifying  a  fixed 
temperature or the amount of heat dissipated from the flow going through the fan. 
The fan characteristics are given by a fan curve defined either by one or two or more 
points. If  a fan curve has  only  one point  its type  is  Fixed  Volume  and is  specified  by 
entering  its  volume flow  rate.  If the fan  curve  has  two points  its type  is  Linear  and is 
specified by entering its volume flow rate for zero pressure and its stagnation pressure. 
If the fan curve has more than two points its type is Nonlinear and each point can be 
entered individually by clicking on the Curve button.Thermoelectric Cooler (not supported by Thermal solver) 
. 
Thermoelectric  Coolers  are  available  via  Simulation:  Sources  and  Loads   
Thermoelectric Cooler 
To define a Thermoelectric Cooler (TEC), one cold surface (i.e. the cold side) and one 
hot surface (i.e. the hot side) on the same object need to be selected. The cold side is 
usually in contact with a heat source while the hot side is in contact with a heat sink, i.e. 
heat  is  transferred  from  the  cold  side  to  the  hot  side  of  the  thermoelectric  cooler. 
Currently the cold and hot sides are required to be both planar and parallel to each other. 
In addition, in absence of contact properties between the TEC and its sides, the material 
of the cells touching the same side (hot or cold and without contact property) must be 
the same.  
Heat Pipe (not supported by Thermal solver) 
Heat Pipes are available via Simulation: Sources and Loads  Heat Pipe 
A heat pipe is defined in two steps: In the first step, the shape(s) forming the heat pipe 
must  be  selected.  In  the  second  step,  the  shapes  in  contact  with  the  heat  pipe  are 
selected. The shapes in contact with the heat pipe generally include a heat source and 
a heat sink. After the second step, the properties of the heat pipe can be entered. 
.
Two-resistor component model (not supported by Thermal solver) 
Two-resistor  component  models  are  available  via  Simulation:  Sources  and  Loads  
Compact Thermal Model  Two-resistor 
. 
The two-resistor component model can be used to approximate the thermal behavior of 
single-die packages that can be effectively represented by a single junction temperature. 
The  model  is  based  on  the  block-and-plate  method  described  in  the  Two-Resistor 
Compact Thermal Model Guideline specified in the JEDEC standard JESD15-3. 
The 3D representation of the two-resistor model is shown below:The input parameters of the model are the case node and board node temperatures, 
which are provided by the heat transfer solvers, and the junction node dissipated power 
together with the junction-to-case Rjc and the junction-to-board Rjb thermal resistances 
that must be provided by the user. 
The  output  parameter  of  the  model  is  the  junction  node  temperature.  In  the  3D 
representation, the package represents the junction node thermal resistance whereas 
the  upper  package  and  the  lower  package  surfaces  represent  the  junction-to-case 
thermal  resistance  and  the  junction-to-board  thermal  resistance,  respectively.  The 
package lateral sides are assumed to be insulated (no heat transfer).  
The two-resistor component model has been extended by making it possible to define 
contact properties on the upper package surface. This is useful when a heatsink covers 
the upper surface package. 
Delphi Compact Thermal Model (not supported by Thermal solver) 
. 
Delphi  Compact Thermal  Models  are  available  via  Simulation:  Sources and  Loads  
Compact Thermal Model  Delphi 
The Delphi compact thermal model can be used to approximate the thermal behavior of 
single-die packages that can be effectively represented by a thermal resistance network. 
It is  based  on  the  Delphi  methodology  JESD15-4  described  in  the  Delphi  Compact 
Thermal  Model  Guideline  published  by  the  JEDEC  standard  Committee  on  Thermal 
Characterization. 
The junction node of the Delphi model is an internal node which doesn't interact with the 
package  environment.  The  top  inner,  top  outer,  bottom  inner,  bottom  outer  and  side 
nodes  of  the  Delphi  model  are  called  surface  or  external  nodes  because  they  are 
associated  to  certain  physical  regions  or  patches  located  on  the  package  surface, 
allowing them to interact with the package environment as shown below:
The  top  inner  node  is  associated  to  a  rectangular  and  centered  patch  on  the  upper 
(package) surface. The top outer node is associated to the patch delimited by the edges 
of the top inner node and the edges of the upper surface. 
The bottom inner node is associated to a rectangular and centered patch on the bottom 
surface. The bottom outer node is associated to the patch delimited by the edges of the 
bottom inner node and the edges of the bottom surface. 
The side node is associated to a patch covering partially (in presence of an optional lead 
node) or totally (without a lead node) the four lateral sides of the packages. 
The junction node and other optional internal nodes are not associated to any physical 
region or patch. 
In the IC Packaging tab, the type can be selected, which is "None" by default. 
If "None" is selected, leads or metal alloy balls (area arrays) must be modeled by the 
customer. 
If  the  type  “Peripheral  leaded”  is  selected,  the  leads  will  be  represented  by  blocks 
(associated  to  the  lead  node)  whose  dimensions  are  entered  in  the  section  Model 
Specification: Peripheral Leaded. 
If  the  type  “Area  arrays”  is  selected,  the  area  arrays  will  be  represented  by  blocks 
(associated  to  the  lead  node)  whose  dimensions  are  entered  in  the  section  Model 
Specification: Area Arrays. 
The Network tab is used to define the thermal network of the Delphi model. The network 
is  predefined  and  includes  six  obligatory  node:  Top  inner,  Top  outer,  Side,  Junction, 
Bottom  inner,  Bottom  outer  and  one  optional  lead  node  which  is  present  if  an  IC 
packaging type has been selected. The nodes and their index are shown in the network 
below with their possible connections:The  junction  is  an  internal  node.  Other  internal  nodes  can  be  added  if  necessary  by 
adding additional nodes to the Node / Resistance table.
Note  that  the  thermal  conductivity  and  specific  heat  of  the  shape  used  to  model  the 
package geometry have no influence on the behavior of the Delphi model. 
You can find more detail about Delphi in the online documentation. 
Fluid domains (not supported by Thermal solver) 
A fluid domain 
 is used to define a region/cavity of the computational domain occupied 
by vacuum or by a fluid specified by its material properties. The region must be non-
manifold i.e. all points inside the region must be reachable from any point inside without 
leaving the region. 
To define a fluid domain pick one face of its surface and orient the normal to the picked 
face toward the inside of fluid domain. Ensure that the fluid domain is closed and forms 
a  cavity  by  closing  any  existing  opening  with  either  a  shape  (considered  for 
simulation) or an interior boundary of type Lid 
. 
Interior boundaries (not supported by Thermal solver) 
Interior boundaries of type Lid  and Opening  are used to defined thermal and flow 
sources inside the computational domain. They must be assigned to the surface of a 
shape considered for simulation. 
When the check box Invert flow direction or the Switch fluid side are visible in the Edit 
Lid  or  Edit  Opening  dialog,  the  normal  flow  direction  at  the  selected  face  may  be 
previewed in the 3D main view. Check or uncheck the box to change the arrow direction 
so that it shows the flow direction (Invert flow direction) or that it points toward the fluid
The type lid 
 is used to close fluid domains For instance a lid must be used to close 
the extremities of a water pipe (defined by a fluid domain) surrounded by the background 
air. It is important to note that neither heat nor mass is transferred across a lid from one 
fluid domain to another fluid domain (including background).  
A lid specifies the flow properties of a fluid inside a fluid domain. The following boundary 
types are available: 
Wall: isothermal 
Set a fixed temperature, U tangential (slip/no-slip) and 
the wall emissivity. 
The emissivity is set to the value specified by the user. 
The wall temperature value is used as the reference 
temperature if Radiation is enabled. 
Wall: adiabatic 
Set U tangential (slip/no-slip). 
The wall emissivity is set to zero. 
Open 
Set  the  flow  temperature.  Set  the  flow  velocity, 
volume flow rate or gauge pressure. 
The opening emissivity is set to one. 
The radiation temperature defined in the CHT Solver 
reference 
Parameters  dialog is  used  as 
temperature. 
the 
The type opening 
Therefore, heat and/or mass can be transferred across an opening. 
 is used to prescribe flow properties within the same fluid domain. 
Open 
Set the flow temperature. Set the flow velocity, volume 
flow rate or gauge pressure. 
The opening emissivity is set to one. 
The radiation  temperature  defined  in the  CHT  Solver 
reference 
Parameters  dialog is  used  as 
temperature. 
the
Bioheat Source (not supported by CHT solver) 
As  described  above  it  is  possible  to  assign  biological  properties  to  a  material.  Two 
different heating mechanisms are available: 
The  Bloodflow  coefficient  determines  the  influence  of  blood  at  a  certain  temperature 
TBlood inside the tissue volume V.  
Depending  if  the  current  temperature  value  T  is  higher  or  lower  than  the  blood 
temperature  this  mechanism  cools  or  heats  the  surrounding  material.  The  blood 
temperature value can be edited inside the Specials dialog box of the thermal solvers 
  Specials or Simulation: Solver  Setup Solver 
(Simulation: Solver  Setup Solver 
  Specials). 
An important mechanism of the local thermoregulation in living tissues is an increased 
bloodflow  coefficient  with  rising  temperature  due  to  the  widening  of  blood  vessels 
(vasodilation).  In  order  to  match  clinical  studies,  the  bloodflow  coefficient  is  typically 
assumed to change exponentially with increasing temperature. The parameters of this 
dependency can be set in the Nonlinear Thermal Material Properties dialog, accessible 
through  the  Nonlinear  Properties  button  in the  Thermal  tab  of the  Material  Properties 
dialog. For more information about these parameters please refer to the online help. 
The Basal metabolic rate describes the amount of heat QMetabolic which is produced by 
tissue per volume V. 
Thermal Contact Properties 
Thermal  contact  properties  can  be  defined  via  Simulation:  Sources  and  Loads   
Contact Properties 
. A contact item is equivalent to a thin layer of thermally conductive 
material at the interface between two (or several) solids. It can be characterized either 
by lumped parameters (absolute thermal resistance [K/W] or thermal resistance per unit 
area [K∙m2/W] as well as thermal capacitance [J/K]), or by its thickness and the thermal 
properties  of  material  assigned.  Both  definitions  are  equivalent  and  can  be  easily 
converted into each other:thermal 
resistance 
Absolute 
(K/W): 
Thermal  resistance  per  unit  area 
(K∙m2/W): 
Thermal capacitance (J/K): 
Here Rθ represents the absolute thermal resistance, rθ the thermal resistance per unit 
area,  C  the  thermal  capacitance  of  the  contact  layer.  In  the  material-based 
representation, thermal conductivity k, specific heat capacity cP, material density ρ and 
layer thickness l are used. The contact area A is calculated by the solver. 
The advantage of contact properties definition through lumped parameters is the ease 
and transparency of the parameter values. Besides, the absolute thermal resistance is 
independent from the contact area A which may vary in case of solid intersections or
depending on the mesh settings. On the other hand, the material-based definition offers 
more flexibility, for example it supports nonlinear material properties. 
Thermal contact properties are only supported by tetrahedral-based thermal solvers and 
the conjugate heat transfer solver. 
Initial conditions (not supported by thermal solver) 
By default, at the start of a simulation the initial temperature in the computational domain 
is set to the ambient temperature and the initial flow velocity in the background and in 
the fluid domains is set to zero. 
To  set  a  user-defined  initial  temperature to  a  shape  please  create  a  "New  Initial 
Temperature On Solid..." and drag and drop the shape on it (or drag the initial condition 
on the shape).To set a user-defined initial temperature and velocity
to a fluid domain please create 
a "New Initial Condition on Fluid Domain..." and drag and drop the fluid domain on it (or 
drag the initial condition on the fluid domain).
Moving Media (not supported by CHT solver) 
For  each  solid  containing  a  non-PTC  thermal  conducting  material,  a  moving  media 
velocity vector may be assigned via Simulation: Motion  Moving Media 
.This vector defines the velocity with which the material comprising the solid is moving 
relatively  to the  sources  and solid geometry.  A typical  example would be a  very  long 
tube moving through a coil for the purpose of induction heating. 
If  a  velocity  vector  has  been  assigned  to  any  solid,  the  solver  saves  important 
information about the distribution and maximum of Peclet number in order to control the 
solution quality. 
Only tetrahedral-based thermal solvers support this feature. In the transient solution, the 
moving  media  velocity  vector  may  be  made  time-dependent  by  assigning  Excitation 
Signals to its components. 
You can find more detail about moving media in the online documentation. 
ECXML Import (not supported by Thermal solver) 
The  Electronics  Cooling  XML  format,  better  known  as  ECXML,  is  a  standard  for 
exchanging geometries/features between Electronics Cooling simulation software. The 
standard is defined in JEDEC JEP181. Files can be imported via Simulation: Imports  
ECXML 
. 
You can find more detail about ECXML import in the online documentation. 
Monitors at Points 
The monitors  of this kind  record  scalar  values  that  are  defined at  a  point  (e.g. the  x-
component of the heat current density at a fixed position). You can create these monitors 
via Simulation: Monitors  Monitor at Point 
.
Steady state thermal solver evaluates the temperature values at the monitor points and 
saves  them  as  0D  data  into  the  Navigation  Tree  under  NT:  Thermal  Solver   
Temperature 0D  <monitor name>. Besides, if adaptive mesh refinement is turned on, 
the  tetrahedral-based  steady  state  solver  records  the  temperature  value  after  each 
refinement  step  and  saves  it  under  NT:  Adaptive  Meshing    Temperature  0D   
<monitor name>. 
Transient thermal solver records the temperature values at the monitor points during the 
whole solution time interval. 
Two  additional  types  of  monitor  at  point  are  available  for  the  conjugate  heat  transfer 
solver. The Pressure and Velocity types evaluate, respectively, the pressure and velocity 
at the monitor point at each iteration. 
The conjugate heat transfer solver saves the values of the monitor points as 1D data 
into the Navigation Tree under NT: 1D Results  Monitors at Points  <monitor name>. 
The conjugate heat transfer solver can use the point monitors activated in Simulation: 
Setup solver: Accuracy: Custom stop criteria to detect the convergence of the solver. 
This  monitor  type  is  similar,  although  not  identical,  to  Probes  available  within  CST 
Microwave Studio. 
Monitors on Faces 
The  monitors  of  this  kind  record  scalar  values  defined  on  a  surface.  You  can  create 
these monitors via Simulation: Monitors  Monitor on Faces 
.  
Two types of monitors on face are available. The type flow flux is used to monitor the 
fluid  flow,  consequently  the  monitor  surfaces  must  not  change  the  flow  and  must  be 
borrowed from a dummy solid. A dummy solid is either a solid whose material is exactly 
the  same  as  the  background  material  or  a  solid  not  considered  for  simulation  but 
considered for the bounding box. If necessary, adjust the local mesh properties of the 
dummy solid to match those of the background to avoid unwanted mesh refinements 
around the dummy solid.
The  flow  flux  monitor  calculates  the  mass  flow  rate,  the  energy  flux  and  the  bulk 
temperature through the monitor surfaces, respectively defined as: 
𝑚̇ = ∯ 𝜌𝐮 ∙ 𝐝𝐀 
𝑄̇ = ∯ 𝜌𝐶𝑝𝐮(𝑇 − 𝑇𝑎𝑚𝑏) ∙ 𝐝𝐀 
𝑇𝑏 =
𝑚̇ 𝐶𝑝
∯ 𝜌𝐶𝑝T𝐮 ∙ 𝐝𝐀 
The type solid flux is used to monitor the heat flux and the heat transfer coefficient at 
solid/fluid interfaces, consequently the monitor surfaces must be borrowed from a solid 
considered for simulation and considered for the bounding box and whose material is 
different from the background material: 
𝑃 = ∯ −𝑘 ∙ ∇𝑇 ∙ 𝐝𝐀The  monitors  on  faces  are  evaluated  at  each  iteration  and  the  surface  quantities  are 
saved as 1D data into the Navigation Tree under NT: 1D Results  Monitors on Faces 
 <monitor name>. 
The conjugate heat transfer solver can use the face monitors activated in  Simulation: 
Setup solver: Accuracy: Custom stop criteria to detect the convergence of the solver. 
3D Field Monitors 
In contrast to steady state solvers, field distributions delivered by transient solvers need 
to  be  requested  by  the  user  in  advance  by  defining  Field  Monitors  via  Simulation: 
Monitors  Field Monitor 
. A dialog box opens where the type of the field, the start 
time and the sample step width can be defined:
Three field types are available: Temperature, Heat Flow Density and CEM43. The latter 
monitor represents the distribution of Cumulative Equivalent Minutes at 43°C, which is 
commonly  used  to  detect  the  damage  of  biological  tissues  exposed  to  strong 
electromagnetic fields. After the solver run has been completed, the recorded result can 
be accessed via the 2D/3D Results folder in the Navigation Tree. The scalar or vector 
field can be animated over the defined time period. 
Steady State Thermal Solver Parameters 
After the thermal problem has been defined, the steady state solver dialog box can be 
opened (Simulation: Solver  Setup Solver 
):Before starting the solver, it is advisable to look at the Ambient temperature, which is by 
default the reference temperature for the radiation and convection models as well as for 
the  open  boundary  conditions.  Moreover,  this  temperature  may  be  assigned  to  PTC 
regions without user-defined temperature or heat sources. 
If Bioheat properties must be adjusted, one can open the Specials dialog:
This also applies to the transient thermal solver. For further details, please refer to the 
online help. 
Steady State and Transient Conjugate Heat Transfer Solver Parameters 
The conjugate heat transfer solver allows the simulation of stationary or transient heat 
transfers  between  solids  immersed  in  the  background  or  in  fluid  domains.  Radiation, 
in 
convection  and  conduction  are  simulated  according 
the Physics section below. 
To  simulate  conduction  and  convection,  please  make  sure  that  the  density,  dynamic 
viscosity, thermal specific heat capacity and thermal conductivity are larger than zero. 
To simulate only heat transfer (including conduction in the fluids) but without advection 
in  the  fluids,  please  make  sure  that  the  thermal  conductivity  is  larger  than  zero.  This 
corresponds to the Fluid flow option turned off. 
The  simulation  takes  place  in  vacuum  whenever  the  fluid  material  is  incompletely 
defined, i.e., the dynamic viscosity is set to zero in the general case or when the thermal 
conductivity is set to zero when the Fluid flow option is turned off. 
the  settings  set 
to 
To switch between the steady state and the transient conjugate heat transfer solver it is 
sufficient to change the simulation regime. By default the simulation regime is steady-
state.   
Two different time integration methods are available in the transient regime: 
Fixed 
The time step width is constant during the entire simulation. This type of 
time integration will be robust but more computationally expensive than an 
adaptive time integration. 
Adaptive  The time step width is adapted during the simulation process according to 
the intermediate results and transient profiles. This type of time integration 
should be preferred for most cases.
Excitation Signal Settings 
For some transient thermal simulations, it is necessary to define time domain excitation 
signals to model, for example, time varying heat sources. A new signal can be defined 
via Simulation: Sources and Loads  Signal 
  New Excitation Signal. A dialog box 
opens where a signal type, its parameters and a name can be set. The parameters of the signal depend on the individual signal type and are described in 
the online help. The parameter Ttotal must be set for almost all signal types and defines 
the  size  of  the  definition  interval.  For  time  values  larger  than  Ttotal  the  signal  is,  in 
general, continued by a constant value. It is also possible to import a signal or to create 
a user defined signal or to select a pre-defined signal from the signal database. 
All  defined  signals  are  visible  in  the  Signal  folder  in  the  Navigation  Tree  and  can  be 
displayed by selection in the Navigation Tree:
Transient Thermal Solver Settings 
You  can  switch  between  the  steady  state  and  transient  thermal  solvers  by  selecting 
either 
Home: Simulation  Setup Solver  Thermal Steady State Solver 
Home: Simulation  Setup Solver  Thermal Transient Solver 
. 
 or 
After selecting the transient solver, the solver parameters dialog box can be opened by 
clicking on the icon in the Home or the Simulation ribbon (Simulation: Solver  Setup 
Solver 
). Before starting the transient thermal solver, a valid Simulation duration time 
must be entered:Most source types can be weighted with a previously defined excitation function, when 
pressing the Excitations button:
For each source, a signal can be assigned via a drop down list. The same signal can be 
assigned to several sources. Optionally, an individual time delay 
can be defined for 
each  source.  The  resulting  time  dependent  excitation
is  the  product  of  the  source 
value 
 (e.g. the temperature) and the (possibly shifted) assigned signal
: 
 . 
The  initial  temperature  distribution  can  be  defined  in  the  Select  Start  Temperature 
dialog,  which  can  be  called  by  pressing  the  Start  temperature:  Settings  button.  The 
default  setting  is  to  assign  the  ambient  temperature  everywhere  except  regions  with 
temperature  sources.  Alternatively,  it  is  possible to  assign  the  solution  of  the  steady-
state problem with initial source values as well as import a temperature distribution from 
an external thermal solution.The solver parameters dialog box also allows changing the ambient temperature in the 
currently active unit. Moreover, the accuracy settings are accessible via the  Accuracy 
button  and  can  be  edited  in  case  simulation  speed  or  accuracy  is  not  sufficient.  For 
further details, please refer to the online help. 
Result Types 
After  a  steady  state  thermal  simulation  run  has  been  completed  successfully,  new 
result entries appear in the navigation tree:
The directory 1D Results contains the convergence curve, heat flow values for the heat 
sources as well as power scaling values for imported fields. 
In the directory 2D/3D Results, beside the scalar temperature field the heat flow density 
can be seen, which is a vector field showing the heat flow inside thermally conductive 
materials. Moreover, a text file is written where the total heat flow for every source is 
listed.  In  case  field  losses  were  imported,  further  information  like  interpolated  loss 
distributions as well as the scaling factor is presented. 
The transient thermal solver creates a different output in the navigation tree: 
Temperature & total Heat Flow on PTC based 
sources vs. time are recorded automatically. 
Monitor at Point: field values vs. time at one 
point. 
1D solver statistics: created automatically 
by the transient thermal solver. 
3D results from previously defined 
time domain monitors and 
automatically created start 
distributions.If time domain temperature monitors have been defined for the transient thermal solver, 
the associated results will be listed under 2D/3D Results as well. In addition, a couple 
of time signals are added to the 1D Results section: 
  ThermalTD / Energy describes the total amount of energy in the computation 
domain vs. time. 
  ThermalTD  /  Timesteps  carries  information  about  the  time-step-width  vs. 
computation step of the adaptive time-stepping scheme. 
  ThermalTD / Timescale shows how the simulated time evolves vs. computation 
steps. 
  ThermalTD  /  Power  shows  the  total  amount  of  power  entering/leaving  the 
thermal conductive regions. 
These 1D signals can be updated during the simulation process by selecting the tree 
item and pressing 1D Plot: Plot Properties  Update Results 
 or the F5 key. 
The conjugate heat transfer solver produces the following results
The  1D  Results  contain  solution  convergence,  point  and  face  monitors  as  well  as 
performance data, plotted against iterations to give user insights into convergence and 
solutions. 
The  2D/3D  results  contain  velocity,  temperature,  pressure  and  heat  source  densities 
data, which can be updated during the iteration process using Plot Properties  Update 
Results
Chapter 4 – Finding Further Information 
After carefully reading this manual, you will already have some idea of how to use CST 
MPhysics Studio efficiently for your own problems. However, when you are creating your 
own  first  models,  some  questions  may  arise.  In  this  chapter,  we  give  you  a  short 
overview of the available additional documentation. 
The Quick Start Guide 
The main task of the Quick Start Guide (not available for Conjugate Heat Transfer solver) 
is  to  remind  you  to  complete  all  necessary  steps  in  order  to  perform  a  simulation 
successfully. Especially for new users – or for those rarely using the software – it may 
be helpful to have some assistance. 
The QuickStart Guide is opened automatically on each project start if the checkbox File: 
Options   Preferences  Open  QuickStart  Guide  is  checked.  Alternatively,  you  may 
start this assistant at any time by selecting QuickStart Guide from the Help button 
 in 
the upper right corner. 
When  the  QuickStart  Guide  is  launched,  a  dialog  box  opens  showing  a  list  of  tasks, 
where  each  item  represents  a  step  in  the  model  definition  and  simulation  process. 
Usually, a project template will already set the problem type and initialize some basic 
settings like units and background properties. Otherwise, the QuickStart Guide will first 
open a dialog box in which you can specify the type of calculation you wish to analyze 
and proceed with the Next button:As  soon  as  you  have  successfully  completed  a  step,  the  corresponding  item  will  be 
checked and the next necessary step will be highlighted. You may, however, change 
any of your previous settings throughout the procedure. 
In order to access information about the QuickStart Guide itself, click the Help button. 
To obtain more information about a particular operation, click on the appropriate item in 
the QuickStart Guide. 
Online Documentation 
The online help system is the primary source of information. You can access the help 
system’s overview page at any time by choosing File: Help  Help Contents 
. The 
online help system includes a powerful full text search engine. 
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is  active.  For  instance, by  pressing  the  F1 key while a  basic 
shape generation mode is active, you can get information about the definition of shapes 
and possible actions.
When  no  specific  information  is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system. 
Please  refer  to  the  CST  Studio  Suite  Getting  Started  manual  to  find  more  detailed 
explanations about the usage of the CST MPhysics Studio Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A  syntax  reference  of  the Visual  Basic for  Applications (VBA)  compatible macro 
language.  
  Some documented macro examples. 
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software described in this document is furnished under a license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a 
retrieval system, or transmitted in any form or any means electronic 
or mechanical, including photocopying and recording, for any 
purpose other than the purchaser’s personal use without the written 
permission of Dassault Systèmes. 
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CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
STUDIO,  CST  EMC  STUDIO,  CST  MICROWAVE  STUDIO,  CST 
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DS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries.3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome  to  CST  Studio  Suite®,  the  powerful  and  easy-to-use  electromagnetic  field 
simulation software. This program combines a user-friendly interface with unsurpassed 
simulation performance. CST Studio Suite contains a large variety of solvers for carrying 
out  High  Frequency  Simulations.  They  are  all  grouped  as  a  specific  High  Frequency 
Module, also known as CST Microwave Studio®. 
Please  refer  to  the  CST  Studio  Suite  -  Getting  Started  manual  first.  The  following 
explanations  assume  that  you  have  already  installed  the  software  and  familiarized 
yourself with the basic concepts of the user interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite - Getting Started manual. 
2.  Work  through  this  document  carefully.  It  provides  all  the  basic  information 
necessary to understand the advanced documentation. 
3.  Look at the examples provided in the Component Library (File: Component Library 
  Examples).  Especially  the  examples  which  are  tagged  as  Tutorial  provide 
detailed information of a specific simulation workflow. Press the Help 
 button of 
the individual component to get to the help page of this component. Please note 
that all these examples are designed to give you a basic insight into a particular 
application domain. Real-world applications are typically much more complex and 
harder to understand if you are not familiar with the basic concepts. 
4.  Start with your own first example. Choose a reasonably simple example, which will 
allow you to quickly become familiar with the software. 
5.  After  you  have  worked  through  your  first  example,  contact  technical  support  for 
hints  on  possible  improvements  to  achieve  even  more  efficient  usage  of  the 
software. 
CST Studio Suite for High Frequency Simulation 
CST Studio Suite for High Frequency Simulation is a fully featured software package for 
electromagnetic  analysis  and  design  in  the  high  frequency  range.  It  simplifies  the 
process of creating the structure by providing a powerful graphical solid modeling front 
end which is based on the ACIS modeling kernel. After the model has been constructed, 
a fully automatic meshing procedure is applied before a simulation engine is started. An 
advanced  visualization  engine  and  flexible  post-processing  allow  you  to  analyze  and 
improve your design in a relevant and efficient way. 
A key feature of CST Studio Suite is the Complete Technology approach which gives 
the  choice  of  simulator  or  mesh  type  that  is  best  suited  to  a  particular  problem, 
seamlessly integrated into one user interface. 
Since  no  one  method  works  equally  well  for  all  applications,  the  software  contains 
several different simulation techniques (time domain solvers, frequency domain solvers, 
integral equation solver, multilayer solver, asymptotic solver, and eigenmode solver) to 
best suit various applications. 
Each  method  in turn  supports meshing types  best suited for  its  simulation  technique.  
Hexahedral  meshes  are  available  in  combination  either  with  the  Perfect  Boundary 
Approximation  (PBA)®  feature,  and  for  some  solvers  additionally  with  the  Thin  Sheet 
Technique (TST)™ extension, or with a powerful octree‐based meshing algorithm which
increases  the  accuracy  of  the  simulation  substantially  in  comparison  to  simulation 
techniques, which employ a conventional hexahedral mesh. 
In addition to the hexahedral mesh, the frequency domain and eigenmode solvers also 
support linear and curved tetrahedral meshes. Furthermore, linear and curved surface 
and  multilayer  meshes  are  available  for  the  integral  equation  and  multilayer  solver, 
respectively. 
The largest simulation flexibility is offered by the time domain solvers, which can obtain 
the  entire  broadband  frequency  behavior  of  the  simulated  device  from  a  single 
calculation  run.  These  solvers  are  remarkably  efficient  for  many  high  frequency 
applications  such  as  connectors,  transmission  lines,  waveguide  components,  and 
antennas, amongst others. 
Two time domain solvers are available, both using a hexahedral mesh, either based on 
the Finite Integration Technique (FIT) or on the Transmission‐Line Matrix (TLM) method. 
The latter is especially well suited to EMC/EMI/E3 applications. 
The time domain solvers are less efficient for structures that are electrically much smaller 
than the shortest wavelength of interest. In such cases, it may be advantageous to solve 
the problem by using the frequency domain solver. The frequency domain solver may 
also be the method of choice for narrow band problems such as filters, or when the use 
of an unstructured tetrahedral mesh is advantageous to resolve very small geometric 
details.  Besides  the  general  purpose  broadband  frequency  sweep,  the  frequency 
domain solver also contains alternatives using fast reduced order model techniques to 
efficiently  generate  broadband  results.  The  frequency  domain  solver  supports 
hexahedral as well as tetrahedral meshes. 
For electrically large structures, volumetric discretization methods generally suffer from 
dispersion  effects  and  thus  require  a  very  fine  mesh.  CST  Studio  Suite  therefore 
contains an integral equation based solver, which is particularly suited to solving this 
kind of problem. The integral equation solver uses a curved triangular and quadrilateral 
surface  mesh,  which  becomes  very  efficient  for  electrically  large  structures.  The 
Multilevel  Fast  Multipole  Method  (MLFMM)  solver  technology  ensures  an  excellent 
scaling of solver time and memory requirements with increasing frequency. For lower 
frequencies where the MLFMM is not as efficient, direct and iterative Method of Moments 
solvers are available. 
The  systematic  design  of  antennas  of  different  shapes  can  be  greatly  facilitated  by 
means of  a characteristic  mode analysis  (CMA)  by  providing  physical  insight  into the 
behavior of a conducting surface. The CMA-tool, which is built into the integral equation 
solver  and  the  multilayer  solver,  automates  the  process  of  calculating  and  analyzing 
such characteristic modes. 
Despite  its  excellent  scalability,  even  the  MLFMM  solver  may  become  inefficient  for 
electrically  extremely  large  structures.  Such  very  high  frequency  problems  are  best 
solved in CST Studio Suite by using the asymptotic solver, which is based on the so-
called ray-tracing technique. 
For structures which are mainly planar, such as microstrip filters or printed circuit boards, 
this  particular  property  can  be  exploited  in  order  to  gain  efficiency.  The  multilayer 
solver,  based  on  the  Method  of  Moments,  does  not  require  discretization  of  the 
transversally  infinite  dielectric  and  metal  stackup.  Therefore,  the  solver  can  be  more 
efficient than general purpose 3D solvers for this specific type of application. Moreover,
Efficient filter design often requires the direct calculation of the operating modes in the 
filter rather than an S-parameter simulation. For these applications, CST Studio Suite 
also  features  an  eigenmode  solver,  available  either  on  hexahedral  or  tetrahedral 
meshes, which efficiently calculates a finite number of modes in closed electromagnetic 
devices. 
If you are unsure which solver best suits your needs, please contact your local sales 
office for further assistance. 
Each solver’s simulation results can be visualized with a variety of different options. A 
strongly interactive interface will help you to quickly achieve the desired insight into your 
device. 
The last – but certainly not least – of the outstanding features is the full parameterization 
of  the  structure  modeler,  which  enables  the  use  of  variables  in  the  definition  of  all 
geometric and material properties of your component. In combination with the built-in 
optimizer and parameter sweep tools, CST Studio Suite is capable of both the analysis 
and design of electromagnetic devices. 
Who Uses CST Studio Suite for High Frequency Simulation? 
Anyone  who  has  to  deal  with  electromagnetic  problems  in  the  high  frequency  range 
should  use  CST  Studio  Suite.  The  program  is  especially  suited  to  the  fast,  efficient 
analysis  and design of  components  like  single  and  multi-element  antennas (including 
phased arrays), filters, transmission lines, couplers, connectors (single and multiple pin), 
printed circuit boards, resonators, optical devices, and many more. Due to the various 
independent solver strategies, CST Studio Suite can solve virtually any high frequency 
field problem.  
Key Features for High Frequency Simulation 
The following list gives you an overview of the main features of CST Studio Suite for 
High Frequency Simulations. Note that not all of these features may be available to you 
because of license restrictions. Please contact a sales office for more information. 
General 
  Native  graphical  user  interface  for  Windows  10,  Windows  Server  2016/2019, 
Windows 11 and Windows Server 2022 
  The structure can be viewed either as a 3D model or as a schematic. The latter 
allows for easy coupling of EM simulation with circuit simulation.  
  Various independent solver strategies (based on hexahedral as well as tetrahedral 
meshes)  allow  accurate  results  with  a  high  performance  for  all  kinds  of  high 
frequency applications 
  For  specific  solvers,  highly  advanced  numerical  techniques  offer  features  like 
Perfect  Boundary  Approximation  (PBA),  Thin  Sheet  Technique  (TST)  or  octree‐
based  meshing  for  hexahedral  grids  and  curved  and  higher  order  elements  for 
tetrahedral meshes 
Structure Modeling 
  Advanced ACIS-based, parametric solid modeling front end with excellent structure 
visualization  
  Feature-based hybrid modeler allows quick structural changes 
  Import  of  3D  CAD  data  from  ACIS®  SAT/SAB,  CATIA®,  SOLIDWORKS®, 
Autodesk Inventor, IGES, VDA-FS, STEP, PTC Creo, Siemens NX, JT, Parasolid, 
Solid Edge, CoventorWare, Mecadtron, NASTRAN, STL or OBJ files
  Import of EDA data from design flows including Cadence Allegro® / APD® / 
SiP®, Mentor Graphics HyperLynx®, Zuken CR-5000® / CR-8000®, IPC-2581 
and ODB++® (e.g. Altium Designer, Mentor Graphics Expedition / PADS / 
Boardstation®, CADSTAR®, Visula®) 
  Import  of  OpenAccess  and  GDSII-based  integrated-circuit  layouts  via  CST  Chip 
Interface 
  Import of PCB designs originating from CST PCB STUDIO® 
  Import of 2D and 3D sub models 
  Import  of  Sonnet®  EM  models,  Cadence®,  AWR®,  Microwave  Office®  and 
Keysight Technologies ADS® layouts 
  Import of a visible human model dataset or other voxel datasets 
  Export of CAD data to ACIS SAT/SAB, IGES, STEP, NASTRAN, STL, DXF, GDSII, 
Gerber or POV files 
  Parameterization for imported CAD files by using local modifications 
  Material database 
  Structure templates for simplified problem setup 
Transient Solver 
  Fast and memory efficient Finite Integration Technique (FIT) 
  Efficient calculation for loss-free and lossy structures 
  Direct time‐domain analysis and broadband calculation of S-parameters from one 
single calculation run by applying DFTs to time signals 
  Possibility to suppress the disk storage of time signals 
  Calculation  of  field  distributions  as  a  function  of  time  or  at  multiple  selected 
frequencies from one simulation run  
  Solver  stop  criteria  based  on  S-parameters,  radiated  power,  probe  results  and 
voltage / current monitors, also for limited frequency ranges 
  Adaptive mesh refinement in 3D using S-Parameter or 0D results as stop criteria 
  Shared  memory  parallelization  of  the  transient  solver  run  and  of  the  matrix 
calculator 
  MPI Cluster parallelization via domain decomposition 
  Support of hardware acceleration (selected NVIDIA and AMD GPUs) 
  Combined simulation with MPI and hardware acceleration 
  Support of Linux batch mode and batch queuing systems (e.g. Slurm, PBS Pro, 
LSF, SGE) including native shell support   
  Support of more than 2 billion mesh cells (with MPI) 
  Isotropic and anisotropic material properties 
  Frequency dependent material properties with arbitrary order for permittivity and 
permeability as well as a material parameter fitting functionality 
  Gyrotropic  materials  (magnetized  ferrites)  as  well  as  field-dependent  microwave 
plasma 
  Non-linear material models (Kerr, Raman) 
  Spatially varying material models (general or with specialized radial dependency) 
with optional dispersive behavior and 3D material monitors 
  Surface  impedance  models  (tabulated  surface  impedance,  Ohmic  sheet,  lossy 
metal, corrugated wall, material coating, metal surface roughness) 
  Frequency dependent thin panel materials defined based on a multilayered stackup 
or an S-Matrix table (isotropic and symmetric) 
  Special perforation materials like wire mesh and air ventilation panels (isotropic) 
  Time dependent conductive materials (volumetric or lossy metal type) 
  Temperature dependent materials with coupling to the Thermal or CHT solver from
  Port mode calculation by a 2D eigenmode solver in the frequency domain  
  Selective calculation of higher order port modes 
  Automatic  waveguide  port  mesh  adaptation  with  optional  result  re-usage  of 
identical ports 
  Multipin and single-ended ports for (Q)TEM mode ports with multiple conductors 
  Broadband treatment of inhomogeneous ports 
  Multiport and multimode excitation (sequentially or simultaneously) 
  PEC or PMC shielding functionality for waveguide ports 
  Plane wave excitation (linear and broadband circular or elliptical polarization) 
  Excitation by external nearfield sources imported from CST Studio Suite or Sigrity® 
tools or NFS nearfield scan data. 
  Online TDR analysis with Gaussian or rectangular shape excitation function 
  User defined excitation signals and signal database 
  Simultaneous  port  excitation  with  different  excitation  signals  for  each  port  and 
broadband phase shift 
  Single port excitation with user definable amplitude and phase setting 
  Transient EM/circuit co-simulation with network elements 
  AC radiation or irradiation cable co-simulation  
  Transient radiation, irradiation or bi-directional cable co-simulation 
  S-parameter symmetry option to decrease solve time for many structures 
  Auto-regressive filtering for efficient treatment of strongly resonating structures 
  Re-normalization of S-parameters for specified port impedances  
  Phase de-embedding of S-parameters 
  Inhomogeneous  port  accuracy  enhancement  for  highly  accurate  S-parameter 
results, considering also low loss dielectrics 
  Single-ended S-parameter calculation 
  Possibility to use waveguide ports as mode monitors only 
  S-parameter sensitivity and yield analysis 
  Combined linear and logarithmic sampling of 1D spectral results 
  High performance radiating/absorbing boundary conditions 
  Conducting wall boundary conditions  
  Periodic boundary conditions without phase shift 
  Calculation of various electromagnetic quantities such as electric fields, magnetic 
fields,  surface  currents,  power  flows,  current  densities,  power  loss  densities, 
electric energy densities, magnetic energy densities, voltages or currents in time 
and frequency domain 
  1D power loss results (time and frequency domain) per material or solid 
  Calculation of time averaged power loss volume monitors 
  Antenna farfield calculation (including gain, beam direction, side lobe suppression, 
etc.) with and without farfield approximation at multiple selected frequencies 
  Broadband  farfield  monitors  and  farfield  probes  to  determine  broadband  farfield 
information over a wide angular range or at certain angles  
  Antenna array farfield calculation 
  Radar Cross Section (RCS) calculation  
  Calculation of Specific Absorption Rate (SAR) distributions  
  Export of field source monitors, which then may be used as excitation for other high 
frequency solvers inside CST Studio Suite 
  Discrete edge and face elements (lumped resistors) as ports 
  Ideal voltage and current sources for EMC problems 
  Discrete  edge  and  face  R,  L,  C,  and  (nonlinear)  diode  lumped  elements  at  any
  General lumped element circuit import from SPICE or Touchstone files 
  Visualization of discretized wire endpoint connectivity 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Uni-  and  bi-directionally  coupled  simulations  from  CST  Studio  Suite  with  the 
Thermal or CHT solver 
  Coupled simulations from CST Studio Suite with Abaqus’ thermal solver 
  Network distributed computing for optimizations, parameter sweeps and multiple 
port/mode excitations 
TLM Solver 
  Time domain Transmission‐Line Matrix (TLM) method with octree-based meshing 
  Efficient calculation for loss-free and lossy structures 
  Direct time‐domain analysis and broadband calculation of S-parameters from one 
single calculation run by applying DFTs to time signals 
  Applicable  to  EMC/EMI  applications  such  as  radiated  and  conducted  emissions 
and  immunity,  EMP  and  lightning,  electrostatic  discharge  (ESD),  high  speed 
interference and shielding analysis 
  Solver  stop  criteria  based  on  S-parameters,  radiated  power,  probe  results  and 
voltage / current monitors, also for limited frequency ranges 
  Support of GPU acceleration 
  Isotropic and anisotropic materials (including materials with axes not aligned to the 
mesh) 
  Frequency dependent material properties with arbitrary order for permittivity and 
permeability as well as a material parameter fitting functionality 
  Gyrotropic materials with homogeneous biasing field  
  Frequency dependent thin panel materials defined based on a multilayered stackup 
or an S-Matrix table 
  Special perforation materials like wire mesh and air ventilation panels 
  User defined excitation signals and signal database 
  Simultaneous  port  excitation  with  different  excitation  signals  for  each  port  and 
broadband phase shift 
  Transient EM/circuit co-simulation with network elements 
  AC radiation or irradiation cable co-simulation 
  Transient radiation, irradiation or bi-directional cable co-simulation 
  Excitation by external nearfield sources imported from CST Studio Suite or Sigrity® 
tools or NFS nearfield scan data. 
  Compact models which avoid excessively fine meshes for: 
  slots, seams and gaskets 
  multi‐conductor wires 
  conductive coatings and absorbers 
  Broadband compact antenna radiation sources based on the Equivalence Principle 
  Calculation of various electromagnetic quantities such as electric fields, magnetic 
fields,  surface  currents,  power  flows,  current  densities,  power  loss  densities, 
electric energy densities, magnetic energy densities, voltages or currents in time 
and frequency domain 
  1D power loss results (time and frequency domain) per material or solid 
  Calculation of time averaged power loss monitors
  Broadband  farfield  monitors  and  farfield  probes  to  determine  broadband  farfield 
information over a wide angular range or at certain angles  
  Radar Cross Section (RCS) calculation  
  Calculation of Specific Absorption Rate (SAR) distributions  
  Export of field source monitors, which then may be used as excitation for other high 
frequency solvers inside CST Studio Suite 
  Cylinder scan for emissions analysis yielding peak radiated fields vs. frequency 
  Discrete edge or face elements (lumped resistors) as ports 
  Ideal voltage and current sources for EMC problems 
  Lumped R, L, C elements at any location in the structure 
  Visualization of discretized wire endpoint connectivity 
Frequency Domain Solver 
  Efficient calculation for loss-free and lossy structures 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Adaptive mesh refinement in 3D using various stopping criteria: S-parameters or 
probe results at multiple frequency points, broadband S-parameters, as well as 0D 
and 1D result templates  
  Special mesh refinement for singular edges 
  True Geometry Adaptation 
  Option to maintain the tetrahedral mesh during optimization and parameter sweep 
with small geometric changes 
  Fast broadband adaptive frequency sweep for S-parameters and field probes 
  Equidistant,  logarithmic,  log-linear  and  user  defined  frequency  sweeps  and 
evaluation for 1D results 
  Continuation of the solver run with additional frequency samples 
  Low frequency stabilization 
  Direct and iterative matrix solvers with convergence acceleration techniques 
  Higher order representation of the fields, with either constant or variable order (with 
tetrahedral mesh) 
  Support of Linux batch mode and batch queuing systems (e.g. OGE, LSF) 
  Isotropic and anisotropic material properties 
  Arbitrary  frequency  dependent  material  properties  (general  purpose  sweep  with 
tetrahedral mesh) 
  Surface  impedance  model  for  good  conductors,  Ohmic  sheets  and  corrugated 
walls,  as  well  as  frequency-dependent,  tabulated  surface  impedance  data  and 
coated materials (with tetrahedral mesh) 
  Frequency dependent thin panel materials defined based on a multilayered stackup 
or  an  S-Matrix  table (isotropic  and  symmetric, for  simple  surface topologies  and 
junctions, general purpose sweep with tetrahedral mesh only) 
  Inhomogeneously biased ferrites with a static biasing field (general purpose sweep 
with tetrahedral mesh), based on SAM (System and Assembly Modeling) 
  Temperature dependent materials with coupling to the Thermal or CHT solver 
from CST Studio Suite 
  Uni- and bi-directionally coupled simulations with the Thermal or CHT solver from 
CST Studio Suite 
  Coupled simulations with the Stress Solver from CST Studio Suite 
  Port mode calculation by a 2D eigenmode solver in the frequency domain 
  Automatic waveguide port mesh adaptation (with tetrahedral mesh) 
  Multipin ports for TEM modes in ports with multiple conductors 
  Simultaneous  excitation  with  individual  amplitude  and  phase  shift  settings  for
  PEC or PMC shielding functionality for waveguide ports 
  Plane wave excitation with linear, circular or elliptical polarization (with tetrahedral 
mesh), as well as plane waves in layered dielectrics (general purpose sweep) 
  Discrete edge and face elements (lumped resistors) as ports (face elements with 
tetrahedral mesh, numerical face port solver for arbitrary shaped geometries with 
general purpose sweep) 
  Ideal current source for EMC problems (general purpose sweep with tetrahedral 
mesh) 
  Nearfield  source  imprint  on  open  boundaries,  lossy  metal,  and  Ohmic  sheets 
(general purpose sweep with tetrahedral mesh) 
  Lumped R, L, C elements at any location in the structure 
  Arbitrary shaped lumped elements (general purpose sweep with tetrahedral mesh) 
  General lumped element circuit import from SPICE and Touchstone files (general 
purpose sweep with tetrahedral mesh) 
  Re-normalization of S-parameters for specified port impedances  
  Phase de-embedding of S-parameters 
  Single-ended S-parameter calculation, with native single-ended field monitors for 
tetrahedral mesh 
  S-parameter sensitivity and yield analysis (with tetrahedral mesh) 
  High performance radiating/absorbing boundary conditions 
  Conducting wall boundary conditions (with tetrahedral mesh) 
  Periodic boundary conditions including phase shift or scan angle 
  Unit cell feature to simplify the simulation of periodic antenna arrays or of frequency 
selective surfaces (general purpose sweep) 
  Convenient generation of the unit cell calculation domain from arbitrary structures 
(with tetrahedral mesh) 
  Floquet mode ports (periodic waveguide ports) 
  Fast farfield calculation based on the Floquet port aperture fields (general purpose 
sweep with tetrahedral mesh) 
  Calculation of various electromagnetic quantities such as electric fields, magnetic 
fields,  surface  currents,  power  flows,  current  densities,  surface  and  volumetric 
power loss densities, electric energy densities, magnetic energy densities 
  Antenna farfield and farfield probe calculation (including gain, beam direction, side 
lobe suppression, etc.) with and without farfield approximation 
  Antenna array farfield calculation 
  RCS calculation (with tetrahedral mesh) 
  Calculation of SAR distributions (with hexahedral mesh) 
  Export of field source monitors (with tetrahedral mesh), which then may be used 
as excitation for other high frequency solvers inside CST Studio Suite 
  Export  of  fields  for  corona  discharge  and  multipactor  analysis  with  Spark3D 
(tetrahedral mesh only) 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps 
  Network distributed computing for frequency samples and remote calculation  
  MPI Cluster parallelization via domain decomposition (general purpose sweep with 
tetrahedral mesh) 
  Option  to  define  repetitions  of  domains  with  the  domain  decomposition  solver,
  Besides  the  general  purpose  frequency  sweep,  a  fast  reduced  order  model 
technique,  specifically  designed for the  efficient calculation of  broadband  results 
such as S-parameters, field probes and far-field probes, is available. 
Integral Equation Solver 
  RCS calculation 
  Fast monostatic RCS sweep 
  Characteristic Mode Analysis (including modal weighting coefficient calculation)  
  Broadband calculation of S-parameters also for near- and farfield excitations 
  Calculation of various electromagnetic quantities such as electric fields, magnetic 
fields, surface currents 
  Antenna farfield calculation (including gain, beam direction, side lobe suppression, 
etc.)  
  Supports antenna coupling workflow 
  Export of field source monitors, which then may be used as excitation for other high 
frequency solvers inside CST Studio Suite 
  Calculation of radiation/scattering per solid 
  Waveguide port excitation 
  Plane wave excitation 
  Nearfield source excitation 
  Farfield source excitation  
  Farfield source excitation with multipole coefficient calculation 
  Receiving farfield source and nearfield source excitation 
  Current distribution 
  Discrete edge and face port excitation 
  Face lumped R, L, C elements 
  Symmetries are supported for discrete ports, waveguide ports, plane wave, farfield 
and nearfield excitations. 
  MPI parallelization for MLFMM and direct solver 
  Support of GPU acceleration for MLFMM and direct solver 
  Support of combined MPI & GPU acceleration 
  Support of Linux batch mode and batch queuing systems (e.g. OGE, LSF) 
  Infinite electric and magnetic ground planes 
  Infinite Real Ground option 
  Multithread parallelization 
  Efficient  calculation  of  loss-free  and  lossy  structures  including  lossy  waveguide 
ports 
  Surface mesh discretization (triangles and quadrilaterals) 
  Wire mesh discretization with special junction meshing strategy 
  Support of Curved Mesh (quadrilateral and triangular surface mesh elements) 
  Handling of layered media, which enables simulation of windshield antennas etc. 
  Support of isotropic and layered thin-panel, which enables simulation of radomes, 
etc. 
  Support S-Parameter definition for thin panel material 
  Isotropic material properties 
  Coated materials 
  Arbitrary frequency dependent material properties 
  Surface  impedance  models  (tabulated  surface  impedance,  Ohmic  sheet,  lossy 
metal) 
  Automatic fast broadband adaptive frequency sweep 
  User defined frequency sweeps 
  Low frequency stabilization
  Higher order representation of the fields including mixed order 
  Single and double precision floating-point representation 
  Port mode calculation by a 2D eigenmode solver in the frequency domain 
  Automatic waveguide port mesh adaptation 
  Simultaneous  excitation  with  individual  amplitude  and  phase  shift  settings  for 
selected excitations 
  Re-normalization of S-parameters for specified port impedances  
  Phase de-embedding of S-parameters 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps  
  Network distributed computing for frequency sweeps 
  Fast farfield and radiated power calculation for direct and ACA solver 
  Abort solver run with “Keep results” option 
  Pause solver option with releasing license 
Multilayer Solver 
  Broadband calculation of S-parameters  
  Calculation of various electromagnetic quantities such as electric fields, magnetic 
fields, surface currents 
  Waveguide (multipin) port excitation 
  Discrete face port excitation 
  Plane wave excitation 
  Characteristic Mode Analysis (including modal weighting coefficient calculation) 
  Face lumped R, L, C elements 
  Multithread parallelization 
  MPI parallelization for the direct solver 
  Efficient calculation of loss-free and lossy structures 
  Surface mesh discretization (curved triangles and quadrilaterals) 
  Support of Curved Mesh (quadrilateral and triangular surface mesh elements) 
  Automatic edge mesh refinement is available for finite-thickness and infinitely thinconductors 
  Isotropic material properties 
  Arbitrary frequency dependent material properties 
  Automatic fast broadband adaptive frequency sweep 
  User defined frequency sweeps 
  Re-normalization of S-parameters for specified port impedances  
  Phase de-embedding of S-parameters 
  Simultaneous  excitation  with  individual  amplitude  and  phase  shift  settings  for 
selected excitations 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps  
  Network distributed computing for frequency sweeps 
Asymptotic Solver 
  Specialized tool for fast monostatic and bistatic RCS sweeps and antenna farfield 
calculations 
  Fast ray tracing technique including multiple reflections and edge diffraction (SBR) 
by using either independent rays or ray-tubes
  Supports antenna coupling workflow 
  Channel propagation simulation 
  Field of view analysis 
  Multiple plane wave excitations with different polarization types 
  Farfield source excitation 
  Nearfield source excitation 
  Receiving farfield source and nearfield source excitation 
  Robust surface mesh discretization including curved meshes 
  PEC and vacuum material properties 
  Complex surface impedance materials 
  Coated materials (incl. frequency dependent and angle dependent properties) 
  Thin dielectrics (incl. frequency dependent and angle dependent properties) 
  Solid lossless dielectrics 
  User defined frequency sweeps and angular sweeps 
  Visualization of rays and their amplitudes, including multiple reflections 
  Visualization of points where the rays initially hit the structure 
  Computation of range profiles, sinograms, and ISAR-images 
  Computation of scattering hotspots 
  Computation of RCS maps 
  Calculation of electric and magnetic fields 
  Export of field source monitors, which then may be used as excitation for other high 
frequency solvers inside CST Studio Suite 
  Export of farfield result data as tab-separated values 
  Export of ray path quantities as HDF5 files 
  Multithread parallelization 
  Support of GPU acceleration for field sources and bistatic calculations 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps  
  Network distributed computing for excitation angles 
  Network distributed computing for near- and farfield sources 
Eigenmode Solver 
  Calculation  of  modal  field  distributions  in  closed  or  open  structures,  with  and 
without consideration of losses 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Isotropic and anisotropic materials  
  Multithread parallelization 
  Adaptive mesh refinement in 3D, with True Geometry Adaptation 
  Open, conducting wall, and periodic boundary conditions including phase shift 
  Unit cell feature to simplify the simulation of periodic structures with translational 
periodicity in the xy-plane, for instance hexagonal lattice (General (Lossy) method 
on tetrahedral mesh, Floquet ports are not supported) 
  Accurate  calculation  of  losses  and  internal  or  external  Q-factors  for  each  mode 
(directly or using a perturbation method) 
  External Q per port and mode, radiated Q, loss-Q for materials (General (Lossy) 
method on tetrahedral mesh) 
  Discrete L, C elements at any location in the structure  
  Target frequency can be set (calculation within the frequency interval)
  Sensitivity analysis with respect to materials and geometric deformations defined 
by face constraints (with tetrahedral mesh) 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps  
  Uni-directionally coupled simulations with the Thermal Solver from CST Studio 
Suite 
  Coupled simulations with the Stress Solver from CST Studio Suite 
  Export  of  fields  for  corona  discharge  and  multipactor  analysis  with  Spark3D 
(tetrahedral mesh only) 
Schematic View 
  Adds a logical view to the current high frequency simulation project 
  Allows adding additional circuitry, build of functional elements. Many different types 
are available: active and passive circuit elements, complex circuit models coming 
from  measured  data  (e.g.  SPICE,  Touchstone  or  IBIS  files),  analytical  or  semi 
analytical  descriptions  (e.g.  microstrip  or  stripline  models)  or  simulated  results 
(other CST Studio Suite projects) 
  Full parametric support and ready for optimization / parameter sweep runs 
  Flexible and powerful hierarchical task concept offering nested parameter sweep / 
optimizer setups 
  Different circuit simulation tasks, including transient EM/circuit co-simulations,  
  Recombination of 3D fields as a result from the surrounding circuitry 
  Specialized SPARK3D task for corona discharge and multipactor analysis 
  Interference  task  to  determine  disturbances  between  different  communication 
channels 
SAM (System Assembly and Modeling) 
  3D representations for individual components 
  Automatic project creation by assembling the schematic’s elements into a full 3D 
representation 
  Fast  parametric  modeling  front  end  for  easy  component  transformation  and 
alignment 
  Manage project variations derived from one common 3D geometry setup 
  Coupled  Multiphysics  simulations  by  using  different  combinations  of  coupled 
circuit/EM/thermal/mechanical projects 
  Hybrid Solver Task (uni- or bi-directional coupling of 3D high frequency solvers) 
  Antenna Array Task 
Visualization and Secondary Result Calculation 
  Multiple 1D result view support 
  Displays S-parameters in xy-plots (linear or logarithmic scale)  
  Displays S-parameters in Smith charts and polar charts  
  Online visualization of intermediate results during simulation 
  Import and visualization of external xy-data 
  Copy / paste of xy-datasets 
  Fast access to parametric data via interactive tuning sliders 
  Automatic parametric 1D result storage 
  Displays port modes (with propagation constant, impedance, etc.) 
  Various field visualization options in 2D and 3D for electric fields, magnetic fields, 
power flows, surface currents, etc.
  Calculation and display of farfields (fields, gain, directivity, RCS) in xy-plots, polar 
plots, scattering maps, radiation plots (3D) 
  Nearfield cylinder scan visualization 
  Calculation of Specific Absorption Rate (SAR) including averaging over specified 
mass 
  Calculation of surface losses by perturbation method and of the Q factor 
  Display and integration of 2D and 3D fields along arbitrary curves 
  Integration of 3D fields across arbitrary faces 
  Automatic extraction of SPICE network models for arbitrary topologies ensuring the 
passivity of the extracted circuits 
  Combination of results from different port excitations 
  Hierarchical result templates for automated extraction and visualization of arbitrary 
results from various simulation runs. These data can also be used for the definition 
of optimization goals. 
Result Export 
  Export of S-parameter data as Touchstone files 
  Export of result data such as fields, curves, etc. as ASCII files 
  Export screen shots of field plots 
  Export of farfield data as excitation for integral equation or asymptotic solver 
  Export  of  frequency  domain  nearfield  data  from  transient  or  frequency  domain 
solver, for use as excitation in transient solver 
Automation 
  Powerful VBA (Visual Basic for Applications) compatible macro language including 
editor and macro debugger 
  CST Python Libraries to control solvers, access 0D/1D results, provide an interface 
to Printed Circuit Board data and more 
  OLE automation for seamless integration into the Windows environment (Microsoft
About This Manual 
This  manual  is  primarily  designed  to  enable  you to get  a quick  start  with CST  Studio 
Suite. It is not intended to be a complete reference guide for all the available features 
but will give you an overview of key concepts. Understanding these concepts will allow 
you to learn how to use the software efficiently with the help of the online documentation. 
The main part of the manual is the Simulation Workflow (Chapter 2) which will guide you 
through the most important features of CST Studio Suite for High Frequency Simulation. 
We strongly encourage you to study this chapter carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the Ctrl key while pressing the S key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document, a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the 
command.  
Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item. 
  Example: NT: 1D Results  Port Signals  i1 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support
Chapter 2 – Simulation Workflow 
The following example shows a simple S-parameter calculation of a coaxial connector. 
Studying  this  example  carefully  will  help  you  become  familiar  with  many  standard 
operations  that  are  important  when  performing  a  high  frequency  simulation  with  CST 
Studio Suite.  
Go through the following explanations carefully, even if you are not planning to use the 
software for S-parameter computations. Only a small portion of the example is specific 
to  this  particular  application  type  while  most  of  the  considerations  are  general  to  all 
solvers and applications. 
In subsequent sections, you will find some remarks concerning how typical procedures 
may differ for other kinds of simulations. 
Setup the Simulation Model 
The following explanations describe the “long” way to open a particular dialog box or to 
launch a particular command. Whenever available, the corresponding Ribbon item will 
be  displayed  next  to  the  command  description.  Because  of  the  limited  space  in  this 
manual,  the  shortest  way  to  activate  a  particular  command  (i.e.  by  activating  the 
command  from  the  context  menu)  is  omitted.  You  should  regularly  open  the  context 
menu by clicking the right mouse button, to check available commands for the currently 
active mode. 
The Structure 
In this example, you will model a simple coaxial bend with a tuning stub. You will then 
calculate  the  broadband  S-parameter  matrix  for  this  structure  before  looking  at  the 
electromagnetic  fields  inside  this  structure  at  various  frequencies.  The  picture  below 
shows the current structure of interest (it has been sliced open to aid visualization), and 
was produced using the POV export option.Before you start modeling the structure, let us spend a few moments discussing how to 
construct this structure efficiently. Due to the outer conductor of the coaxial cable, the 
structure’s interior is sealed as if it were embedded in a perfect electric conducting block 
(apart,  of  course, from the  ports).  For simplification,  you  can thus  model  the  problem 
without the outer conductor and instead embed just the dielectric and inner conductor in 
a perfectly conducting block.  
In order to simplify this procedure, CST Studio Suite allows you to define the properties 
of the background material. Any part of the simulation volume that you do not specifically 
fill with some material will automatically be filled with the background material. For this
structure, it is sufficient to model the dielectric parts and define the background material 
as a perfect electric conductor. 
The method of constructing the structure should therefore be as follows: 
1.  Model the dielectric (air) cylinders. 
2.  Model the inner conductor inside the dielectric part. 
Create a New Project 
After launching the CST Studio Suite, you will enter the start screen showing you a list 
of recently opened projects and allowing you to specify the application type which best 
suits your requirements. The easiest way to get started is to configure a project template 
that defines the basic settings that are meaningful for your typical application. Therefore, 
click on the New Template button in the New Project from Template section. 
Next, you should choose the application area, which is Microwaves & RF / Optical for 
the  example  in  this  tutorial,  and  then  select  the  workflow  by  double-clicking  on  the 
corresponding entry.For  the  coaxial  structure,  please  select  Circuit  &  Components    Coaxial  (TEM) 
Connectors  Time Domain 
. 
Now  you  are  requested  to  select  the  units  which  best  fit  your  application.  For  this 
example, we can leave the pre-selected units as follows: 
Dimensions:  mm 
Frequency:  GHz 
Time: 
ns 
On the next page it is possible to already define a frequency range as well as typical 3D 
field  monitor  specifications  for  your  template,  in  case  these  settings  are  reusable  for 
several of your models. However, we will define these settings later on during the model 
setup,  so  we  can  continue  by  again  clicking  the  Next  button.  Now  you  can  give  the 
project template a name and review a summary of your initial settings:
Finally click the Finish button to save the project template and to create a new project 
with appropriate settings. The high frequency module will be launched automatically due 
to the choice of the application area MW & RF & Optical. 
Please  note:  When  you  click  again  on  File:  New  and  Recent  you  will  see  that  the 
recently defined template appears in the Project Templates section. For further projects 
in the same application area, you can simply click on this template entry to launch the 
high frequency module with useful  basic  settings.  It  is  not  necessary  to define  a  new 
template each time. You are now able to start the software with reasonable initial settings 
quickly with just one click on the corresponding template.  
Please note: All settings made for a project template can be modified later on during 
the construction of your model. For example, the units can be modified in the units dialog 
box  (Home:  Settings   Units 
)  and  the  solver  type  can  be  selected  in  the  Home: 
Simulation  Setup Solver dropdown list.Open the QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
you can open this assistant by selecting QuickStart Guide from the dropdown menu next 
to the Help button 
 in the upper right corner. 
The  following  dialog  box  should  then  be  visible  at  the  upper  right  corner  of  the  main 
view: 
As the project template has already set the solver type, units and background material, 
the Time Domain Analysis is preselected and some entries are marked as done. The
red arrow always indicates the next step necessary for your problem definition. You do 
not have to follow the steps in this order, but we recommend you follow this guide at the 
beginning to ensure that all necessary steps have been completed.  
Look at the dialog box as you follow the various steps in this example. You may close 
the assistant at any time. Even if you re-open the window later, it will always indicate the 
next required step. 
If you are unsure of how to access a certain operation, click on the corresponding line. 
The  QuickStart  Guide  will  then  either  run  an  animation  showing  the  location  of  the 
related menu entry or open the corresponding help page. 
Define the Units 
The coaxial connector template has already made some settings for you. The defaults 
for  this  structure  type  are  geometrical  units  in  mm  and frequencies  in  GHz.  You  can 
change  these  settings  by  entering  the  desired  values  in  the  units  dialog  box  (Home: 
Settings  Units 
), but for this example you should just leave the settings as specified 
by the template. 
Define the Background Material 
As  discussed  above,  the  structure  will  be  described  within  the  perfectly  conducting 
background material which the coaxial connector template has set for you. In order to 
change  it  you  may  enter  the  corresponding  dialog  box  (Modeling:  Materials   
Background 
). For this example, however you do not need to change anything. 
Model the Structure 
The first step is to create a circular cylinder along the z-axis of the coordinate system: 
1.  Select  Modeling:  Shapes   Cylinder 
  to  enter  the  interactive  cylinder  creation 
mode. 
2.  Press  the  Shift+Tab  keys  and  enter  the  center  point  (0,0)  in  the  xy-plane  before 
pressing the Return key to store this setting. 
3.  Press the Tab key again, enter the radius 2 and press the Return key. 
4.  Press the Tab key, enter the height 12 and press the Return key. 
5.  Press Esc to create a solid cylinder (skipping the definition of the inner radius). 
6.  In the shape dialog box, enter “long cylinder” in the Name field. 
7.  You could simply select the predefined material Vacuum (which is very similar to air) 
from the list in the Material field. Here we are going to create a new material “air” to 
show how the layer creation procedure works, so select the [New Material…] entry 
in the Material dropdown list. 
8.  In  the  material  creation  dialog  box,  enter  the  Material  name  “air,"  select  Normal 
dielectric properties (Type) and check the material properties Epsilon = 1.0 and Mue 
= 1.0. Then select a color and close the dialog box by clicking OK.
Click OK to create the cylinder. 
The  result  of  these  operations  should  look  like  the  picture  below.  You  can  press  the 
Space bar to zoom in to a full screen view.The next step is to create a second cylinder perpendicular to the first. The center of the 
new cylinder’s base should be aligned with the center of the first cylinder. 
Follow these steps to define the second cylinder: 
1.  Select  View:  Visibility   Wire  Frame  (Ctrl+W) 
  to  activate  the  wire frame  draw 
mode. 
2.  Activate the “circle center” pick tool:  Modeling: Picks  Pick Points  Pick Circle 
Center (C) 
. 
3.  Double-click on one of the cylinder’s circular edges so that a point is added in the 
center of the circle. 
4.  Perform steps 2 and 3 for the cylinder’s other circular edge. 
Now the construction should look like this:
Next, replace the two selected points by a point half way between the two by selecting 
Modeling: Picks  Pick Points  Mean Last Two Points (Ctrl + Shift + M). 
You can now move the origin of the local working coordinate system (WCS) to this point 
by choosing Modeling: WCS  Align WCS  Align WCS with Selected Point or WCS  
Align WCS (W) 
. The screen should look like this:Now align the w-axis of the WCS with the proposed axis of the second cylinder.  
1.  Select Modeling: WCS  Transform WCS 
2.  Select Rotate as Transform type. 
3.  Select U as rotation axis and enter a rotation Angle of –90 degrees. 
4.  Click the OK button. 
.
Alternatively, you could press Shift+U to rotate the WCS by 90 degrees around its u-
axis. Thus pressing Shift+U three times has the same effect as the rotation by using the 
dialog box described above. 
Furthermore, you can also perform the transformation interactively with the mouse after 
selecting Modeling: WCS  Transform WCS 
. 
Now the structure should look like this:The next step is to create the second cylinder perpendicular to the first one: 
1.  Select again Modeling: Shapes  Cylinder 
2.  Press the Shift+Tab key and enter the center point (0,0) in the uv-plane. 
3.  Press the Tab key again and enter the radius 2. 
4.  Press the Tab key and enter the height 6. 
5.  Press Esc to create a solid cylinder. 
6.  In the shape dialog box, enter “short cylinder” in the Name field. 
7.  Select the material “air” from the material list and click OK. 
 to enter the cylinder creation mode. 
Now the program will automatically detect the intersection between these two cylinders.
In the Shape Intersection dialog box, choose the option Add both shapes and click OK. 
Finally, the structure should look like this:The  creation  of  the  dielectric  air  parts  is  complete.  The  following  operations  will  now 
create the inner conductor inside the air. 
Since the coordinate system is already aligned with the center of the second cylinder, 
you can go ahead and start to create the first part of the conductor: 
 to enter the cylinder creation mode. 
1.  Select Modeling: Shapes  Cylinder 
2.  Press the Shift+Tab key and enter the center point (0, 0) in the uv-plane. 
3.  Press the Tab key again and enter the radius 0.86. 
4.  Press the Tab key and enter the height 6. 
5.  Press Esc to create a solid cylinder. 
6.  In the shape dialog box, enter “short conductor” in the Name field. 
7.  Select  the  predefined  Material  “PEC”  (perfect  electric  conductor)  from  the  list  of 
available materials and click OK to create the cylinder.
At  this  point,  we should briefly  discuss the  intersections between shapes.  In general, 
each point in space should be identified with one particular material. However, perfect 
electric conductors can be seen as a special kind of material. It is allowable for a perfect 
conductor to be present at the same point as a dielectric material. In such cases, the 
perfect  conductor  is  always  the  dominant  material.  The  situation  is  also clear  for  two 
overlapping  perfectly  conducting materials,  since  in  this  case the  overlapping  regions 
will also be perfect conductors. Therefore, the intersection dialog box will not be shown 
automatically in the case of a perfect conductor overlapping with a dielectric material or 
with another perfect conductor. On the other hand, two different dielectric shapes may 
not overlap.  
Background  information:  Some  structures  contain  extremely  complex  conducting 
parts embedded within dielectric materials. In such cases, the overall complexity of the 
model can be significantly reduced by NOT intersecting these two materials. This is the 
reason  why  CST  Studio  Suite  allows  this  exception  for  the  high  frequency  module. 
However, you should make use of this feature whenever possible, even in such simple 
structures as this example. 
The following picture shows the structure as it should currently appear:Now  you  should  add  the  second  conductor.  First  align  the  local  working  coordinate 
system with the upper z-circle of the first dielectric cylinder by selecting Modeling: WCS 
 Align WCS 
 and double-click on the first cylinder’s upper z-plane:
The w-axis of the local coordinate system is aligned with the first cylinder’s axis, so you 
can now create the second part of the conductor: 
 to enter the cylinder creation mode. 
1.  Select Modeling: Shapes  Cylinder 
2.  Press the Shift+Tab key and enter the center point (0,0) in the uv-plane. 
3.  Press the Tab key again and enter the radius 0.86. 
4.  Press the Tab key and enter the height –11. 
5.  Press Esc to create a solid cylinder. 
6.  In the cylinder creation dialog box, enter “long conductor” in the Name field. 
7.  Select the Material “PEC” from the list and click OK. 
The  newly  created  cylinder  intersects  with  the  dielectric  part  as  well  as  with  the 
previously  created  PEC cylinder.  Even  if  there  are two  intersections  (dielectric /  PEC 
and PEC / PEC), the Shape intersection dialog box will not be shown here since both 
types of overlaps are well defined. In both cases, the common volume will be filled with 
PEC. 
Congratulations! You have just created your first structure within CST Studio Suite. The
The  following  gallery  shows  some  views  of  the  structure  available  using  different 
visualization options: Shaded view 
(deactivated working 
plane,  
View: Visibility  
Working Plane 
(Alt+W) 
)                       
Shaded view 
(long conductor 
selected)                       
Shaded view with 
cutplane 
(View: Sectional View 
 Cutting Plane 
(Shift+C) 
, 
Appearance of part 
above 
cutplane = 
transparent)        
Define the Frequency Range 
The  next  important  setting for the  simulation is the frequency  range  of  interest.  If  not 
already specified by your template settings, you can specify the frequency by choosing 
Simulation: Settings  Frequency 
: 
In this example, you should specify a frequency range between 0 and 18 GHz. Since 
you have already set the frequency unit to GHz, you need to define only the absolute 
numbers 0 and 18 (the status bar always displays the current unit settings).
Define Ports 
The following calculation of S-parameters requires the definition of ports through which 
energy  enters  and  leaves  the  structure.  You  can  do  this  by  simply  selecting  the 
corresponding faces before entering the ports dialog box. 
For the definition of the first port, perform the following steps: 
1.  Select Simulation: Picks  Pick Points, Edges or Faces (S) 
2.  Double-click on the upper w-plane aligned face of the dielectric part. The selected 
. 
face will be highlighted: 
3.  Open the ports dialog box by selecting Simulation: Sources and Loads  
Waveguide Port 
:Everything is already set up correctly for the coaxial cable simulation, so you can 
simply click OK in this dialog box. 
Once the first port has been defined, the structure should look like this:
You can now define the second port in exactly the same way. The picture below shows 
the structure after the definition of both ports:The  correct  definition  of  ports  is  very  important  for  obtaining  accurate  S-parameters. 
Please  refer  to  the  Choosing  the  Right  Port  section  later  in  this  manual  for  more 
information about the correct placement of ports for various types of structures. 
Define Boundary and Symmetry Conditions 
The simulation of this structure will only be performed  within the bounding box of the 
structure.  You  must  specify  a  boundary  condition  for  each  plane  (Xmin/Xmax/ 
Ymin/Ymax/Zmin/Zmax) of the bounding box.  
The  boundary  conditions  are  specified  in  a  dialog  box  you  can  open  by  choosing 
Simulation: Settings  Boundaries 
:
While the boundary dialog box is open, the boundary conditions will be visualized in the 
structure view as in the picture above.                                            
In this simple case, the structure is completely embedded in perfect conducting material, 
so all the boundary planes may be specified as “electric” planes (which is the default). 
In  addition  to  these  boundary  planes,  you  can  also  specify  “symmetry  planes".  The 
specification of each symmetry plane will reduce the simulation time by a factor of two. 
In our example, the structure is symmetric in the yz-plane (perpendicular to the x-axis) 
in  the  center  of  the  structure.  The  excitation  of  the  fields  will  be  performed  by  the 
fundamental mode of the coaxial cable for which the magnetic field is shown below:Plane of structure’s symmetry (yz-plane) 
The magnetic field has no component tangential to the plane of the structure’s symmetry 
(the field is always oriented perpendicular to this plane). If you specify this plane as a 
“magnetic” symmetry plane, you can direct CST Studio Suite to limit the simulation to 
one-half of the actual structure while taking the symmetry conditions into account. 
In  order  to  specify  the  symmetry  condition,  you  first  need  to  click  on  the  Symmetry 
Planes tab in the boundary conditions dialog box.  
For the yz-plane symmetry, you can choose magnetic (Ht=0) in one of two ways. Either 
select  the  appropriate  option  in  the  dialog  box,  or  double-click  on  the  corresponding
symmetry plane visualization in the view and select the proper choice from the context 
menu. Once you have done so, your screen will appear as follows: 
Finally click OK in the dialog box to store the settings. The boundary visualization will 
then disappear. 
Visualize the Mesh 
In  this  first  simulation,  we  will  run  the  transient  solver  based  on  a  hexahedral  mesh. 
Since this is the default mesh type, we do not need to change anything here. In a later 
step, we will show how to apply a tetrahedral mesh to this structure, run the frequency 
domain solver, and compare the results. However, let us focus on the hexahedral mesh 
generation options first. 
The  hexahedral  mesh  generation  for  the  structure  analysis  will  be  performed 
automatically based on an expert system. However, in some situations it may be helpful 
to inspect the mesh in order to improve the simulation speed by changing the parameters 
for the mesh generation.  
The  mesh  can  be  visualized  by  entering  the  mesh  mode  (Simulation:  Mesh   Mesh 
View
You can modify the orientation of the mesh plane by adjusting the selection in the Mesh: 
Sectional View  Normal dropdown list or just by pressing the  X/Y/Z keys. Move the 
plane along its normal direction using the Up/Down cursor keys. The current position of 
the plane will be shown in the Mesh: Sectional View  Position field. 
Because of the symmetry setting, the mesh plane extends across only one-half of the 
structure, what can be seen by e.g. changing the plane normal to the z-direction: 
In this view, also the PBA representation of the curved structure is seen in the mesh 
cells that are partly filled with PEC and partly with air. 
There are some thick mesh lines shown in the mesh view. These mesh lines represent 
important  planes  (so-called  snapping  planes)  at  which  the  expert  system  finds  it 
necessary to place mesh lines. You can control these snapping planes in the Special 
Mesh  Properties  dialog  box  by  selecting  Mesh:  Mesh  Control  /  Simulation:  Mesh  
Global Properties 
  Specials  Snapping. 
In most cases, the automatic mesh generation will produce a reasonable initial mesh, 
but  we  recommend  that  you  later  spend  some  time  reviewing  the  mesh  generation 
procedures  in  the  online  documentation  when  you  feel  familiar  with  the  standard 
simulation  procedure.  You  should  now  leave  the  mesh  inspection  mode  by  toggling 
Mesh: Close  Close Mesh View 
 or just by pressing the ESC key. Start the Simulation 
After defining all necessary parameters, you are ready to start your first simulation from 
the time domain solver control dialog box by selecting Simulation: Solver  Setup Solver 
:
In this dialog box, you can specify which column of the S-matrix should be calculated. 
Therefore, select the Source type port for which the couplings to all other ports will then 
be calculated during a single simulation run. In our example, by setting the Source type 
to Port 1, the S-parameters S11 and S21 will be calculated. Setting the Source Type to 
Port 2 will calculate S22 and S12. 
If the full S-matrix is needed, you may also set the Source Type to All Ports. In this case, 
a  calculation  run  will  be  performed  for  each  port.  However,  for  loss  free  two  port 
structures (like the structure investigated here), the second calculation run will not be 
performed  since  all  S-parameters  can  be  calculated  from  one  run  using  analytic 
properties of the S-matrix. 
In this example, you should compute the full S-matrix and leave All Ports as your Source 
type setting. 
The calculated S-parameters will always be normalized to the port impedance (which 
will be calculated automatically) by default. For this model, the port impedance will be 
approximately  
Ohm 
for the coaxial  lines  with  the  specified  dimensions  and dielectric  constants.  However, 
sometimes you may need the S-parameters for a fixed normalization impedance (e.g. 
50 Ohm), so in such a case you should check the Normalize to fixed impedance button 
and  specify  the  desired  normalization  impedance  in  the  entry  field  below.  In  this 
example,  we  assume  that  you  want  to  calculate  the  S-parameters  for  a  reference 
impedance of 50 Ohm. Note that the re-normalization of the S-parameters is possible 
only when all S-parameters have been calculated (Source Type = All Ports). 
While the solution accuracy mainly depends on the discretization of the structure and 
can be improved by refining the mesh, the truncation error introduces a second error 
source in transient simulations.
In  order  to  obtain  the  S-parameters,  the  transformation  of  the  time  signals  into  the 
frequency domain requires the signals to have sufficiently decayed to zero. Otherwise a 
truncation error will occur, causing ripples on the S-parameter curves.  
The time domain solver features an automatic control that stops the transient analysis 
when the energy inside the device, and thus the time signals at the ports, have decayed 
sufficiently close to zero. The ratio between the maximum energy inside the structure at 
any time and the limit at which the simulation will be stopped is specified in the Accuracy 
field (in dB).  
The  chosen coaxial  connector template  already set  the  solver  Accuracy to  –40  dB  to 
limit the maximum truncation error to 1% for this example.  
The solver will excite the structure with a Gaussian pulse in the time domain. However, 
all frequency domain and field data obtained during the simulation will be normalized to 
a frequency-independent input power of 1 W peak. 
After setting these parameters, the dialog box should look like this:In  order  to  also  achieve  accurate  results  for  the  line  impedance  values  of  (Q)TEM 
modes,  an  adaptive  mesh  refinement  in  the  port  regions  is  performed  as  a  pre-
processing step before the transient simulation itself is started. This procedure refines 
the port mesh until a defined accuracy value or a maximum number of passes has been 
reached. These settings can be adjusted in the following dialog box Simulation: Solver 
 Setup Solver 
  Specials  Waveguide:
Since  we  want  to  simulate  a  coaxial  structure  with  static  port  modes,  we  keep  the 
adaptation enabled with its default settings. You can now close the Specials dialog box 
without any changes and then start the simulation by clicking the Start button. 
A progress bar will appear in the progress window that will update you on the solver’s 
progress.  You  can  activate  this  window  by  selecting  View:  Window    Windows   
Progress. Information text regarding the simulation will appear above the progress bar. 
The most important stages are listed below: 
1.  Analyzing port domains: During this first step, the port regions are analyzed for 
the port mesh adaptation to follow. 
2.  Port mode calculation: Here, the port modes are calculated during the port mesh 
adaptation.  This  step  is  performed  several  times  for  each  port  until  a  defined 
accuracy value or a maximum number of passes has been reached. 
3.  Calculating matrices: Processing CAD model: During this step, your input model 
is checked and processed. 
4.  Calculating  matrices:  Computing  coefficients:  During  this  step,  the  system  of 
equations that will subsequently be solved is set up. 
5.  Data  rearrangement:  Merging  results:  For  larger  models,  the  matrices  are 
calculated in parallel and the results are merged at the end.  
6.  Transient analysis: Calculating port modes: In this step, the solver calculates the 
port  mode  field  distributions  and  propagation  characteristics  as  well  as  the  port 
impedances  if  they  have  not  been  previously  calculated.  This  information  will  be 
used later in the time domain analysis of the structure. 
7.  Transient  analysis:  Processing excitation:  During this  stage,  an  input  signal  is 
fed into the stimulation port. The solver then calculates the resulting field distribution 
inside  the  structure  as  well  as  the  mode  amplitudes  at  all  other  ports.  From  this 
information, the frequency dependent S-parameters are calculated in a second step 
using a Fourier transformation. 
8.  Transient  analysis:  Transient  field  analysis:  After  the  excitation  pulse  has 
vanished, there is still electromagnetic field energy inside the structure. The solver 
continues  to  calculate  the  field  distribution  and  the  S-parameters  until  the  energy 
inside the structure and the port signals has decayed below a certain limit (specified 
by the Accuracy setting in the solver dialog box).
For this simple structure, the entire analysis takes only a few seconds to complete. 
Analyze the Port Modes 
After the solver has completed the port mode calculation, you can view the results (even 
while the transient analysis is still running). 
In  order  to  visualize  a  particular  port  mode,  you  must  choose  the  solution  from  the 
navigation tree. You can find the mode at port 1 from NT (navigation tree): 2D/3D Results 
 Port Modes  Port1. If you open this subfolder, you may select the electric or the 
magnetic  mode  field.  Selecting  the  item  for  the  electric  field  of  the  first  mode  e1  will 
display the port mode and its relevant parameters in the main view:Besides  information  on  the  type  of  mode  (in  this  case  TEM),  you  will  also  find  the 
propagation constant (beta) at the center frequency. Additionally, the port impedance is 
calculated automatically (line impedance).  
You will find that the calculated result for the port impedance of 50.74 Ohm agrees well 
with the analytical solution of 50.58 Ohm after the port mesh adaptation has run. The 
small difference is caused by the discretization of the structure. The agreement between 
simulation  and  theoretical  value  can  be  improved  by  defining  a  smaller  value  for  the 
Accuracy limit of the port mesh adaption or by increasing the overall initial mesh density. 
However, the automatic mesh generation always tries to choose a mesh that provides a 
good trade-off between accuracy and simulation speed. 
You can adjust the number and size of arrows in the dialog box that can be opened by 
choosing 2D/3D Plot: Plot Properties  Properties 
 (or Plot Properties in the context 
menu). 
You may visualize the scalar fields by opening the e1 item and selecting Contour from 
the plot type pull-down menu in the 2D/3D Plot ribbon 2D/3D Plot: Plot Type  Contour. 
The field component Abs will be visualized as a contour plot by default. To visualize the 
field component X you can select it from the field component pull-down menu or from 
the context menu:
You  may  again  change  the  type  of  the  scalar  visualization  by  selecting  a  different 
visualization  option  in  the  corresponding  dialog  box:  2D/3D  Plot:  Plot  Properties   
Properties 
 (or Plot Properties in the context menu). 
Please experiment with the various settings in this dialog box to become familiar with 
the different visualization options before you proceed with the next step. 
Analyze the S-Parameters 
After a simulation has finished, you should always look at the time signals of the port 
modes.  You  can  visualize  these  signals  by  choosing  NT:  1D  Results   Port  signals. 
After selecting this folder, the following plot should appear:The input signals are named with reference to their corresponding ports: i1 (for port 1), 
i2  and  so  on.  The  output  signals  are  similarly  named  “o1,1”,  “o2,1”,  etc.,  where  the 
number following the comma indicates the corresponding excitation port.
To obtain a sufficiently smooth frequency spectrum of the S-parameters, it is important 
that all time signals decay to zero before the simulation stops. The simulation will stop 
automatically when the solver Accuracy criterion is met. 
The results in which we are most interested here are the S-parameters themselves. You 
may  obtain  a  visualization  of  these  parameters  in  linear  scale  by  choosing  NT:  1D 
Results  S-Parameters and selecting 1D Plot: Plot Type  Linear 
: 
You can change the axis scaling by selecting 1D Plot: Plot Properties  Properties 
(or Plot Properties in the context menu). In addition, you can display and hide an axis 
marker by toggling 1D Plot: Markers  Axis Marker 
. The marker can be moved either 
with the cursor keys (Left or Right) or by dragging it with the mouse. 
The  marker  can  also  be  adjusted  automatically  to  determine  the  minimum  of  the 
transmission (S1,2  or  S2,1)  at  about  12.9 GHz by  selecting  1D  Plot:  Markers   Axis 
  Move Marker to Minimum. You can restrict the view to specific curves only 
Marker 
by  multi-selection  in the  navigation  tree  or  by  choosing  Select  curves  via  the  context 
menu to show an unambiguous minimum value.In the same way as above, the S-parameters can be visualized in logarithmic scale (dB) 
by choosing NT: 1D Results  S-Parameters and 1D Plot: Plot Type  dB 
 in the 
context menu. The phase, the real or imaginary part of the selected result can also be 
visualized.
Furthermore, the S-parameters can be presented in a Z or Y Smith Chart plot (1D Plot: 
Plot Type  Z Smith Chart 
, respectively). 
 or 1D Plot: Plot Type  Y Smith Chart 
In all 1D plots, multiple curve markers can be added by selecting 1D Plot: Markers  
Curve Markers  Add Curve Marker (M) 
 as shown for example in the Smith Chart 
view  above.  The  individual  markers  can  be  moved  along  the  curve  by  picking  and 
dragging them with the mouse. You may activate or deactivate the visualization of all 
markers  by  choosing  1D  Plot:  Markers   Curve  Markers   Show  Curve  Markers  or 
delete them all with the option 1D Plot: Markers  Curve Markers  Remove All Curve 
Markers. 
Adaptive Mesh Refinement 
As  mentioned  above,  the  mesh  resolution  influences  the  results.  The  expert  system-
based  mesh  generator  analyzes  the  geometry  and  tries  to  identify  the  parts  that  are 
critical to the electromagnetic behavior of the device. The mesh will then automatically 
be  refined  in  these  regions.  However,  due  to  the  complexity  of  electromagnetic 
problems,  this  approach  may  not  be  able  to  determine  all  critical  domains  in  the 
structure. To circumvent this problem, the transient solver features an adaptive mesh 
refinement which uses the results of a previous solver run in order to improve the expert 
system’s settings. 
Activate  the  adaptive  mesh  refinement  by  checking  the  corresponding  option  in  the
Click the Start button. The solver will now perform several mesh refinement passes until 
the S-parameters no longer change significantly between two subsequent passes. The 
S-Parameter based stop criterion is activated by default, but it is also possible to use 
any kind of 0D result template instead, or the two approaches in combination. Please 
refer to the online help for more detailed information. 
After two passes have been completed, the following dialog box will appear:Since the automatic mesh adaptation procedure has successfully adjusted the expert 
system’s settings in order to meet the given accuracy level (2% by default), you may 
now  switch  off  the  adaptive  refinement  procedure  for  subsequent  calculations.  The 
expert  system  will  apply  the  determined  rules  to  the  structure  even  if  it  is  modified 
afterwards. This powerful approach allows you to run the mesh adaptation procedure 
just once and then perform parametric studies or optimizations on the structure without 
the need for further mesh refinement passes.  
You should now confirm deactivation of the mesh adaptation by clicking the Yes button. 
When the analysis has finished, the S-parameters and fields show the converged result. 
The progress of the mesh refinement can be checked by looking at the NT: 1D Results 
 Adaptive Meshing folder. This folder contains a curve which displays the maximum 
difference between two S-parameter results belonging to subsequent passes. This curve 
can be shown by selecting NT: 1D Results  Adaptive Meshing  Delta S.
Since the mesh adaptation required only two passes for this example, the Delta S curve 
consists  of  a  single  data  point  only.  The  result  shows  that  the  maximum  difference 
between the S-parameters from both runs is below 1% over the whole frequency range. 
The  mesh  adaptation  stops  automatically  when the  difference  is  below  2%. This  limit 
can be changed in the mesh refinement Adaptive Properties (accessible from within the 
solver dialog box). 
The S-parameter results will be automatically stored for the different mesh adaptation 
runs and can be selected with help of the Result Navigator. If the window is not visible, 
it can be activated by selecting View: Window  Windows  Result Navigator:  
The convergence of the S-parameter results can be visualized by selecting for example 
NT: 1D Results  S-Parameters  S2,1 and activating 1D Plot: Plot Type  Linear 
:You can see that the expert system based mesher provided a good initial mesh for this 
structure. The convergence of the S-parameters shows only small variations from the 
results  obtained  using  the  expert  system  generated  initial  mesh  to  the  converged 
solution.
In  practice,  it  often  proves  wise  to  activate  the  adaptive  mesh  refinement  to  ensure 
convergence of the results. (This might not be necessary for structures with which you 
are already familiar when you can use your experience to refine the automatic mesh.) 
Analyze the Electromagnetic Field at Various Frequencies 
To  understand the  behavior  of  an  electromagnetic  device,  it  is  often  useful  to  get  an 
insight into the electromagnetic field distribution. In this example, it may be interesting 
to see the difference between the fields at frequencies where the transmission is large 
or small. 
The fields can be recorded at arbitrary frequencies during a simulation. However, it is 
not possible to store the field patterns at all available frequencies as this would require 
a tremendous amount of memory. You should therefore define some frequency points 
at  which  the  solver  will  record  the  fields  during  a  subsequent  analysis.  These  field 
samplers are called monitors. 
Monitors can be defined in the dialog box that opens upon choosing Simulation: Monitors 
 Field Monitor 
. You may need to switch back to the modeler mode by selecting the 
Components folder in the navigation tree before the monitor definition is activated.After  selecting  the  proper  Type  for  the  monitor,  you  may  specify  its  frequency  in  the 
Frequency field. Clicking Apply stores the monitor while leaving the dialog box open. All 
frequencies are specified in the frequency unit previously set to GHz. 
For this analysis, you should add the following monitors: 
Field type 
E-Field 
E-Field 
H-Field and Surface current 
Frequency / GHz 
3 
12.9
H-Field and Surface current 
12.9 
All defined monitors are listed in the NT: Field Monitors folder. Within this folder you may 
select a particular monitor to reveal its parameters in the main view. 
You  should  now  run  the  simulation  again.  Without  the  need  to  change  further  solver 
settings you can press Home: Simulation  Start Simulation 
 to directly start the solver 
run without opening the dialog box. When the simulation finishes, you can visualize the 
recorded  fields  by  choosing  the  corresponding  item  from  the  navigation  tree.  The 
monitor results can be found in the NT: 2D/3D Results folder. The results are ordered 
according to their physical type (E-Field/H-Field/Surface Current). 
Note:   Since you have specified a full S-matrix calculation, two simulation runs would 
generally be required. For each of these runs, the field would be recorded as 
specified in the monitors, and the results would be presented in the navigation 
tree, giving the corresponding stimulation port in square brackets. However, in 
this loss-free example the second run is not necessary, so you will find that the 
monitor data for the second run is not available. You can instruct the solver to 
perform both simulation runs even if they are not necessary for the S-
parameter calculation by deselecting the option Consider two-port reciprocity 
under the General tab in the solver’s Specials dialog box. 
You can investigate the 3D electric field distribution by selecting NT: 2D/3D Results  
E-Field  e-field(f=3)[1]. The plot should look similar to the picture below:If  you  select  the  electric  field  at  12.9  GHz  (NT:  2D/3D  Results   E-Field   e-field 
(f=12.9)[1]) you obtain the following plot:
Please  experiment  with  the  various  field  visualization  options  for  the  3D  vector  plot 
(2D/3D Plot: Plot Properties  Properties 
 or Plot Properties from the context menu). 
The  surface  currents  can  be  visualized  by  selecting  NT:  2D/3D  Results    Surface 
Current   surface  current  (f=3)[1].  You  should  obtain  a  plot  similar  to  the  following 
picture:You  may  change the  plot  options  in the  plot  dialog  box  by  selecting  2D/3D  Plot:  Plot 
Properties  Properties 
. You can obtain a field animation by clicking 2D/3D Plot: Plot 
Type   Animate  Fields 
.  Here  the  phase  of  the  field  will  be  automatically  varied 
between 0 and 360 degrees. You can stop the animation by clicking the button again or 
just pressing the Esc key. After clicking in the main view with the left mouse button, you 
can also change the phase gradually by using the Left and Right cursor keys. 
At the frequency of 3 GHz you can see how the current flows through the structure. If 
you perform the same steps with the other magnetic field monitor at 12.9 GHz, you will 
see that almost no current passes the 90-degree bend of the coaxial cable.
After  obtaining  a  rough overview  of the  3D  electromagnetic field  distribution,  you  can 
inspect  the  fields  in  more  detail  by  analyzing  some  cross  sectional  cuts  through  the 
structure. In order to do this, choose an electric or magnetic field (no surface currents) 
for display and select 2D/3D Plot: Sectional View  Fields on Plane 
. The same plot 
options are available in the 2D plot mode that you have already used for the port mode 
visualization. Since the data is derived from a 3D result, you may additionally specify the 
location of the plane at which the fields will be visualized. This can be done by defining 
2D/3D Plot: Sectional View  Cutting Plane Normal and Position or just by toggling the 
arrow controls shown in the main view. 
Due to the limited space, not all plotting options can be explained here. Please refer to 
the online help for more detailed information and examples. 
Parameterization of the Model  
The steps above demonstrated how to enter and analyze a simple structure. However, 
structures will usually be modified in order to improve their performance. This procedure 
may be called “design” in contrast to the “analysis” done before. 
CST Studio Suite offers many options to parametrically describe the structure in order 
to  easily  change  its  parameters.  In  general  all  relevant  structural  modifications  are 
recorded in the so-called history list, which can be opened by choosing Modeling: Edit 
 History List 
. Please refer to the CST Studio Suite - Getting Started document for 
further information on this general option. 
However, for simple parameter changes an easier solution is available. Let’s assume 
that  you  want  to  change  the  stub  length  of  the  coaxial  cable’s  inner  conductor.  The 
easiest way to do this is to enter the modeler mode by selecting the NT: Components 
folder.  
Select all ports by clicking on the NT: Ports folder. Then press the right mouse button to 
choose Hide All Ports from the context menu. The structure plot should look like this (the 
local  working  coordinate  system  can  be  deactivated  by  selecting  Modeling:  WCS  
Local WCS 
):Now select the long conductor by double-clicking on it with the left mouse button:
You can now choose Modeling: Edit  Edit Properties 
context menu) which will open a list showing the history of the shape’s creation: 
 (or Edit Properties from theSelect  the  “Define  cylinder”  operation  in  the  tree  folder  “component1:long  conductor” 
from the History Tree . The corresponding shape will be highlighted in the 
main window. 
After clicking the Edit button in the History Tree dialog box, the cylinder creation dialog 
box will appear showing the parameters of this shape:
In this dialog box you will find the length of the cylinder (Wmin= –11) as it was previously 
specified during the shape creation. Change this parameter to a value of  –9 and click 
OK. Since you are going to change the structure, the previously calculated results will 
no longer match the modified structure, so the following dialog box will appear: 
Here you may specify whether to store the old model with its results in a cache or as a 
new  file,  or  just  to  go  ahead  and  delete  the  current  results.  In  this  case,  you  should 
simply accept the default choice and click OK. 
After a few seconds, the structure plot will change showing the new structure with the 
different stub length.You may now dismiss the History Tree dialog box by clicking the Close button.
Generally,  you  can  change  all  geometric  parameters  of  any  shape  by  selecting  the 
shape and editing its properties. This fully parametric structural modeling is one of the 
most outstanding features of CST Studio Suite.  
The parametric structure definition also works if some objects have been constructed 
relative  to  each  other  by  using  local  working  coordinate  systems.  In  this  case,  the 
program will try to identify all the picked faces according to their topological order rather 
than their absolute position in space.  
Changes in parameters occasionally alter the topology of the structure so severely that 
the  structure  update  may  fail.  In  this  case,  the  History  List  function  offers  powerful 
options  to  circumvent  these  problems.  Please  refer  to  the  online  documentation  or 
contact technical support for more information. 
In  addition  to  directly  changing  the  parameters  you  may  also  assign  variables  to  the 
structure’s  parameters.  The  easiest  way  to  do  this  is  to  enter  a  variable  name  in  an 
expression field rather than a numerical value. Open the cylinder dialog box again as 
described above, and then enter the string “–length” in the Wmin field.  
The dialog box should look as follows:Since the parameter “length” is still undefined, a new dialog box will open after you click 
OK in the cylinder dialog box: 
You can now assign a value to the new parameter by entering 11 in the Value field. You 
may also enter some text in the  Description field so that you can later remember the 
meaning  of  the  parameter.  Click  OK  to  create  the  parameter  and  update  the  model. 
Finally, dismiss the History Tree dialog box by clicking the Close button.
All  defined  parameters  will  be  listed  in  the  Parameter  List  window,  which  can  be 
activated by selecting View: Window  Windows  Parameter List: 
You can change the value of this parameter in the Value field. Afterwards, a message 
in the main view informs you to press Home: Edit  Parametric Update (F7)   
:You can also select Update Parametric Changes from the context menu, which appears 
when you press the right mouse button in the Parameter List window. 
When performing this update operation, the structure will be regenerated according to 
the current parameter value. You can verify that parameter values between 7 and 11.5 
yield a sensible geometry. The function Home: Edit  Parameters   Animate Para-
meter is also useful in this regard. 
Parameter Sweeps and Processing of Parametric Result Data 
Since you have now successfully parameterized your structure, it might be interesting 
to see how the S-parameters change when the length of the conductor is modified. The 
easiest way to obtain this result variation is to use the Parameter Sweep tool by selecting 
Simulation: Solver  Par. Sweep 
 (or from within the time domain solver control dialog 
box by clicking on the Par. Sweep button):
In this dialog box, you can specify calculation “Sequences” which will consist of various 
parameter combinations. To add such a sequence, click the New Seq. button now. Then 
click the New Par… button to add a parameter variation to the sequence:In the resulting dialog box, you can select the name of the parameter to vary in the Name 
field. Then you can specify different sweep types to define the sampling of the parameter 
space (Linear sweep, Logarithmic sweep, Arbitrary points). Depending on this selection 
the sampling can be defined further, e.g. the linear sweep option allows us to define the 
lower (From) and upper (To) bounds for the parameter variation as well as the definition 
of either the number of samples or the step width. 
In this example, you should perform a linear sweep from 10 to 11.5 with 5 samples. After 
you click the OK button, the parameter sweep dialog box should look as follows:
Note that you can define an arbitrary number of sequences which each can contain an 
unlimited number of different parameter combinations. 
In the next step, you have to specify which results you are interested in. With the help 
of the automated Parametric Result Storage, it is possible to store any one dimensional 
result  curve  parametrically  during  parameter  sweep  sequences.  A  special  parametric 
plot  option  allows  the  convenient  display  of  this  data.  Please  refer  to  the  online 
documentation and the CST Studio Suite – Getting Started manual for more information 
about this convenient functionality. 
Besides this general option, it is also possible to setup specific Result Templates, which 
allow in addition the definition of various secondary results. Pressing the corresponding 
button, the global Template Based Post-Processing dialog box opens, in which you can 
define various post-processing steps, which will be automatically computed after each 
simulation  run.  Please  note  that  this  dialog  box  can  also  be  accessed  directly  by 
choosing Post-Processing: Tools  Result Templates
Now we want to investigate how the location of the transmission minimum changes as 
a function of length. This information can be defined as a single data point result (or so-
called 0D result). 
Select  the  General  1D  template  list  and  choose  0D  or  1D  Result  from  1D  Result 
(Rescale, Derivation, etc.) to open a dialog box in which you can specify details about 
the post-processing step. 
Since you want to know the location of the curve’s (y-) global minimum, after selecting 
0D in the Specify Action frame you should choose x at Global y-Minimum as the desired 
result.  You  can  now  choose  the  desired result  by  selecting the  MagdB  part  of the  S-
parameter result S-Parameters\S2,1:Clicking  OK  will  complete  the  definition  of  the  specific  post-processing  step  in  this 
example.The new result template was added to the list:
All defined post-processing operations are automatically carried out after every solver 
run, and the result of each of these steps is stored as a parametric result.  
Please now accept the settings by pressing the Close button and start the parameter 
sweep by clicking Start. 
Note that the parameter sweep uses the previously specified solver settings. If you want 
to change the solver settings (e.g. to activate the adaptive mesh refinement), make sure 
that the modified settings are stored by clicking Apply in the solver control dialog box. 
After  the  solver  has  finished,  close  the  dialog  box  by  clicking  the  Close  button.  The 
navigation tree will contain a new folder called “Tables” where you will find the results of 
the defined post-processing steps. 
But first  we can  have a look  at  the  basic  parametric  results  of  the  parameter  sweep. 
Please select the S-parameter result NT: 1D Results  S-Parameters  S1,1 and 1D 
Plot: Plot Type  dB 
 to obtain the following view:Similarly, you can also plot the magnitude of the transmission coefficient by selecting 
NT: 1D Results  S-Parameters  S2,1 and 1D Plot: Plot Type  dB 
:
As you see, all available results as well as the last or current result are shown together 
in one plot. Again, with help of the Result Navigator window it is now possible to easily 
select  any  result  combination  of  the  previously  calculated  parameter  values.  If  the 
window  is  not  visible,  it  can  be  activated  by  selecting  View:  Window   Windows  
Result Navigator: 
Please refer to the online documentation and the  CST Studio Suite – Getting Started 
manual for more information about the possibilities to plot parametric result data. 
Finally, the result of the previously defined 0D result template can be accessed from the 
NT: Tables  0D Results  S2,1_0D_xAtGlobalYMin folder:This curve clearly illustrates how the location (= frequency) of the transmission minimum 
changes as a function of the geometrical parameter.  
Because of the limited scope of this manual, we have only given a very brief introduction 
to the many options of storing and displaying parametric data, for example by filtering
for parameter range, so please refer to the online documentation and the CST Studio 
Suite – Getting Started manual for more information. 
Automatic Optimization of the Structure 
Let  us  now  assume  that  you  wish to modify the structure so  that  the minimum  of the 
transmission S21 is at 13 GHz (which can be achieved somewhere within the parameter 
range of 10.5 to 11.5 according to the curve above). By measuring the curve (activate 
the axis marker tool by choosing 1D Plot: Markers  Axis Marker 
), you can check 
that  the  desired  parameter  value  is  between  10.9  and  11.  However,  determining  the 
exact  parameter  value  may  be  a  lengthy  task  that  can  be  performed  equally  well 
automatically.  
CST Studio Suite offers a powerful built-in optimizer feature for this kind of parametric 
optimization.  
Before you start optimizing this structure, set the length parameter to a value within the 
valid parameter range (e.g. 11) and update the structure. You must enter the modeler 
mode (e.g. by clicking on the Components folder in the navigation tree) before you can 
modify the parameters. 
To  use  the  optimizer,  please  select  Simulation:  Solver   Optimizer 
  to  open  the 
optimizer control dialog box (or from within the time domain solver control dialog box by 
clicking on the Optimizer button):First  check  the  desired  parameter(s)  for  the  optimization  in  the  Settings  tab  of  the 
optimization  dialog  box  (the  “length”  parameter  should  be  checked).  Now  specify  the 
minimum and maximum values to be allowed for this parameter during the optimization. 
Enter a parameter range between 10.5 and 11.5.  
The default Trust Region Framework method will be used for the optimization run. The 
optimizer settings can be accessed by pressing the Properties button:
In our example, it is sufficient to keep all default settings, so we can directly close the 
dialog  box  by  pressing  OK.  Please  refer  to  the  online  documentation  for  more 
information on these settings and about the different available optimization techniques. 
The next step is to specify the optimization goal(s) by clicking on the Goals tab.Goals are based either on previously calculated results or on defined result templates. 
In this example the target is to move the minimum of the S-parameter S21 to a given 
frequency. Two goal types are available: the default type Standard as well as the type 
based  on  Filter  Designer  3D.  Please refer to the  online  help to find more  information 
about the latter one. 
We keep the goal type Standard. By clicking on the Add New Goal button, the following 
dialog box should appear, where you can select the desired complex S-parameter S2,1 
as Mag.(dB). Now specify the goal for the previously specified S-parameter data. Since 
you want to move the minimum of S21 dB in this example, you should select the move 
min operator in the Conditions frame. Afterwards, set the Target frequency to which the 
minimum should be moved to 13 GHz:
If more than one minimum exists in the S-parameter data, you can limit the frequency 
range in which the minimum will be searched for in the Range frame. In this example, 
you can just skip these settings and accept the defaults. After you click OK, the optimizer 
dialog box should look as follows:Since  you  have  now  specified  optimization  parameters  and goals,  the  next  step  is  to 
start the optimization by clicking the Start button. The optimizer will show the progress 
of  the  optimization  in  an  output  window  in  the  Info  tab  which  will  be  activated 
automatically. 
When the optimization has finished, you should confirm that the new parameter settings 
have been saved. The optimizer output window will show the best parameter settings 
with respect to the given goal.
Note that due to the sophisticated optimization technology only four transient solver runs 
were required to find the optimal solution with high accuracy. 
You  can  now  visualize  the  S-parameters  for  the  optimal  parameter  setting  (length  = 
10.9674) and should obtain the following picture (you can activate the axis marker tool 
by choosing 1D Plot: Markers  Axis Marker 
 to verify that the location of the peak is 
at 13 GHz).Instead of defining a move min goal for the optimization, you could also have chosen to 
optimize the value of the previously defined 0D result template S2,1_0D_xAtGlobalYMin  
to be equal to the desired resonance frequency of 13 GHz.
Comparison of Time and Frequency Domain Solver Results 
Thus far, all explanations have focused on the transient solver. In the next steps, you 
will compare the results of this time domain solver based on a hexahedral mesh with the 
frequency domain solver using a curved tetrahedral mesh. The frequency domain solver 
may  be  the  better  choice  for  lower  frequency  problems  or  resonant  devices  such  as 
filters. More recommendations follow in the Which Solver to Use section. 
Since these two simulation methods are based on different techniques, a comparison 
allows you to judge the accuracy of the results. Depending on which solver is faster for 
a  given  application,  the  primary  simulation  and  optimization  can  be  performed  using 
either of them, and the final verification can then be done using the other solver. The 
seamless combination of these different techniques in a homogeneous environment is 
another outstanding feature of CST Studio Suite. 
Before you recalculate the S-parameters using the frequency domain solver, you should 
first copy the results from the time domain solver into a new folder for easier comparison 
afterwards. 
Select the 1D Results folder in the navigation tree, and choose New Tree Folder from 
the context menu. You can then assign a name (e.g. “Comparison”) to the newly created 
navigation tree item. After creating the new folder, you can select the NT: 1D Results   
S-Parameters folder and choose Home: Clipboard  Copy 
. Select the newly created 
NT: 1D Results  Comparison folder and choose Home: Clipboard  Paste 
. Note 
that the copied result curves will neither be deleted nor changed when parameters are 
changed  or  S-parameters  are  recalculated.  For  organizational  purposes,  you  should 
now click on each of the new curve entries in the NT: 1D Results  Comparison folder, 
choose Rename from the context menu (or just press the F2 key) and add an appendix 
“TD” to the  curve name in order  to  indicate  that this  is  a  result from  the time  domain 
solver. The navigation tree should finally look as follows:Once  you  have  saved  the  time  domain  solver  results  for  later  comparison,  you  can 
switch  the  currently  active  solver  by  selecting  Home:  Simulation   Setup  Solver  
. Now you can simply open the frequency domain solver 
Frequency Domain Solver 
dialog box by clicking on the solver icon: Home: Simulation  Setup Solver 
:
By  default,  the  frequency  domain  solver  uses  a  tetrahedral  mesh,  automatic  mesh 
adaptation,  and  full  S-parameter  matrix  calculation,  so  you  usually  do  not  need  to 
change anything here.  
For  this  comparison  with  the  transient  solver  however,  please  make  sure  that  the 
Normalize to fixed impedance check button is also activated in the frequency domain 
solver parameters dialog box, and that the corresponding value is set to 50 Ohm. 
Most  of  the  structure's  surfaces  are  curved.  It  is  therefore  recommended  to  use  the 
curved tetrahedral mesh to obtain more accurate results, and this is the default for newly 
created projects. Curved elements provide a better approximation of the geometry than 
linear elements.  
With the default "Second" order solver elements, we recommend a curved element order 
equal  to  two  or  three.  For  higher  solver  order,  it  is  advisable  to  further  increase  the 
curvature order. The curvature order of the elements is by default chosen automatically 
so that it fits the solver order of the solver selected in Home: Simulation  Setup Solver  
  Specials, so usually there is no need to change any setting.  
To verify that the curved element order is set to Automatic, open the special tetrahedral 
mesh properties dialog box. This can generally be accessed by closing the solver dialog 
box and choosing Home: Mesh  Global Properties 
  Tetrahedral and the Specials 
button therein. However, the solver specials dialog box, accessed by the Specials button 
in  the  frequency  domain  solver  parameters  dialog  box,  provides  a  direct  link  to  this 
setting:
The  settings  for  the  solver  order  (first  to  third  order,  possibly  variable)  and  a  button 
Curvature are available in the Solver order frame. Please follow the Curvature link to the 
special mesh properties to verify that the choice for the Curved elements is Automatic:For optimization and parameter sweeps, optionally activate the check box “Move mesh 
on parameter change if possible” to allow the solver to re-use an existing (already refined 
during  mesh  adaptation)  tetrahedral  mesh  by  adjusting  it  to  the  slightly  changed 
structure. This usually saves simulation time as the tetrahedral mesh often needs neither 
to  be  generated  again,  nor  to  be  refined  during  mesh  adaptation.  In  addition,  the 
optimizer benefits from less variation in the solver results and may converge faster. 
We previously had optimized the parameter length with the Time Domain solver, so that 
there is no need to run the optimization again for the time being. Nevertheless, activate 
“Move mesh on parameter change if possible”. We will return to this setting at the end 
of the chapter for demonstration purposes. Click OK to close the special mesh properties 
dialog box, and confirm switching to the tetrahedral mesh as well as the deletion of the 
results  if  necessary.  Close  the  solver  specials  dialog  box  to  return  to  the  frequency 
domain solver parameters dialog box.
You  can  now  perform  the  frequency  domain  simulation  by  clicking  the  Start  button. 
Confirm the deletion of the non-frequency domain solver results if necessary. 
In order to see the tetrahedral mesh used for this simulation while the solver is running, 
activate the mesh mode (Home: Mesh  Mesh View 
). Select View: Sectional View 
 Cutting Plane (Shift+C) 
 to show a cut of the meshed structure, and use the handles 
to move the cutting plane:The  ports  can  be  made  visible  again  by  clicking  on  the  NT:  Ports  folder  and  then 
selecting  Show  All  Ports  from  the  context  menu.  The  solver  first  performs  a  mesh 
adaptation at the ports before the mesh inside the structure is adapted at the highest 
frequency of interest in the second step. 
The mesh adaptation frequency can be set to other values if necessary and more than 
one mesh adaptation frequency sample can be defined. Please note that for the sake of 
accuracy it is important to have a mesh adaptation sample at some frequency where 
power is delivered into the structure, for instance in the pass band of a filter. If the mesh 
adaptation  frequency  is  defined  at  a  frequency  where  most  of  the  input  power  is 
reflected, the error indicator will not "see" the possibly more important interior parts of 
the structure, and the mesh refinement will focus on the terminals of the structure rather 
than on the inner regions.  
The  solver  may  therefore  stop  the  adaptive  mesh  refinement  if  the  minimum  input 
reflection of all S-parameters at the present adaptation frequency seems to be too high. 
It  attempts  to  insert  new  adaptation  frequencies  with  a  trial-and-error  approach  that 
covers the whole frequency range, starting with monitor frequency samples, if any. The 
number of attempts to "move" the automatic adaptation frequency samples is limited. If 
no suitable frequency is found, the adaptive mesh refinement will continue at the first 
adaptation frequency again. In this case, please choose and define a suitable constant 
adaptation frequency in the Frequency samples frame of the Frequency Domain Solver 
Parameters dialog box.  
Now click on NT: Ports  Port 1 in the navigation tree to view the port mesh:
Once the mesh adaptation has converged, the solver calculates the S-parameters as a 
function of frequency by using its fast sweep capability. 
When  the  solver  has  finished,  you  can  view  the  results  in  logarithmic  scale  (dB)  by 
choosing NT: 1D Results  S-Parameters and 1D Plot: Plot Type  dB 
. Optionally, 
configure the 1D plot range with 1D Plot: Y Axis  Min/Max to for instance -70 dB to 
0 dB,  and  choose  1D  Plot:  Plot  Properties   Properties 
   Curve  Style  (or  Curve 
Style in the context menu) to configure the Marker style to use Additional marks:In the context of the General purpose broadband sweep, Additional marks indicate the 
frequency samples calculated by the solver, corresponding to the solver’s text output in 
the Messages output shown above.
The  results  are  quite  similar  to  the  results  previously  obtained  from  the  time  domain 
solver. To get a more direct comparison, copy and paste the frequency domain solver 
S-parameter  results  to  the  NT:  1D  Results    Comparison  folder  as  was  described 
above. You can add an appendix “FD” to the curve names of the new results:As you can see, the results from the time domain solver using a hexahedral mesh and 
the frequency domain solver using a tetrahedral mesh are in excellent agreement. 
It that light, we can expect that another optimization cannot further improve the results. 
Nevertheless,  please  run  the  optimizer  once  more  by  selecting  Simulation:  Solver  
Optimizer 
  and  the  Start  button.  As  we  had  selected  “Move  mesh  on  parameter 
change if possible” before, we adjust the existing mesh to the slightly modified structure 
throughout the optimization, without performing the adaptive mesh refinement again:
The optimization finishes quickly and confirms the optimized parameter length obtained 
by the time domain solver. 
Summary 
This example gave you an overview of the key concepts of a high frequency simulation 
in CST Studio Suite. You should now have a basic idea of how to do the following: 
1.  Model structures by using the solid modeler 
2.  Specify the solver parameters, check the mesh and start a time domain simulation 
3.  Use the adaptive mesh refinement feature 
4.  Visualize the port modes 
5.  Visualize the time signals and S-parameters 
6.  Define field monitors at various frequencies 
7.  Visualize the electromagnetic field distributions 
8.  Define the structure using structure parameters 
9.  Use the parameter sweep tool and visualize parametric results 
10. Use result templates for customized post-processing 
11. Perform automatic optimizations 
12. Compare the results from the time domain solver and the frequency domain solver 
If you are familiar with all these topics, you have a very good starting point for improving 
your usage of CST Studio Suite. 
For more information on a particular topic, we recommend that you browse through the 
online help system which can be opened by selecting File: Help  Help Contents – Get 
help using CST Studio Suite 
. If you have any further questions or remarks, please do 
not hesitate to contact your technical support team. We also strongly recommend that 
you  participate  in  one  of  our  special  training  classes  held  regularly  at  a  location  near
Chapter 3 – Solver Overview 
Which Solver to Use 
Since in the previous example we have mainly focused on the transient solver, and to a 
lesser extent on the general purpose frequency domain solver, it is time to clarify which 
solver  best  fits  which  application.  The  transient  solver  is  general  and  can  solve  the 
widest  range  of  electromagnetic  field  problems.  However,  for  some  applications 
specialized solvers will show much better performance while maintaining the same high 
level of accuracy. 
The  table  below  lists  a  few  typical  applications  along  with  the  solvers  that  are  most 
frequently used for solving that particular type of problem. Please note that because of 
the very wide application spectrum, not all possible examples can be listed in the table. 
Furthermore, depending on the particular structure, it may be that other solvers are more 
efficient for a particular application than those shown in the table. Therefore, this table 
should be used as a guideline rather than a rule for which solver to use. 
For further guidance,  CST Studio  Suite offers  a  configuration  wizard,  which suggests 
the best suited solver types as well as automatically predefines simulation settings for 
your specific application. As described in the Create a New Project chapter, these so-
called Project Templates can be defined by selecting File  New and Recent  New 
Project from Template  New Template. Please find more detailed information in the 
CST Studio Suite – Getting Started manual. 
Adjfl Application  
Solver Type(s) 
Connectors (coaxial, multi-pin) 
Strip lines (microstrip, coplanar 
lines) 
Stripline circuits 
Cross-talk calculations 
Printed circuit boards 
Digital circuit simulation 
Packaging problems 
Network parameter (SPICE) 
extraction 
Nonlinear diode applications 
EMI problems 
Radiation problems 
Shielding (irradiation) problems 
Monopole, dipole and multipole 
antennas 
Patch antennas 
Conformal antennas 
Helical and spiral antennas 
Antenna arrays 
Transient 
Transient, Frequency Domain, 
Multilayer 
Transient, Frequency Domain, 
Multilayer 
Transient 
Transient, Multilayer, Partial 
RLC (LF) 
Transient 
Transient, Frequency Domain, 
Multilayer, Partial RLC (LF) 
Transient, Frequency Domain, 
Partial RLC (LF) 
Transient 
Transient, TLM 
Transient, Integral equation, 
TLM 
Transient, TLM 
Transient 
Transient, Frequency Domain 
Transient, Frequency Domain 
Transient, Integral equation 
Transient, Frequency Domain
Application 
Solver Type(s) 
Waveguides (hollow, dielectric, 
coaxial) 
Transmission line networks 
Transient 
Transient 
Optical wave guides 
Optical couplers 
Optical diplexers and filters 
Transient 
Transient 
Transient, Frequency Domain 
Filters and diplexers 
Frequency Domain, Transient 
Cavities, resonator design 
Traveling wave structures 
Eigenmode 
Eigenmode 
Periodic problems (frequency 
selective surfaces, periodic band 
gap structures) 
Periodic problem with nonzero 
phase shift 
Periodic problems with non-
rectangular lattice (unit cell) 
Antenna placement 
Antenna placement (electrically 
large) 
RCS (electrically large) 
Electrically large antennas 
Frequency Domain, 
Eigenmode, Transient 
Frequency Domain, 
Eigenmode 
Frequency Domain or 
Eigenmode with Tetrahedral 
mesh 
Integral equation, Transient 
Integral equation, Asymptotic 
Integral equation, Asymptotic, 
Transient 
Integral equation, Transient 
Please  note  that  the  application  range  of  the  transient  analysis  can  be  extended 
significantly for devices that are more resonant by applying some advanced digital signal 
processing  techniques  rather  than  simply  using  a  Discrete  Fourier  Transform.  CST 
Studio Suite features an Auto Regressive (AR) Filter capable of predicting the long-term 
response of a device from a short-term response. 
The performance of the transient solver degrades for strongly resonant structures or if 
the device operates at very low frequencies. In such cases, the frequency domain solver 
may be faster, especially since in most cases a few frequency samples are sufficient to 
characterize the structure’s behavior by using the fast broadband frequency sweep tool, 
in particular with the reduced order model sweep. On the other hand, the simulation time 
of the frequency domain solver increases more rapidly with an increase in the number 
of mesh cells than the simulation time of the transient solver.  
Besides these general considerations, there are also some applications that require the 
selection of a particular solver since the corresponding electromagnetic problem can be 
solved only by using the corresponding method: 
1.  Structures  containing  nonlinear  materials  or  diodes:  The  frequency  domain 
solver cannot handle nonlinearities. Therefore, the transient solver must be used for 
these applications. 
2.  Very large structures / high frequencies: The frequency domain solver requires 
the  solution  of  a matrix  equation.  This  becomes  very  slow  and  memory  intensive
the frequency domain solver is in the order of several million, the time domain solvers 
or the integral equation solver should be used. For electrically very large problems, 
using  the  integral  equation  solver  or  even  the  asymptotic  solver  may  be  the  best 
option. 
3.  Periodic structures with non-zero phase shift: The transient solver can handle 
only periodic structures with zero phase shifts, so the frequency domain solver must 
be  used  instead.  The  phase  shift  between  adjacent  boundary  planes  or  the 
geometrical angle of incidence has to be specified in the boundary condition dialog 
box.  Note  that  the  electrical  phase  angle  between  the  boundary  planes  and  the 
geometrical angle of incidence are not identical. The frequency domain solver and 
the  Eigenmode  solver  in  combination  with  a tetrahedral mesh  also  offer a special 
unit  cell  feature,  which  allows  the  simulation  of  periodic  structures  with  a  non-
rectangular lattice. 
4.  Planar  structures:  Predominantly  planar  structures such  as microstrip filters  and 
printed  circuit  boards  can  be  solved  by  general  purpose  3D  solvers  (time  or 
frequency  domain).  However,  in  order to ideally  exploit  the  planar  property  of the 
structure the multilayer solver can be applied to these examples. 
Summarizing these statements, the following diagrams provide a rough guideline for the 
application ranges of the methods: 
Time Domain 
Analysis 
Time Domain 
Analysis 
with AR-Filter 
Frequency Domain Analysis 
Quality factor (resonant devices) 
Frequency Domain 
Analysis 
Time Domain 
Analysis 
Integral 
Equation 
Asymptotic 
Solver 
Frequency (weakly resonant devices) 
You should now have an impression of the pros and cons of the various methods. If you 
are  not  sure  which  solver  would  best  suit  your  application,  please  contact  your  local 
sales office for assistance. 
Furthermore, it should be mentioned, that the solvers can be combined with one another 
to give hybrid solution capability for structures or systems which do not fit neatly into one
Time Domain Solver 
In CST Studio Suite two high frequency time domain solvers are available, which both 
work on hexahedral meshes. One is based on the Finite Integration Technique (FIT), 
just called Transient solver, the second one is based on the Transmission-Line Method 
(TLM) and is referred to as TLM solver. Both time domain solvers are launched via the 
time domain solver dialog box Simulation: Solver  Setup Solver  Time Domain Solver 
  and  can  be  distinguished  in  the  Mesh  type  dropdown  list  by  either  specifying 
Hexahedral to choose the transient FIT solver or Hexahedral TLM for the TLM solver. 
Transient Solver 
The Transient solver applies advanced numerical techniques like the Perfect Boundary 
Approximation  (PBA)  in  combination  with  the  Thin  Sheet  Technique  (TST)  to  allow 
accurate  modeling  of  small  and  curved  structures  without  the  need  for  an  extreme 
refinement  of  the  mesh  at  these  locations.  This  allows  a  very  memory  efficient 
computation  together  with  a  robust  hexahedral  meshing  to  successfully  simulate 
extremely complex structures. 
Features like AR-Filtering or S-Parameter symmetries and reciprocity help to increase 
the performance of this solver. Furthermore, the simulation becomes even more efficient 
when applying hardware acceleration like GPU or MPI computing as described later on 
in the general chapter Acceleration Features. 
The  usage  of  the  Transient  solver  is  explained  in  detail  in  Chapter  2  -  Simulation 
Workflow, showing the basic construction steps of a coaxial connector model as well 
as the solver setup and some post-processing steps. Therefore, in the next section the 
TLM solver will be discussed in more detail: 
TLM Solver 
The TLM solver has many of the features of the Transient solver and shares a similar 
application range. This section describes the differences in model definition between 
the TLM and the Transient solver: 
Materials 
Most of the materials which are supported by the Transient solver are also available for 
the TLM solver. 
The unavailable materials are: 
  Corrugated wall and frequency dependent Ohmic sheet 
  Temperature dependent and spatially varying material 
In return the TLM solver is able to model special material types and compact models 
which will be discussed on the following pages. 
Thin panel and coated metal 
The TLM solver is able to model thin sheets of Anisotropic or Normal material without 
needing to add any mesh cells in the thickness of the sheet. This can lead to a significant 
improvement  in  simulation  time  for  devices  containing  such  thin  sheets,  for  example 
radomes or carbon fiber composite surfaces on aircraft. 
To  take  advantage  of  this  feature  in  modeling  penetrable  thin  objects,  define  a  new 
material of type Thin panel and attach to it any number of layers of Normal, Anisotropic 
or Perforations material. Perforations material is used to define wire meshes that can be
Alternatively, scattering parameters defining the reflection and transmission for a sheet 
material can be imported directly into the Thin Panel material dialog box. 
This Thin Panel material can be attached to any sheet object. If the layers of the material 
are  asymmetrically  defined,  it  is  necessary  to  attach  Local  Solid Coordinates to  each 
object made of the Thin panel material (Local Solid Coordinates  Attach Active WCS 
from the context menu). The W direction of the Local Solid Coordinates is then used to 
indicate  the  direction  of  layer  stackup,  and  the  U  direction  is  used  to  indicate  the  x 
direction of any anisotropic material in the stackup. 
Slots and seams 
Slots  and  seams  in  thin  metal  sheets  can  be  a  significant  source  of  electromagnetic 
interference. The TLM solver can model these narrow apertures without having to add 
mesh cells across the gap. This can lead to significantly faster simulations. 
To  add  a  slot  to  a  thin  metal  sheet,  first  select  the  sheet  object,  and  then  choose 
Modeling: Shapes  Faces and Apertures  Slot 
:The Type can be set to Slot, Seam or Transfer impedance.  
A  Slot  type  should  be  used  when  there  is  a  thin  gap  cut  into  the  metal.  The  slot 
dimensions are defined by the Depth and Gap values. There are limitations to the type 
of slot that can be modeled. The slot gap should be less than approximately 40% of the 
corresponding cell size that the slot passes through, and the slot depth should be less
than 5 times the cell size normal to the slot plane. Conductivity and Relative permittivity 
can be defined to represent a gasket material in the gap. 
A Seam type should be used when two sheets of metal overlap. It is defined using an 
Overlap and a Gap. The number of Segments along the slot/seam can be specified to 
represent electrical connections such as rivets along the length of the slot. 
The Transfer impedance type is used to represent the frequency dependent penetration 
of  signals through more complex  materials  in the  slot gap.  If a  number  of  points  or  a 
curve are picked before the slot dialog box is opened, then these will be used to define 
the path of the slot. Otherwise, you must define the path as a series of xyz coordinates 
along the length. Note that these coordinates must lie on the selected object. 
Waveguide ports 
The TLM solver supports most waveguide ports but only the fundamental mode can be 
excited at each port. All waveguide ports in a model must be excited before the TLM 
solver can generate scattering parameters. 
Excitation signal 
The TLM and Transient solvers use different default excitation signals. If the reference 
excitation signal is set to default, then the TLM solver will apply an impulse excitation, 
which  is  filtered  to  the  maximum  model  frequency.  The  excitation  will  then  have  a 
uniform magnitude across the frequency range of interest. 
Mesh definition 
The  TLM  solver  uses  the  same  hexahedral  mesh  as  the  Transient  solver,  but  has 
different default values since the TLM solver sometimes needs a finer mesh to capture 
the  geometry  accurately.  To  compensate  for  the  increased  mesh  fineness,  the  TLM 
solver  employs  an  octree‐based  meshing  algorithm  to  reduce  the  overall  cell  count. 
Small cells are lumped together into larger cells to create a mesh that gradually becomes 
coarser with increasing distance from the geometry.  
Launch the TLM solver and view results 
The TLM solver can be launched by choosing Home: Simulation  Setup Solver  Time 
Domain Solver 
:The Mesh type should be set to Hexahedral TLM to launch the TLM solver.
Frequency Domain Solver 
The  basic  procedure  of  running  the  frequency  domain  solver  is  demonstrated  in  the 
previous section Comparison of Time and Frequency Domain Solver Results. The 
following explanations provide some more detailed information about the settings in the 
frequency domain solver dialog box which you can open by choosing Home: Simulation 
 Setup Solver  Frequency Domain Solver 
:A special feature of the frequency domain solver is the support of both hexahedral and 
tetrahedral  meshes.  In most  cases,  you  will  compare  the  results  from  the  tetrahedral 
frequency domain solver and the hexahedral transient solver, since this allows you to 
compare results from two completely independent simulation techniques. 
An important difference between the transient solver and the frequency domain solver 
is the number of frequency samples that are calculated. Whereas in the time domain the 
number of frequency samples has almost no influence on the solver time, a classical 
frequency  domain  calculation  has  to  carry  out  the  simulation  frequency  point  by 
frequency point. Every frequency point requires a complete equation system solution. 
The frequency domain solver does however use special broadband frequency sweep 
techniques in order to derive the full broadband spectrum from a relatively small number 
of frequency samples. 
The  Method  field  in  the  solver  dialog  box  allows  choosing  the  mesh  type  and  the 
technique to generate results for the whole frequency range:
The frequency domain solver with General purpose broadband frequency sweep can be 
seen as the counterpart of the transient solver.  
As an alternative to the General purpose sweep, a Fast reduced order model sweep is 
available, which efficiently generates broadband results from very few equation system 
solver runs. 
If you are only interested in results at a few specific frequencies, the Discrete samples 
only option may be used. 
For CPU acceleration, MPI Cluster computing and distributed computing options choose 
Home:  Simulation   Setup  Solver   Acceleration.  MPI  Cluster  computing  by  default 
utilizes a domain decomposition method, which is also available on a single workstation 
if  activated  in  the  special  frequency  domain  solver  parameters.  Please  refer  to  the 
chapter  Acceleration  Features  and  to  the  online  help  for  more  detailed  information 
about the different acceleration features. 
Solver Result Settings 
To  record the fields at  particular frequencies,  monitors can  be  defined  in advance  as 
described previously for the transient solver. S-parameters and fields can be accessed 
as usual from the entries in the navigation tree. 
In order to obtain the complete S-matrix and fields, All Ports are by default selected as 
an  excitation,  which  includes  both  waveguide  port  modes  and  discrete  ports.  If  you 
consider some ports as output terminals only, for instance in a device with higher order 
waveguide port modes, the amount of result data as well as the simulation time can be 
reduced by limiting the excitation to some sources only. Some post-processing steps however may require the full S-matrix and thus All Ports 
and  All Modes.  An  example  thereof  is  the  normalization  of  S-parameters,  which  has 
been enabled for the coaxial connector example:
With Calculate port modes only enabled the solver run stops after the waveguide port 
modes have been calculated without generating any further results. This allows you to 
quickly check the port modes as described in the chapter Analyze the Port Modes. 
Store result data in cache creates full backups of the project after parametric changes, 
for instance in the course of a parameter sweep or optimization run. These results are 
stored in a subfolder of the project like Result\Cache\run000001. 
Information  about  how many  monitor  samples are  left  to calculate  is  displayed  in  the 
Frequency  samples  frame  in  a  row  labelled  Monitors,  provided  in  case  that  some 
monitors  have  been  defined.  If  no  results  have  been  calculated,  the  sample  count 
corresponds to the overall number of monitor samples. You can exclude the monitors 
from being calculated by removing the Active flag in this row. In the same way, any other 
sampling row can be ignored by removing the Active flag.By  default,  frequency  samples  are  added  automatically  until  the  S-parameters  in  the 
given  frequency  range  are  known  accurately  enough  also  between  the  calculated 
frequency  samples.  For  the  General  purpose  sweep,  this  is  indicated  by  the  third 
sampling row shown above: it has no limit for the number of samples, and blank entries 
to let From and To match the global frequency range, in this example from zero up to 
18 GHz. 
The check box in the third column Adapt. tells whether or not adaptive mesh refinement 
will be performed for the frequency samples in that row. By default, the solver runs the 
mesh adaptation at one automatically chosen frequency, as indicated by the row below 
Monitors. More details about mesh refinement samples follow in the section Adaptive 
Tetrahedral Mesh Refinement hereafter. 
Please note that the frequency domain solver cannot calculate the fields at a frequency 
of zero. Therefore, a frequency of zero will automatically be shifted to a reasonably small 
value, and S-parameters will be extrapolated to 0 Hz if the global frequency range starts 
at zero. 
Only sample definitions for the adaptive mesh refinement are considered when the Fast 
reduced  order  model  sweep  is  selected,  since  this  technique  always  generates 
broadband results during the frequency sweep:
For  the  General  purpose  sweep,  it  is  possible  to  let  the  solver  record  electric  and 
magnetic fields and fluxes for all of the frequency samples without an explicitly defined 
field monitor (option Save field results at samples in the Specials dialog box.)  
A convenient feature of the General purpose sweep with tetrahedral mesh is the ability 
to continue a solver run to calculate or even just quickly evaluate additional monitors. 
With either sweep method, you can even invoke a single calculation of the fields at a 
frequency marked in the S-parameter plot. This is described later. 
Usually there is no need to change the default settings in the list of Frequency samples. 
However,  sometimes  it  might  be  helpful  to  specify  additional  samples  . One example for such a case 
is given below.  
Adaptive Tetrahedral Mesh Refinement 
The  tetrahedral  mesh  generation  normally  yields  a  relatively  coarse  initial  mesh. 
Therefore,  we  strongly  recommend  using  the  Adaptive  tetrahedral  mesh  refinement 
option in order to ensure accurate simulation results.  
By default, curved elements are used for newly generated projects. In order to enable 
curved elements for projects created with earlier versions, first select  Home: Mesh  
    Tetrahedral.  Then  push  the  Specials  button  and  choose 
Global  Properties 
Automatic if this is not yet set. 
The  mesh  adaptation  strategies  of  the  transient  and  frequency  domain  solvers  are 
fundamentally  different.  The  transient  solver  runs  the  entire  broadband  simulation for 
every mesh adaptation pass and evaluates the worst-case deviation of two subsequent 
S-parameter results  (broadband.) The mesh  refinement  then  utilizes  information from 
the broadband result data.  
In contrast, the frequency  domain solver  usually  runs  the  mesh  adaptation only  for  a 
single frequency point at a time. Once the adaptation is complete, the broadband results 
are  computed  by  keeping  the  adapted  mesh  fixed  (however,  mesh  adaptation  on 
broadband  results  like  in  the  transient  solver  is  available  as  an  option  as  well,  as 
mentioned below.) 
Since  by  default the frequency  domain solver mesh  adaptation  runs  only  for  a single 
frequency point at a time, the location of this point within the frequency spectrum is very 
important. For weakly resonant devices, it is usually a good policy to select the highest 
frequency of interest for the mesh adaptation. This corresponds with the default setting 
and will ensure that even the fields with the shortest wavelength in the frequency sweep 
are sampled properly. 
The situation is different for strongly resonant devices as shown in the following picture
This low pass type filter has very low transmission at the highest frequency of interest. 
Running  the  mesh  adaptation  at  this  frequency  will  not  provide  sufficient  information 
about the actual filter characteristics. The adaptation will keep refining the mesh around 
the input port since all the energy is stored there and too little information is available 
about the behavior of the fields inside the structure. 
In cases like this, it is very important to specify the adaptation frequency such that it is 
located in the pass band of the filter. Please note that the solver tries to detect those 
situations by looking at the minimum input reflection of all S-parameter ports (information 
or a warning will be displayed in the message window.) If necessary, the adaptation at 
this frequency sample is stopped and continued at a different frequency: 
However, you can save some time by manually setting the adaptation frequency to a 
constant value: First select Single from the Type dropdown box of the adaptive mesh 
refinement line in the frequency list (the one that has Adapt. checked.) Then specify for 
instance 10 GHz as an adaptation frequency in the From column of the list: It is possible to define multiple adaptation frequency points, for instance equidistantly 
distributed  or  even  with  logarithmic  spacing,  by  using  the  drop  down  list  in  the  Type 
column. The highlighted line in the following figure defines three equidistantly distributed 
mesh adaptation samples from three to thirteen Gigahertz, hence 3, 8, and 13 GHz:
The  adaptive  mesh  refinement  will  then  be  sequentially  performed  at  those  discrete 
mesh adaptation frequency samples (three in the example above) before the broadband 
sweep is started with the adaptively refined mesh.  
All settings related to the adaptive mesh refinement are displayed if you press on the 
corresponding Properties button: 
The adaptive tetrahedral mesh refinement dialog box by default lets the solver run three 
to  eight  mesh  refinement  passes.  If  multiple  adaptation  frequencies  are  defined  as 
shown above, these limits hold for each mesh adaptation sample individually.  
Stopping or convergence criteria are very important for the accuracy of the results. They 
are defined in the Convergence criteria frame:Convergence  criteria  can  be  checked  after  each  discrete  adaptive  mesh  refinement 
sample  or  after  the  broadband  results  are  available.  Each  criterion  has  a  threshold 
associated with it, and a number of checks. This number defines how often the criterion 
must  fall  below  the  threshold  in  consecutive  mesh  adaptation  passes  until  the 
convergence criterion is considered as being met.  
In  the  case  of  S-parameters,  the  criterion  (Delta S)  is  determined  as  the  maximum 
deviation of the absolute value of the complex difference of the S-parameters between 
two subsequent passes. By default, all S-parameters are taken into account. In addition, 
predefined  groups  for  reflection  and  transmission  S-parameters  exist,  and  fully 
customized groups can be defined as well. The criterion may be calculated in two ways: 
  Checking the convergence criterion at discrete adaptation samples means that 
some mesh adaptation frequencies are calculated in a sequential fashion, and 
Delta S  is  used  as  a  criterion  for  the  adaptive  mesh  refinement  loop  at  those
mesh  adaptation  samples.  It  refers  to  the  S-parameters  at  those  particular 
frequencies. For each adaptation frequency, the mesh is refined several times. 
The broadband frequency sweep is calculated afterwards.  
 
In order to take the S-parameters in a specified frequency range into account, 
the broadband frequency sweep must be applied before calculating Delta S as 
the maximum difference of all S-parameters in the frequency range.  
For field probe results, the stopping criterion is relative, with the maximum of the probe 
values of a specific probe type calculated so far used as a reference value.  
In  addition  to  the  S-parameters  and  probe  results,  any  Result  Template  may  be 
employed as convergence criterion. In particular, for models without S-parameter ports 
this is a convenient way to ensure the convergence of the mesh adaption process. An 
arbitrary  number  of  0D and  1D  Result Templates  can  be  defined  and selected  in the 
Check after broadband calculation list in the Result Template… drop down menu: 
New Result Templates may be defined choosing [New Result Template…] in the drop 
down menu or by Post-Processing: Tools  Result Templates 
, enabling user defined 
specifications  of  application-tailored  convergence  criteria.  Please  refer  to  the  online 
documentation and the CST Studio Suite – Getting Started manual for more information 
about this versatile functionality. 
The  convergence  criterion  Portmode kz/k0  applies  to  the  adaptive  mesh  refinement 
during the port mode calculation for waveguide ports. It is the maximum magnitude of 
the difference of the port modes' complex propagation constant kz divided by the free 
space propagation constant k0 between two port mesh refinement passes.  
During the adaptive mesh refinement, newly created nodes in the tetrahedral mesh will 
be  projected  onto  the  original  geometry  in  order  to  improve  the  approximation  of  the 
geometry (True Geometry Adaptation.)  
If you expand the Details in the Adaptive Tetrahedral Mesh Refinement properties dialog 
box  by  pressing  the  corresponding  button,  you  can  access  some  special  refinement 
settings and the refinement percentage:The settings in the Refinement percentage frame determine how much the mesh may 
grow between two consecutive adaptive mesh refinement passes. The default values 
are  a  compromise  between  accuracy  and  computational  resources.  A  larger  mesh 
growth per pass might lead to more accurate results in less passes at the cost of higher 
memory requirements and possibly a longer simulation time. However, a very high mesh 
growth percentage might lead to mesh refinement also far away from regions of interest.
In  this  case,  it  may  be  more  efficient  to  perform  more  mesh  adaptation  passes  with 
moderate mesh growth for each single pass. 
The  performance  of  the  adaptive  mesh  refinement  can  be  further  accelerated  by  an 
appropriate refinement of mesh edges on conductors. Because of the potentially highly 
varying  field  strength  and  distribution,  a  special  treatment  for  these  areas  during  the 
adaptive  mesh  refinement  passes  often  leads  to  faster  overall  convergence  and  is 
recommended  especially  for  planar  structures  as  the  low  pass  filter  example  shown 
above. Different levels of this strategy are selectable within the Singular edge refinement 
frame. 
Please  close  the  adaptive  tetrahedral  mesh  refinement  dialog  box  to  return  to  the 
frequency domain solver parameters dialog box.  
Note that with the Hexahedral mesh chosen as the Mesh type, the adaptive refinement 
is performed in a broadband fashion as described for the time domain solver in “Adaptive 
Mesh  Refinement”  on  page 41.  Adaptive  mesh  refinement  frequency  samples  are 
therefore ignored for the methods based on the hexahedral mesh. 
Adaptive mesh refinement is one ingredient for reaching a certain level of accuracy. The 
default  settings  satisfy  the  accuracy  needs  for  many  applications,  with  reasonable 
computational effort. However, if the thresholds of the mesh refinement stop criteria are 
tightened, it is recommended to change other settings correspondingly. 
Solver Order and Curved Elements 
The  special  settings  which  influence  the  accuracy  of  the  results  as  well  as  the 
performance of the simulation comprise Accuracy in the Equation system solver frame 
(smaller  values  represent  higher  accuracy)  and  the  solver  order.  In  the  frequency 
domain solver dialog box, choose the Specials... button to open the following dialog box:By default, the tetrahedral frequency domain solver uses second order elements to get 
an  excellent  sampling  of  the  fields  at  high  frequencies.  This  also  allows  the  use  of 
relatively few elements per wavelength by comparison with the first order elements used 
by the solvers based on hexahedral grids.
A higher solver order allows you to achieve accurate results with less mesh cells and 
potentially  less  memory  consumption  than  a  lower  order  if  the  structure  contains 
electrically large regions free of geometric details. For a given mesh resolution, a higher 
order  will  provide  more  accurate  results.  However,  some  structures  may  need  a 
relatively fine mesh if their geometry is much finer than required to properly sample the 
wave  phenomena.  Typical  application  examples  for  this  are  printed  circuit  boards  or 
integrated  circuit  packages.  In  such  cases,  using  first  order  elements  rather  than  the 
standard second order elements can reduce simulation time and memory requirement 
significantly.  
To  use  first  order  elements,  select  1st  (low  memory)  in  the  Solver  order  field  in  the 
Specials dialog box: 
Whenever  the  solver  order  is  changed,  for  instance  from  second  to  first  order,  the 
resolution  of  the  initial  mesh  and  some  parameters  in  the  adaptive  mesh  refinement 
dialog box should be adjusted accordingly.  
For  new  projects,  these  settings  are  applied  automatically  in  a  way  that  ensures  a 
suitable  resolution  of  the  wavelength  in  media  (for  projects  generated  with  earlier 
  
versions of CST Studio Suite, please choose Home: Mesh  Global Properties 
Tetrahedral and select Automatic from the drop down menu in the Maximum cell frame). 
A higher solver order may result in a smaller number of mesh cells. 
A third order field approximation scheme is available, and can be selected in the drop 
down box:Another  reason  for  choosing  higher  order  is  to  increase  the  accuracy  of  the  solver 
results. As an example for "third order", select Home: Mesh  Global Properties 
  
Tetrahedral,  and  specify  for  instance  four  Cells  per  wavelength  as  the  Maximum  cell 
size:
The initial tetrahedral mesh then will be sufficiently dense for second order, but as third 
order has been chosen, the results are even more accurate for the given mesh.  
If the option for Variable order is activated, the frequency domain solver with tetrahedral 
mesh is allowed to use a different solver order for each tetrahedron, rather than constant 
order throughout the calculation domain.  
The solver order's upper limit is then given by the order selected in the drop down combo 
box left to the Variable check box (for instance first to third order, for the selection shown 
above.)  
A constant second or third order usually is the best choice, unless the amount of memory 
available is not sufficient. In that situation, you may want to enable the Variable option, 
especially if the structure contains electrically small details as well as large voids. The 
solver will then assign an initial distribution of the solver order to the tetrahedrons, and 
this distribution may potentially be changed automatically in the course of the adaptive 
mesh refinement. 
Dispersive Materials 
Another  important  difference  between  the  frequency  domain  solver  and  the  transient 
solver is the way both simulators handle dispersive materials.  
For a given list of material parameters at various frequencies, the transient solver always 
needs to fit a certain dispersion model of general order to the data. During the simulation, 
the broadband material behavior will then be taken from the model rather than using the 
originally specified data.  
Since the frequency domain solver computes the broadband sweep by a sequence of 
individual  frequency  point  calculations,  the  solver  can  simply  linearly  interpolate  the 
given list of frequency points directly. As a result, the frequency domain solver can use 
user-specified material property tables more directly than the transient solver can.
When comparing the results of these two solvers it may be advantageous to configure 
the  frequency  domain  solver  to  use  the  same  material  model  with  fitted  data  as  the 
transient  solver. This  can  be  done  by  checking the  Fit  as in  Time Domain  box  in the 
Materials frame of the solver Specials dialog box. 
Continued solver runs 
You may continue the solver's frequency sweep with additional fixed or automatically 
chosen samples, newly added field monitors, and additional adaptive mesh refinement 
after one solver run has finished.  
If  additional  results  for  already  calculated  frequencies  are  requested,  for  instance  by 
defining  new  monitors  or  by  using  Calculate  Fields  at  Axis  Marker,  the  solvers  with 
tetrahedral mesh will attempt to reload the solution to quickly perform additional post-
processing steps without the need to solve the equation system again. 
A very interesting feature of this solver is that some intermediate information concerning 
the fields is stored even if no field monitors are specified. Once a simulation is completed 
and the S-parameters are visualized, it is relatively fast and straightforward to obtain the 
fields at certain frequencies. 
To  demonstrate this feature,  let  us  assume  that you  have run  a  simulation for  a filter 
structure  using  either  the  general  purpose  or  the  fast  reduced  order  model  sweep 
method and are now inspecting the S-parameters:You may now be particularly interested in the fields at the resonance peak. The easiest 
way to obtain this information is to place the axis marker at the location of the resonance 
(1D Plot: Markers  Axis Marker 
  Move Marker to Minimum):
Then click on the plot and choose Calculate Fields at Axis Marker from the context menu 
to  obtain  the  fields  at  this  particular  frequency.  The  field  computation  itself  will  be 
relatively quick since many intermediate data have already been stored during the initial 
S-parameter calculation. 
Workflow Summary 
The following summarizes the input necessary for frequency domain analysis: 
1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material (optional). 
4.  Define the structure. 
5.  Set the frequency range. 
6.  Set the boundary conditions (optional). 
7.  Define the excitation ports. 
8.  Set the monitors (optional). 
9.  Select sweep method (optional). 
10.  Start the frequency domain solver. 
11.  Analyze the results (S-parameters, field patterns, result templates, etc.). 
12.  Continue to generate additional results (optional).Integral Equation Solver 
An integral equation solver computation is an analysis in the frequency domain based 
on  a  surface  and  wire  mesh.  The  model  setup  is  very  similar  to  a  general  purpose 
frequency  domain  computation.  The  following  explanations  provide  some  more 
information about the specific settings in the integral equation solver dialog box. 
Integral Equation Solver Parameters 
You can open the dialog box by choosing Home: Simulation  Setup Solver  Integral 
Equation  Solver 
.  As  with  the  general  purpose  frequency  domain  computation,  an 
integral  equation  calculation  has  to  carry  out  the  simulation  frequency  by  frequency. 
Every frequency point requires a complete solver run.
A special broadband frequency sweep technique can be used in order to derive the full 
broadband spectrum from a relatively small number of frequency samples. In order to 
make use of this technique, you should allow an automatic sampling of frequency points 
by  selecting  the  type  Automatic  in  the  table  and  then  activating  the  Use  broadband 
frequency  sweep  option.  The  solver  will  then  automatically  adapt  the  selection  of 
frequency points so that the broadband curve can be obtained by calculating a minimum 
number of samples.To store the fields at particular frequencies, monitors need to be defined in advance as 
described previously for the transient solver. These monitor frequencies are then added 
to the frequency list. 
The integral equation solver cannot calculate the fields at a frequency of zero. Therefore, 
a zero frequency will automatically be shifted to a reasonably small value. 
The S-parameters and fields can be accessed as usual from the navigation tree. 
Acceleration 
For  CPU  and  GPU  acceleration,  distributed  computing  options  and  MPI  computing 
  Acceleration. Please refer to 
settings choose Simulation: Solver  Setup Solver
the chapter Acceleration Features or to the online help for more detailed information 
about the different acceleration features. 
Accuracy Settings 
The solver accuracy can be controlled by selecting one of the predefined values (Low, 
Medium  or  High)  in  the  Accuracy  field.  Alternatively,  selecting the  option  Custom  will 
activate a Settings button to open a dialog box for more detailed solver control. Please 
refer to the online documentation for more information about the available settings within 
this dialog box.  
Special settings 
The special settings dialog box can be opened by choosing Simulation: Solver  Setup 
  Specials. It is possible to enable real ground or infinite PEC or PMC ground 
Solver 
and to choose a preconditioner for the linear equation system solver in this dialog box. 
The  integral  equation  solver  can  make  use  of  user-specified  material  property  tables 
more directly than the transient solver can. For the sake of comparing these two solvers’ 
results, it may be advantageous to advise the integral equation solver to use the same 
material model fitted data as the transient solver does by checking the Constant fit and 
dispersion fit as in Time Domain box in the solver Specials dialog box. 
MLFMM 
In its  standard  implementation, the  integral  method generates  a full  matrix  containing 
information  about  the  coupling  between  each  pair  of  surface  mesh  elements.  The 
Multilevel  Fast  Multipole  Method  (MLFMM)  is  a  fast  method  to  reduce  the  simulation 
complexity. It uses boxes (clusters of surface mesh elements) to combine the couplings, 
together  with  a  recursive  scheme  to  increase  the  efficiency  (please  see  schematic 
below). The MLFMM speeds up the matrix vector multiplication for an iterative solver 
and  also  enhances  the  memory  efficiency.  It  scales  very  well  for  large  problems 
(geometry >> wavelength) with a complexity of O(N log N).                FMM 
MLFMM 
Characteristic Mode Analysis (CMA) 
A  dedicated  tool  for  the  efficient  analysis  of  characteristic  modes  on  PEC-structures 
including  the  influence  of  possibly  present  dielectrics  is  included  with  the  integral 
equation solver. It is activated by selecting CMA in the Excitation / CMA settings frame 
of the solver dialog box.
The analysis can be performed either at discrete, user-defined frequency samples or in 
a frequency range with automatic mode tracking. If the option Enable mode tracking is 
inactive, the mode analysis is performed at the frequency points as defined in the list of 
samples.  At  every  discrete  frequency,  the  user-defined  Number  of  modes  with  the 
largest modal significance is calculated. No mode matching between different samples 
is done with this setting. In contrast, mode matching and automatic mode tracking are 
performed if the option Enable mode tracking is selected. With this setting, the specified 
Number of modes with the highest modal significance is calculated at the user-defined 
Frequency  for  mode  sorting.  These  selected  modes  are  tracked  over  the  whole 
simulation frequency range. Add field monitors and select the option Calculate monitors 
to visualize the eigencurrents and related quantities.  
The following summarizes the input necessary for a frequency domain analysis using 
the integral equation solver: 
1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material (optional). 
4.  Define the structure. 
5.  Set the frequency range. 
6.  Set the boundary conditions (optional). 
7.  Define the excitation. 
8.  Set the monitors (optional). 
9.  Start the integral equation solver. 
10. Analyze the results (S-parameters, field patterns, result templates, etc.). 
Multilayer Solver 
For structures which are mainly planar, such as microstrip filters, patch antennas, etc., 
the  multilayer  solver  might  be  the  best  choice.  The  multilayer  solver,  based  on  the 
method of moments, does not require discretization of the transversally infinite dielectric
and metal stackup. Therefore, this solver can be more efficient than general purpose 3D 
solvers for this specific type of application. 
To create an appropriate mesh for the multilayer solver the mesh type Multilayer has to 
be selected (Simulation: Mesh  Global Properties 
  Multilayer). 
A simulation model consists of two parts:  
  The metallic structure modelling the conductors and ports 
  The layer stackup 
The  layer  stackup  will  be  created  automatically  if  the  layers  are  defined  by  normal 
material bricks. The layer stackup can also be defined by using the background dialog 
box (Modeling: Materials  Background 
).  
Generating the layer stackup from the geometric model 
When the stackup is defined in the geometric model by means of several metal/dielectric 
layers,  the  mesh  generation  will  automatically  exclude  the  bricks  used  for  layer 
definition. Metal sheets which define a decoupling plane will be added to the layer stack 
automatically.  Holes  in  the  metal  sheets  will  be  considered  as  apertures  in  the 
simulation. 
Whether a solid or sheet will be considered for the layer stackup or not can be modified 
by the local mesh properties dialog box.  
Generating the layer stackup by using the background dialog box 
The second way of defining the layer stackup is by means of the background properties. 
In this case, the background dialog box has to be expanded by enabling the check box 
Multiple layers first.An arbitrary number of dielectric and metal layers can then be defined in the  Multiple 
layers frame. 
Multilayer Solver Parameters 
You can open the multilayer solver dialog box by choosing Home: Simulation  Setup 
Solver  Multilayer Solver 
. A multilayer calculation has to carry out the simulation 
frequency by frequency, and every frequency point requires a complete solver run.
A special broadband frequency sweep technique can be used in order to derive the full 
broadband spectrum from a relatively small number of frequency samples. In order to 
make use of this technique, you should allow an automatic sampling of frequency points 
by  selecting  the  type  Automatic  in  the  table  and  then  activating  the  Use  broadband 
frequency  sweep  option.  The  solver  will  then  automatically  adapt  the  selection  of 
frequency points so that the broadband curve can be obtained by calculating a minimum 
number of samples.To store the fields at particular frequencies, monitors need to be defined in advance as 
described previously for the transient solver. These monitor frequencies are then added 
to the list of calculated frequencies. 
For  CPU  acceleration,  distributed  computing  options  and  MPI  computing  settings, 
choose  Simulation:  Solver    Setup  Solver 
    Acceleration.  Please  refer  to  the 
chapter Acceleration Features or to the online help for more detailed information about 
the different acceleration features. 
The multilayer solver cannot calculate the fields at a frequency of zero. Therefore, a zero 
frequency  will  automatically  be  shifted  to  a  reasonably  small  value.  For  very  low 
frequencies the multilayer solver supports low frequency stabilization. 
The  S-parameter  and  field  results  can  be  accessed  as  usual  from  the  entries  in  the 
navigation tree. 
Advanced  settings  are  available  in  the  special  multilayer  solver  settings.  This  can  be 
opened by choosing Simulation: Solver  Setup Solver 
  Specials:
General 
The Deembedding option activates the automatic internal deembedding of waveguide 
and  multipin  ports  to  ensure  most  accurate  S-Parameter  results.  In  addition,  the  S-
Parameters are then normalized to the calculated port impedances. 
The multilayer solver uses an open boundary formulation in x- and y-direction and will 
ignore electric boundary conditions in x- and y- direction by default. This can be changed 
by deactivating the option Open BC (x, y). 
Materials 
The  multilayer  solver  can  make  use  of  user-specified  material  property  tables  more 
directly than the transient solver can. For the sake of comparing the results of these two 
solvers it may be advantageous to advise the multilayer solver to use the same material 
model fitted data as the transient solver does by checking the Constant fit and dispersion 
fit as in Time Domain. 
Characteristic Mode Analysis (CMA) 
A dedicated tool for the efficient analysis of characteristic modes is integrated into the 
multilayer solver. It is activated by selecting CMA in the Excitation / CMA settings frame 
of  the  solver  dialog  box.  Please  refer  to  the  relevant  paragraph  in  section  Integral 
Equation Computations for an explanation of specific settings for CMA. 
The  following  summarizes  the  input  necessary  for  frequency  domain  analysis 
calculations using the multilayer solver:1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material and layer stackup (optional). 
4.  Define the structure. 
5.  Set the frequency range. 
6.  Set the boundary conditions (optional). 
7.  Define the excitation. 
8.  Set the monitors (optional). 
9.  Start the multilayer solver. 
10. Analyze the results (S-parameters, field patterns, result templates, etc.). 
Asymptotic Solver 
An asymptotic computation is an analysis in the frequency domain based on a so-called 
ray-tracing (shooting and bouncing rays) technique. In this approach, the scattered fields 
are  determined  by  performing  a  local  surface  integration  of  the  ray-fields  at  the  ray-
object  intersections.  The  solver  is  typically  used  for  scattering  or  antenna  placement 
computations of electrically very large objects which are difficult to handle by other EM 
solution methods. 
Due to its limited range of applications, the asymptotic solver's setup is a little different 
from that of the other more general solvers. The following explanations provide some
basic  information  about  the  asymptotic  analysis  workflow.  Please  refer  to  the  online 
documentation for more detailed information. 
Asymptotic Solver Parameters Dialog Box 
The  dialog  box  can  be  opened  by  choosing  Home:  Simulation    Setup  Solver   
Asymptotic Solver 
:The actual layout of this dialog box will change depending on the selection in the Mode 
field. The lower part of the dialog only shows the tabs that are useful in the context of 
the selected mode. 
For Monostatic scattering calculations, the sweep parameter definitions are located in 
two different tabs. One tab specifies the Frequency sweeps and the other one describes 
the Observation angle sweeps. 
For Bistatic scattering calculations excitation directions and observation directions are 
not identical as in the case of monostatic calculations. Therefore, the sweep parameters 
require an additional Excitation angle sweeps tab. 
In addition to the monostatic and bistatic scattering modes described above, the solver 
also features a Field sources mode, which allows scattering computations with farfield 
(point)  or  nearfield (box)  sources rather than plane  waves.  A  Range  profiles  mode is 
available to calculate range profiles and sinograms of radar targets efficiently. Similarly, 
the ISAR mode computes 2D-images of a scattering target. Finally, with the Field of view 
mode visibility diagrams of antennas on a platform can be computed. 
The availability of tabs in the solver dialog changes depending on the application specific 
requirements of the selected mode. Please refer to the online documentation for more 
information about the modes of operation.
The electric field strength and the polarization of the incident plane wave can be set in 
the Incident field polarization settings frame by adding plane wave definitions to the list. 
After pressing the Add button, the following dialog box will appear: 
This dialog box allows you to select a particular type of polarization such as Horizontal, 
Vertical,  Left  hand  circular  polarized  or  Right  hand  circular  polarized.  In  addition,  a 
Custom  option  can  be  selected  where  the  complex  amplitudes  for  the  incident  plane 
wave's theta and phi components can be specified. 
Sweep Definitions 
Each of the sweep definition lists can contain a number of individual sweep descriptions. 
A particular sweep can be added by pressing the Add button. For frequency sweeps the 
following dialog box allows the specification of lower and upper frequency bounds as 
well as a step width: 
A single frequency point can be specified by setting the lower and upper bounds to the 
same value. 
For angular sweeps, the following dialog box will appear:Here, you can select a particular type of sweep:
Single Point:  Single theta / phi direction rather than a sweep 
Theta / Phi:   Sweep for both theta and phi angles 
Theta:   
Phi: 
Sweep for theta while keeping phi to a fixed value 
Sweep for phi while keeping theta to a fixed value 
For varying angles theta or phi, upper and lower bounds as well as the corresponding 
step width are specified in degrees. 
In addition, the Store rays for each excitation direction option can be checked in which 
case the solver will store information for a certain number of representative rays. These 
rays can be visualized by selecting the corresponding result entry in the navigation tree. 
Please note that for Bistatic scattering mode, the Store rays option needs to be checked 
for both the excitation angle sweep as well as the observation angle sweep in order to 
store the rays for the respective incident / observation angle pairs. 
The  Calculate  hotspots  for  each  excitation  direction  option  is  only  displayed  in 
Monostatic  scattering  mode.  Turning  this  option  on  for  a  particular  observation  angle 
sweep will calculate hotspot images for each of its excitation / observation directions. A 
hotspot result can then be visualized by selecting its corresponding result entry in the 
navigation tree. 
Accuracy Settings 
The solver accuracy can be controlled by selecting one of the predefined values (Low, 
Medium  or  High)  in the  Accuracy  field.  Alternatively,  selecting  the  option  Custom  will 
activate a Settings button to open a dialog box for more detailed solver control. Please 
refer to the online documentation for more information about the available settings within 
this dialog box.  
Another  important  parameter  is  specified  in the  Maximum  number  of  reflections field. 
This  setting  limits  the  maximum  number  of  reflections  for  each  particular  ray  as  it  is 
bouncing back and forth inside the simulation domain. Typical settings for this parameter 
are in the range of two to five. The solver will display some statistics about the actual 
number of multiple reflections, and also will provide some feedback as to whether this 
parameter may need to be increased further. 
For  CPU  and  GPU  acceleration  as  well  as  distributed  computing  options  choose 
    Acceleration.  Please  refer  to  the  chapter 
Simulation:  Solver    Setup  Solver 
Acceleration  Features  or  to  the  online  help  for  more  detailed  information  about  the 
different acceleration features.Workflow Summary 
The following list summarizes the input necessary for asymptotic analysis: 
1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material to vacuum. 
4.  Define the structure. 
5.  Set the frequency range. 
6.  Set all boundary conditions to open. 
7.  Start the asymptotic solver. 
8.  Analyze the farfield or RCS results.
Eigenmode Solver 
The eigenmode solver calculates a finite number of modal field distributions in a closed 
device.  Linear  and  curved  tetrahedral  meshes  as  well  as  hexahedral  meshes  are 
supported.  
Since the eigenmode analysis does not always require the definition of excitation ports, 
this  step  can  often  be  omitted.  The  definition  of  field  monitors  is  also  not  necessary 
because the modes themselves contain all available information about the device. Thus, 
after setting up the model, you can immediately proceed to the eigenmode solver dialog 
box (Home: Simulation  Setup Solver  Eigenmode Solver 
), which looks as follows:The  eigenmode  solver  by  default  uses  the  tetrahedral  mesh,  which  we  therefore 
describe first. 
Tetrahedral Mesh 
Three different eigenmode solver method settings are available for the tetrahedral mesh: 
Automatic,  Classical  (Lossless)  and  General  (Lossy).  The  Automatic  mode  choses 
between the two solver options, depending on the materials, the boundary conditions, 
and  whether  or  not  ports  should  be  considered  for  external  Q  factor  calculation. 
Automatic is the recommended choice. 
The  Classical  (Lossless)  and  General  (Lossy)  methods  work  on  completely  different 
mathematical foundations and implement a different set of features.  
Classical (Lossless) is sufficient for most of the cases where an Eigenmode analysis is 
applied, especially for closed and loss-free structures. This solver can be considered as 
a robust, fast, and memory efficient solver.  
However, we recommend the General (Lossy) solver if the analyzed structure is either 
not closed, or contains lossy materials with frequency dependent complex permittivity or 
permeability.  Because  the  General  (Lossy)  solver  considers  the  waveguide  ports  as 
open, it also computes an accurate external Q-factor for each mode. Also for structures 
with unit cell, open, or conducting wall boundaries, this solver should be the first choice. 
The  unit  cell  feature  (Floquet  ports  are  not  supported)  simplifies  the  simulation  of 
periodic  structures  with  translational  periodicity  in  the  xy-plane,  for  instance  with 
rectangular or non-rectangular lattice.
The simulation time increases with the number of modes. Thus, only as many modes as 
required should be specified in the corresponding field. A strict lower limit to the modes' 
frequencies can be defined in Frequencies above. 
The external Q-factor can be calculated for structures with waveguide ports attached to 
the device.  
If the Classical (Lossless) method is forced instead of relying on the Automatic choice, 
losses  are  ignored  for  the  eigenmode  calculation  itself.  This  is  justified  for  many 
applications  and results in  a  better  performance  of the  eigenmode  solver. With  some 
level  of  approximation,  losses  then  can  be  considered  by  post-processing  after  the 
eigenmode solver run.  
If  in  addition  the  option  Consider  material  losses  in  post-processing  only  is  disabled, 
lossy  and  dispersive  materials  are  evaluated  at  a  fixed  frequency  and  the  materials’ 
complex  permeability  and  permittivity  are  then  applied  to  the  whole  frequency  range. 
This Evaluation frequency for the material parameters is defined in the Specials dialog 
box and defaults to the center frequency. It can be modified if Consider material losses 
in post-processing only was disabled before:The  option  Consider  material  losses  in  post-processing  only  is  not  relevant  for  the 
General (Lossy) solver, as it always considers the defined losses and directly computes 
a  total  Q-factor  for  each  calculated  mode  (e.g.  due  to  volume,  external  Q  losses). 
Consequently, the Materials frame is disabled for the General (Lossy) solver:
It is important to note that the General (Lossy) solver calculates complex eigenvalues, 
where  the  imaginary  part  belongs  into  the  defined frequency  range  and  the  Q-factor, 
which is also dependent from the real part of the complex eigenvalue, is greater or equal 
to the value specified in Minimum Q. As already mentioned above, a strict lower limit to 
the modes' frequencies can be defined in Frequencies above. 
Because many applications which require an eigenmode solver have curved surfaces, 
it  is  advisable  to  activate  the  curved  elements  for  the  tetrahedral  mesh,  since  they 
provide a better approximation of the geometry than linear elements. The latter are a 
special case of the former: linear elements are "curved" with a curved element order of 
one. Curved elements are activated automatically for newly created projects. 
The curvature order of the elements is usually chosen automatically so that it fits with 
the  solver  order  of  the  solver  selected  in  Home:  Simulation    Setup  Solver   
Eigenmode Solver 
. 
For projects created with earlier versions, the curved element order can be changed in 
the  special  tetrahedral  mesh  properties.  This  would  require  closing  the  solver  dialog 
boxes  and  choosing  Home:  Mesh    Global  Properties 
    Tetrahedral  and  the 
Specials  therein.  However,  a link  in  the  solver  specials  provides  direct  access to this
The settings for the solver order (first to third order) and a button Curvature are available 
in  the  Solver  order  frame.  Please  follow  the  Curvature  link  to  the  special  mesh 
properties. Verify that the choice for the Curved element is “Automatic” or change the 
selection accordingly:The option “Move mesh on parameter change if possible” works as for the frequency 
domain solver with tetrahedral mesh (described on page 63). It is in particular useful for 
parameter sweeps and optimization runs with small modifications of the structure. 
You may confirm the settings and close the special mesh properties dialog box and the 
solver specials dialog box by pressing OK to return to the eigenmode solver dialog box.  
Please  enable  the  option  Consider  material  losses  in  post-processing  only  again  if 
necessary, to restore the defaults shown at the beginning of the section. Note that is 
only  available  for  the  Classical  (Lossless)  method.  Also  finally  restore  the  default 
Automatic for the method. 
The  adaptive  tetrahedral  mesh  refinement  is  activated  by  default  for  new  projects  to 
ensure that the results are converged to a certain level of accuracy:
For  projects  generated  with  earlier  versions,  please  consider  enabling  the  adaptive 
tetrahedral mesh refinement. 
Click on Properties to open the Mesh Adaptation Properties dialog box. The stopping 
criterion  for  the  adaptive  mesh  refinement  of  the  eigenmode  solver  is  the  Maximum 
frequency  variation.  For  each  eigenmode,  the  magnitude  of  the  difference  of  the 
eigenmode's  frequency  between  two  subsequent  passes  is  calculated.  This  value  is 
then  divided  by  the  corresponding  eigenmode  frequency  at  the  first  of  the  two 
subsequent passes. The maximum of these values for all modes up to the Number of 
modes to check finally yields the Maximum frequency variation. 
You can now perform the eigenmode simulation by clicking the Start button. 
In order to see the tetrahedral mesh used for this simulation while the solver is running, 
activate the mesh mode (Home: Mesh  Mesh View 
). 
Results are stored in a common location in the navigation tree for both tetrahedral and 
hexahedral mesh. 
Hexahedral Mesh 
First change the Mesh type to Hexahedral in the eigenmode solver dialog box (Home: 
Simulation  Setup Solver  Eigenmode Solver
Two different eigenmode solvers are available for the hexahedral mesh: AKS (Advanced 
Krylov Subspace) and JDM (Jacobi Davidson Method). 
These methods work on completely different mathematical foundations. The JDM solver 
can be considered as a more robust Eigenmode solver technology, but the AKS solver 
may be faster if many modes are requested. Therefore, we recommend the JDM solver 
especially  if  a  small  number  of  modes  (for  instance  one  to  five  modes)  has  to  be 
calculated. Otherwise, the AKS solver should be used. 
The  solution  of  lossy  eigenmode  problems  is  a  challenging  task  and  the  proper 
consideration of losses will significantly slow down the simulation. Even if the JDM solver 
is able to directly solve the lossy eigenmode problem, it may sometimes be advisable 
(especially for very small losses) to first calculate the loss-free eigenmode problem and 
then obtain losses and Q-factors of the device using a perturbation method in the post-
processing.  
The perturbation method requires material losses to be defined before the eigenmode 
simulation is started. Running the AKS solver will always calculate the loss free problem 
by simply ignoring the loss definition. The JDM solver by default also ignores the losses
In the  eigenmode  solver  control  dialog  box  with hexahedral  mesh  selected,  the  most 
important controls are the Method (as discussed above) and the number of Modes. 
The typical simulation procedure with a hexahedral mesh is as follows: 
1.  Depending on the number of modes, choose the proper Eigenmode solver method 
for the hexahedral mesh:  
  For loss free problems with a small number of modes (for instance one to 
five modes) choose JDM. 
  For  loss  free  problems  with  many  modes  (for  instance  more  than  five 
modes) choose AKS. 
  For the direct solution of lossy problems choose JDM and disable Consider 
material losses in post-processing only. 
  If  only  higher  order  modes  are  required  with  eigenfrequencies  above  a 
certain threshold, choose the JDM solver and enter a value for Frequencies 
above, which is slightly lower than the threshold. 
2.  Enter  the  desired  number  of  Modes  (N).  The  solver  will  then  compute  the  first  N 
modes of the device. For the AKS solver it is often advantageous to specify more 
modes to be calculated than you actually need, e.g. enter 20 modes to be calculated 
if you actually need 15. In most cases, it is a good choice to calculate at least the 
first ten modes of the device.  
3.  Click the Start button. 
The following description applies to the AKS method with ten modes. After the solver 
has finished, a summary of the calculated modes will appear in the message window:
When using the AKS solver, sometimes a few of the higher modes will not be calculated 
with sufficient accuracy and thus be marked with “*”. However, this does not affect the 
accuracy of the lower modes and is the reason you should specify a higher number of 
modes than you actually need. 
The AKS eigenmode solver internally needs an estimate for the frequency of the highest 
mode  of  interest.  Usually  this  frequency  is  estimated  automatically  and  improved  by 
refinement passes if necessary.  
Performing  estimation  refinement  passes  reduces  the  performance  of  the  AKS 
eigenmode calculation. To speed up the AKS eigenmode calculation in such a case, you 
can manually enter a guess for the frequency of the highest mode you are looking for. 
The  AKS  eigenmode  solver  automatically  derives  such  a  guess  from  previously 
calculated results and displays this value in the message window: 
You  can  set  this  guess  in  the  special  settings  dialog  box,  which  can  be  opened  by 
clicking the Specials button in the solver control dialog box. In the Guess field you should 
enter the proposed guess as 18.3438 GHz in this example:If  you  are  unsure about this setting  you should specify  zero for  automatic  estimation. 
Note  that  this  setting  is  used  only  by  the  AKS  method.  This  guess  will  now  affect  all 
subsequent calculations and should speed up the AKS solver significantly.
Results 
You can access the eigenmode solver results for the Nth mode from the navigation tree: 
Navigation tree 
2D/3D Results  Modes  Mode N  e 
2D/3D Results  Modes  Mode N  h 
2D/3D Results  Modes  Mode N  Surface 
Current 
2D/3D Results  Modes  Mode N  Energy 
Density 
Type of result 
Electric field 
Magnetic field 
Surface current 
field 
Energy density 
Please  refer  to  the  Resonator  Tutorial  for  more  information  on  post-processing  the 
results. 
For CPU acceleration and distributed computing options choose Home: Simulation  
Setup  Solver    Eigenmode  Solver 
    Acceleration.  Please  refer  to  the  chapter 
Acceleration  Features  or  to  the  online  help  for  more  detailed  information  about  the 
different acceleration features. 
Workflow Summary 
The following summarizes the input necessary for eigenmode calculations: 
1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material (optional). 
4.  Define structure. 
5.  Set frequency range. 
6.  Set closed boundary conditions (optional). 
7.  Start eigenmode solver. 
8.  Analyze  results  (field  patterns,  frequencies,  losses/Q-factors,  result 
templates, etc.). 
Choosing the Right Port Type 
The  proper  definition  of  ports  is  essential  for  accurate  S-parameter  computations.  In 
measurement  set-ups,  the  device  under  test  needs  to  be  connected  to  the  network 
analyzer by using low reflection probes or applying proper de-embedding techniques. 
Care must be taken with the probe connection because the measured S-parameters will 
otherwise become inaccurate. 
In general, the same problems exist for EM field simulations. The port connection needs 
to be loss-free and have very low levels of reflection. The basic problem here is to launch 
and extract the fields as seamlessly as possible at the ports. Fringing effects should be 
kept to a minimum. 
In general, three types of ports need to be distinguished: 
1.  Discrete edge ports 
2.  Discrete face ports 
3.  Waveguide ports 
Discrete edge ports can be seen as lumped circuit elements with an internal resistor 
and a current source in parallel. Depending on the solver type, these ports consist of a 
single  lumped  element  in  the  middle  and  two  perfectly  electrically  conducting  wires
edge. A certain voltage / current relation is then introduced across the lumped element, 
and the S-parameters are calculated based on the element’s currents and voltages. Any 
discrete port can also be defined as a current or voltage source. 
Discrete face ports are very similar to the discrete edge ports described above. The 
major  difference  is  that  this  lumped  element  is  represented  by  a  face  rather  than  an 
edge.  Again,  depending  on  the  solver  type,  these  ports  consist  of  a  single  lumped 
element in the middle and two perfectly electrically conducting faces connecting the port 
to  the  structure  or  a  distributed  lumped  element  over  the  complete  face  area.  The 
advantage of the latter type of connection is that the port has a lower self-inductance. 
It  is  important to  note  that there may  be fringing  effects  at  the transition between  the 
structure and the discrete port (of either type). This will always be the case when the 
geometry  of  the  structure’s  transmission  lines  is  different  from  the  geometry  of  the 
discrete  ports,  that  is,  in  most  cases.  Please  note  that  discrete  face  ports  typically 
introduce smaller discontinuities than discrete edge ports when connected to stripline or 
microstrip type structures. 
Despite  these  shortcomings,  discrete  ports  provide  a  convenient  and  flexible  way  to 
attach ports to a given structure. The accuracy of the simulation is normally sufficient 
when the size of the discrete port is a tenth of a wavelength or less. 
The  most  accurate  results  can  be  obtained  by  using  waveguide  ports.  These  ports 
normally provide very low levels of reflection and distortion and therefore are the best 
choice whenever very high accuracy is required. 
CST Studio Suite uses a 2D eigenmode solver to calculate the relevant mode patterns 
in the port plane. Consequently, the definition of waveguide ports requires enclosing the 
entire field filled  domain  in  the  cross  section  of  the  port  area.  This  general  approach 
allows the accurate modeling of arbitrary port types, like empty or coaxial waveguides, 
microstrip or coplanar lines and even more complex setups like multi-conductor, single-
ended  or  periodic  waveguide  structures.  The  calculated  modes  are  automatically 
classified  and  characteristic  properties  like  wave  or  line  impedance  are  presented. 
Please refer to the online documentation for more detailed information.  
Please note that with the help of the Schematic of CST Studio Suite it is possible to de-
embed the port influence from the S-matrix by removing the effect of the port to structure 
transmission matrix from each of the ports. Please refer to the CST Studio Suite - Circuit 
Simulation and SAM (System Assembly and Modelling) manual for more information. 
Please refer to the port overview page in the online help system for more information 
about all port types. 
Antenna Computations 
As presented before in the Which Solver to Use section, different antenna applications 
can  be  optimally  solved  with  appropriate  solvers  recommended  by  the  configuration 
wizard.  However,  some  general  principles  of  antenna  computations  are  common, 
regardless of which solver type is used and will be discussed in the following. 
The main difference between an antenna calculation and the S-parameter calculation 
described earlier in this document lies in the definition of the boundary conditions. Since 
the antenna radiates into free space, open (or absorbing) boundary conditions must be 
used.  Therefore  simply  select  “open”  boundaries  in  the  Simulation:  Settings   
Boundaries
When simulating antennas, open boundary conditions require some space between the 
device  and  the  boundary  planes  for  optimum  performance  and  accurate  farfield 
calculations.  Since  the  open  boundary  conditions  are  very  accurate,  only  a  small 
distance is necessary. However, if you are not sure about the amount of space needed, 
simply  choose  “open  (add  space)”  from  the  boundary  options.  In  this  case,  the 
necessary space is estimated automatically. The settings for space to be added can be 
adjusted in the dialog box accessed by the Open Boundary… button. 
For the calculation of the antenna farfield gain or directivity patterns (farfield distribution 
in spherical or Ludwig coordinate systems, left and right hand polarization, axial ratio), 
“farfield monitors” need to be defined before the simulation starts. Similar to the definition 
of  the  other  field  monitors,  an  arbitrary  number  of  these  monitors  can  be  defined  for 
various frequencies. This means that you can compute the antenna farfield for multiple 
frequency  points  from  a  single  transient  analysis.  Each  farfield  monitor  records  the 
farfield  over  the  sphere  in  all  directions.  They  can  be  specified  in  the  Simulation: 
Monitors  Field Monitor
After  the  simulation  is  complete,  you  can  access  your  farfield  results  from  the  NT: 
Farfields  folder.  Typical  antenna  characteristics  such  as  main  beam  direction,  gain, 
efficiency,  side  lobe  suppression,  etc.  are  automatically  calculated  and  displayed. 
Please refer to the online help tutorial Patch Antenna for more information. 
As  mentioned  above  it  is  possible  to  define  farfield  monitors  at  selected  frequencies. 
However, if you are using the transient solver and are interested in the farfield behavior 
over a wide frequency range you have the options of either defining a broadband farfield 
monitor  or  to  use  farfield  probes.  Similar  to  the  frequency  farfield  monitors,  the 
broadband monitor calculates the farfield data for the full angular range (theta, phi) and
Some applications require the farfield information only at a few (theta, phi) locations. In 
such cases it may be advantageous to use farfield probes: Simulation: Monitors  Field 
Probe 
, Field = E-field (Farfield) or H-field (Farfield):In this dialog box, you can specify the type of farfield, the location and the orientation of 
the desired probe in Cartesian, spherical or Ludwig coordinate systems. Please refer to 
the online documentation for more information about this feature. 
Another very interesting functionality is the use of result templates in combination with 
farfield  calculations.  The  basic  functionality  of  result  templates  has  already  been 
demonstrated  in  the  previous  example.  There  are  also  some  automated  farfield 
templates  available  when  selecting  Farfield  and  Antenna  Properties  from  the  Select 
Template  Group  dropdown  list  (Post-Processing:  Tools    Result  Templates 
).
Choosing the Farfield Result template from the Add new post-processing step dropdown 
list will open the following dialog box: 
Here you can select one of the pre-configured farfield results. However, if needed the 
corresponding settings can be adjusted in detail by pressing the All Settings button:You  can  now  select  which  one  of  the  previously  defined  farfield  monitors  should  be 
processed with an already performed excitation (e.g. [1] corresponds to excitation at port 
1, and [pw] corresponds to a plane wave excitation). You can change several farfield
settings such as the farfield component, the polarization, the coordinate system or even 
an  antenna  array  setup.  Finally,  the  modified  settings  can  be  stored  as  a  new 
configuration by selecting Store Setup button. 
The result of this farfield processing template is either a single result curve or a 0D value, 
which can then be further processed by other result templates or simulation steps. As 
an example, you could extract the location of a certain farfield maximum by using a 0D 
result template and then use this value for an optimization of the main lobe direction to 
a certain angular location or magnitude. Please refer to the online help system for more 
information. 
The following summarizes the input necessary for antenna calculations: 
1.  Select an antenna project template (optional). 
2.  Set units (optional). 
3.  Set background material (optional). 
4.  Define structure. 
5.  Set frequency range. 
6.  Set (open) boundary conditions (optional). 
7.  Define excitation ports. 
8.  Set (farfield) monitors and/or probes. 
9.  Specify farfield result processing templates (optional). 
10. Start appropriate solver. 
11. Analyze results (input impedance, farfields, etc.). 
Simplifying Antenna Farfield Calculations 
In  many  cases  where  only  the  antenna  farfield  pattern  is  of  interest,  rather  than  the 
feeding point impedance, it is not necessary to model the actual geometry of the feeding 
point. However, when you want very accurate results of the antenna’s input reflection, it 
is essential to model the feeding point exactly as it is.  
In cases where you are able to use a simplified model, you can use discrete ports rather 
than waveguide ports (please refer to the Choosing the Right Port Type section earlier 
in this chapter).  
If you start the analysis of a new antenna, it is usually a good approach to begin with a 
discrete port. Since the model is easier to build, you will obtain initial S-parameter and 
farfield pattern results quickly. This will allow you to assess the principles of operation 
of  the  antenna  before  optionally  increasing  the  accuracy  by  constructing  a  detailed 
model of the feeding point geometry. 
The  following  pictures  show  feeding  point  models  of  a  simple  patch  antenna  as  an 
example.  
a) Simplified model of the feeding point with a discrete
b) Detailed model of the feeding point using a waveguide 
port 
In picture a) the antenna is fed by a discrete edge port which represents a current source 
with an internal resistance. This approach delivers accurate farfield results but may yield 
S-parameters, which are not directly comparable to the measurements. 
In picture b) the antenna is fed by a coaxial line (as in the real-world structure) which 
gives accurate farfield patterns and S-parameters. 
Sensitivity Analysis 
Derivatives  of  S-parameters  and  of  other  network  characteristics  such  as  Y-  and  Z-
parameters  with  respect  to  geometric  and/or  (simple)  material  parameters  can  be 
calculated  via  the  so-called  "sensitivity  analysis".  This  functionality  is  available  with 
different  feature  sets  for  the  tetrahedral  frequency  domain  solver  as  well  as  for  the 
hexahedral transient solver. The eigenmode solver with tetrahedral mesh can calculate 
derivatives of the modes’ frequencies in the course of the sensitivity analysis. 
Referring to the coaxial connector example of chapter 2, you can define a face constraint 
by first selecting the corresponding end face of the inner conductor stub, then defining 
a  geometric  face  constraint  (Modeling:  Tools    Modify  Locally    Define  Face 
Constraints
Keep the default selection of Set distance to plane to define the new face constraint as 
the distance of the face to the local coordinate system in w-direction. Before closing the 
dialog  box,  please  click  on  the  Parameterize  button  to  define  a  new  correspondent 
parameter with the initial values as shown below: 
In  the  following,  the  sensitivity  analysis  is  performed  with  the  tetrahedral  frequency 
domain  solver.  In  order  to  consider  sensitivity  results  during  the  simulation,  the  Use 
sensitivity analysis box at the bottom of the solver dialog box has to be activated: 
Press the Properties button to see the list of parameters that are currently available for 
the sensitivity analysis. In this case, geometric parameter “length” is not available for the
With knowledge of the nominal value and of the first derivative, the sensitivity (i.e. the 
variation of a network parameter with respect to a design parameter) can be calculated 
in  a  small  neighborhood  of  the  nominal  value.  The  results  will  be  displayed  in  the 
navigation tree NT: 1D Results  S-Parameter Sensitivity in separate folders for each 
design parameter. 
As a post-processing step, a yield analysis can be performed using the sensitivity data 
calculated  in  the  solver  run.  Select  Post-Processing:  Signal  Post-Processing   Yield 
  and  find  the  results  again  in  the  navigation  tree  NT:  1D  Results    S-
Analysis 
Parameter Yield:In addition to the yield analysis, the sensitivity of the S-parameter results can also be 
investigated with help of a tuning slider. Selecting the results of interest in the navigation 
tree, the Sensitivity Tuning is available in the context menu. After activation, a tuning 
slider allows the modification of all defined design parameters:
Interactively changing the parameter with the slider will directly show the corresponding 
tuned results compared to the nominal values in the 1D plot window:Please consult the online help for further details about the sensitivity and yield analysis. 
Digital-Signal Calculations 
A  digital-signal  calculation  is  typically  performed  using  the  transient  solver.  Thus,  the 
overall  simulation  procedure  is  similar  to  the  procedure  described  earlier  in  this 
document. 
The main difference between a digital calculation and a typical S-parameter calculation 
is the definition of the excitation signal. 
For S-parameter calculations, the excitation signal for the transient analysis is typically 
defined by a Gaussian pulse, for which the Fourier spectrum is also given by a Gaussian 
pulse  covering  the  entire  frequency  band  of  interest.  Therefore,  the  time  signal  is 
determined mainly by the frequency band.  
By contrast, the excitation signal for a digital simulation is described in the time domain 
by  specifying  rise-,  hold-  and fall-times  of  a  rectangular  pulse.  You  can  define  a new 
excitation  signal  by  clicking  on  NT:  Excitation  Signals  and  selecting  New  Excitation 
Signal 
 from the context menu to open the following dialog box:
In  the  example  studied  above  (with  the  time  unit  set  to  ps)  the  settings  define  a 
rectangular shape with a rise-time of 100 ps, a hold-time of 200 ps and a fall-time of 100 
ps. The rise- and fall-times of 100 ps correspond to a bandwidth of approximately 10 
GHz. The maximum simulation time is given in the Ttotal field and is set to 1000 ps in 
this  example.  For  manually  defined  excitation  signals,  the  solver  automatically  stops 
after simulating the given total time range. The parameters of the rectangular excitation 
function are specified in the currently selected time units.  
Once the rectangular excitation signal has been defined, it can be viewed by selecting 
it from the navigation tree NT: Excitation Signals:You can now define the rectangular signal signal1 as the reference signal by selecting 
Use as Reference from the context menu:
The new reference signal is now used for all subsequent transient simulations. However, 
you can also specify additional excitation signals in order to excite different ports with 
individual  excitation  signals.  Please  refer  to  the  online  documentation  for  more 
information about this feature. 
In our example, the coaxial bend shows the following response to the digital excitation:The excitation signal “i1” shows the given rise-, hold- and fall-times. The output signal 
“o2,1” has a distinctly distorted pulse shape (due to the dispersion of the coaxial bend) 
and a time delay because of the finite length of the transmission line. 
In addition to this simplified description of the excitation signal, it is also possible to set 
a user defined pulse shape. Please refer to the online documentation for details. 
The following summarizes the input necessary for digital calculations: 
1.  Select an appropriate project template (optional). 
2.  Set units (optional). 
3.  Set background material (optional). 
4.  Define the structure. 
5.  Set the frequency range (covering all desired harmonics). 
6.  Set the boundary conditions (optional). 
7.  Define the excitation ports. 
8.  Set the monitors and/or probes (optional). 
9.  Define the excitation signal parameters. 
10.  Start the transient solver.
11.  Analyze the results (usually the time signals). 
There  are  some  post-processing  macros  available  which  are  especially  dedicated  to 
  Results  
digital simulations such as eye diagram computations (Home: Macros 
Eye Diagram, TDR, etc.  Eye Diagram) or the exchange of excitation signals after the 
    Results    Eye  Diagram,  TDR,  etc.    Exchange 
simulation  (Home:  Macros 
Excitation).  
Coupled Simulations 
The smooth interaction between different modules or solvers of CST Studio Suite allows 
for a straightforward coupling of 3D EM simulation with other simulation methods. 
 Adding Circuit Elements to External Ports 
For each 3D EM simulation setup inside CST Studio Suite two fundamentally different 
views of the model exist. The standard view is the 3D model representation, which is 
visible by default. However, in addition, a schematic view can be activated by selecting 
the corresponding tab under the main view: Once  this  view  is  activated,  a  schematic  canvas  is  shown  where  the  3D  structure  is 
represented by a single block (CST Studio Suite block) with terminals: 
The  terminals  have  a  one-to-one  correspondence  with  the  3D  structure’s  waveguide 
modes or discrete ports. The schematic view now allows for easy addition of external
circuit elements to the terminals of the 3D structure. The connection of these arbitrary 
networks to the 3D model can either be realized as a standard or a transient EM/circuit 
co-simulation.  
Please refer to the online help system and the CST Studio Suite - Circuit Simulation and 
SAM (System Assembly and Modelling) manual for more information about this topic. 
Coupled Simulations between High Frequency Solvers 
In order to establish a coupling between 3D high frequency solvers inside CST Studio 
Suite, near- or far-field data from one solver can be reused as field sources in another 
solver. This can be useful for antenna placement or EMC radiated emission simulations 
or to exchange component information without exchanging the model itself. A special 
Hybrid Solver Task is available to simplify the setup of such workflows. 
Please refer to the Field Source Overview page in the online help description and to the 
CST  Studio  Suite  –  Circuit  Simulation  and  SAM  (System  Assembly  and  Modelling) 
document for more detailed information about this topic. 
Coupled Simulations with Thermal or Mechanical Solvers 
Field monitor results from a high frequency transient, eigenmode or frequency domain 
solver can be used as heat sources for thermal simulations. Furthermore, based on the 
thermal results a subsequent stress simulation can be performed, and the impact of the 
stress  on  the  EM  simulation  can  then  be  considered  when  performing  a  sensitivity 
analysis  with  the  frequency  domain  or  eigenmode  solver  with  a  tetrahedral  mesh.  
Besides  the  above  coupling  between  the  EM  solvers  and  the  thermal  solvers, 
temperature  fields  calculated  by  the  thermal  solvers  can  be  imported  by  the  high 
frequency  time  and  frequency  domain  solvers  to  simulate  the  effects  of  temperature 
dependent materials. 
Please refer to the CST Studio Suite - Thermal and Mechanical Simulation document 
for  more  detailed  information  about  the  workflows  for  setting  up  EM-Multiphysics 
couplings and refer to the Material Overview page in the online help for information about 
temperature-dependent materials supported by the high frequency transient solver and 
frequency domain solver. 
Coupled Workflow with Cable Simulation 
Hybrid  simulations  considering  radiation  from  and  irradiation  into  a  cable  can  be 
performed using the high frequency time domain 3D field solvers together with the cable 
modeling  tools  inside  CST  Studio  Suite.  Unidirectional  coupling  is  either  done  in  the 
frequency or in the time domain, while bi-directional coupling is available when doing a 
transient simulation.  
Please  refer  to the  CST  Studio  Suite  -  Cable  Simulation  document  for  more  detailed 
information about this simulation type. 
Acceleration Features 
In addition to  optimization and  parameter  sweep techniques,  CST  Studio Suite  offers 
other more hardware related possibilities to accelerate the simulation. In the case of the 
transient solver choose Simulation: Solver  Setup Solver 
  Acceleration in order 
to specify the control for CPU and hardware (GPU) acceleration, distributed computing
Similar options are available for the other solvers in CST Studio Suite. Please refer to 
the online help (section Simulation Acceleration) for more detailed information about
Chapter 4 – Finding Further Information 
After carefully reading this manual, you will already have some idea of how to use CST 
Studio Suite efficiently for your own high frequency simulations. However, when you are 
creating your own first models, some questions will arise. In this chapter, we give you a 
short overview of the available documentation. 
The QuickStart Guide 
The main task of the QuickStart Guide is to remind you to complete all necessary steps 
in order  to  perform  a  simulation successfully.  Especially  for  new  users  –  or for  those 
rarely using the software – it may be helpful to have some assistance. 
The QuickStart Guide is opened automatically on each project start if the checkbox File: 
Options   Preferences  Open  QuickStart  Guide  is  checked.  Alternatively,  you  may 
start this assistant at any time by selecting QuickStart Guide from the Help button 
 in 
the upper right corner. 
When  the  QuickStart  Guide  is  launched,  a  dialog  box  opens  showing  a  list  of  tasks, 
where  each  item  represents  a  step  in  the  model  definition  and  simulation  process. 
Usually, a project template will already set the problem type and initialize some basic 
settings like units and background properties. Otherwise, the QuickStart Guide will first 
open a dialog box in which you can specify the type of calculation you wish to analyze 
and proceed with the Next button:As  soon  as  you  have  successfully  completed  a  step,  the  corresponding  item  will  be 
checked and the next necessary step will be highlighted. You may, however, change 
any of your previous settings throughout the procedure. 
In order to access information about the QuickStart Guide itself, click the Help button. 
To obtain more information about a particular operation, click on the appropriate item in 
the QuickStart Guide. 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by choosing File: Help  Help 
. The online help 
system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  directly  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties. 
When no  specific  information is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system.
Please refer to the CST Studio Suite - Getting Started manual to find some more detailed 
explanations about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  Some documented macro examples.  
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Spark3D User Manual
Spark3D Online Help
The Spark3D help system is organized into the following main topics:
Tutorials
Guided tour of Spark3D features. Recommended for new users.
Manual
Using Spark3D - reference manual.
Objective
Spark3D is a general software tool  for Radio Frequency (RF) breakdown analysis. It is based on powerful and accurate
numeric algorithms for predicting both Corona (arcing) and Multipactor breakdown onsets, which are two of the main
high power effects that can severely damage a device. In this context, it is the final objective of this software tool to
help the microwave components designing/manufacturing industries to decrease both the time to market and the
development costs for the next generation of communication systems.
Features
Spark3D is an efficient software tool for the accurate analysis of high power effects in RF structures. It imports the
electromagnetic field computed with some of the most widespread electromagnetic simulation software tools like:
Fest3D®
CST® 2015 SP3 (or higher)
CST® 2012-2015 SP2    
ANSYS® HFSS™  
Besides, Spark3D, is also able to incorporate arbitrary external DC fields to the simulation, either Electric or Magnetic,
computed with CST EM Studio® and with ANSYS® MAXWELL™, or by importing rectangular CSV format mesh files.
Spark3D offers a great versatility and is the first commercial software capable to compare high power results using
different electromagnetic kernels.
Multipactor analysis
The Multipactor module is based on a full 3D electron tracker that employs a Leap-Frog algorithm for the path
integration and the Vaughan model for SEY characterization of materials. This technique allows the analysis of
Multipactor in complicated structures which involve arbitrary shapes in short computational times.
Corona analysis
Corona module is based on a numeric algorithm that uses an adapted FEM technique to solve the free electron
density continuity equation. This technique allows the analysis of Corona in complicated structures which involve
arbitrary shapes in short computational times.
Limitations
There are few limitations when importing fields:
Spark3D does not have information on the kind of material of the imported mesh points and will take
everything (besides boundaries) as air/vacuum. Therefore the following considerations must be done:
Importing from HFSS™: The user must take care of exporting only the air/vacuum region of the device.
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2.1 Spark3D Tutorials
The goal of the tutorials is to show you how to use the basic features of Spark3D with practical examples.
There are two tutorials dedicated to Multipactor and Corona analysis, respectively. They are self-contained and are
structured in a similar way. The different sections of the tutorials allow you to create, set-up and run a simulation from
scratch. The files used in this tutorial are distributed with Spark3D installation in the "Tutorial Examples" folder. It is
also recommended  to explore the list of examples provided to you during the installation in the "Examples" folder.
Corona tutorial: A step-by-step guide to set-up and run a Corona analysis.
Multipactor tutorial: A step-by-step guide to set-up and run a Multipactor analysis.
2.1.1 Corona Tutorial
In this tutorial you will learn how to run your first Corona simulation with Spark3D. It presents a guided example for
which the whole Corona analysis process is explained step-by-step using TUTORIAL_EXAMPLE.spkx file located in
Examples folder, distributed with the installation of the software. It is divided in 4 parts:
1.  Preliminaries shows you how to create new models by importing EM solutions from compatible external EM
software.
2.  Specifying Regions describes you how to define regions of interest where the analysis of Corona can be
focused.
3.  Specifying Signals describes you how to define new pulsed signal for Corona simulation.
4.  Running a Corona configuration. The main parameters are set for Corona analysis and the simulation is
launched. An overview of the Corona output is given.
1.  Running Corona video. We set the parameters to record a Corona video and describe how to play it.
5.  Analysis of Corona Results shows you how to interpret and visualize the output data.
2.1.1.1 Preliminaries
First, the EM field data of the device under study must be loaded. From the Start working window, you can either
create a new project or open an existing one, in which the EM field is automatically loaded.
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To create a new project, press the New Project button and browse in the explorer to select a EM field file previously
created with one of the Spark3D compatible EM solvers . The different formats supported by
Spark3D include Fest3D, CST, HFSS, each one with its corresponding file extension.
In this tutorial, you will load an existing example. Click on the Open examples button and select
TUTORIAL_EXAMPLE.spkx.
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A new window will appear with the information of the newly opened file. You see in the left side of the window the
tree structure of the current project, which includes a Model with:
Four analysis regions: the so called Circuit, which corresponds to the imported mesh of the entire device, and
three more regions defined for corona and multipactor analysis.
Three continuous wave signals, which contain the EM fields that were imported from CST Microwave Studio.
Two multicarrier signals, defined through the previous continuous wave signals.
One modulated signal, defined from an imported baseband signal ASCII file.
Three multipactor configurations, each one with its already existing results and a video configuration.
Two corona configurations, each one with its already existing results and a video configuration.
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Once the EM files have been loaded, it is advisable to visualize the EM fields through the 3D CAD viewer included with
Spark3D distribution, Paraview (more information on Kitware's Paraview can be found in http://www.paraview.org/).
Click on the View model button of the toolbar and the main window of Paraview will open with the EM fields
corresponding to the continuous wave signals previously computed inside the device for each region of analysis,
which looks like:
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In the Pipeline browser (located in the left side of Paraview window) there is a list of the fields corresponding to the
different analysis regions and continuous wave signals defined in the Model. You can enable/disable the view of each
one by clicking on the icon eye located at the left side of the browser.
With the left, right and center buttons of your mouse you can rotate, zoom and translate the camera view. In the
menu bar there is a display list where the different fields (magnitude, real and imaginary parts of electric and magnetic
fields) can be selected.
2D cuts allow you to visualize the fields inside the structure, so that you can detect the potential areas of the structure
where the breakdown onset is more likely to occur, that is, where the electric field is maximum. For each field
corresponding to a certain analysis region and continuous wave signal, you can create a 2D cut with the slice button 
 that is located in the menu bar.
In the figure below you see for Circuit region and signal CW4 that the irises in the center of the device are the main
candidates for breakdown onset.
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2.1.1.2 Specifying Regions
The high power analysis of a device can be carried out in two different ways:
analyzing the whole device in one shot or
focusing the simulation on critical regions defined by the user.
There are different reasons to take advantage of user-defined regions. As long as the device is divided in several areas
it is possible to compare the breakdown threshold of each one and determine where the discharge will take place.
Besides, computing the breakdown onset on specific regions is faster than taking into account the whole circuit.
Finally, the user can increase the mesh density involved in the solution of the problem improving the precision of the
calculation and avoiding memory overflow limitations.
Prior to the creation of simulation regions it is advisable visualizing the electromagnetic fields in order to detect the
critical areas of the structure in terms of breakdown.
Working with regions
A region of study corresponds to a box, which is defined through its center and size. These input variables can be
determined from the visualization window of Paraview, where a cube axis helps us to obtain their values. In our
example, the regions will be defined through the following values:
RectangularRegion 1
Center (m)
Size (m)
0.0245
0.024
0.01
0.006
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RectangularRegion 2
Center (m)
Size (m)
RectangularRegion 3
Center (m)
Size (m)
0.017128
0.024
0.01
0.006
0.032338
0.024
0.01
0.006
In order to define an analysis region, you should double click on the Analysis Regions tree item of Spark3D. A new
window will be opened:
On the left hand side of the window, you see the tree corresponding to all existing regions. By default, there is a
predefined region named Circuit, which takes into account the whole imported model and is enabled for analysis.
From this window you will be able to:
add a new region from the Add Region button,
modify the existing ones by changing the values of its defining properties,
change a region's name by right clicking on a certain region item,
copy/paste/delete a region using the corresponding right-click options on a specific region item,
visualize all defined regions together with the device through the Visualize button,
or visualize a single region together with the device through the Visualize 3D right-click option of the chosen
region item.
By clicking on a specific region you can modify its defining properties. Click on RectangularRegion 1 and you see that
in our example the input variables:
Center x, Center y, Center z
Size x, Size y, Size z
have the values given in the table above corresponding to one of the analysis regions. Note that the units of these
variables are ALWAYS meters.
The validity of all defined regions will be checked when accepting the actions done through the OK button. It checks if
every region contains any mesh points. If there is some region which is not correct, an error message will pop up and
you will have to adjust the region's properties so that the region intersects the device.
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Besides, you can also visualize the relative position of all regions with respect the structure under study. Press
Visualize button and you see that the defined regions correspond to the critical areas previously recognized in the
lowpass filter.
Through the 3D CAD viewer it is possible to modify the defined boxes and visualize at once the changes. From the
Pipeline browser located on the left hand side of the window, select the box you want to modify . Then in the Object inspector window select Properties tab, where the
geometrical parameters of the box, that is, its dimensions and center position, will be displayed. You can change them
and by clicking on Apply button you can see the result of the modification. It is important to point out that the
changes made in the 3D CAD viewer will not be automatically transferred to the defining parameters of the regions.
Once you have found the proper values that suit your problem, you have to write them in the corresponding cells of
the Analysis regions window of Spark3D.
If you want to create a new region you just click on Add region button. A new region will be created with a default
name that you can change with the Rename right-click option. You can fill in the input parameters. On the contrary, if
you want to erase a region, you should select it and either select the Delete right-click option or directly press the
Supr button. You can also copy and paste one existing region through the corresponding options by right clicking on
the selected region.
Once you have done all your modifications, you can either preserve them through OK button or discard them through
the Cancel button (or alternatively closing the window).
Errors
When checking the validity of a region it may occur that it is not correct, that is, there are no mesh points inside it. The
reason for this could be one of the following:
The region does not lie inside the model mesh. You should check its defining input variables.
The region is smaller than the mesh elements. You should enlarge the region or change the mesh.
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2.1.1.3 Specifying Signals
When a model is imported, a list of CW signals, corresponding to the imported frequencies, is automatically defined in
the Project tree.  For Corona simulations, the user can also add two kind of signals:
modulated signals, using an existing CW signal as carrier and importing an ASCII file for the baseband signal (I-
Q quadrature modulation).
pulsed signals, using an existing CW signal and defining the properties of a train of pulses.
See Creating or modifying signals section for detailed information.
Open the Signal window by double-click on the Signals node in the tree, or by right-click and selecting Edit
Signals.
The Signal window shows, to the left-hand side, the single carrier signals, divided in three sections:
Continuous wave: It shows the different CW signals that have been imported. These signals can be renamed or
deleted, but no CW signals can be added unless a new model is imported.
Modulated: It shows the defined modulated signals (if any) and the assigned CW carrier.
Pulsed: It shows the defined pulsed signals (if any) and the assigned CW carrier.
The MC signals are in the right-hand side part of the window.
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Adding Modulated Signals
To add a modulated signal press the button "Add Modulated Signal" in the Signal window. A new Modulated Signal
window will open in order to edit it. In this example a modulated signal has been defined. Press right-click on it and
 button) to open its corresponding Modulated Signal window.
select Edit (or press the
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Press Import File button in Input data section to import the modulated base-band signal from an ASCII file.
See Creating or modifying signals section for further information on import data format. In this example a 4-QAM
modulation has been imported with 150 symbols, raised cosine filter with roll-off factor of 0.25 and 90e6
symbols/second (duration of 166 ns, 112.5 MHz of bandwidth).
Adding Pulsed Signals
To add a pulsed signal press the button "Add Pulsed Signal" in the Signal window. A new Pulsed Signal window will
open in order to edit it. In this example a pulsed signal has been defined. Press right-click on it and select
Edit (or press the 
 button) to open its corresponding Pulsed Signal window.
In this example, the pulsed signal is characterized by a duty cycle of 1% and a Pulsed Repetition Rate (PRF) of 10 KHz,
which correspond to a Pulse Repetition Interval of 0.1 milisecond and a pulse length of 1 microsecond. As you change
the values of PRF and duty cycle, the corresponding ones for PRI and pulse length are automatically updated.
2.1.1.4 Running Corona mode
 In order to configure a Corona simulation, you must
either right click on the CoronaConfig item of the Project tree and choose Open Corona Configuration,
or double click on it.
Corona configuration window will be opened.
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In the left hand side of the window lies a tree, Fields, which shows all continuous wave signals and regions defined in
the Model. Through its check-boxes you can select which combinations of continuous wave signals and regions will be
analyzed in the simulation. In our example, there are three continuous wave signals, whose frequency values are 9, 9.5
and 10 GHz and three already defined regions, which correspond to the central irises of the lowpass filter.
Press the Edit Regions button and a new window will be opened, where you can configure the analysis regions. 
You can see the defined regions of study for this example by clicking on the Visualize button. The 3D CAD
viewer Paraview will open the EM field of the device together with the defined regions, represented by boxes. For
further information on how to work with regions see Specifying Regions tutorial.
We are now ready to launch the simulation. Press the Run button in the CoronaConfig window.
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The simulation starts now and in the main window, the results window is opened so you can see the output in run-
time.
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For each analyzed region and signal, the results include:
The representation of the Paschen curve, that is, the breakdown power threshold versus pressure.
A table located in the left hand side of the window that corresponds to the points of the Paschen curve.
Besides, in the table situated on the top of the window, for each analyzed region and signal, the breakdown power
threshold in the whole pressure sweep is shown. With this information it is straightforward to identify for each signal
which is the critical region of the device. For further details on how to interpret the results see Analysis of Results
tutorial.
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In this example, the Corona simulation shows that in the chosen pressure range the lowest breakdown power ocurrs
at 9 GHz at region RectangularRegion 1. It  is located in the center of the circuit and has a Corona breakdown of
220.27 W at 9 mBars, which is, finally, the limiting power of the device.
 Command-line execution
In order to run Corona configuration in command-line, you must use the following:
spark3d.exe --
input="C:\Users\User1\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx"
--config=Project:1/Model:1/Configurations:1/EMConfigGroup:1/CoronaConfig:1//
For futher information see command-line interface section.
2.1.1.4.1 Running Corona video
Alternatively to a corona analysis, it is possible to record a video of the electron density growing inside the 3D
structure for a particular input power above the breakdown threshold.
In order to set the Corona video parameters, you must
either right click on the VideoCoronaConfig item of the Project tree and choose Open video configuration,
or double click on it.
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Video Corona configuration window will be opened.
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Select:
1.  Fields: CW 4 (9.5 GHz) and RectangularRegion 1 
2.  Input Power (W): 350
3.  Pressure (mBar): 12
4.  Number of Frames: 15
5.  Accuracy: High
6.  Stop criterion: Maximum electron density aprox. (e/cm^3): 1000
The remaining parameters, such as gas type and temperature, are defined in the Configuration window. Press Run
button and the video generation will start.
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The video is saved inside the solution and, as in any other configuration, if the video configuration parameters are
modified, the existing video will be erased.
When the simulation is finished, the video is automatically opened with Paraview. 3D rotations, perspective
customization and zoom are allowed on recorded animations. Play, pause, forward and backward buttons can be
found on top.
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In the tree located on the Pipeline browser of Paraview window, there are different visualizations of the electron
density evolution:
Electron density: it corresponds to the electron density in the volume of the device at different video frames.
Animation clip: it is a clip made on the electron density volume in order to visualize the discharge inside the
device in a proper way.  You can change the plane of the clip to center it in the proper place where the
maximum of the discharge occurs by using the "Properties" tab or by dragging the plane on the visualization
panel.
ElectronDensity last frame: it corresponds to the last frame of the volume electron density.
You can hide/unhide each one by clicking on the eye icon located in their left side.
The video can be exported in Paraview using File -> Save Animation... The video size, duration and format can be
chosen as shown in the following pictures.
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Command-line execution
In order to run video Corona configuration in command-line, you must use the following: spark3d.exe --
input="C:\Users\User1\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:1/Configurations:1/EMConfigGroup:1/CoronaConfig:2/VideoCoronaConfig:1//.
For futher information see command-line interface section.
2.1.1.5 Analysis of Corona Results
In this tutorial the capabilities of Spark3D GUI to handle and better analyze the Corona results are shown. As general
features you can find that:
results are given both in tabular and graphic form for a better understanding and can be saved in .csv or .png
formats respectively;
partial results can be seen in run-time, that is, both tables and graphs are updated as results are
being obtained;
the simulation process can be followed in the info tab of the GUI where a sweep in input power is shown as the
simulation runs, indicating how the simulator tries to approach the breakdown threshold level.
Corona configuration results window
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Corona results can be consulted in run-time. For the particular example followed in the tutorial,
TUTORIAL_EXAMPLE.spkx, Corona results window looks as follows during the simulation:
There are two tables and one graph that are refreshed as new results are obtained: 
1.  The left-side table contains the threshold breakdown power for each pressure point corresponding to a
certain region and signal. If both the high pressure analytical rule and the numeric simulation type  have been selected for evaluation, the table will have three columns
instead of two, where the last one corresponds to the analytical rule.
2.  In the graph is represented the Paschen curve corresponding to the data showed in the left-side table. If both
the high pressure analytical rule and the numeric simulation type  are enabled, there will be two curves, one corresponding to the numerical analysis and the other
one to the analytical rule. 
By right-clicking on the graph, you can save it in a .png file and its data, which correspond to the left-side table,
in .csv format, respectively.
3.  The upper table shows the minimum breakdown power in the whole pressure sweep for each region
analyzed and for each signal under study. During the simulation process, the word "Simulating" appears in the
cell corresponding to the signal/region combination which is being analyzed. Besides, through this table the
user can handle the results shown both in the left-side table and the graph:
By left-clicking on a cell corresponding to a particular signal/region combination both the graph and the
left-side table update their values to the current element.
By left-clicking on the cell corresponding to the signal value, the whole row is selected and the graph
shows together the Paschen curves of all the regions analyzed. With this information it is easy to
recognize which is the most critical region for Corona discharge and the minimum breakdown power
supported by the device.
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By left-clicking on the cell's name of a region, the whole column is selected and the graph shows
together the Paschen curves of all the signals analyzed.
2.1.2 Multipactor Tutorial
In this tutorial you will learn how to run your first Multipactor simulation with Spark3D. It presents a guided example
for which the whole Multipactor analysis process is explained step-by-step using TUTORIAL_EXAMPLE.spkx file
located in Examples->TutorialExamples folder, distributed with the installation of the software. It is divided in 6 parts:
1.  Preliminaries shows you how to create new models by importing EM solutions from compatible external EM
software.
2.  Computing voltage contains the procedure to calculate the voltage in a certain area of the device using
Paraview.
3.  Specifying Regions describes you how to define regions of interest where the analysis of Multipactor can be
focused.
4.  Specifying Signals describes you how to define new multicarrier, modulated or pulsed signals for Multipactor
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simulation.
5.  Running a Multipactor configuration. The main parameters are set for Multipactor analysis and the simulation
is launched. An overview of the Multipactor output is given.
1.  Running Multipactor video. We set the parameters to record Multipactor video and describe how to
play it.
6.  Analysis of Multipactor Results shows you how to interpret and visualize the output data.
2.1.2.1 Preliminaries
First, the EM field data of the device under study must be loaded. From the Start working window, you can either
create a new project or open an existing one, in which the EM field is automatically loaded.
To create a new project, press the New Project button and browse in the explorer to select a EM field file previously
created with one of the Spark3D compatible EM solvers . The different formats supported by
Spark3D include Fest3D, CST, HFSS, each one with its corresponding file extension.
In this tutorial, you will load an existing example. Click on the Open examples button and select
TUTORIAL_EXAMPLE.spkx.
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A new window will appear with the information of the newly opened file. You see in the left side of the window the
tree structure of the current project, which includes a Model with:
Four analysis regions: the so called Circuit, which corresponds to the imported mesh of the entire device, and
three more regions defined for corona and multipactor analysis.
Three continuous wave signals, which contain the EM fields that were imported from CST Microwave Studio.
Two multicarrier signals, defined through the previous continuous wave signals.
One modulated signal, defined from an imported baseband signal ASCII file.
Three multipactor configurations, each one with its already existing results and a video configuration.
Two corona configurations, each one with its already existing results and a video configuration.
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Once the EM files have been loaded, it is advisable to visualize the EM fields through the 3D CAD viewer included with
Spark3D distribution, Paraview (more information on Kitware's Paraview can be found in http://www.paraview.org/).
Click on the View model button of the toolbar and the main window of Paraview will open with the EM fields
corresponding to the continuous wave signals previously computed inside the device for each region of analysis,
which looks like:
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In the Pipeline browser (located in the left side of Paraview window) there is a list of the fields corresponding to the
different analysis regions and continuous wave signals defined in the Model. You can enable/disable the view of each
one by clicking on the icon eye located at the left side of the browser.
With the left, right and center buttons of your mouse you can rotate, zoom and translate the camera view. In the
menu bar there is a display list where the different fields (magnitude, real and imaginary parts of electric and magnetic
fields) can be selected.
2D cuts allow you to visualize the fields inside the structure, so that you can detect the potential areas of the structure
where the breakdown onset is more likely to occur, that is, where the electric field is maximum. For each field
corresponding to a certain analysis region and continuous wave signal, you can create a 2D cut with the slice button 
 that is located in the menu bar.
In the figure below you see for Circuit region and signal CW4 that the irises in the center of the device are the main
candidates for breakdown onset.
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2.1.2.2 Computing voltage
With Paraview it is also possible to compute the voltage as the integration of the electrical field between two points in
the mesh. In SPARK3D, the fields are defined for an input power of 1W, therefore the computed voltage is also at 1W,
called V1W. This can be useful for multipactor to translate from breakdown power to breakdown voltage and compare
results with theoretical parallel-plate predictions. The expression to convert from power to voltage is the following:
V=V1W√P
Be careful because the voltage computed this way depends on the selected path in the mesh. In order to have
meaningful results, the device geometry and fields, should be similar to a parallel-plate case.
The process is as follows:
1.  Apply paraview filter "plot over line"
2.  Specify the coordinates of the line.
3.  Apply paraview filter "Integrate variables". The line must be entirely contained in the mesh. Otherwise this step
will lead to NaN value.
In this particular case we will compute the voltage in the center of the centre iris, where the maximum field is located.
In order to do so, one has to select the "Plot Over Line" filter in Filters->Alphabetical->Plot Over Line menu.
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Select the line for displaying the data by either moving the start and end points with the mouse, or by inserting
coordinates manually. In this case, just press "y axis" button to automatically orient the line properly. Adjust the y
coordinates between [-0.001085 and 0.001085]  to confine the line inside the gap (gap size is of 2.17mm in this
example). Then press "Apply" button.
A 2D plot with the fields displayed along the selected line appears. Now, apply another filter called "Integrate
Variables" in Filters->Alphabetical->Integrate Variables. This filter will integrate all quantities displayed in the 2D plot.
In this case, we obtain a voltage at 1W of V1W= 18.5 V as shown below.
Note: Line start and end points must be adjusted to be inside a valid data region. If any of the line nodes lies
outside, NaN integration values may appear.
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2.1.2.3 Specifying Regions
The high power analysis of a device can be carried out in two different ways:
analyzing the whole device in one shot or
focusing the simulation on critical regions defined by the user.
There are different reasons to take advantage of user-defined regions. As long as the device is divided in several areas
it is possible to compare the breakdown threshold of each one and determine where the discharge will take place.
Besides, computing the breakdown onset on specific regions is faster than taking into account the whole circuit.
Finally, the user can increase the mesh density involved in the solution of the problem improving the precision of the
calculation and avoiding memory overflow limitations.
Prior to the creation of simulation regions it is advisable visualizing the electromagnetic fields in order to detect the
critical areas of the structure in terms of breakdown.
Working with regions
A region of study corresponds to a box, which is defined through its center and size. These input variables can be
determined from the visualization window of Paraview, where a cube axis helps us to obtain their values. In our
example, the regions will be defined through the following values:
RectangularRegion 1
Center (m)
Size (m)
RectangularRegion 2
Center (m)
Size (m)
0.0245
0.024
0.01
0.006
0.017128
0.024
0.01
0.006
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RectangularRegion 3
Center (m)
Size (m)
0.032338
0.024
0.01
0.006
In order to define an analysis region, you should double click on the Analysis Regions tree item of Spark3D. A new
window will be opened:
On the left hand side of the window, you see the tree corresponding to all existing regions. By default, there is a
predefined region named Circuit, which takes into account the whole imported model and is enabled for analysis.
From this window you will be able to:
add a new region from the Add Region button,
modify the existing ones by changing the values of its defining properties,
change a region's name by right clicking on a certain region item,
copy/paste/delete a region using the corresponding right-click options on a specific region item,
visualize all defined regions together with the device through the Visualize button,
or visualize a single region together with the device through the Visualize 3D right-click option of the chosen
region item.
By clicking on a specific region you can modify its defining properties. Click on RectangularRegion 1 and you see that
in our example the input variables:
Center x, Center y, Center z
Size x, Size y, Size z
have the values given in the table above corresponding to one of the analysis regions. Note that the units of these
variables are ALWAYS meters.
The validity of all defined regions will be checked when accepting the actions done through the OK button. It checks if
every region contains any mesh points. If there is some region which is not correct, an error message will pop up and
you will have to adjust the region's properties so that the region intersects the device.
Besides, you can also visualize the relative position of all regions with respect the structure under study. Press
Visualize button and you see that the defined regions correspond to the critical areas previously recognized in the
lowpass filter.
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Through the 3D CAD viewer it is possible to modify the defined boxes and visualize at once the changes. From the
Pipeline browser located on the left hand side of the window, select the box you want to modify . Then in the Object inspector window select Properties tab, where the
geometrical parameters of the box, that is, its dimensions and center position, will be displayed. You can change them
and by clicking on Apply button you can see the result of the modification. It is important to point out that the
changes made in the 3D CAD viewer will not be automatically transferred to the defining parameters of the regions.
Once you have found the proper values that suit your problem, you have to write them in the corresponding cells of
the Analysis regions window of Spark3D.
If you want to create a new region you just click on Add region button. A new region will be created with a default
name that you can change with the Rename right-click option. You can fill in the input parameters. On the contrary, if
you want to erase a region, you should select it and either select the Delete right-click option or directly press the
Supr button. You can also copy and paste one existing region through the corresponding options by right clicking on
the selected region.
Once you have done all your modifications, you can either preserve them through OK button or discard them through
the Cancel button (or alternatively closing the window).
In Multipactor simulations, when regions are specified, all non-metallic surfaces (corresponding to vacuum condition)
of the mesh enclosed in a specific region are considered as open boundaries. As a consequence, all electrons
impacting with such regions are automatically absorbed.
Errors
When checking the validity of a region it may occur that it is not correct, that is, there are no mesh points inside it. The
reason for this could be one of the following:
The region does not lie inside the model mesh. You should check its defining input variables.
The region is smaller than the mesh elements. You should enlarge the region or change the mesh.
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2.1.2.4 Specifying Signals
When a model is imported, a list of CW signals, corresponding to the imported frequencies, is automatically defined in
the Project tree.  The user can add three kind of signals:
modulated signals, using an existing CW signal as carrier and importing an ASCII file for the baseband signal (I-
Q quadrature modulation).
pulsed signals, using an existing CW signal and defining the properties of a train of pulses.
multicarrier (MC) signals as a combination of the different single carrier signals (including both CW and
modulated ones)
Working with multiple CW signals and adding multicarrier signals is only possible with models imported from
CST MWS software.
See Creating or modifying signals section for detailed information.
Open the Signal window by double-click on the Signals node in the tree, or by right-click and selecting Edit
Signals.
The Signal window shows, to the left-hand side, the single carrier signals, divided in three sections:
Continuous wave: It shows the different CW signals that have been imported. These signals can be renamed or
deleted, but no CW signals can be added unless a new model is imported.
Modulated: It shows the defined modulated signals (if any) and the assigned CW carrier.
Pulsed: It shows the defined pulsed signals (if any) and the assigned CW carrier.
The MC signals are in the right-hand side part of the window. An MC signal can contain any combination of CW,
modulated or pulsed signals.
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Adding Multicarrier Signals
To add a multicarrier signal press the button "Add Multicarrier Signal" in the Signal window and specify the number
of carriers, which is three in this case. The relative phase as well as the relative amplitude can be set individually for
each carrier.
In this tutorial, two multicarrier signals have been already defined:
MC1: Three carrier signal with zero phase for all phases. This is known as a in-phase signal and has the
particularity that it reaches the maximum instantaneous peak-power. See a plot o the time evolution of the
multicarrier envelope.
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MC2: Three carrier signal with a specific phase distribution (0-270-0). This distribution implies an almost flat
envelope, close to the average (RMS) power. See a plot o the time evolution of the multicarrier envelope.
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Adding Modulated Signals
To add a modulated signal press the button "Add Modulated Signal" in the Signal window. A new Modulated Signal
window will open in order to edit it. In this example a modulated signal has been defined. Press right-click on it and
 button) to open its corresponding Modulated Signal window.
select Edit (or press the
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Press Import File button in Input data section to import the modulated base-band signal from an ASCII file.
See Creating or modifying signals section for further information on import data format. In this example a 4-QAM
modulation has been imported with 150 symbols, raised cosine filter with roll-off factor of 0.25 and 90e6
symbols/second (duration of 166 ns, 112.5 MHz of bandwidth).
In the Configuration section, the Start time for multipactor simulation can be set. This time is when the initial
electrons are injected in the multipactor simulation. It is usually chosen in an interval with higher average amplitude in
order to reduce the multipactor threshold. Leave the value in this example as it is.
Adding Pulsed Signals
To add a pulsed signal press the button "Add Pulsed Signal" in the Signal window. A new Pulsed Signal window will
open in order to edit it. In this example a pulsed signal has been defined. Press right-click on it and select
Edit (or press the 
 button) to open its corresponding Pulsed Signal window.
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In this example, the pulsed signal is characterized by a duty cycle of 1% and a Pulsed Repetition Rate (PRF) of 10 KHz,
which correspond to a Pulse Repetition Interval of 0.1 milisecond and a pulse length of 1 microsecond. As you change
the values of PRF and duty cycle, the corresponding ones for PRI and pulse length are automatically updated.
2.1.2.5 Running Multipactor mode
In this tutorial example two multipactor configurations are defined for two different materials, silver and aluminium.
We will set-up and run the second configuration, corresponding to aluminium.
In order to configure a Multipactor simulation, you must
either right click on the MultipactorConfig item of the Solution tree and choose Open Multipactor
Configuration,
or double click on it.
Open the multipactor configuration with label "MultipactorConfig-Aluminium".
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 Multipactor configuration window will be opened.
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From this window you can set up the configuration parameters. See Multipactor Analysis manual for a description of
all the available options. In the configuration window, fill in
1.  SEY name: Aluminium
2.  Precision (dB): 0.1
3.  Initial power (W): 4000
4.  Maximum power (W): 1e+6
5.  Initial number of electrons: 1000
6.  Multipactor criterion: "Charge trend"
In the left-hand side of the window lies the Fields tree, where you can select which combinations of signal/region will
be analyzed in the simulation. In our example, there are three already defined regions, which correspond to the
central irises of the lowpass filter.
Press the Edit Regions button and a new window will be opened, where you can configure the analysis regions.
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You can see the defined regions of study for this example by clicking on the Visualize button. The 3D CAD
viewer Paraview will open the EM field of the device together with the defined regions, represented by boxes. For
further information on how to work with regions see Specifying Regions tutorial.
Apart from the imported continuous wave signals, new multicarrier signals can be added and simulated. In this
example, there are:
Three CW signals at 9, 9.5 and 10 GHz
Two multicarrier signals, of three carriers each, with different phase distribution.
See Specifying Signals tutorial for further information.
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We are now ready to launch the simulation. Press the Run button in the MultipactorConfig window.
The simulation starts now and in the main window, the results window is opened so you can see the output in run-
time.
For each analyzed region, the results include:
A table located in the left-hand side of the window, which shows the analyzed power levels in the process of
searching the breakdown power threshold. For each power, depending on whether multipactor occurs or not,
it appears either the order of multipactor or the message "No break", respectively.
A graph, where for each analyzed power the electron population evolution is represented versus time.
Multipactor output data also includes a table situated on the top of the window, where it is shown the breakdown
power threshold for the regions under study. With this information it is easy to recognize which is the most critical
signal/region in the device for multipactor onset and the limiting power. For a detailed description on multipactor
results interpretation read the Analysis of Results tutorial.
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For the current example, we find that for all frequencies of study and regions, the lowest breakdown power threshold
is 4343.64 W and occurs for the RectangularRegion 1 at 9.0 GHz. Thus, this is the limiting power of the device.  For the
two multicarrier signals, we see that the lowest breakdown power corresponds to MC2 and, again, for
RectangularRegion 1. In this case, the breakdown power threshold is of 5437.14 W (average).
Command-line execution
In order to run Multipactor configuration in command-line, you must use the following:
spark3d.exe --
input="C:\Users\User1\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx"
--config=Project:1/Model:1/Configurations:1/EMConfigGroup:1/MultipactorConfig:1//
For futher information see command-line interface section.
2.1.2.5.1 Running Multipactor video
Alternatively to a Multipactor analysis, it is possible to record a video of the electrons moving inside the 3D structure
for a particular input power.
In order to set the Multipactor video parameters, you must
either right click on the VideoMultipactorConfig item of the Solution tree and choose Open video
configuration,
or double click on it.
Open the video multipactor configuration under the "MultipactorConfig-Silver" item.
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 Video Multipactor configuration window will be opened.
Select:
1.  Fields: CW1/RectangularRegion 1 
2.  Input Power (W): 10000
3.  Number of Frames / period : 15
4.  Start time (ns): 0
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5.  End time (ns): 30
The remaining parameters, such as SEY properties, number of initial electrons, multipactor criterion, etc. are defined in
the  Configuration window.
Press Run button and the video generation will start. The video is saved inside the solution and, as in any other
configuration, if the video configuration parameters are modified, the existing video will be erased.
When the simulation is finished, the video is automatically opened with Paraview. 3D rotations, perspective
customization and zoom are allowed on recorded animations. Play, pause, forward and backward buttons can be
found on top. Animation parameters can be changed in the Animation View panel (View -> Animation View).
Concretely, the video duration can be changed in the Duration textbox.
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 Video can be exported using File -> Save Animation... The video size, duration and format can be chosen.
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Command-line execution
In order to run video Multipactor configuration in command-line, you must use the following: spark3d.exe --
input="C:\Users\User1\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:1/Configurations:1/EMConfigGroup:1/MultipactorConfig:1/VideoMultipactorConfig:1//.
For futher information see command-line interface section.
2.1.2.6 Analysis of Multipactor Results
In this tutorial the capabilities of Spark3D GUI to handle and better analyze Multipactor results are shown. As general
features you can find that:
results are given both in tabular and graphic form for a better understanding and can be saved in .csv or .png
format respectively;
partial results can be seen in run-time, that is, both tables and graphs are updated as results are being
obtained;
the simulation process can be followed in the Power vs Order table.
Multipactor results window
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Multipactor results are given both in tabular and graphic form. They can be seen in run-time through the results
window, which for the example treated in the tutorial looks as follows:
There are two tables and one graph:
1.  The left hand side table shows for each analyzed power whether there has been breakdown or not. When
breakdown occurs for a certain input power, the multipactor order is given in the second column of the table
whereas when there is no breakdown the message "No break" appears.
2.  In the graph it is represented the electron evolution with time for each power analyzed. This way it is easy to
follow the increase/decrease of the electron population as the simulation runs. When left-clicking on the cell
corresponding to a certain power of the left hand side table, its corresponding curve is highlighted on the
graph for a better recognition.
By right-clicking on the graph, you can save the graph in a .png file and its data, which correspond to the left-
side table, in .csv format, respectively.
3.  The upper table contains the breakdown power threshold for each field (signal/region) under study. Through
this table the user can handle the results shown both in the left hand side table and the graph:
By left-clicking on a cell corresponding to a particular signal/region both the graph and the left hand
side table update their values to the selected field.
By right-clicking on a cell corresponding to a particular signal/region the option Visualize 3D statistics
appears. This option launches a paraview window and shows the position of the electrons in the
structure, and the 3D Statistics, if enabled in the configuration window .
It is possible to select whole rows or columns by left-clicking on the cell corresponding to the signal or
the region name. A bar diagram appears in the graph comparing the breakdown power threshold for
the selected cells. With this information it is easy to recognize which is the most critical signal/region for
Multipactor and the maximum power level supported by the device.
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2.2 Spark3D Manual
This section describes the structure of Spark3D and documents the features of each subsystem Spark3D is composed
of (Graphical User Interface, Multipactor module, Corona module).
The Spark3D manual contains the following topics:
Architecture
Requirements
The top-level architecture of Spark3D
The minimum hardware and software requirements needed to run Spark3D.
What is a Spark3D project?
The main structure of a Spark3D project is presented.
Creating a new project
It details the steps to create a Spark3D project
Creating or modifying a model
New models can be created by importing EM solutions from external software.
Creating or modifying regions
The high power analysis can be restricted to user defined regions in order to
speed-up the simulation.
Creating or modifying signals
New Multicarrier signals can be created using the imported Continuous Wave
signals.
Visualizing a model and its regions
and signals
The model and its regions and signals can be easily visualized in a 3D viewer.
Importing or using DC Fields
External DC fields (electrical and magnetic) can be incorporated to the analysis.
Mesh export from external software Compatible software and procedures to successfully export EM solutions are
given here.
Launching Spark3D in command
line mode
Command line mode and modification of input .xml file are described.
Corona analysis
Description of the corona module
Multipactor analysis
Description of the multipactor module
Architecture
Spark3D is a general software tool for Radio Frequency (RF) breakdown analysis, which allows predicting both Corona
and Multipactor breakdown onsets in a great variety of RF structures. It has as input data the electromagnetic field
distribution of the device under study at one or several frequencies. It allows the user to define the regions where the
High Power analysis will be carried out and perform the result visualization using an intuitive, user-friendly graphical
interface.
At the top-level, Spark3D is composed of two subsystems:
Graphical User Interface (GUI)
High Power Computational Engine (HPCE), which includes Multipactor and Corona modules.
The GUI is a QT application. It is the part of Spark3D program in charge of interacting with the user, also executes and
coordinates the other subsystem at user's demand and represents the results data.
The HPCE implements the high power capabilities of Spark3D. The HPCE is designed and tuned for performance and
exploits state-of-the-art techniques in multipactor, corona and information technology research fields.
Requirements
Spark3D requires at least the following:
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Hardware: Dual core with 4GB of RAM and 3GB free disk space.
Operating System: Windows 7, Windows 8, Windows 10. Special requests for Linux or other Windows
versions.
Screen resolution: A minimum of 1280 x 768 is required.
2.2.1 What is a Spark3D project? How is it structured?
Project is the top-level entity in Spark3D. It is merely a container of Models.
You can open/create as many projects as you need. Each saved Project corresponds to a Spark3D file, whose
extension is spkx. Indeed, the Project name is the name of the file. Moreover, for each Spark3D file, there may exist a
folder with the same name containing all the Project results (if any). This folder and the Spark3D file are located in the
same directory.
A Project may contain as many Models as needed.
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Model is the entity that contains the circuit/component under study and the configurations (Multipactor or Corona)
applied in the analysis. For this reason, the main sections that form a Model are:
Materials
Project materials are listed under this tree node. Materials are loaded from the imported mesh and cannot be
edited. Only CST 2021 exported files, and above, incorporate material definitions. See EM Field export from
external software .
Materials can be used in Multipactor Configurations to assign different SEY curves to the model.
Double click on any of the material items will visualize them in a Paraview window, Visualizing a model:
Regions, signals and materials.
Materials are used only for assigning SEY properties for Multipactor analysis. Therefore, Spark3D does not
use any electromagnetic property of the imported materials in the simulation. However, Vacuum regions,
where multipactor and corona are to be solved, are differentiated from solid regions according to their
permittivity and permeability values (relative value of one, for both of them, is used to identify vacuum
materials).
Analysis Regions
This section holds the regions of analysis that one defines in order to cut portions of the component mesh and
field. There is always one region representing the whole component, called Circuit. The user cannot modify this
region.
Signals
This section holds single carrier CW signals imported by the user, as well as multicarrier signals created by the
user to be analysed.
DC Fields
This section holds the external DC Fields imported by the user (both Electric and/or Magnetic Fields).
Multipactor Configuration Group
This section groups all the Multipactor Configurations and Multipactor Videos created by the user, as well as
the simulation results. One can create as many different Multipactor Configurations as required.
Corona Configuration Group 
This section groups all the Corona Configurations and Corona Videos created by the user, as well as the
simulation results. One can create as many different Corona Configurations as required.
Spark3D is compatible with old Spark3D 1.6.x format. One can open an old version file (spk extension) and work with
it. When saving it, the software will automatically ask the user to save it as a new version file (spkx extension).
2.2.2 Creating a new project
New Project
In order to create a new Project, you can click directly the New Project button in the Tool bar or File->New Project
in the Menu bar.
By doing so, an empty Project is created, and the Importation Window pops up asking for the EM field file to be
imported.
Once you select an EM field file, a Model is generated importing the corresponding mesh and EM field. The Model
contains default Configurations and Video Configurations both for Multipactor and Corona simulations.
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2.2.3
Creating or modifying a model (Importing or
replacing the RF EM field)
Creating a Model (Importing the external RF EM Field).
One may want to create a new Model inside an already existing Project.
In order to create a new Model inside an already existing Project, you can right-click on the Project item in the SPARK
tree, and select Import Model, as shown next,
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By doing so, the Import Window pops up asking for the mesh file with the EM field to be imported.
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It allows importing the electromagnetic field computed with some of the most widespread electromagnetic simulation
software tools :
Fest3D®
CST® 2012 (or higher)
ANSYS® HFSS™ v. 11 (or higher) 
Once an EM field file is selected, a Model is generated importing the corresponding mesh and EM field. The Model
contains default Configurations and Video Configurations both for Multipactor and Corona simulations.
Editing a Model (Replacing the EM Field).
In some cases, it may happen that, after creating different configurations and performing different simulations, you
want to repeat them over a different  EM Field (Model). For this purpose, you can replace the mesh and the EM Field
by simply right-clicking on the Model item in the Spark3D tree and selecting Replace Model.
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By doing so, the Import Window will pop up, being the process to follow the same as when importing a new mesh.
Alternatively, you can open the Model Window by double-clicking on the Model item in the Spark3D tree, and then
click on the Replace Model button on that window.
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Attention: The replace model process will automatically erase all the results obtained with the previous EM field
file.
2.2.4 Creating or modifying regions
Creating Regions
In order to create a new region, you can click right-button on the Analysis Regions item in the Spark3D tree, and
select the Add Region option.
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This action will open the Analysis Regions Window, where the dimensions and position of the newly created region
can be defined.
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In this window, you can create new regions by:
Clicking on the Add Region button,
Right-clicking on the Analysis Regions item and selecting the Add Region option,
Copying and pasting regions in the tree. One can copy regions by selecting the region to be copied in the tree,
then right-clicking and selecting copy, and after right-clicking and selecting paste. Alternatively, simply by
following the classical Ctr+C and Ctr+V procedure.
Note: One can also copy and paste regions directly in the Spark3D tree.
Editing Regions
In order to edit regions, you can open the Analysis Regions Window by doing double-click on the Analysis Regions
item of the Spark3D tree, or by right-clicking on the region item of the Spark3D tree and selecting the Edit option, as
follows,
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Once the region dimensions and position in the Analysis Regions Window have been set, you can visualize all regions
by clicking the Visualize button.
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Alternatively, you can right-click on the region item of the tree and select Visualize 3D. In this second case, you will
only visualize the region selected together with the circuit.
 More information about visualizing regions is available at Visualizing a Model and its regions.
Let's suppose that you have performed a simulation on a particular analysis region. If you edit any of the region's
parameters and you click the OK button in the Analysis Regions Window, the results associated to that particular
region will be deleted.
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2.2.5 Creating or modifying signals
When a model is imported, a list of CW signals, corresponding to the imported frequencies, is automatically added to
the Project tree. These CW signals can be used directly for Multipactor or Corona Simulations. Additionally, the user
can create three extra kind of signals:
modulated signals, using an existing CW signal as carrier and importing an ASCII file for the baseband signal (I-
Q quadrature modulation)
pulsed signals, using an existing CW signal and defining the properties of a train of pulses.
multicarrier (MC) signals as a combination of the different single carrier signals (including CW, pulsed and
modulated ones)
Note: Working with multiple CW signals and adding multicarrier signals is only possible with models imported
from CST MWS software.
Note: Multicarrier signals are only available for Multipactor simulations
Creating Modulated Signals
In order to create a new Modulated signal, you can click right-button on the Signals item in the Spark3D tree, and
select the Add Modulated Signal option. Alternatively, right-click over the Modulated item in the Spark3D tree and
select the Add Modulated Signal option.
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The signal window will open with the newly created modulated signal. See Editing Signals section for configuring the
modulated signal.
Creating Pulsed Signals
In order to create a new Pulsed signal, you can click right-button on the Signals item in the Spark3D tree, and select
the Add Pulsed Signal option. Alternatively, right-click over the Pulsed item in the Spark3D tree and select the Add
Pulsed Signal option.
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The signal window will open with the newly created pulsed signal. See Editing Signals section for configuring the
pulsed signal.
Creating Multicarrier Signals
In order to create a new Multicarrier signal, you can click right-button on the Signals item in the Spark3D tree, and
select the Add Multicarrier Signal option. Alternatively, right-click over the Multicarrier item in the Spark3D tree and
select the Add Multicarrier Signal option.
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This action will open a window to enter the number of single carriers containing the new multicarrier signal.
Once the number of single carriers is set, the Signal Window is open. See Editing Signals section for configuring the
multicarrier signal.
Note: the minimum number of single carriers to define a multicarrier signal is two.
Note: Working with multiple CW signals and adding multicarrier signals is only possible whith models imported
from CST MWS software.
Editing Signals
In order to edit signals, you can open the Signals Window by doing double-clicking on the Signals item of the
Spark3D tree, or by right-clicking on the Signals item of the Spark3D tree and selecting the Edit Signals option.
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The Signal Window contains tables for Single Carrier signals (CW, modulated and pulsed) and Multicarrier signals. All
signals can be renamed or deleted by right-clicking it and selecting Rename or Delete, however, it is mandatory that,
at least, one CW Signal per Model exists.
Note: Continuous Wave Signals may be deleted by the user. However, it is mandatory that, at least, one CW
Signal does exist per Model.
Note: It is also allowed adding new multicarrier signals in the Signal Window from the button Add Multicarrier
Signal.
Note: It is also allowed adding new modulated signals in the Signal Window from the button Add Modulated
Signal.
Note: It is also allowed adding new pulsed signals in the Signal Window from the button Add Pulsed Signal.
Editing Multicarrier Signals
In the right-hand side of the Signal Window, the parameters of the multicarrier signals can be defined. Each carrier of
the multicarrier signal can be set to one of the Single Carrier Signals, present on the left-hand side of the Signal
Window (imported CW signals, pulsed signals or modulated signals). Each carrier indicates both the frequency and the
corresponding port excited in the imported mesh. Furthermore, one can define both a specific phase and relative
amplitude for each carrier.
Editing Pulsed Signals
Pulsed signals are characterized by two parameters: the duty cycle (dt) and the Pulse Repetition Frequency (PRF).
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Considering a train of pulses, as illustrated below, the duty cycle is defined as the ratio dt=w/PRI, where w
corresponds to the pulse width and PRI is the Pulse Repetition Interval. The Pulse Repetition Rate is defined as the
inverse of PRI, PRF = 1/PRI.
Editing Modulated Signals
To change the modulating carrier of the modulated signal, select one of the available CW signals in the Signal
combobox.
To edit a modulated signal, just right-click on it in the item in the Signal Window, and select Edit. You can optionally
double-click on the signal item or press the 
 button. Afterwards the Modulated Signal Window opens.
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This window allows importing ASCII files containing the baseband signal (In-phase and quadrature signals). Spark3D
then constructs a modulated signal by combining such imported signal with one CW signal present in the model. The
type of modulation is a typical quadrature amplitude modulation.
Spark3D imports field values given at a certain frequency but has no information about the frequency response
and bandwidth of the component. Therefore, it is responsability of the user to ensure that the bandwith of the
modulated signal fits within the bandwidth of the component under analysis. See  Corona and Multipactor
practical considerationsfor more information.
The Modulated Signal Window has the following sections:
Input data: By pressing the Import File button, ascii text files can be selected with the baseband signal of the
modulated signal. The file format is a three column file with space separator and one row per line.
First column: time in seconds
Second column: In-phase signal
Third columns: Quadrature signal
Properties: Once imported, this section shows some statistical properties of the imported signal, such as time
span, minimum and maximum amplitudes, signal average power and PAPR which stands for Peak to Average
Power Ratio (given in dB).
Note: The imported modulated signal is dimensionless, as well as its average power (defined as the
integral of the squared signal). In order to obtain the modulated fields at the specified input average
power (in Watts), Spark3D multiplies the imported EM fields (at 1W input power) by the modulated signal,
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and then uses the signal average power (dimensionless) to automatically scale the EMFields to the desired
physical input power.
Configuration: This section contains a parameter which is used by the Multipactor configurations that
simulate this signal. The Start time parameter is the time at which the electrons are injected in the multipactor
simulation. Therefore, the interval of the signal before the Start time is not considered in the simulation.
Graphical representation: There are two plots. The In-Phase / Quadrature one represents the data as it has
been imported from file. It is the baseband signal (not modulated) The Signal plot represents the amplitude of
the modulated signal. If the Draw RF signal checkbox is ticked, the RF signal is also plot. The frequency of the
selected CW signal is used.
Since the modulated signal has a time-dependent arbitrary waveform, the multipactor threshold may be very
sensitive to the Start time parameter. Try to select intervals that have a high average value. It is also possible to
copy the same modulated signal, but with different Start times, to perform simulations on different intervals.
This allows checking the differences and select the lowest threshold among all of them.
Power definitions
Spark3D provides two types of power levels for a signal x(t):
Average power: For all kind of signals, the average power is obtained by integrating the squared value of the
signal x(t) from 0 to infinity.
Pavg = lim T → ∞ 1/T ∫0
∞ |x(t)|2 dt
For periodic signals, it is enough to integrate just over one period of the signal. This is the case for CW
and pulsed signals. For the latter, the period of the signal is the Pulse Repetition Interval PRI .
For modulated signals, the averaging is done over the entire imported time series.
For multicarrier signals, the average power is just the sum of the average power of each individual
carrier.
Pavg,mc = ∑Pavg,i
Peak power: The peak power provided by Spark3D is the average power of a CW signal whose amplitude is
equal to the maximum value of x(t).
Since for CW signals the ratio between amplitude and rms value is √2, then
Ppeak = 1/2 max (|x(t)|2)
In general, given the average power, the peak power is Ppeak = 1/2 PAPR Pavg
For CW signals, PAPR=2, and therefore the Ppeak = Pavg. Only Pavg is displayed in report windows.
For pulsed signals, PAPR=2PRI/w, and therefore Ppeak = (PRI/w) Pavg. Equivalently, the peak power is the
average power of the signal during the pulse duration, w.
For modulated signals, the PAPR is calculated when the signal is imported.
For multicarrier signals, the peak power is the addition of the peak power of all carriers in amplitude
Ppeak,mc = (∑√Ppeak,i)2
Note that Spark3D definition of peak power does not match with the standard one, which is
Ppeak,std = max (|x(t)|2)
The reason for this ad-hoc definition of peak power is motivated by its typical use in pulsed and multicarrier
signals. For multicarrier operation, the peak power term traditionally refers to the average power of an equivalent
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CW signal with same amplitude as the multicarrier peak amplitude. This is useful since it directly provides the CW
power level in a multipactor test set-up. On the other hand, when working with pulsed signals, peak power is
normally defined as the signal average power over the pulse duration, which is, again, equivalent to the average
power of a CW signal. Spark3D uses a definition of peak power which matches with the two definitions above,
and which is different from the standard one. The relationship is simply
Ppeak = 1/2 Ppeak,std
2.2.6 Visualizing a model: Regions, signals and materials
In order to visualize the 3D structure with the EM field imported, you can select the Model under study in the Spark3D
tree and click on the View Model button in the Menu bar. Alternatively, right-click over the Model item in the tree
and select Visualize 3D.
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By doing so, Paraview is launched, showing the EM field imported, which can be composed by several Continuous
Wave signals. Therefore this imported field for each Continuous Wave signal together with all the regions defined by
the user are shown. Materials are also displayed for the whole structure and for each particular region, if defined. If DC
fields have been imported, they are shown as well.
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If you want to visualize the mesh, EM field and material selected in a particular region or a particular DC field, just
right-click the region or the DC field item in the Spark3D tree and select Visualize 3D. Note that for a particular
region all EM fields for each CW signal are shown.
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If, on the contrary, you want to visualize all the meshes and EM fields for a particular CW signal, just right-click the CW
signal item in the Spark3D tree and select Visualize 3D.
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It is important to remark that when you visualize a region from the Spark3D tree, you see the mesh cut and the EM
field imported. If you want to visualize the box that defines the region, you can do it from the Analysis Regions
Window . In that case, you see the following:
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 It is also possible to visualize only the materials associated with the imported mesh, by right-clicking on the materials
item in the project tree and pressing Visualize 3D.
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A Paraview  window is opened, showing the materials of the imported mesh, with different colors assigned to each
one of them.
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2.2.7 Importing or using DC fields
In order to import an Electric/Magnetic DC Field, you can right-click on the Electric/Magnetic Fields item in the
Spark3D tree and select Import DC Field, as follows,
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Then, the External Electric/Magnetic Field Window pops up, where the user can select the file to import. Spark3D is
able to import external DC fields to the simulation, computed with CST EM Studio®, ANSYS® MAXWELL™ or
rectangular CSV format mesh files .
When you import a rectangular CSV format mesh file, you must choose the separator that you have used to export
the data.
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In the case you import a DC field computed with ANSYS® MAXWELL™, you must choose the same metric units (m,
mm or inches) as used in such a solver to save the DC field.
2.2.8 EM Field export from external software
In order to carry out the high power analysis with Spark3D, first of all the electromagnetic fields must be computed for
the frequency under study and exported in the format required by Spark3D from one of the compatible
electromagnetic software tools:
CST MWS® 2015 SP3 (or higher)
CST MWS® 2012-2015 SP2
ANSYS® HFSS™ v. 11 (or higher)
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Besides, Spark3D is also capable to import arbitrary DC fields computed with external software in the following
formats.
CST EMS® 2018 (or higher)
ANSYS ® MAXWELL ™ 
Structured rectangular CSV mesh 
Please refer to the Introduction for more information on features and limitations.
CST MWS® 2015 SP3 (or higher)
The exportation of the EM fields from CST MWS ® to Spark3D is done as follows:
In CST MWS®, one just has to define two fields monitors for the same frequency: "E-field" and "H-field and Surface
current". Once these monitors have been computed, click on the Home main menu in  Macros->Results->Import
and Export->Export Fields to Spark3D and a file with extension  .f3e will be created in the "Result" folder of the
CST MWS®project. This file can then be imported from Spark3D.
Limitations up to CST® MWS 2020
Although CST MWS® writes dielectric volumes and boundary material information to the Spark3D file,
boundary surface information is not included in the export, and therefore Spark3D is not able to import the
materials associated with the boundaries.
CST® MWS 2021 and above exports correctly full material information.
CST MWS® 2012-2015 SP2
The exportation of the EM fields from CST MWS® to Spark3D is done as follows:
In the menu bar of CST MWS®, click on Macros->Solver->F-solver->Export Fields to Spark3D to open the
exportation window. You must specify the frequency under study and the directory where the created file will be
saved. The extension of this file is .f3e and it will be used as input data of Spark3D.
Limitations
Spark3D does not have information on the kind of material of the imported mesh points and will take
everything (besides boundaries) as air/vacuum.  CST ® 2012-2015 SP2 does not allow exporting separately
different volumes of the solution. Therefore, circuits with dielectrics could be tricky to analyze since they are
not correctly interpreted by Spark3D.
ANSYS® HFSS™ v. 11 (or higher)
Requirements
In order to export the EM fields from HFSS™ to Spark3D format you must take into account that:
The EM field has to be saved for the frequency under study,
The mesh used for the simulation has to be of first order (that is, in the menu bar of HFSS™ Solution Setup-
>Options->Solution Options->Order of basis functions must be set to First Order).
Spark3D assumes that the the fields are given in peak values and that the total average power of the imported
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field is Pt = 1 W. Therefore, in the case that multiple ports are excited at the same time, the fields in HFSS™ must
be computed with the following considerations:
The excitation signals must be scaled so that, the sum of the average input power for all ports must be 1
Pt = Σ Pi = 1 W
,where Pi, i=1,2,...,n, is the average input power at each port and n is the number of ports.
If Spark3D applied power is Pd, the applied power for a specific port i, Pdi, must be scaled with its original
input power, i.e Pdi = Pd*Pi/Pt = Pd*Pi/1W (since Pt = 1 W).
Procedure
Once the electromagnetic response of the structure has been simulated and the EM fields have been computed for
the frequency under study, you must follow the following steps:
1.  In the menu bar of HFSS™, go to Tools-> Run script and select the script named ExportToSpark3D.vbs,
which has been distributed together with Spark3D software. You can find it in the folder of Spark3D
installation, typically:
1.  Spark3D standalone:  "C:\Progam Files(x86)\Spark3D\dist\HFSSexportscript").
2.  Spark3D with Fest3D: "C:\Program Files(x86)\FEST3Dx.y\bin\external \spark3d\dist\HFSSexportscript".
Through this script, the following variables will be created:
1.  Real_vector_E
2.  Imag_vector_E
3.  Real_vector_H
4.  Imag_vector_H
which will be used as input data in Spark3D.
2.  Select from the Solids of HFSS model the ones corresponding to vacuum. Right-click on them and select the
option Plot Fields->Named Expressions. From the displayed options, you must plot all the previously created
variables, described in step 1. It is mandatory to use the variables created through the script. 
3.  Select the proper solution corresponding to one where the EM fields have been saved for the frequency under
study.
4.  In the Project Manager, go to Field Overlays, right click on it and select the option Save As. Choose all the
four Named Expressions presented before. They will be saved on a unique file of extension .dsp, that will be
used as input data in Spark3D.
Limitations
Spark3D does not have information on the kind of material of the imported mesh points and will take
everything (besides boundaries) as air/vacuum. This is the reason why it is mandatory to export the EM fields
corresponding to vacuum from the HFSS™ model. The same SEY curve is set for all boundaries (in multipactor
simulations).
Spark3D is not prepared to accept EM fields from HFSS projects considering symmetries. If you have an already
existing project which was simulated taking into account symmetries, it is mandatory that you compute the EM
fields again disregarding the symmetries. Make sure that in Project Manager-> Excitations, the parameter
Port Impedance Multiplier is set to 1.
When using a very dense mesh in the HFSS™ solution or when the problem is quite large, there could be some
memory problems when importing the fields. In this case, it could be necessary to divide the geometry of the
problem in several pieces/solids and work with the EM fields exported from each one.
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DC Fields
CST EMS®
In order to export the DC fields to Spark3D, you have to follow these steps in CST EMS:
1.  Click on the "2D/3D Results" entry of the tree and then, in the menu bar, go to Result Templates.
2.  In the window, select "2D and 3D Field Results" and then select "Export 3D Field Result". A window like this
appears:
3.  In "Browse Results" you have to select the B-Field (or E-field) and you have to select a subvolume in which you
would like to save the DC fields. Then, you have to click on "Specials" and the following window will pop up:
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4.  You have to ensure that the "Export ASCII File in CSV Format" option is selected, that the CSV Delimiter is
Semicolon and that the option "Export Coordinates in Meter" is activated.
Now, every time the project is run, the file is exported. The path to the exported file is given in the output screen of
CST EMS.
ANSYS® MAXWELL™
Once the magnetic or electric DC fields have been computed, you must follow these steps:
1.  Select from the Solids of MAXWELL model the ones corresponding to vacuum. Right-click on them and select
the option Fields->B->B_Vector, for magnetic field, or Fields->E->E_Vector, for electric field.
2.  Select the proper solution corresponding to one where the DC fields have been saved.
3.  In the Project Manager, go to Field Overlays, right click on it and select the option Save As. Choose the
B_Vector (or E_Vector) box. It will be saved on a unique file of extension .dsp, that will be used as input data in
Spark3D.
CSV format
CSV (comma-separated-values) format files are text files with . csv extension that consist on tabulated data. Spark3D
can import DC fields which are saved in CSV format files, whenever the mesh is rectangular, structured and based on
regular hexahedra.
Next, we describe the specific format that the CSV data should have in order to be imported by
Spark3D. Columns should be separated by one of the following characters: space, tab, comma, semi-colon. Each
column represents a magnitude. Rows are separated by newlines. The format follows a 6-column scheme: x y z F DCx F
DCy F DCz , being x, y, z the coordinates of each node in the mesh and F DC the values of the DC field.
2.2.9
Fest3D/CST Design Studio™ automatic coupling with
Spark3D
Spark3D can be used directly coupled to a Fest3D or a CST Studio Suite project.
Fest3D
In the case of Fest3D, this coupling is done through its High Power Analysis option. It automatically computes and
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exports the EM fields of a Fest3D project and creates with them a new Spark3D project. This process is carried out
transparently, so that once the EM fields are computed in Fest3D, Spark3D GUI is opened. From there, the user can
define Corona and Multipactor configurations, add new regions of analysis or new signals. All High Power features are
available and in this case Spark3D project is mandatorily linked to the EM fields of the Fest3D project from which it
was created. For further information on how Fest3D High Power Analysis works, please consult Fest3D manual.
CST Design Studio™
In CST Studio Suite, it is possible coupling a MWS® project, where RF fields are computed, with a Spark3D project.
The coupling is established through Design Studio™ schematic design tool:
The user should create a High Frequency Simulation Project Task, where E and H field monitors should be
defined and computed, so that RF fields are available.
 The user must create a Spark3D Task and select as source an already defined High Frequency Simultion Project
Task. Spark3D Task directly exports the EM fields of the High Frequency Simulation Project selected as source
and creates with them a new Spark3D project. Spark3D GUI is automatically opened and the user can define
Corona and Multipactor configurations, add new regions of analysis or new signals. All High Power features are
available and in this case Spark3D project is mandatorily linked to the EM fields of the High Frequency
Simulation Project Task, which is selected as source for the Spark3D Task. For further information on how
Spark3D Task works, please consult CST Studio Suite manual.
2.2.10 Command-line interface
The executable file to launch Spark3D in command-line mode can be found in the installation directory of Spark3D. The file is different depending on the platform
where it is being used:
spark3d.exe for Windows platforms
spark3d for Linux platforms.
The executable can be invoked with different combinations of options. Options can be:
optional (enclosed with square brackets "[ ]" ),
required (shown between parenthesis "( )" ) or
mutually exclusive (separated by pipes " | ").
All options are required by default, if not included in brackets "[ ]". However, sometimes options are marked explicitly as required with parenthesis "( )". For example,
when they belong to a group of mutually-exclusive or mutually-dependent options.
Together, these elements form valid usage patterns, each starting with Spark3D executable.
Usage patterns
Spark3D has four patterns for different usages in command-line mode:
spark3d.exe --help
spark3d.exe --gui
To show the usage and all comand-line options
To launch GUI of Spark3D
spark3d.exe --input=<file.spkx> (--config | --validate | --
To work with *.spkx project as input file for Spark3D
list) [(--importDC=<file> --fileTypeDC=<argument> --
fieldTypeDC=<argument>)] [--output=<path>]
spark3d.exe (--XMLfile=<file.xml> --importRF=<file>) (--
To work with *.xml and RF import files as input for Spark3D
validate | --list | (--config --projectName=<argument>) | (-
-generateProject --projectName=<argument>)) [(--importDC=
<file> --fileTypeDC=<argument> --fieldTypeDC=<argument>)] [-
-output=<path>]
To better understand the syntax of the usage patterns, next we analyze one of them:
spark3d.exe --input=<file.spkx> (--config | --validate | --list) [(--importDC=<file> --fileTypeDC=<argument> --
fieldTypeDC=<argument>)] [--output=<path>]
The option --input determines the path of the .spkx file and is a required option for the command-line to be executed.
In the above pattern --config, --validate and --list are written between parenthesis and separated with pipes. This implies that they are
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mutually exclusive options and it is mandatory that one of them appears in a command-line.
Options --importDC, --fileTypeDC and --fieldTypeDC are written between square brackets, which means that they are optional for the
command-line. In a second level, they are also written between parenthesis, which implies that they are mutually dependent and it is mandatory that
they appear all together when they are used in the command-line.
Options
Spark3D command-line options can be written in either a long or short form:
Long options are words preceded with two dashes "--" and can have arguments specified after space or equal "=" sign: --input=file.spkx is equivalent to
--input file.spkx.
Short options are formed by a letter preceded with one dash "-" and can have arguments specified after optional space: -I file.spkx is equivalent to -
Ifile.spkx.
The table below collects Spark3D command-line options in both long and short forms together with their description. Options with arguments are followed by "arg" in
the table.
Option
Usage and meaning
--help [-h ]
Prints help usage.
--gui [-g ]
Launches GUI of the program.
--input [-I ] arg
Specifies the path for the input .spkx project.
--config [-C ] arg
Performs the analysis of a high power configuration that is selected through its argument. Argument format for the different high
power configurations is the following:
Corona configuration:
Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#//
Video Corona configuration:
Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#/VideoCoronaConfig:#//
Multipactor configuration:
Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#//
Video Multipactor configuration:
Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#/VideoMultipactorConfig:#//
where # stands for the number of model/configuration selected for analysis.
--validate [-v ]
Validates all entities defined in project.
--list [-l ]
Enumerates all entities defined in project.
--XMLfile [-X ] arg
Specifies the name of the .xml input file, where all project entities are defined.
--importRF [-R ] arg
Specifies the path to RF EM field import file .
--unitsRF [-r ] arg
Defines the metric units used in ANSYS® HFSS™RF field import file. Argument value can be: m (meters), mm (milimeters) or inches.
--generateProject [-P ] Generates a new .spkx project from a .xml file and a RF EM field import file.
--projectName [-N ] arg Specifies the name of a new .spkx project that will be generated from a .xml file and a RF EM field import file.
--output [-O ] arg
Specifies the path where output results will be written in a user-friendly way in text files.
--importDC [-D ] arg
Specifies the path to DC field import file .
--unitsDC [-d ] arg
Defines the metric units used in ANSYS® MAXWELL™ DC field import file. Argument value can be: m (meters), mm (milimeters) or
--fieldTypeDC [-F ] arg Specifies the type of DC field: B (magnetic) or E (electric).
inches.
--fileTypeDC [-f ] arg
Specifies the type of DC field import file: CST (for CST®), Maxwell (for ANSYS® MAXWELL™) or csv (for comma-separated value
files). For CSV files it is mandatory to specify the separator used in the file:
csv:blank
blank space
csv:,
csv:;
colon
semi-colon
csv:tab
tab
 # refers to an integer number.
Compatiblity with versions before Spark3D 2016
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Spark3D 1.6.x version files (before Spark3D 2016) have .spk extension and can be used with the command line interface, similarly to .spkx ones. The only difference is
that, when importing a <filename>.spk file, Spark3D will automatically export it to the newest version as <filename>.spkx. The simulation results will be stored in the
new <filename>.spkx format.
Command-line mode examples
This section collects several examples for the main command-line operation modes of Spark3D.
Validating a Spark3D project
Working with *.spkx project:
spark3d.exe --input="<examples folder>\TUTORIAL_EXAMPLE.spkx" --validate
Working with *.xml and RF import files:
spark3d.exe --XMLfile="...\Project.xml" --importRF "...\bandpass.mfe" --validate
Listing Spark3D project entities
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --list
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --list
Launching Corona configuration
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#//
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#// --projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx"
Launching video Corona configuration
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#/VideoCoronaConfig:#//
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#/VideoCoronaConfig:#// --
projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx"
Launching Multipactor configuration
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#//
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#// --projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx"
Launching video Multipactor configuration
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#/VideoMultipactorConfig:#//
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#/VideoMultipactorConfig:#// --
projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx"
Launching a configuration with user-friendly results
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#// --output="C:\Users\...\Documents\spark3d_workspace_2018\examples\myResults\"
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/CoronaConfig:#// --projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx" --
output="C:\Users\...\Documents\spark3d_workspace_2018\examples\myResults\"
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Generating a Spark3D project .spkx from *.xml and RF import files
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
generateProject --projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx"
Using DC fields for Multipactor simulations
Working with *.spkx project:
spark3d.exe --input="C:\Users\...\Documents\spark3d_workspace_2018\examples\TUTORIAL_EXAMPLE.spkx" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#// --importDC="C:\Users\...\Documents\spark3d_workspace_2018\...\Circulator_CST.csv" --
fileTypeDC=CST --fieldTypeDC=B
Working with *.xml and RF import files:
spark3d.exe --XMLfile="C:\Users\...\Documents\spark3d_workspace_2018\...\Project.xml" --importRF"C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.mfe" --
config=Project:1/Model:#/Configurations:1/EMConfigGroup:1/MultipactorConfig:#// --projectName="C:\Users\...\Documents\spark3d_workspace_2018\...\bandpass.spkx" --
importDC="C:\Users\...\Documents\spark3d_workspace_2018\...\Circulator_CST.csv" --fileTypeDC=CST --fieldTypeDC=B
XML file creation
Spark3D projects are .spkx packed files, which contain a .xml file with all information related to models and configurations in the project. This .xml file can be extracted
from the .spkx one to be used in command line mode.
In order to do that, you should use a compression/extraction file tool. You can either right-click on Spark3D project and open it with the extraction tool or you can
manually change the extension of Spark3D project from .spkx to a .zip and then open it with the extraction tool (changing the extension again to the original one when
finished the extraction). Once you have extracted the .xml file, you can modify it to prepare the simulations you want to run.
XML file modification
In this section we describe how to modify the .xml file used in Spark3D command-line in order to prepare a simulation.
Important: Each .xml file is related to a certain RF EM import file, which defines some properties of Model. You should make sure that you are using the right pair
of .xml and RF EM import files when entering the corresponding command-line arguments.
A Spark3D project is defined through a set of entities and properties that are specified in a .xml file. Through Spark3D GUI the user can easily modify them. Through
"Save" button a .xml file is automatically created as part of the .spkx project. Here are some of the main features of Spark3D .xml file:
As in any xml file, information is wrapped in tags, which correspond to entities and properties that define a Spark3D project.
Used tags are quite self-descriptive. For example, <Project> </Project> is the tag to define a Spark3D project.
Elements that correspond to entities may include properties and other entities, so their tags are nested. For example, <Project> entity includes both a
<Model> entity and a property <name>, whose tags are nested as shown below:
  <Project>
    <...>
    <name>{TUTORIAL_EXAMPLE.spkx}</name>
    <Model>
      <...>
     </Model>
  </Project>
Elements that correspond to properties contain text between their tags which correspond to the value of the property they represent. For example, in <name>
{TUTORIAL_EXAMPLE.spkx}</name>, the value of the property name is {TUTORIAL_EXAMPLE.spkx}. Depending on the type of property the text syntax
varies:
Property type
Syntax
user defined string of
characters
predefined tring of
characters
set of characters enclosed between curl brackets { }
set of characters with a predefined value
real number
number with decimal dot
integer number
number without decimal part
Example
{Model 1}
mm
1.234
12
vector
between parenthesis and components separated by semi-colon ( ; )
(0;0;0)
vector(element, vector) between parenthesis; vector components separated by colon ( ; ); element
(({MeshConfigImported 1},...
and vector separated by a colon ( , )
...({ImportRFField 1};{ImportRFField 2})))
A first approach to work with a Spark3D .xml file is to retrieve it from a .spkx project created through the GUI. To do so, you must apply a file archiver utility to the
.spkx file and extract the .xml file. Then you have a good starting point to work with. You can edit the file through any text editor. In the following sections, we will
explain in more detail how to add or modify the value of .xml elements, which should be adapted to characterize a simulation.
Some entities and properties included in the .xml file do NOT have a direct correspondence with elements shown in the GUI. This applies to:
<Configurations>, <EMConfigGroup>, <MeshConfigImported>, <ImportRFMesh>, <ImportRFField>, <MeshConfigSpark>,
<FieldConfigSingleSPARK>, <FieldConfigCollection>
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How to add or change a new region
Region entity is defined by the tags <RectangularRegion> </RectangularRegion>. As an entity belonging to <Model>, their tags should be nested. In the
same way, region properties are enclosed between region tags as shown below:
     <Model>
     <...>
      <RectangularRegion>
        <name>{RectangularRegion 2}</name>
        <Id>2</Id>
        <analyze>0</analyze>
        <originCoordinates>(0;0;0)</originCoordinates>
        <dimensions>(0.01;0.01;0.01)</dimensions>
      </RectangularRegion>
      <...>
    </Model>
Values of highlighted properties may be modified by the user. In the following table a description of each property is given:
Property
<name>
Type: user defined string of characters.
Description: User region name. It should not be repeated in other regions within the same Model.
<Id>
Type: integer.
Description: Region identification number. It should not be repeated in other regions within the same Model.
<originCoordinates> Type: vector of real numbers
Description: Corresponds to the center of a rectangular box that defines the region using cartesian coordinates. Should be given in meters.
<dimensions>
Type: vector of real numbers
Description: Corresponds to the size of a rectangular box that defines the region using cartesian coordinates. Should be given in meters.
In order to add a new region to Model:
1.  You should include between Model tags a new whole <RectangularRegion> section as the one shown above, changing at least both <name> and <Id>
property values.
2.  It is mandatory that for every new region added to a Model you create a new entity <MeshConfigSpark> </MeshConfigSpark> inside
<EMConfigGroup> element of the same Model as shown below. This entity corresponds to a mesh configuration associated to a certain region, which keeps
the part of the Circuit mesh contained in that region.
     <Model>
       <...>
       <Configurations>
         <...>
         <EMConfigGroup>
          <...>
           <MeshConfigSpark>
            <name>{MeshConfigSpark 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 2}</regionLabel>
            <FieldConfigCollection>
              <name>{FieldConfigCollection 1}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigCollection>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 1}</name>
              <Id>2</Id>
              <signalLabel>{CW 6}</signalLabel>
            </FieldConfigSingleSPARK>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 2}</name>
              <Id>3</Id>
              <signalLabel>{CW 4}</signalLabel>
            </FieldConfigSingleSPARK>
          </MeshConfigSpark>
          <...>
         </EMConfigGroup>
      </Configurations>
    </Model>
3.  Values of <name> and <Id> properties of <MeshConfigSpark> should not be repeated in other <MeshConfigSpark>  which lie in the same scope. 
4.  The property <regionLabel> should match <name> value of the Region previously added.
5.  For each existing signal in <Model> <MeshConfigSpark> should have an entity associated to one signal. Depending on the type of signal, you should add:
<FieldConfigSingleSPARK> </FieldConfigSingleSPARK> related to continuous wave single carrier signals.
<FieldConfigCollection> </FieldConfigCollection> corresponding to multicarrier signals.
For both entities, values of <name> and <Id> properties should not be repeated in the same <MeshConfigSpark> scope. Property <signalLabel>
must have the value of <name> of the signal associated to it.
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How to add or change a multicarrier signal
Multicarrier signal is an entity of Model defined by the tags <MultiCarrierSignal> </MultiCarrierSignal>. As an entity belonging to <Model>, their tags
should be nested. Multicarrier element is defined by some properties and also its own entities, <CarrierDef></CarrierDef>. Each <CarrierDef> represents a single
carrier signal that belongs to the multicarrier and has its own properties. The single carrier signals should be selected from the ones defined in Model.
     <Model>
      <...>
      <MultiCarrierSignal>
        <name>{MC 1}</name>
        <Id>1</Id>
        <CarrierDef>
          <carrierLabel>{CW 4}</carrierLabel>
          <carrierPhase>0</carrierPhase>
          <carrierPower>1</carrierPower>
        </CarrierDef>
        <CarrierDef>
          <carrierLabel>{CW 6}</carrierLabel>
          <carrierPhase>0</carrierPhase>
          <carrierPower>1</carrierPower>
        </CarrierDef>
      </MultiCarrierSignal>
      <...>
    </Model>
Values of highlighted properties may be modified by the user. In the following table a description of each property is given:
Property
<name>
Type: user defined string of characters.
Description: User signal name. It should not be repeated in other signals within the same Model.
<Id>
Type: integer
Description: Signal identification number. It should not be repeated in other signals within the same Model.
<carrierLabel> Type: user defined string of characters
Description: Name of a continous wave single carrier that defines the multicarrier. It should correspond to one of the single carriers defined in
Model.
<carrierPhase> Type: real number
Description: Corresponds to the phase in degrees associated by the user to the single carrier selected in <CarrierDef>.
<carrierPower> Type: real number
Description: Corresponds to the power in wats associated by the user to the single carrier selected in <CarrierDef>.
In order to add a new multicarrier to Model:
1.  You should include between Model tags a new whole <MultiCarrierSignal> section as the one shown above, changing at least both <name> and <Id>
property values.
2.  It is mandatory that for every new multicarrier signal added to a Model you create a new entity <FieldConfigCollection>
</FieldConfigCollection> associated to it within two different entities:
<MeshConfigImported>
<MeshConfigSpark
This entity corresponds to the EM field associated to the multicarrier signal.        
3.  Values of <name> and <Id> properties of <FieldConfigCollection> should not be repeated in other <FieldConfigCollection>
4.  Property <signalLabel> should match <name> value of the multicarrier associated to it.
     <Model>
      <...>
       <Configurations>
        <...>
         <EMConfigGroup>
          <...>
           <MeshConfigImported>
            <name>{MeshConfigImported 1}</name>
            <Id>1</Id>
            <regionLabel>{Circuit}</regionLabel>
            <FieldConfigCollection>
              <name>{FieldConfigCollection 1}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigCollection>
            <...>
           </MeshConfigImported>        
           <MeshConfigSpark>
            <name>{MeshConfigSpark 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 2}</regionLabel>
            <FieldConfigCollection>
              <name>{FieldConfigCollection 1}</name>
              <Id>1</Id>
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              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigCollection>
            <...>
           </MeshConfigSpark>
          <...>
         </EMConfigGroup>
      </Configurations>
    </Model>
Modulated signals cannot be edited directly in the XML, they can be launched from command line if a .spkx (or xml file) has been created previously with the GUI.
How to add or change a Corona configuration
Corona configuration is an entity of Model defined by the tags <CoronaConfig> </CoronaConfig>. As a <Model> entity, their tags are nested as shown below.
Corona configuration is defined by some properties and the entity, <PressureSweep> </PressureSweep>, which determines pressure values where Corona analysis will
be done.
    <Model>
      <...>
      <Configurations>
        <EMConfigGroup>
          <...>
          <CoronaConfig>
            <name>{CoronaConfig 1}</name>
            <Id>1</Id>
            <selectedFields>(({MeshConfigImported 1},({ImportRFField 1})))</selectedFields>
            <initialPower>100</initialPower>
            <initial_power_type>userdefined</initial_power_type>
            <temperature>293</temperature>
            <precision>0.10000000000000001</precision>
            <gas>air</gas>
            <simulationType>numeric_high_pressure</simulationType>
            <...>
            <PressureSweep enable="1">
              <name>{PressureSweep 1}</name>
              <Id>1</Id>
              <sweepMode>SWEEP_STEP</sweepMode>
              <start>1</start>
              <end>6</end>
              <step>1</step>
              <numberPoints>6</numberPoints>
              <sweepPoints>()</sweepPoints>
            </PressureSweep>
          </CoronaConfig>
        </EMConfigGroup>
      </Configurations>
    </Model>
In order to configure a Corona simulation, you should change the properties highlighted above. In the following table, a description of each property is given:
Property
<name>
Type: user defined string of characters
Description: User name for Corona configuration. It should not be repeated in other Corona configurations within the same Model.
<Id>
Type: integer
Description: Corona configuration identification number. It should not be repeated in other Corona configurations within the same
Model.
<selectedFields>
Type: vector(mesh configuration <name>, vector(field configuration <name>)) of strings of characters
Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the
<name> of region and signal entities, you should include the <name> of the mesh and field configurations associated to them (shown
in red below).
This information is located in the following sections.
For Circuit region:
          <MeshConfigImported>
            <name>{MeshConfigImported 1}</name>
            <Id>1</Id>
            <regionLabel>{Circuit}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 1}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <ImportRFMesh>
              <name>{ImportRFMesh 1}</name>
              <Id>1</Id>
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              <importFile>{ExportToSPARK3D(1).f3e}</importFile>
              <fileFormat>CST</fileFormat>
              <ImportRFField>
                <name>{ImportRFField 1}</name>
                <Id>1</Id>
                <signalLabel>{CW 6}</signalLabel>
              </ImportRFField>
              <...>
            </ImportRFMesh>
          </MeshConfigImported>
For a user defined region:
          <MeshConfigSingleSPARK>
            <name>{MeshConfigSingleSPARK 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 1}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 2}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 1}</name>
              <Id>3</Id>
              <signalLabel>{CW 6}</signalLabel>
            </FieldConfigSingleSPARK>
            <...>
          </MeshConfigSingleSPARK>
<initialPower>
Type: real number
<initial_power_type> Type: predefined string of characters
Description: Power (in W) from which the threshold breakdown power is looked for.
Description: Two options can be considered for the initial power used in the threshold search process:
"userdefined": the value of <initialPower> will be used as starting point
"automatic": the initial value is taken automatically from the high pressure analytical approach.
<temperature>
Type: real number
Description: Corresponds to the ambient temperature (in Kelvin).
<precision>
Type: real number
<gas>
Type: predefined string of characters
Description: Sets the desired precision in power level (in dB) for the corona breakdown onset.
Description: Different gases can be considered in the simulation: "nitrogen", "air", "argon", "helium", "sf6", "co2"
<simulationType>
Type: predefined string of characters
Description: Three different simulation types can be considered:
"numeric": corresponds to a numeric algorithm that uses an adapted FEM technique to solve the free electron density continuity
equation.
"high_pressure_rule": uses an analytical rule based in empirical estimations at high pressures to calculate the breakdown onset.
"numeric_high_pressure": enables both simulation types.
<PressureSweep
Type: real number
enable="1">
<start>
Description: Represents the pressure value at which the sweep will start.
<PressureSweep
Type: real number
enable="1">
<end>
Description: Represents the pressure value at which the sweep will finish.
<PressureSweep
Type: real number
enable="1">
<step>
Description: Represents the step in pressure for the sweep.
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In order to add a new Corona configuration to Model you should include between Model tags a new whole <CoronaConfig> section as the one shown above,
changing at least both <name> and <Id> property values. Then you can change any other properties according to the specific conditions you want to simulate.
How to add or change a Multipactor configuration
Multipactor configuration is an entity of Model defined by the tags <MultipactorConfig> </MultipactorConfig>. As an entity belonging to <Model>, their
tags are nested as shown below. Multipactor configuration is defined by some properties and the entity, <SweepUtil> </SweepUtil>, which determines a set of
power values defined by the user where Multipactor analysis will be done. See Setting a Multipactor configuration for further information.
    <Model>
       <...>
       <Configurations>
         <EMConfigGroup>
          <...>
          <MultipactorConfig>
            <name>{MultipactorConfig 1}</name>
            <Id>1</Id>
            <selectedFields>(({MeshConfigImported 1},({ImportRFField 1})))</selectedFields>
            <DC_BField>()</DC_BField>
            <DC_EField>()</DC_EField>
            <DC_BMultiplier>()</DC_BMultiplier>
            <DC_EMultiplier>()</DC_EMultiplier>
            <initialNumberElectrons>300</initialNumberElectrons>
            <SCInitialPower>500</SCInitialPower>
            <SCPrecision>0.10000000000000001</SCPrecision>
            <SCMaxPower>1000000</SCMaxPower>
            <multipactorCriterion>default</multipactorCriterion>
            <criterionFixedFactor>10</criterionFixedFactor>
            <material>silver</material>
            <SEYModelName>Vaughan</SEYModelName>
            <maxSecondaryEmissionCoeff>2.2200000000000002</maxSecondaryEmissionCoeff>
            <lowerCrossoverElectronEnergy>30</lowerCrossoverElectronEnergy>
            <secondaryEmissionCoeffBelowLowCrossover>0.5</secondaryEmissionCoeffBelowLowCrossover>
            <electronEnergyAtMaxSEY>165</electronEnergyAtMaxSEY>
            <customEVec>()</customEVec>
            <customSEYRVec>()</customSEYRVec>
            <customSEYSVec>()</customSEYSVec>
            <customSEYFileName>{}</customSEYFileName>
            <extDCBfieldUniform>0</extDCBfieldUniform>
            <BDCx>0</BDCx>
            <BDCy>0</BDCy>
            <BDCz>0</BDCz>
            <extDCEfieldUniform>0</extDCEfieldUniform>
            <EDCx>0</EDCx>
            <EDCy>0</EDCy>
            <EDCz>0</EDCz>
            <pathRelativePrecision>1</pathRelativePrecision>
            <homogeneousEmission>0</homogeneousEmission>
            <write3DStats>1</write3DStats>
            <customFixedTime>0</customFixedTime>
            <customMaxTime>10</customMaxTime>
            <iterationType>bisection</iterationType>
            <...>
            <SweepUtil enable="1">
              <name>{SweepUtil 1}</name>
              <Id>1</Id>
              <sweepMode>SWEEP_LIST</sweepMode>
              <start>9.9999999999999995e-07</start>
              <end>9.9999999999999995e-07</end>
              <step>0</step>
              <numberPoints>1</numberPoints>
              <sweepPoints>(500)</sweepPoints>
            </SweepUtil>
          </MultipactorConfig>
        </EMConfigGroup>
       </Configurations>
    </Model>
In order to configure a Multipactor simulation, you should change the properties highlighted above. In the following table, a description of each property is given:
Property
<name>
Type: user defined string of characters
Description: User name for Multipactor configuration. It should not be repeated in other Multipactor configurations within the same
Model.
<Id>
Type: integer
Description: Multipactor configuration identification number. It should not be repeated in other Multipactor configurations within the
same Model.
<selectedFields>
Type: vector(mesh configuration <name>, vector(field configuration <name>)) of strings of characters
Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the
<name> of region and signal entities, you should include the <name> of the mesh and field configurations associated to them (shown
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in red below).
This information is located in the following sections.
For Circuit region:
          <MeshConfigImported>
            <name>{MeshConfigImported 1}</name>
            <Id>1</Id>
            <regionLabel>{Circuit}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 1}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <ImportRFMesh>
              <name>{ImportRFMesh 1}</name>
              <Id>1</Id>
              <importFile>{ExportToSPARK3D(1).f3e}</importFile>
              <fileFormat>CST</fileFormat>
              <ImportRFField>
                <name>{ImportRFField 1}</name>
                <Id>1</Id>
                <signalLabel>{CW 6}</signalLabel>
              </ImportRFField>
              <...>
            </ImportRFMesh>
          </MeshConfigImported>
For a user defined region:
          <MeshConfigSingleSPARK>
            <name>{MeshConfigSingleSPARK 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 1}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 2}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 1}</name>
              <Id>3</Id>
              <signalLabel>{CW 6}</signalLabel>
            </FieldConfigSingleSPARK>
            <...>
          </MeshConfigSingleSPARK>
<DC_BField>
Type: vector(DC_field<name>)
Description: Selected DC imported magnetic field labels to be considered in this configuration. The DC field labels must correspond
to the names of existing DC magnetic fields previously imported in the model.
<DC_EField>
Type: vector(DC_field<name>)
Description: Selected DC imported electric fields to be considered in this configuration. The DC field labels must correspond to the
names of existing DC electric fields previously imported in the model.
<DC_BMultiplier>
Type: vector(real number)
Description: Factors to scale the imported DC magnetic fields. The size of this vector must be equal to the size of vector <DC_BField>.
<DC_EMultiplier>
Type: vector(real number)
Description: Factors to scale the imported DC electric fields. The size of this vector must be equal to the size of vector <DC_EField>.
<initialNumber
Type: integer
Electrons>
Description: Number of electrons at the beginning of the simulation.
<SCInitialPower>
Type: real number
Description: Starting power (W) used in the automatic multipactor breakdown search.
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<SCPrecision>
Type: real number
Description: Sets the desired precision in power level (in dB) for the automatic multipactor breakdown search.
<SCMaxPower>
Type: real number
Description: Maximum simulation power allowed in the automatic multipactor breakdown search.
<multipactor
Type: predefined string of characters
Criterion>
Description: Three different multipactor criterion for the automatic search may be selected:
default: corresponds to "Default" option in GUI
chargeFixed: corresponds to "Charge (fixed factor)" option in GUI
chargeTrend: corresponds to "Charge trend" option in GUI
See Setting a Multipactor configuration for further information.
<criterionFixed
Type: real number
Factor>
Description: If the previous parameter is set to charge_min, this specifies the growth factor for considering multipactor.
<material>
Type: user defined string of characters
Description: Arbitrary name that the user may set to the defined material.
<SEYModelName>
Type: upredefined string of characters
Description: SEY curve may be computed in two different ways:
Vaughan: SEY is analytically computed with the Vaughan curve taking the SEY parameters given below
fromFile: SEY is given by tabulated values coming from ASCII input file
<maxSecondary
Type: ureal number
EmissionCoeff>
Description: If <SEYModelName> is set to Vaughan:
This parameter specifies the maximum value of the SEY curve.
<lowerCrossover
Type: real number
ElectronEnergy>
Description: If <SEYModelName> is set to Vaughan:
This parameter specifies the first cross-over energy of the SEY curve (lowest energy at which SEY = 1).
<secondaryEmission
Type: real number
CoeffBelow
Description: If <SEYModelName> is set to Vaughan:
LowCrossover>
This parameter specifies the value of the SEY curve at low energies below the first cross-over energy.
<electronEnergy
Type: real number
AtMaxSEY>
Description: If <SEYModelName> is set to Vaughan:
This parameter specifies the value of the energy of the incident electron for which the value of the SEY curve is maximum.
<customEVec>
Type: vector(real number)
Description: If <SEYModelName> is set to fromFile:
Vector of real numbers with the energy values of the SEY curve.
<customEVec>, <customSEYRVec> and <customSEYSVec> must have the same length
<customSEYRVec>
Type: vector(real number)
Description: If <SEYModelName> is set to fromFile:
Vector of real numbers with the value of the SEY coming from ellastically reflected electrons.
<customEVec>, <customSEYRVec> and <customSEYSVec> must have the same length
<customSEYSVec>
Type: vector(real number)
Description: If <SEYModelName> is set to fromFile:
Vector of real numbers with value of the SEY coming from true secondary electrons.
<customEVec>, <customSEYRVec> and <customSEYSVec> must have the same length
<customSEYFileName>
Type: user defined string of characters
Description: Name of file from which the above curves where imported. It is only an informative field.
<extDCBfieldUniform>
Type: integer
Description: Can be 0 (false) or 1 (true).
If true, an external uniform DC magnetic field is added to the simulation.
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<BDCx>
Type: real number
Description: if <extDCBfieldUniform> is true, this parameter is the x-component of the external uniform DC magnetic field.
<BDCy>
Type: real number
Description: if <extDCBfieldUniform> is true, this parameter is the y-component of the external uniform DC magnetic field.
<BDCz>
Type: real number
Description: if <extDCBfieldUniform> is true, this parameter is the z-component of the external uniform DC magnetic field.
<extDCEfieldUniform>
Type: integer
Description: Can be 0 (false) or 1 (true).
If true, an external uniform DC electric field is added to the simulation.
<EDCx>
Type: real number
Description: if <extDCEfieldUniform> is true, this parameter is the x-component of the external uniform DC electric field.
<EDCy>
Type: real number
Description: if <extDCEfieldUniform> is true, this parameter is the y-component of the external uniform DC electric field
<EDCz>
Type: real number
Description: if <extDCEfieldUniform> is true, this parameter is the z-component of the external uniform DC electric field
<pathRelative
Type: real number
Precision>
Description: It is the path integration error for the adaptive electron tracking step given in %. The lower the more precise (but slower)
<homogeneousEmission> Type: integer
Description: Can be 0 (false) or 1 (true).
If false, the initial electrons are automatically located at the surfaces with highest electric field value.
If true, the initial electrons are randomly located in all metallic surfaces with a homogeneous distribution.
<write3DStats>
Type: integer
Description: Can be 0 (false) or 1 (true).
If true, extra 3D statistic files are stored in the simulation.
<customFixedTime>
Type: integer
Description: if <iterationType> is set to custom
Can be 0 (false) or 1 (true).
If true, multipactor simulation won't stop until <customMaxTime> is reached.
If false, the selected <multipactorCriterion> will be used.
<customMaxTime>
Type: real number
Description: if <iterationType> is set to custom and <customFixedTime> is set to true
This value specifies the maximum simulation time.
<iterationType>
Type: user defined string of characters
Description: Can have two values:
bisection: The simulation will perform an automatic breakdown power search.
custom: The simulation will used a set of predefined power values.
<SweepUtil
enable="1">
<numberPoints>
<SweepUtil
enable="1">
<sweepPoints>
Type: nteger
Description: if <iterationType> is set to custom
This is the number of points in the custom power list.
Type: vector(real number)
Description: if <iterationType> is set to custom
This vector contains the values of the custom power loop. Its size must be equal to <numberPoints>
How to add or change a video Corona configuration
Video Corona configuration is an entity of Corona Configuration defined by the tags <VideoCoronaConfig> </VideoCoronaConfig>. As a <CoronaConfig>
configuration entity, their tags are nested as shown below.
          <CoronaConfig>
            <...>
            <VideoCoronaConfig>
              <name>{VideoCoronaConfig 1}</name>
              <Id>1</Id>
              <selectedFields>(({MeshConfigImported 1},({ImportRFField 1})))</selectedFields>
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              <FramesPerPeriod>15</FramesPerPeriod>
              <InputPower>100</InputPower>
              <MaxSize>0</MaxSize>
              <StopCriterion>densMax</StopCriterion>
              <ElectronMaxDens>1000</ElectronMaxDens>
              <EndTime>1</EndTime>
              <CoronaPressure>1</CoronaPressure>
              <AccuracyType>high</AccuracyType>
            </VideoCoronaConfig>
            <...>
          </CoronaConfig>
Video Corona configuration is defined by some properties that can be modified in order to prepare the simulation. In order to configure a video Corona simulation,
you should change the properties highlighted above. In the following table, a description of each property is given:
Property
<name>
Type: user defined string of characters
Description: User name for video Corona configuration. It should not be repeated in other video Corona configurations within the same
Corona configuration.
<Id>
Type: integer
Description: Video Corona configuration identification number. It should not be repeated in other video Corona configurations within the
same Corona configuration.
<selectedFields>
Type: vector(mesh configuration <name>, vector(field configuration <name>)) of strings of characters
Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the <name> of
region and signal entities, you should include the <name> of the mesh and field configurations associated to them (shown in red below).
This information is located in the following sections.
For Circuit region:
          <MeshConfigImported>
            <name>{MeshConfigImported 1}</name>
            <Id>1</Id>
            <regionLabel>{Circuit}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 1}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <ImportRFMesh>
              <name>{ImportRFMesh 1}</name>
              <Id>1</Id>
              <importFile>{ExportToSPARK3D(1).f3e}</importFile>
              <fileFormat>CST</fileFormat>
              <ImportRFField>
                <name>{ImportRFField 1}</name>
                <Id>1</Id>
                <signalLabel>{CW 6}</signalLabel>
              </ImportRFField>
              <...>
            </ImportRFMesh>
          </MeshConfigImported>
For a user defined region:
          <MeshConfigSingleSPARK>
            <name>{MeshConfigSingleSPARK 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 1}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 2}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 1}</name>
              <Id>3</Id>
              <signalLabel>{CW 6}</signalLabel>
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            </FieldConfigSingleSPARK>
            <...>
          </MeshConfigSingleSPARK>
Just one pair of  mesh and field configurations should be selected.
<FramesPerPeriod> Type: integer
Description: Specifies the frame rate of the recording. The higher, the smoother the animation, but bigger video sizes will be generated.
<InputPower>
Type: real number
Description: Sets the input power (in W) for this specific video recording.
<StopCriterion>
Type: predefined string of characters
Description: Sets the criterion used in the last frame of the video to stop the computation of the electron density:"densMax" or "timeMax".
<ElectronMaxDens> Type: real number
Description: Sets the maximum value of the computed electron density in the last frame of the video.
<EndTime>
Type: real number
Description: Sets the maximum time where the electron density time evolution will be calculated.
<CoronaPressure>
Type: real number
Description: Sets the pressure value (in mbar) for this specific video recording.
<AccuracyType>
Type: predefined string of characters
Description: Sets the level of accuracy that will be used in the electron density computation. The higher is this level, the more accurate, time
and memory consuming is the computation. Three options are possible: "medium", "high", "veryHigh".
In order to add a new video Corona configuration you should include between Corona tags a new whole <VideoCoronaConfig> section as the one shown above,
changing at least both <name> and <Id> property values. Then you can change any other properties according to the specific conditions you want to simulate.
How to add or change a video Multipactor configuration
Video Multipactor configuration is an entity of Multipactor Configuration defined by the tags <VideoMultipactorConfig> </VideoMultipactorConfig>. As a
<MultipactorConfig> configuration entity, their tags are nested as shown below.
          <MultipactorConfig>
            <...>
            <VideoMultipactorConfig>
              <name>{VideoMultipactorConfig 1}</name>
              <Id>1</Id>
              <selectedFields>(({MeshConfigImported 1},({ImportRFField 1})))</selectedFields>
              <FramesPerPeriod>15</FramesPerPeriod>
              <InputPower>100</InputPower>
              <StartTime>0</StartTime>
              <EndTime>10</EndTime>
            </VideoMultipactorConfig>
            <...>
          </MultipactorConfig>
Video Multipactor configuration is defined by some properties that can be modified in order to prepare the simulation. In order to configure a video Multipactor
simulation, you should change the properties highlighted above. In the following table, a description of each property is given:
Property
<name>
Type: user defined string of characters
Description: User name for video Multipactor configuration. It should not be repeated in other video Multipactor configurations within the
same Multipactor configuration.
<Id>
Type: integer
Description: Video Multipactor configuration identification number. It should not be repeated in other video Multipactor configurations
within the same Multipactor configuration.
<selectedFields>
Type: vector(mesh configuration <name>, vector(field configuration <name>)) of strings of characters
Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the <name> of
region and signal entities, you should include the <name> of the mesh and field configurations associated to them (shown in red below).
This information is located in the following sections.
For Circuit region:
          <MeshConfigImported>
            <name>{MeshConfigImported 1}</name>
            <Id>1</Id>
            <regionLabel>{Circuit}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 1}</name>
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              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <ImportRFMesh>
              <name>{ImportRFMesh 1}</name>
              <Id>1</Id>
              <importFile>{ExportToSPARK3D(1).f3e}</importFile>
              <fileFormat>CST</fileFormat>
              <ImportRFField>
                <name>{ImportRFField 1}</name>
                <Id>1</Id>
                <signalLabel>{CW 6}</signalLabel>
              </ImportRFField>
              <...>
            </ImportRFMesh>
          </MeshConfigImported>
For a user defined region:
          <MeshConfigSingleSPARK>
            <name>{MeshConfigSingleSPARK 2}</name>
            <Id>2</Id>
            <regionLabel>{RectangularRegion 1}</regionLabel>
            <FieldConfigMulti>
              <name>{FieldConfigMulti 2}</name>
              <Id>1</Id>
              <signalLabel>{MC 1}</signalLabel>
            </FieldConfigMulti>
            <FieldConfigSingleSPARK>
              <name>{FieldConfigSingleSPARK 1}</name>
              <Id>3</Id>
              <signalLabel>{CW 6}</signalLabel>
            </FieldConfigSingleSPARK>
            <...>
          </MeshConfigSingleSPARK>
Just one pair of  mesh and field configurations should be selected.
<FramesPerPeriod> Type: integer
Description: Specifies the frame rate of the recording. The higher the smoother the animation, but bigger video sizes will be generated.
<InputPower>
Type: real number
Description: Sets the input power (in W) for this specific video recording.
<StartTime>
Type: real number
Description: Sets the initial time (in ns) for video recording.
<EndTime>
Type: real number
Description: Sets the maximum time (in ns) for video recording.
In order to add a new video Multipactor configuration you should include between Multipactor tags a new whole <VideoMultipactorConfig> section as the one
shown above, changing at least both <name> and <Id> property values. Then you can change any other properties according to the specific conditions you want to
simulate.
2.2.11 Multipactor Analysis
Multipactor discharge analysis involves computing the breakdown power threshold of several regions defined by the
user in a specific device. This is the objective of what we call a Multipactor configuration. The breakdown power
calculated is the input power at the entrance of the device. 
On top of that, a video of the multipactor discharge occurring for a certain power level can be recorded by means
of what we call a Multipactor video configuration, which is defined in the framework of a certain Multipactor
configuration.
The following items shall be considered:
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What is a Multipactor analysis?
Brief description of the phenomenon and the current SPARK3D Multipactor analysis features.
Setting a Multipactor configuration
It is described how to create a new Multipactor configuration and how to set its parameters.
Running/Stopping a Multipactor configuration
An explanation on how to run or stop a Multipactor simulation is given.
Analyzing Multipactor results
It is explained how to visualize and analyze the output results of a Multipactor discharge simulation.
Recording and playing a Multipactor video
Multipactor video parameters are considered in detail and it is also explained how to create, open and run
a Multipactor video configuration.
Multipactor practical considerations
Some important considerations are taken into account: Multipactor limitations you should be aware of, possible errors
and solutions or workarounds to them, and other non-trivial properties of the use of Multipactor configurations.
2.2.11.1 What is a Multipactor analysis?
Definition
The Multipactor analysis computes the multipactor breakdown power threshold of one or more particular regions of
the structure. It supports single and multi-carrier operation.
For a more detailed information about multipactor theory and results see:
S. Anza, C. Vicente, B. Gimeno, V. E. Boria, and J. Armendariz, "Long-term multipactor discharge in multicarrier
systems," Physics of Plasmas, vol. 14, pp. 082112–082112–8, Aug. 2007.
S. Anza, C. Vicente, D. Raboso, J. Gil, B. Gimeno, V. E. Boria, “Enhanced Prediction of Multipaction Breakdown in Passive
Waveguide Components including Space Charge Effects", in IEEE 2008 International Microwave Symposium , June
2008, Atlanta (Georgia), USA.
S. Anza, C. Vicente, J. Gil, B. Gimeno, V. E. Boria, and D. Raboso, "Non-stationary Statistical Theory for Multipactor,"
Physics of Plasmas, vol. 17, June 2010.
S. Anza, M. Mattes, C. Vicente, J. Gil, D. Raboso, V. E. Boria, and B. Gimeno, Multipactor theory for multicarrier signals,
Physics of Plasmas 18, 032105 (2011)
S. Anza et al., "Prediction of Multipactor Breakdown for Multicarrier Applications: The Quasi-Stationary Method," in
IEEE Transactions on Microwave Theory and Techniques, vol. 60, no. 7, pp. 2093-2105, July 2012.
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Features
Single-carrier and multi-carrier simulations with arbitrary number of carriers and phase schemes.
Custom SEY curves. Possibility of using Predefined SEY materials (according to ECSS standards and The
Aerospace Corporation aluminium (TOR-2014)), user defined parameters or import from text file.
Computation of electron evolution for each applied input power.
Automatic multipactor threshold determination.  
Advanced 3D output statistics with average impact energy, average SEY, and emitted electron density for the
different surfaces in the structure.
Possibility to add external uniform DC magnetic and/or electric field.
Arbitrary external electric and/or magnetic DC fields, with CST® EMS™, ANSYS® MAXWELL™ or rectangular
CSV mesh formats, can be imported and incorporated to the simulation.
Electron path algorithm with adaptive refinement which allows for faster and more accurate simulations.
Different multipactor criteria. The multipactor criteria allows for automatically stop the simulation and
decide whether there is multipactor discharge or not. The election of one or another have implications on the
accuracy and speed of the simulation. This is of special importance in multi-carrier simulations. The user can
easily change the criteria from the configuration window. The available criteria are: charge (automatic), charge
(fixed factor) and charge trend.
Impact angle dependence for SEY curves imported from text files.
Multipactor video recording feature. The user can export videos of electrons moving in a 3D structure and
open them at any time. Final export to popular video formats (such as .avi) can also be done.
Automatic power loop, in which input power levels are automatically computed to find the multipactor
threshold, and Custom power loop, in which the user can specify as many arbitrary input power levels as
desired
Multipactor analysis can be run on the entire imported mesh or on different user defined regions to speed up
the simulation.  
2.2.11.2 Setting a Multipactor configuration
Adding a new Multipactor configuration
It is possible to create as many Multipactor configurations as needed in the Multipactor Configuration Group. This
way, you can analyze the multipactor discharge in the same device with different multipactor parameters. For
example, you can change the SEY properties of the material.
In order to create a new multipactor configuration, right-click on the Configuration Group tree item and select Add
Multipactor Configuration option as is shown below
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A new Multipactor configuration item will appear in the tree in the framework of the Multipactor Configuration Group.
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Setting Multipactor configuration parameters
Multipactor configuration parameters are set from its corresponding window, which can be opened from the
Multipactor configuration tree item by double clicking on it or using Open Multipactor Configuration right-click
option.
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Configuration window
The configuration window allows setting the multipactor simulation parameters.
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Fields
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Fields Through this option the user can choose the different combinations of signals and regions of the structure
where the analysis will be carried out by simply enabling their check-boxes. If a field corresponding to a
specific signal-region, that has been previously simulated, is disabled, its results will be preserved and shown
in the Multipactor window. This way, the user can incorporate new fields of analysis keeping the results of
the already defined ones. 
It is also possible to access the Analysis Regions window from the Edit Regions button. It is important to
point out that all modifications made on the regions from that window will apply to all configurations. So, if
a region, which is used in several configurations both of Corona and Multipactor, is changed or deleted
all existing results corresponding to it will be erased.
Signals can be edited with the Signal Window.
Material
It allows asigning Secondary Electron Yield (SEY) properties to the materials present in the model. It also allows
creating new SEY definitions and save them for future simulations.
 On the left-hand side of the section, The materials and associated SEY definitions are listed
Material/SEY
table
It shows the list of project materials and associated SEY curve. By clicking on each material's row, it is
possible to view and edit the SEY parameters correspondingt to that material, which are shown on
the right-hand side of the Material section.
Set All
Assigns the SEY definition next to it to all materials in the table.
View
Materials
It opens a paraview window and visualizes the materials in the model, similarly to Visualize
3D option in Project tree .
The SEY properties are shown on the right-hand side. They can be defined in two ways:
Default materials: They are defined by parameters and modeled by the Vaughan formula. Some predefined
materials can be selected. User defined parameters can be entered as well.
SEY name
Six materials are included with their SEY properties. User defined
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materials are saved and loaded with the Solution.            
Maximum secondary emission
coefficient
Maximum SEY of the material. Typical values are between 1.5 and 3.
Secondary emission coefficient
below lower crossover
SEY of elastically reflected electrons at low impact energies. By default,
0.5.
Lower crossover electron
energy (eV)
The lowest electron impact energy at which the SEY crosses the value of
1. This is a typical value between 15 and 100 eV.
Electron energy at maximum
SEY (eV)
The electron impact energy at which the SEY is maximum. Typical values
are between 150 and 300 eV.
It is also possible to use a custom SEY by importing it from an input file. The file must be in CSV (comma-
separated-value) format, which is text file with .csv extension that consists on tabulated data. The SEY file
should have 2 (or three) columns: the first one contains the electron impact energy in eV and the second one
corresponds to the SEY of the material at normal incidence. The third column is optional and contains the
elastically reflected electrons. If not present, these are assumed to be zero at all energies.  Spark3D will
automatically add the angle dependence for each electron impact. For energies outside the range defined in
the input file, the SEY will be set to 0.
Press the button with icon  
  to open a new window with a plot of the selected SEY curve.
The selection and definition of the SEY curve has an important effect on the multipactor simulation. See some
practical considerations when selecting the material properties.
DC fields
By selecting the check boxes inside Uniform Fields, uniform DC fields are added to the simulation. Units are Tesla and
V/m respectively.
If External DC Fields have been added to the model, these will be listed in the table. They can be independently
activated or deactivated for the simulation. A Scale Factor can be applied to the fields magnitude.
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Simulation preferences
Automatic
power loop
If selected, the multipactor module will search automatically for the multipactor threshold, starting
from the initial power and stopping when the desired precision is reached. Bisection method is
employed, and the multipactor criterion (to determine whether there has been a discharge or not) is
set by the Multipactor criterion menu below. The parameters are:
Precision (dB): This parameter sets the precision in power level desired for the multipactor
breakdown onset. The default is 0.1 dB.
Initial power (W): This will be the initial input power used to search the multipactor
breakdown onset. This can be changed to an input power level close to the final breakdown
onset if some information is known a priori.
Maximum power (W): Sets the maximum allowed power for multipactor breakdown search. If
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the simulation reaches this power and no multipactor is observed the element is considered
multipactor free. The default is 1 MW.
Custom
power loop
If selected, the input power steps are selected by the user by pressing the edit button. A multipactor
simulation will be done for each step.
The criterion for stopping the simulation can be chosen from:
Stop based on multipactor criterion: The simulation will stop if a discharge (or not discharge)
is detected, using the selected criterion in the menu below.
Stop on fixed time: The simulation time is fixed, no matter whether there is a discharge or not,
unless the number of electrons decreases to 0, or reaches the maximum allowed number of
electrons (1e15 for numerical stability reasons).
Initial
number of
electrons
This defines the initial number of electrons launched in a particular component element. This number
can vary in order to obtain reliable results. The default value of 300 electrons should be quite accurate
in single-carrier mode and in waveguide elements where the parallel plate approximation holds.
However, if the length of the waveguide element is of the order of its height more electrons could be
necessary. For a complete simulation, the best idea is to start with a low number of electrons in order
to get a fast idea of the approximated breakdown power level. After that, more electrons can be
launched using an input power level close to the one obtained in the simulation with few electrons.
Multipactor
criterion
Multipactor criterion is the mechanism that automatically decides whether there is a discharge or not
at a certain input power. There are three different criteria, all of them based on the electron
population:
Default: This is the default mode. At each RF half-cycle, the ratio between the current number
of electrons and the initial ones are checked. This criterion establishes a factor depending on
the current number of simulated half-cycles. If the number of electrons is above such a factor,
multipactor is detected. Basically, it sets higher factors for lower number of half-cycles
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(beginning of the simulation) and more relaxed ones for larger number of half-cycles (longer
simulations). This is done in order to avoid false detection during the initial stages of the
simulation. Additionally, if after a certain number of cycles, the ratio is below a certain number,
the simulation is stopped and no multipactor is detected. This is done in order to avoid
excessively large simulations in which there is not a clear electron growth.
The default criterion for multi-carrier signals is equal to the "Charge trend" criterion.
The default criterion for modulated signals (or a multi-carrier signal containing one or
more modulated signals) is equal to the "Charge (fixed factor)" criterion with a factor of
1e10.
Charge (fixed factor): It is similar the automatic one, but the factor is not automatic but set by
the user. Gives more control on the simulation but needs of more knowledge on the specific
problem from the user side. It does not have any check for low number of electrons. Only
populations decreasing to zero are considered no discharges. Therefore there is a risk of long
simulations.
Charge trend: It fits the electron evolution to a exponential curve and checks whether there is
positive or negative growth. It detects both discharges and no discharges. In general, this
method detects multipactor much faster than the others. However, it may suffer from higher
variability between consecutive simulations. In such cases, it is advisable to use a high number
of initial electrons.
Charge trend for multi-carrier signals: This criterion takes the advantage of the multi-carrier
envelope periodicity. First, it checks the electron ratio. If it is higher than 1e7, multipactor is
detected. In addition, it checks inter-period accumulation. This is, it stores the maximum
population at each period of the envelope and compares it with the initial one. If noticeable
growth is detected, then there is a multipactor discharge
Charge trend criterion for modulated signals (or a multi-carrier signal containing one or
more modulated signals) is equal to the "Charge (fixed factor)" criterion with a factor of
1e10.
Since modulated signals have a time varying arbitrary non-periodic amplitude, it is not possible
to define a charge trend criterion for them. Only "Charge (fixed factor)" criterion is suitable in this
case. However, since a multipactor simulation can be run simultaneously for different signals, it is
necessary to define a behaviour for the rest of criterions, since they could be chosen for other
kind of signals present in the simulation (continuous wave and/or Multicarrier).
Write 3D
stats
It writes advanced statistics in Paraview mesh format that can be visualized from the results tab :
Average SEY: It shows the average SEY of the impacting electrons in each surface mesh
triangle.
Average Impact Energy: It shows the average impact energy of the impacting electrons in
each surface mesh triangle.
Impact Density: It shows the electron impact density (impacts/m2) for each surface mesh
triangle.
Emission Density: It shows the electron emission density (emitted electrons/m2) for each
surface mesh triangle. It can be positive (more electrons were emitted than absorbed) or
negative (more electrons were absorbed than emitted).
Advanced Parameters Dialog
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The Advanced Parameters Dialog allows for setting extra simulation parameters which are not usually needed for
typical simulations but that provides extra control for advanced users.
The Advanced Parameters Dialog allows for setting the following parameters:
Relative error for adaptive electron path integration: This parameter specifies the maximum error in the
electron path integration. The SPARK3D electron tracker incorporates an automatic step refinement for each
electron at each time step. This implies that the integration step for electrons in high field regions will
be smaller than for those in low field regions, ensuring a maximum error for all of them. This process is
iterative. Large values imply less accurate simulations but less adaptive iterations and thus faster simulations.
Small values imply more accurate but slower simulations. The default value (1%) is normally a good trade-off
for most cases.
Homogeneous initial electron distribution: Normally, initial electrons are located on high electric field
locations on surfaces. If this option is checked, initial electrons will distribute uniformly on all surfaces. This can
be useful in situations where high electrical fields is present in reduced areas (metal edges or corners)
and multipactor is known to occur in other places.
Any modification in the above parameters can be confirmed with the OK button and will lead to dele all existing
results. Otherwise, the user can also cancel this action through Cancel button.
There is only one exception to this behavior: the selection of regions. If one region which was already simulated is
disabled for analysis, its results are kept and shown in the results window.
2.2.11.3 Running-Stopping a Multipactor configuration
Running a Multipactor configuration
In order to start a simulation, you can:
either press the Run button in the Multipactor configuration window
or choose the Run Multipactor Configuration right-click option from the Multipactor Configuration tree item
as shown below
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It is also possible to run all configurations defined in a Multipactor Configuration Group using the right-click option
Run Multipactor Configuration Group of its tree item. The existing configurations will run one after the other.
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Stopping/Pausing a Multipactor Simulation
When a Multipactor configuration is running it is possible to pause or stop the simulation through the Pause and
Stop buttons respectively, which are located in the toolbar:
In case the simulation is paused, it can continue running from the point where it was paused using the Resume
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button:
2.2.11.4 Analyzing Multipactor results
Multipactor configuration provides the input breakdown power threshold of the selected regions of the structure. The
simulation process can be followed in the Results configuration window, where a sweep in input power is shown as
the simulation runs, indicating how the simulator tries to approach to the Multipactor breakdown threshold level.
The existence of results in a Multipactor configuration is emphasized by the Results tree icon, which is highlighted
when there are results and is dimmed otherwise.
Multipactor configuration results can be analyzed in its corresponding results window, which can be opened:
either double clicking on its Results tree item
or selecting its right-click option Open Results as is shown in the image below
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Output
The multipactor module provides the input power breakdown threshold per carrier of the selected regions of the
structure. The simulation process can be visualized in the info window of the main SPARK3D canvas, where a sweep in
input power is shown as the simulation runs, showing how the simulator tries to approach the breakdown threshold.
Multipactor results are given both in tabular and graphic form. They can be seen in run-time through the results
window, which looks like follows:
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There are two tables and one graph:
1.  The left hand side table shows for each analyzed power whether there has been breakdown or not. When
breakdown occurs for a certain input power, the multipactor order is given in the second column of the table
whereas when there is no breakdown the message "No break" appears.
2.  In the graph it is represented the electron evolution with time for each power analyzed. This way it is easy to
follow the increase/decrease of the electron population as the simulation runs. When left-clicking on the
cell corresponding to a certain power of the left hand side table, its corresponding curve is highlighted on the
graph for a better recognition.
3.  The upper table contains the threshold breakdown power for each field (signal/region) under study. Through
this table the user can handle the results shown both in the left hand side table and the graph:
By left-clicking on a cell corresponding to a particular signal/region both the graph and the left hand
side table update their values to the selected field.
By right-clicking on a cell corresponding to a particular signal/region an option "Visualize 3D Statistics"
appears. This option launches a paraview window and shows the position of the electrons in the
structure, and the 3D stats, if enabled in the configuration window .
It is possible to select whole rows or columns by left-clicking on the cell corresponding to the signal or
the region name. A bar diagram appears in the graph comparing the breakdown power threshold for
the selected cells. With this information it is easy to recognize which is the most critical signal/region for
Multipactor and the maximum power level supported by the device.
Threshold values are given in average power (in Watts) for CW signals , and average | peak power for the rest of
them. See section Power Definitions for detailed information.
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The data represented in the graph can be saved into an image file or a CSV file by using the right-click options
"Export to Image" and "Export to CSV" on the graph.
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3D statistics
As explained in Output section above, when a cell of the general results table (upper table) is right-clicked, a context
menu indicating "Visualize 3d Statistics" appears.
If clicked, a Paraview window opens with the 3D statistics of the multipactor simulation associated to the region and
the signal of the cell. Different datasets are present:
Init_Elec_Positions.vtu: Initial electron positions at time t=0.
Final_Elec_Positions_X_W.vtu:  Electron positions at the moment of the discharge for input power X W. This
dataset is only present if a multipactor was detected at this power during the simulation.
Mesh3DFields_X_GHz.vtu: Electromagnetic fields for the region at the input frequency X GHz
Surface3D_stats_X_W.vtu: Collection of 3D surface statistics for the region at the specific input power of X W.
These datasets are only present if the option "3D statistics" is enabled in the configuration window. Different
statistics can be visualized for this dataset:
Avg_Impact_energy: For each of the surfaces (triangles) in the region, this represents the average
impact energy of all impacting electrons.
Avg_SEY: For each of the surfaces (triangles) in the region, this represents the average SEY value of all
impacting electrons.
Emission_Density: For each of the surfaces (triangles) in the region, this represents the total number of
emitted electrons minus the total number of absorbed electrons, divided by the area of the surface. The
units are electrons / m2. Therefore, a positive number indicates that surface contributed positively for
the discharge (source) and a negative number indicates that it contributed negatively to the discharge
(sink).
Impact_Density: For each of the surfaces (triangles) in the region, this represents the total number
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of impacting electrons divided by the area of the surface. The units are impacts / m2.
Material_boundaries.vtu: The different materials associated with the boundaries.
Hints
To speed up the simulation use the multipactor module with the minimum accuracy possible to have a rough
idea about the breakdown level.
Set the multipactor criterion to charge-trend. This will speed up the simulations significantly. Only if high
variability is found between simulations change back to charge (automatic), or charge (fixed factor) criteria.
2.2.11.5 Recording and playing a Multipactor video
Creating a Multipactor video configuration
It is possible to create as many Multipactor videos as needed in a Multipactor Configuration. This way, you can record
different videos for the same Multipactor configuration parameters. For example, you can choose a different
region for the video. In order to create a new Multipactor video configuration, right-click on the Multipactor
Configuration tree item and select Add Multipactor Video Configuration option as is shown below
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A new Multipactor video configuration item will appear in the tree in the framework of the Multipactor Configuration.
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Setting Multipactor video configuration parameters
Multipactor video configuration parameters are set from its corresponding window, which can be opened from
Multipactor video configuration tree item by double clicking on it or using Open Video Configuration right-click
option.
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Video Configuration
The video Configuration window is the following
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Fields
Here, the field (signal/region) in which the video is going to be recorded is selected
Input Power (W)
Sets the input power for this specific video recording.
Number of Frames /
period
Specifies the frame rate of the recording. The higher the smoother the animation, but bigger
video sizes will be generated.
Start time (ns)
Sets the initial time for video recording.
End time (ns)
Sets the maximum time for video recording.
Other parameters are taken from the current configuration, such as SEY definition, number of electrons,
multipactor criterion etc.
Running a Multipactor video configuration
In order to start a simulation, you can:
either press the Run button in the Multipactor video configuration window.
or choose the Run Video Configuration right-click option from the Multipactor video configuration tree item
as shown below.
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If there is a video of a previous simulation, it will be deleted. The progress of the simulation can be followed in the
info tab of the Main window.
Once the simulation is finished, the recorded video will open immediately with Paraview, which allows for 3D
rotations, perspective customization and zoom on the saved animations. It also allows for exporting the animation to
common video formats, such as .avi format. For a more detail explanation on the visualization of the recorded video
see Running Multipactor video tutorial section.
It is possible to play an existing video from the Movie tree item:
either double clicking on it,
or selecting Visualize Video from its right-clicking options as shown in the following picture.
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2.2.11.6 Multipactor practical considerations
Secondary Emission Yield (SEY)
The multipactor discharge is a complex physical phenomenon which is strongly related to many factors. Concretely, the most important
one is the Secondary Emission Yield (SEY) of the surfaces of the device.
The correct modeling of the SEY properties of the surface is crucial for having reliable simulations. SPARK3D multipactor module, allows for
using custom SEY parameters or even importing ASCII SEY definition files .
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Unfortunately, in the real world, there is a high uncertainty with the real values of the SEY:
First of all, the SEY of a certain surface depends not only on the material itself but on the microscopic roughness, impurities,
cleanness, and oxidization processes. This means that there are no "universal" SEY curves for the different materials. For example
the SEY of the silver coating of a company may differ from the SEY of the silver coating of another company.
In addition, there are more caveats. The SEY properties of a material may change with time in which is known as Ageing process.
That means that a certain sample may present important deviations of the SEY measured at a particular time, and the SEY measured
some time later. In [1] variations of the SEY during 6 and 18 months of many types of coatings coming from different companies
have been reported. As a result, it has been observed that the Ageing can cause an important variation in the multipactor
breakdown (2dB-7dB).
See below an example in Table 1, where the measured SEY properties of silver coatings coming from different companies are compared
(extracted from [1], company names are confidential). A big difference can be observed. Values measured at different moments are also
presented, showing a noticeable variation.
Table 1: Comparison of Silver SEY for different companies and variation with time (Ageing).
Initial
After 6 months
After 18 months
Company1
Company2a
Company2b
Company3
E1
20
40
44
43
SEYmax
Emax
2.8
1,9
2,0
1,7
380
410
484
210
E1
20
29
39
34
SEYmax
Emax
3.1
2,1
2,3
2,1
298
322
376
366
E1
20
24
39
34
SEYmax
Emax
3.1
2,6
2,2
2,1
268
288
376
385
With all this in mind, the engineer must interpret the breakdown discharges given by the software with caution, expecting some margin in
experimental measurements. Our recommendation is to do a SEY sensitivity analysis, simulating the same structure with different SEY
curves, to see the impact on the breakdown power, since this impact will strongly depend on the particular component under analysis.
Standard SEY materials
SPARK3D includes typical SEY parameters for most relevant materials, extracted from European ECSS standard [2] and The American
Aerospace Corporation standard [3]. Both standards give worst-case multipactor breakdown charts which may be useful to easily estimate
the breakdown levels for the parallel-plate case. For real structures, numerical simulation with SPARK3D provides more accurate results.
The ECSS standard figures correspond to different materials and come from the fitting of the multipactor breakdown results to a particular
test campaign done in [4]. For that reason, numerical simulations with SPARK3D (with simple structures, close to parallel-plate geometry)
and ECSS SEY parameters,  provide results similar to those of the ECSS standard.
In turn, the SEY parameters provided by The Aerospace Corporation standard do not correspond to real measurements, but correspond
rather to a single material which represents theoretically the worst-case (lowest breakdown levels). On the other hand, The Aerospace Corp.
standard is based on the classical multipactor theory for parallel plates without experimental data fitting. As a result, numerical simulations
with SPARK3D (with simple structures, close to parallel-plate geometry) and The Aerospace Corp. SEY,  provide more realistic (higher)
breakdown levels. Figure below shows the difference (around 3 dB).
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Modulated Signals
Spark3D allows defining modulated signals based on previoulsy imported CW signals at a specific frequency. The procedure consists on
importing an ASCII file with the baseband signal in quadrature form (In-Phase and quadrature signals) and associate it to a CW signal.
Spark3D will perform the modulation at the specific frequency of the imported signals.
However, the modulated signal has a certain bandwidth and Spark3D imports meshes with EM fields at specific frequencies with no
information of the component frequency response nor bandwidth. Spark3D assumes then, that the modulated signal is narrowband, i.e.
the component response is reasonable flat in the frequency interval of the modulated signal. Spark3D has no way of automatically checking
that both component and signal have compatible bandwiths. Therefore it is responsability of the user to ensure that the bandwidth of the
modulated signal complies with the specifications of the component under analysis.
It is advisable to previously filter the baseband signal with the response of the component under analysis before importing the signal in
Spark3D. This would yield a more realistic waveform and threshold results.
References
[1] ESA-ESTEC TRP AO/1-4978/05/NL/GLC "SEY Database",  Final Report, December 2011.
[2] "Space Engineering: Multipacting Design and Test", volume ECSS-20-01A, edited by ESA-ESTEC. ESA Publication Division, The
Netherlands, May 2003.
[3] AEROSPACE REPORT NO. TOR-2014-02198, "Standard/Handbook for Radio Frequency (RF) Breakdown Prevention in Spacecraft
Components"
[4] A. Woode and J.Petit. "Diagnostic investigations into the multipactor effect, susceptibility zone measurements and parameters affecting
a discharge". Technical report, ESTEC working paper No. 1556, Noordwijk, Nov. 1989.
Limitations
For some mesh file formats (Fest3D and HFSS), all surfaces in the problem are considered to have the same SEY properties. This is,
regarding to Secondary Emission Properties, there is no distinction between different metals or dielectrics within the same problem. They
all will be assigned a common SEY curve defined by the user. This does not happen with fields imported from CST MWS Studio, where all
the defined materials in the model are correctly exported to Spark3D.
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Due to numerical limitations on the electron path integration, in rare cases and for very high fields, false single-surface discharges may
occur at very low multipactor orders (below 0.05). These are easily identified and must not be taken as real discharges. If this occurs, try to
increase the precision of the electron path integration in the advanced parameters section in the configuration window.
Spark3D imports fields at a specific frequency with no information of the bandwidth. This makes impossible for Spark3D to automatically
check the validity of defined modulated signals. It is responsability of the user to perform previous verification of the component and
modulated signal bandwidths.
Errors
Due to the nature of the phenomenon, the results can slightly differ from simulation to simulation. This deviation can be considered an
intrinsic error caused by the phenomenon itself. However, this error is normally so small (typically in the range of 0.1-0.2 dB) that it is not
relevant for practical applications.
2.2.12 Corona Analysis
Corona discharge analysis involves computing the breakdown power threshold for a range of pressures of several
continuous wave signals and regions defined by the user in a specific device. This is the objective of what we call a
Corona configuration. The breakdown power calculated is the input power at the entrance of the device. 
On top of that, a video of the gas discharge ocurring for a certain power level and pressure can be recorded by means
of what we call a Corona video configuration, which is defined in the framework of a certain Corona configuration.
The following items shall be considered:
What is a Corona Analysis?
Brief description of the phenomenon and the current SPARK3D Corona analysis features.
Setting a Corona configuration
It is described how to create a new Corona configuration and how to set its parameters.
Running/Stopping a Corona configuration
An explanation on how to run or stop a Corona simulation is given.
Analyzing Corona results
It is explained how to visualize and analyze the output results of a Corona discharge simulation.
Recording and playing a Corona video
Corona video parameters are considered in detail and it is also explained how to create, open and run a Corona video
configuration.
Corona considerations
Some important considerations are taken into account: Corona limitations you should be aware of, possible errors and
solutions or workarounds to them, and other non-trivial properties of the use of Corona configurations.
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2.2.12.1 What is a Corona analysis?
Definition
The Corona Discharge analysis computes the corona breakdown power threshold for a range of pressures of one or
more single carrier signals and regions defined by the user from the current device. The breakdown power calculated
is the input power at the input of the device.
Features
Automatic corona threshold determination.
Analysis of corona discharge at a fixed input power.
Single-carrier loop simulations for CW, pulsed and modulated signals.
Possibility of using: dry Air, Nitrogen, Helium, Argon, SF6, CO2 and H2 as filling gases.
Computation of Paschen curves for a chosen pressure range.
High pressure breakdown estimate based on empirical rule.
Corona analysis can be run on the entire imported mesh or on different user defined regions to speed up the
simulation.
2.2.12.2 Setting a Corona configuration
Adding a new Corona configuration
It is possible to create as many Corona configurations as needed in the Corona Configuration Group. This way, you
can analyze Corona discharge in the same device with different Corona parameters. For example, you can change the
type of gas (dry air, nitrogen, helium, argon, SF6, CO2 or H2).
In order to create a new Corona configuration, right-click on the Corona Configuration Group tree item and select
Add Corona Configuration option as is shown below
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A new Corona configuration item will appear in the tree in the framework of the Corona Configuration Group.
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Setting Corona configuration parameters
Corona configuration parameters are set from its corresponding window, which can be opened from the Corona
configuration tree item by double clicking on it or using Open Corona Configuration right-click option.
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Corona configuration window
It looks like this:
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Fields
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Fields Through this option the user can choose the specific combinations of signals and regions of the structure
where the analysis will be carried out by simply enabling their check-boxes. If a combination signal-region,
that has been previously simulated, is disabled, its results will be preserved and shown in the Corona
configuration results window. This way, the user can incorporate new combinations for analysis keeping the
results of the already defined ones. 
It is also possible to access the Analysis Regions window from the Edit Regions button. It is important to
point out that all modifications made on the regions from that window will apply to all configurations. So, if
a region, which is used in several configurations both of Corona and Multipactor, is changed or deleted
all existing results corresponding to it will be erased.
Signals can be edited with the Signal Window.
Gas
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Gas
Several gases can be considered in the simulation: dry air, nitrogen, helium, argon, SF6, CO2 and H2.
Data for helium, argon, SF6, CO2 and H2 were downloaded from LXCat, which is an open-access
website with databases contributed by members of scientific community.
Results obtained for SF6 and CO2 should be considered with care, due to the lack of enough
breakdown measurements to cross-check with our simulations.
Temperature
(K)
Ambient Temperature. The reference is taken as the room temperature of 293 K.
Pressure sweep
It allows choosing between two different pressure sweep scales, which are:
linear,
or logarithmic.
Minimum pressure (mBar)
Pressure at which the pressure sweep will start.
Maximum pressure (mBar)
Pressure at which the pressure sweep will finish.
Number of pressure points 
Number of points in pressure sweep.
Simulation
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It is possible to simulate Corona discharge for the pressure sweep in two different ways:
looking for the threshold breakdown power
Simulation
type
Three different simulation types can be considered:
Numerical, which corresponds to a numeric algorithm that uses an adapted FEM
technique to solve the free electron density continuity equation.
Analytical rule, which is detailed in high pressure analytical rule section.
Numerical & analytical, which enables both simulation types.
Initial
power (W)
Power from which the threshold breakdown power is looked for. It must be set only for
"Numerical" and "Numerical & analytical" simulation types. Its value may be set by the user or it
may be taken automatically (enabling the "Automatic" check box) from the high pressure
analytical approach.
Precision
(dB)
This parameter sets the desired precision in power level for the corona breakdown onset.
or analyzing whether there is breakdown or not for a fixed power
Fixed
power (W)
Power for which Corona discharge will be analyzed in order to know whether there is
breakdown or NOT.
Simulation
type
Three different simulation types can be considered:
Numerical, which corresponds to a numeric algorithm that uses an adapted FEM
technique to solve the free electron density continuity equation.
Analytical rule, which is detailed in high pressure analytical rule section.
Numerical & analytical, which enables both simulation types.
Any modification in the above parameters can be confirmed with the OK button and will delete all existing
results. Otherwise, the user can also cancel this action through Cancel button.
There is only one exception to this behavior: the selection of signal/region combinations. If one signal/region
combination which was already simulated is disabled for analysis, its results are kept and shown in results
window.
High pressure analytical rule
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At high pressures, where diffusion is negligible, it is also possible to include the breakdown power threshold
corresponding to a high pressure analytical rule by selecting in Simulation Type parameter of Corona
configuration either the option "Conservative (Analytical)" or "Numerical & Analytical" . 
The obtained results are based on the well-known relation for ionization breakdown at sea level (W. Woo and J.
DeGroot, Microwave absorption and plasma heating due to microwave breakdown in the atmosphere", IEEE Physical Fluids,
vol. 27, no. 2, pp. 475-487, 1984), which in the case of air corresponds to:
Ebreakdown = 30.17 (pressure^2 + 2·frequency^2)^0.5 (V/cm)
Similar analytical approaches are used for nitrogen, helium, argon, SF6 or CO2. These rules are conservative at all
pressure ranges. At high pressures, they give an estimation for the breakdown power threshold whereas at low
pressures - where diffusion losses are much more important- they only result in a very conservative breakdown onset.
It is important to point out that the results are extremely dependent on the maximum value of the Electric field
magnitude, Emax. This means that if this value changes, the high pressure analytical results will also change. Such a
modification usually occurs in problems where the maximum electric field is concentrated on small localized regions,
like in devices where metal corners are present. There are several reasons for such a variation:  
Change in the mesh used to compute the EM field. If the mesh is not dense enough, the maximum value found
for Emax may not be the absolute maximum and small changes in the mesh may lead to different results. 
The use of non-convergent results for EM field calculation. If the EM field computation has not converged, a
change in the simulation parameters may lead to different values of Emax and consequently to different results.
Corona analysis approach for pulsed signals
For the analysis of Corona breakdown, a pulse excitation is sometimes used instead of a CW. For some applications
pulsed signals are required. In other cases, using a pulse source allows reaching higher powers and/or avoids the
possible damage that could cause a high-power continuous signal.
When considering pulsed signals, we can differantiate if the breakdown process occurs in a single cycle or if some
kind of charge accumulation is needed in successive cycles in order to form the electron plasma. Corona configuration
considers both possibilities in the computation of breakdown threshold power and gives the most conservative result. 
LXCat references:
Argon
Dutton database, www.lxcat.net, retrieved on 09/05/2018
Jack Dutton, Survey of Electron Swarm Data, J.Phys.Chem.Ref.Data, 4, 577, 1975
Wagner, E.B., Davis, F.J., Hurst, G.S., J.Chem.Phys. 47, 3138, (1967)
Kruithof A A 1940 Physica 7 519
EHTZ database, www.lxcat.net, retrieved on 09/05/2018
Haefliger P, Franck C M, 2018, Detailed precision and accuracy analysis of swarm parameters from a Pulsed Townsend
experiment, Review of Scientific Instruments 89, 023114
Laplace database, www.lxcat.net, retrieved on 09/05/2018/p>
Nakamura, Y., Kurachi, M., J.Phys.D: Appl.Phys. 21, 718 (1988)
Kucukarpaci, H.N., Lucas, J., J.Phys.D 14, 2001 (1981);
Pack, J.L., Voshall, R.E., Phelps, A.V., Kline, L.E., J.App.Phys., 71, 5363, (1992);
IST - Lisbon database, www.lxcat.net, retrieved on 09/05/2018
L.L.Alves, The IST - Lisbon database on LXCat, J.Phys.Conf.Series 2014, 565, 1
Bozin J V, Jelenak Z M, Velikic Z V, Belca I D, Petrovic Z Lj and Jelenkovic B M 1996 Phys.Rev.E 53 4007
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Jelenak Z M, Velikic Z B, Bozin J V, Petrovic Z Lj and Jelenkovic B M 1993 Phys.Rev.E 47 3566;
Helium
IST - Lisbon database, www.lxcat.net, retrieved on 29/03/2018
L.L.Alves, The IST - Lisbon database on LXCat, J.Phys.Conf.Series 2014, 565, 1
Cavalleri G 1969 Phys.Rev. 179 186;
Laplace database, www.lxcat.net, retrieved on 29/03/2018
DallArmi, G., Brown, K.L., Purdie, P.H. and Fletcher, J., Aust.J.Phys., 45, 185 (1992)
Pack, J.L., Voshall, R.E., Phelps, A.V., Kline, L.E., J.App.Phys., 71, 5363, (1992);
Dutton database, www.lxcat.net, retrieved on 29/03/2018
Jack Dutton, “Survey of Electron Swarm Data”, J.Phys.Chem.Ref.Data, 4, 577, 1975
Stern, in Proceedings of the sixth International Conference on Ionization Phenomena in Gases(Paris, 8 - 13 July 1963)
P.Hubert and E Cremieu - Alcan, eds. (Serma, Paris, 1963), Vol. 1, p. 331
Chanin, L.M.Rork, G.D., Phys.Rev. 133, A1005(1964);
SF6
CHRISTOPHOROU database, www.lxcat.net, retrieved on 13/02/2018
L.G. Christophorou and J.K. Olthoff (2000) Electron Interactions With SF6. Journal of physical and chemical reference
data, 29(3), p.267.
UNAM database, www.lxcat.net, retrieved on 16/08/2018
L. G. Christophorou and J. K. Olthoff, Electron Interactions with SF6, Journal of Physical and Chemical Reference Data,
Vol. 29, No. 3, pp.267 - 330 (2000);
CO2
Dutton database, www.lxcat.net, retrieved on 05/09/2018
Wagner, E. B., Davis, F. J., Hurst, G. S., J. Chem. Phys. 47, 3138 (1967)
Elford, M. T., Austr. J. Phys. 19, 629 (1966)
Frommhold, L., Z. Physik 160, 554 (1960)
Pack, J. L., Voshall, R. E., Phelps, A. V., Phys. Rev. 127, 2084 (1962)
Schlumbohm, H., Z., Phys. 18 317 (1965)
Schlumbohm, H., Z. Physik 184, 492 (1965)
EHTZ database, www.lxcat.net, retrieved on 09/05/2018
Haefliger P, Franck C M, 2018, Detailed precision and accuracy analysis of swarm parameters from a Pulsed Townsend
experiment, Review of Scientific Instruments 89, 023114
Laplace database, www.lxcat.net, retrieved on 05/09/2018
Elford, M.T., and Haddad, G. N., Aust. J. Phys. 33, 517 (1980)
Roznerski W, Leja K J. Phys. D: Appl. Phys. 17, 279-285 (1984);
UNAM database, www.lxcat.net, retrieved on 05/09/2018
J L Hernández-Ávila, E Basurto and J de Urquijo, Electron transport and swarm parameters in CO2 and its mixtures
with SF6, Journal of Physics D, 35 2264 (2002);
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H2
Dutton database, www.lxcat.net, retrieved on 24/03/2020
Breare, J.M., Von Engel, A., Proc.Roy.Soc. (London) Ser.A 28 390 (1964)
Wagner, E. B., Davis, F. J., Hurst, G. S., J. Chem. Phys. 47, 3138 (1967)
Schlumbohm, H., Z., Phys. 18 317 (1965)
Schlumbohm, H., Z. Physik 184, 492 (1965)
IST - Lisbon database, www.lxcat.net, retrieved on 24/03/2020
L.L.Alves, The IST - Lisbon database on LXCat, J.Phys.Conf.Series 2014, 565, 1
Jack Dutton, “Survey of Electron Swarm Data”, J.Phys.Chem.Ref.Data, 4, 577, 1975
2.2.12.3 Running-Stopping a Corona configuration
Running a Corona configuration
In order to start a simulation, you can:
either press the Run button in the Corona configuration window
or choose the Run Corona Configuration right-click option from the Corona Configuration tree item as shown
below
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It is also possible to run all configurations defined in a Corona Configuration Group using the right-click option Run
Corona Configuration Group of its tree item. The existing configurations will run one after the other.
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Stopping/Pausing a Corona Simulation
When a Corona configuration is running it is possible to pause or stop the simulation through the Pause and Stop
buttons respectively, which are located in the toolbar:
In case the simulation is paused, it can continue running from the point where it was paused using the Resume
button:
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2.2.12.4 Analyzing Corona results
Corona results provide the input breakdown power threshold of the selected regions and signals of the Model. The
simulation process can be followed in the info tab of the GUI: a sweep in input power is shown as the simulation runs,
indicating how the simulator tries to approach to the Corona breakdown threshold level.
The existence of results in a Corona configuration is emphasized by the Results tree icon, which is highlighted when
there are results and is dimmed otherwise.
Corona configuration results can be analyzed in its corresponding results window, which can be opened:
either double clicking on its Results tree item
or selecting its right-click option Open Results as is shown in the image below
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Corona results window
The results of the analysis are given both in graphic and tabular form to make their interpretation easier. There are
two tables and one graph in Results window.
Graph axis will be set to a linear or logarithmic scale, according to the pressure sweep scale selected in Corona
configuration.
Depending on the simulation type choosen in the configuration window, the Corona results window will be filled with
the corresponding obtained results:
Threshold breakdown power
In the left hand side table is represented the breakdown power threshold for each pressure point
corresponding to a certain region and signal, which is selected by left-clicking on its corresponding cell in the
upper table. If the high pressure analytical rule has been also selected for evaluation, the table will have three
columns instead of two, where the last one corresponds to the empirical rule.
The data of the left hand side table corresponds to the breakdown curve, which is represented in the graph. If
the high pressure analytical rule is enabled, there will be two curves, one corresponding to the numerical
analysis and the other one to the analytical rule.
The upper table contains the minimum breakdown power in the whole pressure sweep for each region
analyzed and for each frequency studied. Besides, through this table the user can handle the results shown
both in the left hand side table and the graph:
By left-clicking on a cell corresponding to a particular region both the graph and the left hand side table
update their values to the current element.
By left-clicking on the cell corresponding to the signal value, the whole row is selected and the graph
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shows together the breakdown curves of all the regions analyzed. With this information it is easy to
recognize which is the most critical region for Corona discharge and the maximum power
level supported by the device.
By left-clicking in the cell's name of an element, the whole column is selected and the graph shows
together the Paschen curves of all the frequencies analyzed.
Threshold values are given in average power (in Watts) for CW and modulated signals, and average | peak power
for pulsed ones. See section Power Definitions for detailed information.
Breakdown analysis at fixed power
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In the left hand side table it is represented whether there is breakdown or NOT for each pressure point
corresponding to a certain region and signal, which is selected by left-clicking on its corresponding cell in the
upper table. If the high pressure analytical rule has been also selected for evaluation, the table will have three
columns instead of two, where the last one corresponds to the empirical rule.
The data of the left hand side table corresponds to the markers, which are represented in the graph. If the high
pressure analytical rule is enabled, there will be two arrays of markers, one corresponding to the numerical
analysis and the other one to the analytical rule. Red circular markers correspond to breakdown situations,
whereas green triangular ones imply that there is NO breakdown.
In the table located on the top of the results window it is shown whether there is breakdown or NOT in the
whole pressure sweep for each region analyzed and for each frequency studied. Besides, through this table the
user can handle the results shown both in the left hand side table and the graph: by left-clicking on a cell
corresponding to a particular region both the graph and the left hand side table update their values to the
current element.
The data represented in the graph can be saved into an image file or a CSV file by using the right-click options
"Export to Image" and "Export to CSV" on the graph.
2.2.12.5 Recording and playing a Corona video
Creating a Corona video configuration
It is possible to create as many Corona videos as needed in a Corona Configuration. This way, you can record different
videos for the same Corona configuration parameters. For example, you can choose a different
signal/region combination for the video. In order to create a new Corona video configuration, right-click on the
Corona Configuration tree item and select Add Corona Video Configuration option as is shown below
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A new Corona video configuration item will appear in the tree in the framework of the Corona Configuration.
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Setting Corona video configuration parameters
Corona video configuration parameters are set from its corresponding window, which can be opened from Corona
video configuration tree item by double clicking on it or using Open Video Configuration right-click option.
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Corona video configuration window
It looks like this
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 The meaning of the different parameters is the following:
Fields
The combination of signal and region in which the video is going to be recorded is selected.
Input
Power
(W)
Pressure
(mBar)
Sets the input power for this specific video recording.
Sets the pressure value for this specific video recording.
Number
of Frames
Specifies the frame rate of the recording. The higher, the smoother the animation, but bigger video
sizes will be generated.
Accuracy
Sets the level of accuracy that will be used in the electron density computation. The higher is this level,
the more accurate, time and memory consuming is the computation.
Stop
criterion
Sets the criterion used in the last frame of the video to stop the computation of the electron density:
If "Maximum electron density" is selected, the maximum value of the computed electron density
in the last frame of the video will be approximately the value fixed by the user.
If "End time" is chosen, the electron density time evolution will be calculated till the time
specified by the user.
Other parameters, such as gas type and temperature, are taken from the Corona configuration to which the
current Corona video belongs (in terms of tree hierarchy).
Spark3D User Manual
157
Running a Corona video configuration
In order to start a simulation, you can:
either press the Run button in the Corona video configuration window
or choose the Run Video Configuration right-click option from the Corona video configuration tree item as
shown below.
If there is a video of a previous simulation, it will be deleted. The progress of the simulation can be followed in the
info tab of the Main window.
Once the simulation is finished, the recorded video will open immediately with Paraview, which allows for 3D
rotations, perspective customization and zoom on the saved animations. It also allows for exporting the animation to
common video formats, such as .avi format. For a more detail explanation on the visualization of the recorded video
see Running Corona video tutorial section.
Spark3D User Manual
158
It is possible to play an existing video from the Movie tree item:
either double clicking on it,
or selecting Visualize Video from its right-clicking options as shown in the following picture.
2.2.12.6 Corona considerations
Limitations
Depending on the particular geometry, a too dense mesh could be necessary in order to achieve a convergent result
in the breakdown power threshold. This situation could then lead to a memory overflow, which ultimately would fix
the limit in the results' accuracy.
Spark3D User Manual
159
Errors
Errors can occur when importing the EM fields. Considering a mesh too dense,  a memory overflow could occur in the
numerical simulation. When this happens, a coarser mesh for the EM fields should be taken, even though this could
lead to a loss of accuracy.
Alternatively, the user can focus the simulation on regions of analysis specified inside the device . This way, the mesh used in the computation is still dense, so that the accuracy is maintained, but a
memory overflow is avoided.
Hints
The minimum of corona discharge breakdown occurs at pressure levels (in mBar) close to the frequency value
(in GHz). It is therefore recommended to include such a value in the pressure interval to be given.
It is necessary to carry out a convergence study of the breakdown power threshold as a function of the mesh
used in the description of the EM fields. It should be pointed out that too dense meshes can lead to a memory
overflow. In theses cases it is highly advisable to use analysis regions.
Whenever user-defined regions are considered, a convergence study with the size of the region should be
carried out. Once you have simulated Corona effect within a certain region, you should enlarge the region till
the results remain unaltered or change slightly.
Modulated Signals
Spark3D allows defining modulated signals based on previoulsy imported CW signals at a specific frequency. The
procedure consists on importing an ASCII file with the baseband signal in quadrature form (In-Phase and quadrature
signals) and associate it to a CW signal. Spark3D will perform the modulation at the specific frequency of the imported
signals.
However, the modulated signal has a certain bandwidth and Spark3D imports meshes with EM fields at specific
frequencies with no information of the component frequency response nor bandwidth. Spark3D assumes then, that
the modulated signal is narrowband, i.e. the component response is reasonable flat in the frequency interval of the
modulated signal. Spark3D has no way of automatically checking that both component and signal have compatible
bandwiths. Therefore it is responsability of the user to ensure that the bandwidth of the modulated signal complies
with the specifications of the component under analysis.
It is advisable to previously filter the baseband signal with the response of the component under analysis before
importing the signal in Spark3D. This would yield a more realistic waveform and threshold results.
2.3 Legal Notices
Please refer to <installation folder>\Licenses to find the Legal notices web page. Typically this is placed in C:\Program
files (x86)\CST Studio <version>\Licenses
Spark3D User Manual
160
Index
Analysis of Corona Results,  25-27
Analysis of Multipactor Results,  51-53
Analyzing Corona results,  149-152
Analyzing Multipactor results,  121-126
Command-line interface,  92-106
Computing voltage,  32-34
Corona Analysis,  135
Corona considerations,  158-159
Corona Tutorial,  4
Creating a new project,  56-57
Creating or modifying a model (Importing or replacing the RF EM field),  57-61
Creating or modifying regions,  61-66
Creating or modifying signals,  66-78
EM Field export from external software ,  87-91
Fest3D/CST Design Studio™ automatic coupling with Spark3D,  91-92
Importing or using DC fields,  85-87
Legal Notices,  159
Multipactor Analysis,  106-107
Multipactor practical considerations,  132-135
Multipactor Tutorial,  27-28
Preliminaries,  4-9 ,  28-32
Recording and playing a Corona video,  152-158
Recording and playing a Multipactor video,  126-132
Running Corona mode,  14-19
Running Corona video,  19-25
Running Multipactor mode,  42-47
Running Multipactor video,  47-51
Running-Stopping a Corona configuration,  146-149
Running-Stopping a Multipactor configuration,  118-121
Setting a Corona configuration,  136-146
Setting a Multipactor configuration,  108-118
Spark3D Manual,  53-55
Spark3D Online Help,  3-4
Spark3D Tutorials,  4
Spark3D User Manual,  0
Specifying Regions,  9-11 ,  34-36
Specifying Signals,  37-42 ,  11-14
Spark3D User Manual
161
Visualizing a model: Regions, signals and materials,  78-85
What is a Corona analysis?,  135-136
What is a Multipactor analysis?,  107-108
What is a Spark3D project? How is it structured?,  55-56

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software  described  in  this  document  is  furnished  under  a  license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a retrieval 
system,  or  transmitted  in  any  form  or  any  means  electronic  or 
mechanical,  including  photocopying  and  recording,  for  any  purpose 
other than the purchaser’s personal use without the written permission 
of Dassault Systèmes. 
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3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome  
Welcome to CST Design Studio, the schematic design simulator of CST Studio Suite®. 
The  powerful  and  easy-to-use  front  end,  the  different  functional  components  and  the 
diverse  3D  centric  simulation  options  makes  it  a  unique  tool  for  fast  synthesis  and 
optimization of complex 3D systems. 
The  tight  integration  with  our  3D  electromagnetic  (EM)  field  simulators  allows 
considering systems at different levels of detail and various different effects. 
Please  refer  to  the  CST  Studio  Suite  Getting  Started  manual  first.  The  following 
explanations  assume that  you  already  installed  the  software  and familiarized  yourself 
with the basic concepts of the user interface. 
Within CST Studio Suite, CST Design Studio appears in two different configurations: 
  As a stand-alone tool. It runs independently, without any connections to a specific field 
simulator project. 
  As an associated view to a 3D project. It represents the schematic view that shows the 
system level description of the current field simulator project. 
All steps necessary to define the schematic and to set up simulation tasks are identical 
for both configurations. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite - Getting Started manual. 
2.  Work  through  this  document  carefully.  It  provides  all  the  basic  information 
necessary to understand the advanced documentation. 
3.  Look  at  the  examples  provided  in  the  Component  Library  (File:  Component 
Library  Examples / Tutorials). Especially the examples which are tagged as 
Tutorial provide detailed information of a specific simulation workflow. Press the 
  button  of  the  individual  component  to  get  to  the  help  page  of  this 
Help 
component. Please note that all these examples are designed to give you a basic 
insight into a particular application domain. Real-world applications are typically 
much  more  complex  and  harder  to  understand  if  you  are  not  familiar  with  the 
basic concepts. 
4.  Start with your own first example. Choose a reasonably simple example which 
will allow you to quickly become familiar with the software. 
5.  After you have worked through your first example, contact technical support for 
hints  on  possible  improvements  to  achieve  even  more  efficient  usage  of  the 
software. 
What is CST Design Studio? 
CST  Design  Studio  is  a  schematic  design  tool  for  system  level  simulation.  Several 
different  components  are  available,  based  on  analytical  and  semi-analytical  models. 
Customizable  libraries  with  3D  EM  simulation  projects  easily  extend  the  number  of 
available components. SPICE netlist format for detailed electronic models is available 
as  well  as  measured  data  represented  by  the  TOUCHSTONE  file  format.  The  IBIS 
standard  allows  easy  I/O  device  description.  Vendor  libraries  of  linear  and  non-linear 
components help to set up a design quickly. 
The hierarchical task concept orchestrates coupled field simulations, complex simulation 
flows and post processing tasks. Together with the 3D assembly view, it is a powerful
the next level of complexity. It collects individual 3D components on the schematic into 
a larger 3D system and derives fully prepared simulation projects out of it. 
Main Applications for CST Design Studio 
CST Design Studio users will take advantage of its versatility and the seamless workflow 
between a circuit simulator and electromagnetic (or multiphysics) field simulators. Main 
applications are: 
  Antenna module design with system performance optimization including matching/driver 
networks 
  Signal Integrity (SI) simulation of packages, 3D connectors and cables,  control PBCs, 
system channels,  including channels for high speed digital designs 
  EMC/EMI analysis of complex systems, considering radiation phenomena  for instance 
from and into connected cable harnesses 
  Microwave/RF device and system design, applicable for filters, diplexers, phase shifters, 
high performance / high power distribution networks etc. 
  Multiphysics  simulations  like  resonator  optimizations  to  compensate  the  resonance 
frequency shift due to temperature  depending deformation of the resonator geometry, 
induced by EM material losses 
  Entry point for SAM: When moving from component complexity into system complexity, 
like  array  antenna  design  or  antenna  placement  on  a  supporting  platform  like  cars, 
airplanes, etc. 
CST Design Studio Key Features 
Please Note that not all of the listed features may be available to you because of license 
restrictions. Please contact a sales office for more information. 
User Interface 
 
Intuitive  and  easy-to-use  schematic  view,  for  quick  setup  and  definition  of 
assemblies or circuits. 
  Fast assembly viewer, showing and positioning the assembled components in full 
3D. 
Components / Circuit Models 
  Several analytical components. 
  Comprehensive  analytical  and  2D  EM  based  microstrip  and  stripline  component 
libraries. 
  Active, passive, linear and non-linear circuit elements. 
  Support of hierarchical modeling, i.e. separation of a system into logical parts. 
  Tight integration with 3D EM field simulation of CST Studio Suite. 
 
Import of net lists and semiconductor device models in Berkeley SPICE, Cadence® 
PSpice® or Synopsis® HSPICE®1 format. 
  Support of the IBIS data file format. 
  FEST3D blocks for highly efficient wave guide distribution network modeling. 
 
Import of measured or simulated data in the TOUCHSTONE file format. 
  Control and use of extensible element library. 
SAM (System Assembly and Modeling) 
  3D representations for individual components. 
  Automatic  project creation  by  assembling the schematic’s  elements  into a full  3D 
representation. 
  Fast  parametric  modeling  front  end  for  easy  component  transformation  and 
alignment. 
  Manage project variations derived from one common 3D geometry setup.1 Only available if the HSPICE simulation kernel is used
  Coupled multiphysics simulations by using different combinations of coupled 
Circuit/EM/Thermal/Stress projects. 
  Hybrid Solver Task (uni- or bi-directional coupling of 3D high frequency solvers). 
  Antenna Array Task. 
  Electrical Machine Task that performs and analyses various drive scenarios. 
Analysis  
  Global parameterization. 
  Flexible and powerful hierarchical task concept offering nested sequence/parameter 
sweep/optimizer setups. 
  Parameter sweep task with an arbitrary number of parameters. 
  Optimization  task  for  an  arbitrary  number  of  parameters  and  a  combination  of 
weighted goals. 
  Template-based post-processing for user defined result processing. 
  Tuning parameters by moving sliders and immediately updating the results. 
  Powerful circuit simulator, offering DC, AC, S-Parameter, Transient and Harmonic 
 
Balance simulations. 
Interference Task to estimate possible interference violations on platforms carrying 
multiple sender and receiver modules. 
  SPARK3D task for corona and multipaction simulations 
  Robust and accurate handling of frequency domain data (e.g. S-Parameters) in time 
domain, including IDEM macro modeling capabilities. 
  Net list file export in HSPICE format. 
  Recombination  of  fields  in  CST  Studio  Suite  for  stimulations  calculated  in  CST 
Design Studio. 
  Fast  time  domain  simulation  of  coupled  problems  by  transient  EM/circuit  co-
simulation. 
  Automatic  solver  choice that  automatically  selects  either  an  analytic  or  numerical 
evaluation of microstrip and stripline components depending on the validity of the 
analytic models. 
  Consideration of higher order modes for wave guide port definitions. 
Synthesis 
  Filter  Designer  3D  synthesizes  /  optimizes  band  pass  filter  structures  of  arbitrary 
topology.  SAM  technology  is  used  to  automatically  assemble  the  final  3D  filter 
design by using predefined resonator / coupler elements from the component library. 
  FEST3D synthesizes Low-Pass, Band-Pass and Dual-Mode wave guide filters, as 
well as wave guide Impedance Transformers. 
Visualization 
  Multiple 1D result view support. 
  Automatic parametric 1D result storage. 
  1D/2D Eye diagram plots. 
  Displays S-Parameters in xy-plots (linear or logarithmic scale). 
  Displays S-Parameters in Smith charts and polar charts. 
  Fast access to parametric data via interactive tuning sliders. 
  Measurement functionality inside the views (axis markers, curve markers). 
  Possibility of keeping and comparing results in user-defined result folders. 
Result Export 
  Export of S-Parameter data as TOUCHSTONE files. 
  SPICE macro model export, representing Vector Fitting model results.
Documentation 
  Creation  and  insertion  of  text  boxes  and  images  inside  the  drawing  for 
documentation purposes. 
  Annotations inside the data views. 
Automation 
  Powerful VBA (Visual Basic for Applications) compatible macro language including 
editor and macro debugger. 
  OLE automation for seamless integration into the Windows environment (Microsoft
About This Manual 
The primary goal of this manual is to enable you to get a quick start with CST Design 
Studio. It is not intended to be a complete reference guide for all the available features 
but will give you an overview of key concepts. Understanding these concepts will allow 
you to learn how to use the software efficiently with the help of the online documentation. 
The main part of the manual is a Quick Tour (Chapter 2) that will guide you through the 
most important features of CST Design Studio. We strongly recommend that you study 
this chapter carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the Ctrl key while pressing the S key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the command. Example: View: Change View  Reset View (Space) 
  To add a project from the Component Library open the 3D Component Library 
by  choosing  Home:  Components   3D  Component  Library 
.  Then  use  the 
Search  components  field  to  filter  the  available  components.  Once  you  have 
located the correct component, hover the mouse over its preview area and click 
Download a copy of the latest revision 
, followed by Add as a Block 
. 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item. 
Example: NT: Tasks  SPara1  S-Parameters  S1,1 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support 
center: 3DS.com/Support. 
Support 
Dassault  Systèmes  is  happy  to  receive  your  feedback.  If  you  have  any  questions 
concerning  sales,  please  contact  your  local  sales  office.  In  case  you  have  problems 
using  our  software,  see  the  information  provided  in  Chapter  7  –  Finding  Further 
Information.
Chapter 2 – Quick Tour 
This chapter will help you to get started quickly. It introduces some key concepts of the 
tool and it should give you an overview of the main software’s capabilities. Please read 
this chapter carefully, as it will help you to use the software efficiently. 
This chapter comprises the following sections: 
  Overview of the User Interface’s structure 
  Overview of available elements 
  Creating a system 
  Defining simulation tasks and running a calculation 
  Dealing with parameters 
  Performing a parameter sweep and an optimization 
  Viewing and simulating circuits in 3D 
The following explanations are useful for users of the schematic only module as well as 
for users of CST Studio Suite 3D EM simulations. All these modules offer a schematic 
view where a circuit model can be constructed. The simulation setup is also identical for 
all modules. 
The only difference between the schematic only main view and the 3D EM associated 
schematic  view  is  the  presence  of  a  predefined  block  inside  the  3D  EM  associated 
schematic  view.  This  block  represents  the  corresponding  3D  simulation  . 
Overview of the User Interface’s Structure 
Before  we guide  you  through  your  first  example,  we  will  explain  the  interface  and  its 
main components. We will do so by means of the 3D EM associated schematic view 
because it contains additional elements that need to be explained. If you are working with a schematic only project, you will see a main window similar to 
the one shown below immediately after you have started the program. If you are using 
any  CST  Studio  Suite  3D  EM  solver,  you  will  need 
the  
Schematic view. Please observe the two tabs within the main view: 
to  switch 
to 
3D view tab for 
CST Studio Suite 3D view 
Schematic view tab for 
CST Studio Suite Schematic view 
Please click on the Schematic view tab now.
Ribbon 
Main View 
Navigation 
Tree 
Window 
Block 
Selection 
Tree window 
Context Menu 
Predefined 
CST Studio 
Suite blockBlock Parameter List 
window 
Parameter List/ Result 
Navigator window 
Messages/Progress 
window 
Status bar 
As  you  can  see,  the  interface  consists  of  several  windows.  Hidden  windows  can  be 
activated by virtue of the menu that is opened by clicking onto the triangle below View: 
Window  Windows 
. The function of these windows is the following: 
  The main view consists of  a collection of different  windows  with different  views.  Each 
window can visualize a project or any available result. In the above example there are 
already two windows: The 3D view and the Schematic view. If the views are maximized, 
they may be selected by the already mentioned view tabs. The contents of a view depend 
on the selection in the Navigation Tree (NT). 
  All  results  and  structural  details  can  be  accessed  through  the  Navigation  Tree.  It  is 
organized in folders and subfolders with specific contents. When you select an item from 
the  tree,  the  currently  active  view  visualizes  its  content  in  the  main  window  in  an 
appropriate manner.  
  The Block Selection Tree can be thought of as a library of all elements that are available 
for creating a design and setting up a simulation. An element may be a circuit element 
like  a  resistor  or  a  capacitor,  a  microwave  element,  a  link  to  an  external  simulator, 
measured S-Parameters, or any other offered type of element. 
  The Parameter List window shows all global parameters that are currently defined. Local 
parameters of a selected block are accessible through the Block Parameter List window. 
  Whenever the program has information for the user it will print this text into the Message 
window. It may contain general information, warnings, or errors.  
  The Progress window shows the progress of a currently running process, presented by 
 
one or more progress bars. 
If parametric results are available, the Result Navigator window allows easy navigation 
through the existing results.  
All windows, with the exception of the main view, are freely configurable. You may place 
them  into  your  favored  position.  Furthermore,  they  may  be  docked  into  a  separate 
window, tabbed into an existing window, or removed from the main frame, such that they 
become a standalone window. The standalone parameter window, for example, looks 
like this:
The next noteworthy element is the status bar. The status bar primarily lists the currently 
selected global units. 
The  other  elements  are  quite  common  to  all  windows  programs.  The  Ribbon  offers 
access to the functions of the program (Please have a look into the CST Studio Suite – 
Getting Started document for a more detailed explanation about the Ribbon). In addition, 
context  menus  offer  quick  access  to  frequent  used  functions.  Which  functions  are 
offered  in  the  context  menus  depend  on  the  current  selection  (a  window,  block, 
navigation tree item or other program elements) and on the current program status. 
Overview of Available Components 
CST Design Studio offers a large variety of elements that can be used to assemble your 
system. To help you to get started with this collection, this section explains the existing 
element categories and introduces their most important members. 
Components or Circuit Models 
A Component or a Circuit Model implements the physical behavior of a sub-system or 
represents a lumped circuit element. Throughout the CST Design Studio documentation 
all  these  elements  are  referred  to  as  blocks.  We  distinguish  between  analytical, 
measured, simulated and some special blocks.  
  Analytical Blocks: Most of the available  blocks are analytical or semi-analytical blocks 
whose  physical  behaviors  are  described  by  parameterized  circuit  models  or 
mathematical formulas. 
  Measured Blocks: To consider measurement results, CST Studio Suite schematic offers 
the TOUCHSTONE block that imports S-Parameters in the well-known TOUCHSTONE 
format and the IBIS block that interprets the IBIS behavioral descriptions of buffer type 
components, and Capacitance / Inductance / Reactance matrix blocks. 
  Simulated Blocks: These block types reference or store projects of our field simulators 
e.g. CST Studio Suite 3D EM simulators, or external simulators. These blocks keep track 
of the projects’ results and some of them even allow parametric control of the projects 
from  within  the  schematic.  All  blocks  whose  properties  can  be  controlled  by  free 
parameters will also be called parameterized blocks.  
  Special Blocks: The most important ones are the ground element, the CST Design Studio 
block and the reference block. The ground marks the common ground of a circuit. The 
CST  Design  Studio  block  represents  a  placeholder  for  a  sub-system  and  therefore 
supports hierarchical designs. Finally, the reference block defines a common property 
set  that  can  be  assigned  to  analytical  blocks.  Reference  blocks  themselves  show  no 
physical behavior. 
The online documentation discusses all these blocks in more detail. 
External Ports 
External  Ports  represent  sources  or  sinks  of  your  system.  Depending  on  the  defined
signal for a time domain simulation task and it may deliver a specific complex amplitude 
for an AC simulation task. 
Connectors 
A  connector  is  the graphical  representation  of the  electrical  connectivity  between two 
elements. 
Probes 
Probes can be placed on any connector. They record voltages, currents and quantities 
derived from those for circuit simulation tasks. 
Connection Labels 
Connection labels are a graphical alternative to connectors. They too define an electrical 
connection and can be used to make the schematic more clearly arranged. They are 
characterized by a name. All block pins connected to labels with the same name are 
electrically connected. 
Creating a System 
Now  it  is  time  to  create  your  first  circuit  in  CST Design  Studio.  You  will  learn  how  to 
create a design, how to add components, and how to electrically connect them. You will 
modify the components’ properties and use parameters. 
The  already  set  up  and  simulated  version  of  this  example  can  be  found  in  the 
Component Library by searching for Lumped Filter. 
Adding and Connecting Components 
A simple band pass filter will serve as an example in the following sections. It consists 
of simple inductors and capacitors that form three resonating elements (LC sections) in 
so-called pi configuration. The filter’s topology is shown below. Let us begin the circuit’s setup by inserting the first inductor. Select the Circuit Elements 
folder in the block selection tree. You will see all elements collected in this folder in the 
lower part of the window. Find the symbol for an inductor and press the left mouse button 
over  this  type  of  block.  Keep  the  button  pressed,  move  to  the  location  inside  the 
schematic view where you want to insert the block, and release the button to finish the 
insertion. During movement inside the schematic view, the component is displayed for 
better  orientation.  As  shown  below,  the  inserted  block  is  selected  and  can  be moved 
inside the schematic view.
Besides  the  block  symbol  in  the  schematic,  a  tree  item  has  also  been  added  to  the 
Blocks folder of the navigation tree. It has the same name as the block it belongs to. An 
inductor block’s default name is INDn, where n is a positive integer, and therefore the 
added block is called IND1 unless its name is manually changed afterwards.  
A block tree item may itself contain items. Its sub-items allow the access of block-related 
results. We will refer to these items later. 
A block contains a certain number of internal ports according to the physical behavior 
attributed to it. These internal ports are the terminals where the block’s model can be 
connected  to  the  outer  schematic.  The  block’s  symbol  represents  these  ports  by 
individual pins. 
A pin is represented by a short line adjacent to the block. If it is not connected, this short 
line is drawn in red, otherwise it is blue. For example, the inserted inductor block has 
two pins whose short lines are both red because they are not yet connected. 
In  order  to  connect  the  first  capacitor,  “drag’n’drop”  a  capacitor  next  to  the  existing 
inductor as described earlier. Select the capacitor on the schematic by pressing the left 
mouse  button  (keep  the  button  pressed).  By  pressing  c,  you  activate  the  auto 
connection. Drag the capacitor towards the right pin of the previously added inductor. 
When the two pins contact each other, a red circle is displayed.
Release the mouse button when the red circle appears. As a result, the capacitor will be 
connected with the inductor. A valid connection is indicated by the fact that the colors of 
the right inductor leg and the left capacitor leg change from red to blue.  
You  may  also  manually  create  a  connector  between  two  elements.  To  do  so,  place 
another inductor next to the previously added capacitor.  
Now move the mouse pointer on the left pin of the right inductor. As soon as the mouse 
pointer reaches the vicinity of that pin it will be highlighted by a red circle. 
To define the starting point of the connector, single-click or double-click on the red circle. 
A rubber band line is drawn from the pin to the actual mouse position.  
Whenever  your  mouse  pointer  meets  an  element  to  which  the  connector  can  be 
attached, the element will be highlighted. Click on the right pin of the capacitor to finish 
the  connection.  As  soon  as  the  connector  is  created  it  will  be  drawn  as  a  blue  line 
between the two connected elements.  
Please note that a connector has no physical properties, i.e. there is no electrical length 
associated with a connector. A connector only combines interfaces (i.e. internal ports).  
Now, insert another capacitor into your model. Place it to the left of the already inserted 
components and connect it as shown below: Now rotate the left capacitor and the right inductor by selecting them one after the other 
by choosing Home: Drawing  Arrange  Rotate Left/Right 
 or using the shortcut 
key l or r (for left or right). Reposition these two blocks with the arrow keys to obtain the 
following model: 
,
At  this  point,  one  pin was  connected to exactly  one  other  pin,  which means  that  one 
internal  port  was connected  to  exactly  one  other  internal  port. We  always obtained a 
one-to-one assignment. However, circuits often have T-junctions or cross-junctions. In 
CST DES, these junctions are realized by inserting nodes that can be connected to up 
to four connectors. Such a node is automatically created when you drop a selected pin 
on  a  connection  line  instead  of  on  another  pin.  If  a  pin  of  an  element  is  placed  on  a 
connection  line,  the  element  will  be  automatically  positioned  perpendicular  to  the 
connection line in a direction such that the element is moved towards it.  
Try  this  behavior  with  the  next  element.  Select  another  capacitor  and  move  it  to  the 
design. Enter the auto connection mode and hover one pin over an existing connection 
as shown below:  
Release the element such that a node will be established. Insert the last inductor and 
rotate or move the elements until your schematic is as followsFinally, you need to connect all open pins with ground blocks. You find the ground block 
in the Circuit Elements folder and in the Ribbon under Home: Components  Ground 
. However, the fastest method of establishing ground connections is to use the shortcut 
key g when the schematic view is active (you may need to single-click into the schematic 
view in order to activate it). The shortcut key g (for ground) creates a ground block with 
the next mouse click. Try this feature now and add the ground elements as shown in the 
following picture:
External ports define sources and sinks of a design. Except for some specialized circuit 
simulation tasks, external ports are required to perform a calculation. This is especially 
true for S-Parameter calculations. 
An external port may be inserted by the same drag‘n’drop procedure as for a block. You 
find the port component in the Circuit Elements  Sources / Ports folder of the block 
selection tree. Alternatively, you will find the port in the Ribbon Home: Components  
External Port 
 or you may take advantage of the shortcut key p (for port) that works 
very similar to the previously introduced shortcut key g. Press p and click inside the main 
view to create the first port at your current mouse pointer position. Create a second port 
in the  same manner  and  locate the  ports  as  in the  picture  below.  Note that  ports  are 
automatically  numbered  sequentially,  starting  at  one.  However,  port  numbers  can  be 
changed by the user as will be explained later.  
The connection of an external port symbol to a pin or a node is established in the same 
way as the manual connection of two blocks: Perform a single-click on the external port 
No. 1 (You have to click somewhere near its boundary. A red frame will 
indicate that it has been selected for connecting) and afterwards single-
click on the edge of the connection line to its right. Do the same for the
Now, all ports should be connected. Please make sure that there are no red lines in your 
design  view  that  would  indicate  unconnected  pins.  If  necessary,  repeat  one  of  the 
actions explained above to establish the missing connection.  
Nodes and edges of connection lines can also be moved manually to different locations. 
For more complex circuits it may sometimes be useful to modify the automatic layout. 
The circuit is now setup and correctly connected. However, in case, you want to remove, 
add or replace single elements of your connected circuit, snap-in/snap-out is the most 
efficient  workflow  to  alter  already  connected  circuits.  It  is  activated  during  drag  of  an 
element by pressing shift. If the dragged element is connected, connections will remain 
but the element itself will be disconnected. In case the dragged element is unconnected 
and moved over a connection, it will be inserted in between the connection. 
For  example  if  you  want  to  replace  the  inductance  in  the  middle  of  the  circuit  with  a 
resistor. Simply drag the inductor away from the circuit by pressing shift. Afterwards  drag  an  unconnected  resistor  to  the  place  where  the  inductance  was  by 
pressing shift: 
As a summary, all important shortcut keys are listed in the following table:
Shortcut key  Description 
g 
p 
l 
r 
c 
shift 
Place a ground element. Simply click on the end 
of a connection line after activating this shortcut 
Place a port element. Click on the end of a 
connection line to place the port 
Rotates the selected element counter clockwise 
Rotates the selected element clockwise 
Enable (or disable) the auto connection mode if 
one or more blocks are selected 
Keep pressed for entering snap-in/snap-out 
workflow 
For a complete summary of shortcut keys please take a look into the CST Studio Suite 
Getting Started manual. 
Changing Properties of a Block 
After creating the circuit’s topology, we want to assign the values for C1, C2, L1 and L2 
to the blocks’ corresponding properties. This is easily accomplished by selecting a block 
and editing its properties in the docked block parameter window. It is a tabbed window. 
The window generally consists of several tabs whose appearance may differ depending 
on the type of the selected block By default, the General tab is selected, which holds the 
general and solver-related parameters of the block (such as frequency bounds). Those 
parameters, describing the actual physics or geometry of the block, are accommodated 
by the Settings tab. Therefore, to modify the inductance value you need to switch to the 
Settings tab.  The content of the list depends on the block’s type. The properties’ names should clearly 
reflect the physical property to which they belong. However, if there are some doubts 
about the meaning of a property, the online help can be consulted for more information 
by pressing the F1 key in the context of the block’s parameter list. 
You  can  edit  a value  associated  with a  parameter  after  clicking  on  it.  If you  enter  an 
invalid value, an error message will be displayed. By default, the units of all parameters 
are associated with the global units defined for the project (we will refer to those settings 
later). 
To edit the value for Inductance, perform a double-click in the Expression column of the 
Inductance row. You may also choose a different unit within the selector box in the Unit 
column.  However,  for  our  example,  keep  the  default  units.  Initial  conditions  may  be
useful  in  transient  simulation.  We  do  not  require  them  in  S-Parameter  simulations. 
Therefore, we leave the Initial Condition checkbox and the Initial Current row untouched. 
Select the blocks one after the other and specify the following values for them: 
Element Names 
IND2, IND3 
IND1 
CAP2, CAP3 
CAP1 
Value 
1.6 nH 
44 nH 
35 pF 
1.2 pF 
Please make sure that all values have been set correctly. Now your model should look 
similar to the following picture.  
Changing Properties of an External Port 
To modify  the  properties  of  an  external  port,  e.g.  Port  1,  click  on  it.  Its  docked  block 
parameter list window will show the properties of the external port.  The Name of the port is alphanumeric and does not necessarily have to be an integer 
number. However, by default, the first external port is named 1 and this port number is 
incremented for all following external ports, added to the schematic.   
The other properties of the external port are: 
  The Label is an additional identifier of the external port that is shown in rounded brackets 
after the port name when referring to it. 
  By  default,  the  common  ground  (that  does  not  need  to  be  explicitly 
defined, but can also be a point at infinity) represents the reference node 
for an external port. For circuit simulations, you might want to define a 
differential  port  that  refers  to  a  node  inside  your  circuit.  In  this  case, 
check the Differential checkbox. The external port will be expanded by a pin (as shown 
in the image on the right hand side) to which you can connect the reference node. 
  Common  Reference  is only  relevant for differential  bus ports. If checked all reference 
nodes of the differential bus port are unified into a single node. 
By  selecting  a  Bus  size  larger  than  1  the  external  port  acts  as  a  bus  port,  carrying  a 
number of independent excitation signals.
Performing a Simulation 
This  section  will  demonstrate  how  to  generate  the  results  that  you  are  interested  in. 
Therefore, global settings are explained and a simulation task is defined. 
Unit Settings 
At this point, we have assigned some values to the element’s properties and decided to 
keep their association with the global project units. Therefore, if you change the global 
inductance unit e.g. from nH to μH, you scale all inductances referring to the global unit 
by a factor of 1000, because the values assigned to the properties are retained. To avoid 
this scaling you may select local units for each block. 
You can check whether a property refers to the local or to the global unit by having a 
look into the block parameter list: 
If you see the world icon 
value. 
The global units currently used in your project are displayed in the status bar. They can 
be modified from the Units dialog box. To open it, choose Home: Settings  Units 
 in the Units drop-down list, global unit will be taken for this 
.In our example, all inductances are given in nH and all capacitances are given in pF, 
which are the default settings for Inductance and Capacitance properties. However, our 
circuit should operate in the MHz / μs range. So please change the Frequency and Time 
settings  accordingly  and press the  OK  button.  Please note,  that  in the  status  bar  the 
frequency and time units have changed correspondingly.
Defining Simulation Tasks 
In order to obtain information about the filter’s characteristics, we intend to calculate the 
S-Parameters for our design.  
To define a new task, choose Home: Simulation  New Task 
.The  Select  Simulation  Task  dialog  box  shows  a  tree  view  of  all  available  tasks.  The 
Details frame displays some information about the selected task.  
As you can see, the S-Parameter calculation is only one of several tasks that can be 
performed  by  CST  DES.  You  can  find  a  detailed  explanation  of  all  these  simulation 
methods in the online documentation. 
Depending on the selected task, a task specific Task Parameter List is preselected after 
adding the new task, in which you can define the specific settings.  
Select Circuit  S-Parameters 
added to the Tasks folder inside the navigation tree as shown below.  
 and press the OK button. The task item S-Para1 is
For newly added tasks, the Task Parameter List will be preselected after adding where 
you can input task specific settings. The Task Parameter List of the S-Parameter task has three tabs. The S-Parameters tab, 
in  which  you  can  specify  the  simulation  settings,  the  Terminations  tab,  in  which  the 
impedances of external ports can be specified and the  Results tab, in which you can 
specify which results are to be calculated. 
We  stay  with  the  defaults  in  the  Results  tab.  S-Parameters,  port  impedances,  and 
balances will be calculated. 
The S-Parameter tab has four sections:  
 
 
 
 
Inside the first section you have two rows. In the first row named Circuit simulator you 
may choose to perform a CST simulation or export the circuit from the schematic into a 
Synopsis HSPICE® netlist file. In the second row named Local Units you may specify 
the frequency unit that all task properties refer to. If unchecked the global frequency unit 
is used. Otherwise, you may enter a dialog to specify local units of the task by pushing 
the … button.   
Inside  the  Simulation  settings  section,  the  frequency  range  for  the  S-Parameter 
calculation and the number of frequency samples are specified. There is a check box 
labeled  Maximum  frequency  range.  If  this  property  is  checked,  the  maximum  valid 
frequency  range  will  be  used  for  the  simulation.  Note  that  frequency  bounds  must  be 
shown in the Frequency limits frame if you choose this option. If there is a valid frequency 
range, this option is switched on by default. In addition to this control, there are three edit 
fields: The Fmin and Fmax fields are only editable if the Maximum frequency range option 
is unchecked. There, you can enter values that must be within the range given by Lower 
limit  and  Upper  limit.  Finally,  you  should  specify  the  number  of  frequency  samples  to 
consider in the Samples edit field. You may also choose the Logarithmic sweep option 
to perform a logarithmic sweep instead of a linear sweep inside the specified frequency 
range. However, Fmin must be positive in this case. 
Inside the Frequency limits section, the largest frequency range for which the model is 
valid is displayed. If your model does not contain any frequency-bound blocks, None is 
displayed for the lower and upper limits. Otherwise, the range represents the intersection 
of all block frequency ranges.  
Inside the Individual blocks section you may choose to store the S-Parameter results for 
the individual blocks that are calculated by the simulation task. Depending on the number 
of blocks that your model contains, this option may slow down the simulation significantly. 
Furthermore,  you  can  choose  the  interpolation  scheme  for  the  blocks’  native  S-
Parameter data here. The selection of Real/Imaginary may lead to small inaccuracies for 
the amplitude and phase and vice versa. Finally, under Specials a Solver Specials dialog 
can be opened. Normally it does not need to be touched but it can be useful to change 
some of its settings if simulation problems show up in terms of simulation time, simulation 
accuracy, or convergence.
Our design does not have frequency limits since only lumped components are used. As 
the frequency range of interest we choose 400  f / MHz  1000, i.e., we specify 1000 
for  Fmax  and  400  for  Fmin.  We  keep  the  default  value  of  1001  for  Samples,  which 
defines the number of frequency samples.  
Let us return to our example of a band pass filter. This filter has been designed for a  
50  environment. Therefore, we switch to a constant reference impedance within the 
tab Terminations of the docked Task Parameter List and keep the default value of 50 
 in the Reference Impedance field as shown below. 
You  can  add  an  arbitrary  number  of  tasks  to  your  project.  Some  of  the  tasks  like 
Parameter sweep or Optimization tasks may also be nested. Each task can be moved 
or  modified  from  the  navigation  tree.  If  you  invoke  an  update  of  the  results  for  your 
design, all simulation tasks will be performed one after the other, but you can also update 
individual tasks via their context menu. If you want to exclude a task from the update 
loop but do not wish to delete it, you can simply disable it. To do so, open the tree item’s 
context  menu  by  right-clicking  the  corresponding  task’s  item  and  choose  Disable. 
Disabling a task will recursively disable all its child tasks as well. To re-enable it, carry 
out the same procedure choosing Enable instead. 
Starting a Simulation 
After  all  required  settings  have  been  established,  a  calculation  of  the  S-Parameters 
according to the defined task can be performed. Choose Home: Simulation  Update 
  or  use  the  shortcut  key  Ctrl+F5  to  update  the  results  of  all  simulation  tasks.  As 
mentioned above, all simulation tasks are executed one after another during an update 
operation.  You  should  examine  the  message  window  where  information  about  the 
simulation progress is displayed in addition to  warnings and error messages. For our 
example,  just  three  lines  are  displayed  indicating  the  beginning  and  the  end  of  the 
execution of the task and an additional info message, informing the user that the default 
impedance of 50 Ohm has been applied to the external ports. This is because the port 
impedances  have  been  set  to  block  dependent,  but  the  connected  lumped  circuit 
elements do not have a native port impedance. Visualization of the Results 
This  section  will  explain  how  to  view  results  from  inside  the  navigation  tree.  We 
distinguish standard results that are automatically generated by CST Design Studio from 
user-defined results that are added by the user. In the user-defined results, individual 
results of the task’s current result set can be inserted.
Standard Results 
CST Design Studio automatically generates result folders associated with the executed 
simulation tasks.  For  instance, for  the  S-Parameter  simulation  task, result folders  are 
added that contain S-Parameters, port impedances, and the power balance as a function 
of frequency for the complete design. The result views of these folders can be activated 
by expanding the task item inside the navigation tree. 
Inside  these  result  folders  are  tree  items  that  are  related  to  single  curves  of  the  S-
Parameters.  
To view the S-Parameters of the complete design, click on the S-Parameters folder 
and change the plot type to Linear via the context-driven ribbon 1D Plot: Plot Type  
Linear 
 :Note that the S11 and S12 curves are not visible here because they are hidden by the 
S22 and S21 curves, respectively. Double click on a label in the legend on the right hand 
side to see one particular curve emphasized. Double clicking somewhere in an empty 
area  restores  the  original  view.  The  customization  of  plots  is  introduced  in  another 
section. 
Initially, a result view shows the magnitude of the tree items in the result folder. In fact, 
our model represents a band pass filter. A better idea of its performance is given by the
Magnitude in dB representation. Switch to Magnitude in dB by choosing 1D Plot: Plot 
Type  dB 
, obtaining the following plot: 
Initially, the Zoom mode (View: Mouse Control  Zoom 
) is active: You can define a 
zoom rectangle by clicking inside the view, keeping the mouse button pressed, moving 
the cursor to a different location and releasing the button. Immediately after releasing 
the button, a more detailed view will be displayed. There are additional modes that can 
be activated via View: Mouse Control. To navigate inside a zoomed view, activate the 
Pan mode (View: Mouse Control  Pan 
). It allows moving the view in vertical and 
horizontal directions.  
In addition to the modes, there are some viewing tools available such as axis markers, 
measure lines, and curve markers. They are activated via 1D Plot: Markers. These tools 
are for performing measurements inside a plot view. The following information can be 
obtained using these tools: 
  The axis marker (1D Plot: Markers  Axis Marker  Axis Marker  
) is a vertical line 
that is initially located in the middle of the x-axis. Its current x-value and the y-values of 
the intersections of the axis marker and the curves are displayed. Thus you can retrieve 
the position of a pole, for instance. 
  The measure lines (1D Plot: Markers  Axis Marker  Measure Lines 
) are two pairs 
of lines, one pair in parallel to the x-axis and one pair parallel to the y-axis. The difference 
between the  values  of each pair  is displayed as  well  as the measure lines’ current x-
values or y-values, respectively. Thus you can retrieve the minimum and the maximum 
value of a curve and the distance between them, for instance.  
To demonstrate how measure lines can be utilized, let us assume that we would like to 
have a filter characteristic for our band pass filter as follows:Description 
Frequency range 
Stop band 
400 < f / MHz < 550 
Transition region  550 < f / MHz < 610 
Pass band 
610 < f / MHz < 790 
Transition region  790 < f / MHz < 850 
Stop band 
850 < f / MHz < 
1000 
Condition 
|S11| = 
maximal 
- 
|S11| = 
minimal 
- 
|S11| = 
maximal 
The frequency range of the pass band can be represented within the plot very easily, 
using the measure lines. Choose 1D Plot: Markers  Axis Marker  Measure Lines
to switch them on. Move one of the vertical measure lines to 610 MHz by clicking on it 
and  dragging  it  to  the  desired  position  while  keeping  the  mouse  button  pressed. 
Alternatively, when double-clicking on the vertical measure line, you can directly enter 
the desired value 610. 
The current position of the axis marker will be plotted below the frequency axis. In the 
same manner, move the other vertical measure line to 790 MHz to have a visualization 
of the pass band of our filter. 
Now  we can check the performance of our current filter design within the pass band. 
Move one of the horizontal measure lines to the maximum |S11| value in the range of 
the pass band. The maximum value is plotted left of the measure line. As you can see, the performance already looks reasonable but the curves suggest that 
an overall minimum of S11 within the pass band has not yet been reached. Note that 
the legend has been shifted into the plot by drag’n’drop to not hide the vertical distance 
between the measure lines. 
In a subsequent section we will demonstrate how to optimize our filter design. We will 
introduce parameters, study their influence by performing a parameter sweep and finally 
optimize the filter using the built-in optimizer tool. 
But first, let us return to the visualization subject. The following sections will teach you 
how to modify the plot’s properties. Furthermore, we will show you how to create user-
defined result views and add data there. 
Customizing Result View Properties 
In addition to the buttons used to switch between the visualization types and interaction 
modes, there are more options to manipulate the plot: 
  Several plot options can be set in the 1D Plot: Plot Properties  Properties dialog box. 
 
Individual  plots  can  be  shown  or  hidden  by  using  1D  Plot:  Plot  Properties   Select 
Curves.
  Selecting  1D  Plot:  Windows   New  Plot  Window 
  opens  another  plot  view,  initially 
displaying the same contents as the current one. To switch between the plots, you may 
click on the corresponding tab at the bottom of the main window.  
Let us now examine the Plot Properties dialog box. Choose 1D Plot: Properties  Plot 
Properties  Properties 
 or use the plot’s context menu item Plot Properties: 
  Within the X Axis frame you can customize the range and appearance of the x-axis and 
the positions of the horizontal ticks: 
  If Auto range is chosen, the plot’s minimum and maximum abscissa values are automatically 
calculated. To specify your customized values, switch off this option and edit the Min and Max 
fields.  
  The Round option expands the plot range to the next rounded minimum and maximum abscissa 
values. This option is only available if Auto scale is set.  
  Ticks  subdivide  an  axis  into  intervals  of  identical  size.  Switch  on  Auto  tick  for  an  automatic 
calculation of an interval’s width. To specify your customized tick width, switch off this option 
and specify Tick. 
  Choose the Logarithmic option to establish a logarithmic axis. A logarithmic axis does not allow 
customized ticks. Furthermore, you have to ensure that all axis values are positive. 
  Within the Y Axis frame the settings described for the x-axis can be applied to the y-axis. 
In phase plots, there is a further option, Wrap phase, that limits the display of a phase to 
-180° < arg < 180°. 
  The Font… button leads to a dialog box where you can specify the font for the title, axis 
labels, etc. 
  The  Curve  Style…  button  leads  to  a  dialog  box  where  you  can  manipulate  the 
appearance of your curves within the plot. 
To exclude some curves from the current plot view, choose 1D Plot: Properties  Plot
The Curve Selection dialog box will open that consists of two list boxes: The box labeled 
Hidden Curves shows a list of the curves that are currently not displayed and the box 
Displayed Curves contains the curves that are currently displayed. Use the buttons  > 
and < to move entries from one list box to the other or press  All or None to move all 
entries to one of the boxes. Pressing OK or Apply applies the selection to the plot. 
If you want to exclude only distinct curves from the plot there is an even faster way to 
do this. Select the result item in the result tree and select Hide from its context menu. 
 User-Defined Result Views 
In addition to the standard result views that are automatically generated, a user-defined 
result plot can also be created: 
Select the Results item inside the navigation tree and choose Add Result Plot from the 
item’s context menu. A tree item is added to the folder with an editable label. This tree 
item represents a new result folder. You may enter a name for it or accept the default 
name Result. 
Click on this new tree item to activate the folder’s view. Since the folder is initially empty, 
the view only displays the message “Select a subfolder or a tree item.”. It prompts the 
user  to  populate  the  new  result  folder.  To  add  data  to  the  new  result  folder,  choose 
Manage  Results…  from  the  item’s  context  menu  to  open  the  Manage  Results  dialog 
box. 
In this dialog box all existing results are listed. To add the reflection factor S1,1 choose
By  default,  the  result  name  will  be  used  as  a  default  value  for  the  plot  label.  For  our 
example, please change the label to Initial S1,1.  
In  the  dialog  box  you  will  also  find  an  Update  automatically  option.  If  this  setting  is 
switched on,  a  result reference is  created  that  is  updated  whenever  a  simulation has 
been  started.  Please  uncheck  this  setting  now,  since  we  would  like  to  preserve  the 
results of this simulation run. 
Press the Add button and the selected curve will be added to the result folder. 
If  the  Update  automatically  option  had  been  switched  on,  the  result  icon  would  have 
shown a small link symbol at its lower left corner. 
Adding a result item into a user defined result folder can also be done via drag’n’drop.  
Select S1,2 from the result tree and drag it onto the Result folder while pressing the Ctrl
If you now release the mouse button, a copy of S1,2 is created in the Result folder. A reference 
would have been created if you had not pressed the Ctrl button when releasing the mouse 
button. Please rename the S1,2 curve to Initial S1,2 by selecting the Rename option via the 
context menu.
Parameterization and Optimization 
The parameterization of a design enables you to easily consider variations. If properties 
are associated with parameters, the properties can be changed and therefore influence 
the  design’s  behavior.  In  the  following  section,  the  use  of  parameters  will  be 
demonstrated and a parameter sweep will be performed. Another common application 
of parameters is their optimization with respect to goal functions, a topic that will also be 
explained in this section.  
Using Parameters 
CST Design Studio offers the possibility to deal with global variables that may serve as 
parameters  for  global  settings  or  block  properties.  Working  with  parameters  is 
straightforward: First, you need to define them inside the parameter list control; you may 
then  assign  them  to  a  property  (including  mathematical  expressions  containing 
parameters). 
The  parameter  list  control  displays  a  table  consisting  of  five  columns  labeled  Name, 
Expression, Value and Description. The table itself initially shows one single empty line 
(except  for  the  Name  column  displaying  <new  parameter>)  as  shown  below.  If  you 
define a new parameter, it does not matter which column you edit first. The definition of 
a parameter is not completed until a name has been specified. However, we recommend 
that  you  start  with the first  column. The  Value  column  is  non-editable and  shows  the 
result of an expression evaluation of the associated Expression column. 
Valid names are all strings that are valid variable names in VBA. In particular, they must 
not be interpreted as a VBA command and must not contain special characters such as 
spaces, etc. Valid values are all expressions consisting of mathematical VBA functions, 
real numbers and previously defined parameters. The specification of a description is 
optional.  
Moreover, the parameter list control provides the following features: 
  A subset of all parameters can be displayed by clicking on the filter symbol (
) left of 
Name and typing the substring to be matched. 
  A parameter can be removed from the list and will be deleted from your project, as well. 
To do so, select the parameter row by clicking on any field in this row and choose Delete 
from the context menu. If the selected parameter is used somewhere in your project the 
following message box will appear:  Pressing  OK  would  delete  all  parametric  results  and  would  replace  the  selected 
parameter by its value everywhere it is in use.
  The name of a parameter inside the list is editable. References to the renamed parameter 
are updated automatically. 
  To check whether a parameter is in use (and whether you can rename or delete it without 
any consequences), select it and choose Dependencies from the parameter list control’s 
context menu. If it is used by any properties, a dialog box will open containing a list of 
those properties. Otherwise, a message will be displayed, indicating that the parameter 
is not used. 
  A parameter can be replaced by its value by choosing Replace Parameter by Value from 
its context menu. The parameter will not be deleted afterwards. 
  When performing simulations for different parameter values, results of every parameter 
set are stored. To identify  these result sets, each result of a specific parameter set is 
associated to a unique integer run ID. This ID can be used to reset all parameter values 
connected  to  this  specific  result  set.  Choose  Set  Parameters  to  Run  ID  from  the 
parameter list control’s context menu to use this functionality. You will learn more about 
parametric result handling further below. 
For our example, we are going to introduce four parameters: C1, C2 (representing the 
capacitances  of  the  capacitors)  and  L1,  L2  (representing  the  inductances  of  the 
inductors).  
Parameter Name 
L1 
L2 
C1 
C2 
Value 
1.6 (nH) 
44 (nH) 
35 (pF) 
1.2 (pF) 
To start to define C1, double-click the left mouse button on the top left cell inside the 
parameter window that will then become editable. Enter the name  C1. Press the Tab 
key to proceed to the Expression cell or select it with a left mouse click. We recommend 
using the Tab key as it allows you to add your entries very quickly. The value 0 has been 
automatically assigned to the new parameter. 
The value can now be edited (after selecting it by mouse click or using the Tab key). 
Enter 35 there and press Tab again to change to the Description column where you can 
optionally give a short description of the parameter. If you press Tab again, a new row 
will be added to the table and its Name cell will be selected and editable. Continue as 
described for all parameters.  
After everything is set, the parameter list should look as follows: Now,  select  the  leftmost  inductor  inside  the  schematic  view.  With  the  selection,  the 
global  parameter  window  will  change  and  show  the  local  parameters  of  the  selected 
block. Navigate to the Settings tab of the block parameter list and replace the current 
value for the inductance by the previously defined parameter L1.
Repeat this procedure for the remaining elements until your drawing looks like the figure 
below: 
Note  that  although the  blocks  parameters  have  changed  from  numbers  to  parameter 
names, the results are still valid. The values of their associated results are still the same. 
To check our model once more and become more familiar with the parameter list control, 
single click  into  the  schematic  view  to  activate the global  parameter  list and  click  the 
right  mouse  button  over  the  row  belonging  to  the  parameter  C1.  Then,  choose 
Dependencies from the activated context menu. The following Dependencies dialog box 
appears and displays the blocks and properties that depend on the selected parameter.After  closing  this  dialog  box  by  pressing  the  OK  button,  press  the  Ctrl+F5  key 
combination to update the results. All standard result views are automatically generated 
showing the same contents as before.
Let us now modify the parameter C2. Double-click into the Expression cell and enter 1.4. 
Please note that the plot view in the main view window shows a grey background now 
to indicate that the currently shown result is not valid anymore because of the parametric 
change. However, the S-Parameters in the navigation tree are still valid, because the 
results for the previous parameter set are still available and still valid for this topology.  
After a topological change, such as adding another circuit element to the schematic, the 
S-Parameters in the result tree would also have been invalidated. In the tree, outdated 
results would have been indicated by changed S-Parameter tree item icons (
):  
Let us now move back to the actual workflow. Activate the design’s S-Parameter view 
now  by  clicking  on  the  S-Parameters  folder  and  change  the  plot  to  Magnitude  in  dB 
representation by clicking 1D Plot: Plot Type  dB 
. Then, update the results (Ctrl+F5). 
The results are now calculated for the current parameters. The changed S-Parameter 
results now look like this:To continue, reset the parameter C2 back to 1.2, delete the results via Post-Processing: 
Manage  Results   Delete  Results 
  and  selecting  All  results  created  by  simulation 
tasks. Then update the results again.
Performing a Parameter Sweep 
Because  you  have  successfully  introduced  parameters,  it  might  be  interesting  to  see 
how the results change when these parameters are modified. The easiest way to obtain 
these varying results is to perform a parameter sweep task.  
To  create  a  new  parameter  sweep  task,  choose  Home:  Simulation   New  Task  
Parameter sweep 
. The new parameter sweep task will be listed in the navigation tree. 
Like all other Simulation control tasks, a parameter sweep task cannot be executed on 
its own. It needs to be associated with another simulation task. In our case, we want 
the parameter sweep to execute an S-Parameter task for each parameter combination. 
This relation is represented in the tree by defining an S-Parameter task as a child entry 
of the parameter sweep task. This can be done by moving task S-Para1 onto Sweep 1 
via drag’n’drop: 
As a second step, we need to define the results of interest that are to be recorded during 
the sweep. For user-defined results this needs to be done via a post-processing task 
(Home: Simulation  New Task  Post-Processing 
) as child of the S-Parameter task. 
For built-in results such as the S-Parameters generated by the S-Parameter task there 
is no need to use post-processing tasks, since they are stored in a parametric fashion 
anyway. 
Please view the Task Parameter List of the S-Parameter task SPara1 by selecting the 
task in the navigation tree. Inside the Task Parameter List, select the Results tab. In this 
tab you can specify which results are to be stored during simulation and in which format
All  results  that  are  set  to  On  (Parametric)  will  be  stored  as  a  function  of  global 
parameters, namely, as a function of the parameter(s) that we are going to define as 
sweep variable(s).  
Now let us return to the definition of the parameter sweep itself. Open the  Parameter 
Sweep dialog box by double clicking on the navigation tree entry Sweep1. 
Within the Sequences frame you can specify the parameters to sweep, the number of 
steps  to  perform,  etc.  It  contains  a  list  that  displays  the  defined  sequences  and  the 
parameter  ranges  assigned  to the sweep.  Furthermore,  there  are  buttons  to  add  and 
delete a sequence or a parameter, respectively. 
Let  us  now  perform  a  parameter  sweep  step-by-step.  First,  we  create  a  new  sweep 
sequence by pressing the New Seq. button. A sequence Sequence1 is added to the list 
of sequences that is selected right after its creation, which causes the buttons New Par, 
Edit and Delete to become active. 
Pressing  the  Edit  button  makes  the  name  of  the  sequence  editable.  Clicking  on  the 
Delete button simply deletes the sequence.  
Clicking on New Par opens the Parameter Sweep Parameter dialog box where we can 
select  a  parameter  and  specify  the  range  of  values  assigned  to  it  during  the  sweep. 
Choose the parameter C1 as the first parameter to alter during the sweep. There  are  various  sweep  types  such  as  logarithmic  sweep  or  a  sweep  with  arbitrary 
sweep points. We stay with the preselected linear sweep. Let us specify an appropriate
parameter range for the sweep. Enter 33 as the lower limit (From), 37 as the upper limit 
(To) and assign 5 to the Samples field as shown below.  
Press OK to add the parameter variation to the sequence. The parameter variation is 
added to the sequence and is displayed in the Sequences frame:  
CST  Design  Studio is  able  to  perform  parameter  sweeps  with an  arbitrary  number  of 
parameters. For demonstration purposes it is sufficient to consider only one parameter. 
If you define more than one parameter variation and assign it to a sequence, calculations 
for  all  combinations  of  the  possible  parameter  values  are  performed  during  the 
parameter sweep. 
After  successfully  defining  parameter  variations  the  Start  and  Check  buttons  of  the 
Parameter Sweep dialog box become active. 
During  a  parameter  sweep  the  values  that  will  be  assigned  to  the  parameters  might 
exceed the range of valid values for some of the associated properties. For example, 
the  transmission  lines’  characteristic  impedances  must  be  greater  than  zero;  a  value 
less than zero would lead to an error. Clicking on Check performs a sequential update 
of  the  databases.  If  an  update  fails,  a  message  will  be  displayed  such  that  you  can 
modify your settings. 
Please perform a check (which finishes successfully for our settings) and start the sweep 
afterwards by pressing the Start button.  
To view the results for S1,1 Select NT: Tasks  Sweep1  S-Para1  S-Parameters 
 S1,1.  
A new view opens, showing the S-Parameter S1,1 as a function of the swept parameter 
C1. Also the Result Navigator window opens and shows the parameter settings for each 
run.
Result Navigator: 
In the plot view, you can see the parameter value of the swept parameter C1 as label 
text. When sweeping two or more parameters, only the unique Run ID of each simulation 
run is shown to keep the labels short. The mapping between Run ID and its associated 
parameter values is presented in the Result Navigator window. 
In  fact,  the  results  have  been  stored  not  only  depending  to  parameter  C1  but  also 
depending to the other defined global variables (C2, L1, L2). The default parametric view 
realizes that these parameters are constant and therefore hides them from the view. To 
get  a  complete  view  of  all  considered  variables  right  click  into  Result  Navigator  and 
deselect Hide Constant Parameters. The table will look like this:Further details on working with parametric results can also be found in the Getting 
Started document. 
Performing an Optimization 
CST  Design  Studio  offers  a  very  powerful  built-in  optimization  feature  that  is  able  to 
consider an arbitrary number of parameters and a combination of differently weighted 
goal functions.
In  the  following,  we  will  optimize  the  characteristics  of  our  band  pass  filter.  The 
optimization goals for our filter will be as follows: 
To  achieve  this  goal,  we  need  to  define  a  new  optimization  task.  Choose  Home: 
Simulation  New Task  Optimization 
. By default, it is named Opt1.  
Very similar to the parameter sweep task, we need to connect an S-Parameter task to 
the optimization task. The easiest way to do this is to duplicate the  S-Para1 task and 
move  it  into  the  optimization  task.  You  will  find  the  Duplicate  operation  in  the  task’s 
context  menu.  After  the  duplication  and  drag’n’dropping  the  duplicated  task  into  the 
optimization task, the task structure in the navigation tree should look as follows:If the value of C1 has been changed to 37 by the sweep task, set it back to 35 in the 
global  Parameter  List.  Now  open  the  optimizer  dialog  box  by  double  clicking  on  the 
corresponding tree item Opt1. The initially displayed Settings page allows specifying the 
optimization algorithm and shows a list of all previously defined parameters that can be 
used for the optimization.  
For our optimization we will choose the Trust Region Framework. This algorithm uses a  
Domain accuracy value that controls its convergence behavior. Please refer to the online 
help for a more detailed explanation. In our example we stay with the defaults. 
The  parameter  list  shows  all  available  parameters  and  their  optimization  settings, 
namely  the  parameters’  minimum  and  maximum  values,  the  initial  value,  the  current 
value, and the best value achieved in the previous optimization. To the left hand side of 
the  parameters  a  column  of  check  boxes  is  displayed,  where  you  can  select  the 
parameters to use for the optimization.
Select C1, C2 and L1 to include them in the optimization process. 
For the selected parameters you can specify the minimum and maximum values and, if 
the Use current as initial value option at the top of the list is switched off, the initial value. 
By default, this option is switched on to initialize each parameter by its current value. 
For our example please disable this option. 
The optimizer attempts to optimize a goal function by evaluating the goal function for 
different  parameter  sets.  Since  the  evaluation  of  the  goal  function  might  be  very 
expensive,  the  aim  of  every  optimizer  is  to  find  the  function’s  optimum  with  as  few 
evaluations as possible. Therefore, different algorithms are available that are suitable 
for  different  types  of  problems.  Each  algorithm  uses  its  own  strategies  to  reduce  the 
number of simulation runs. Some use an interpolation technique, others like the Trust 
Region Framework use cached data from already simulated results when needed. 
The 10% parameter range in the edit field associated with the Reset min/max button on 
top of the parameter list restricts the variability of the parameters. Clicking on the Reset 
min/max button automatically adjusts the range of the selected parameters: The entries 
in the Min column are set to the initial values minus the specified percentage; the entries 
in the Max column are set to the initial values plus the specified percentage. 
Enter a value of 30% and press the Reset min/max button to update the Min/Max values
Now,  we  need  to  specify  the  goal  function  for  our  optimization.  Change  to the  Goals 
page by clicking on the corresponding label at the top of the dialog box.The Goals page allows manipulating goals used for the optimization process. Every goal 
is  based  on  built-in  results  of  the  underlying  tasks  and/or  on  the  results  of  post-
processing  templates  and  some  general  rules  how  to  calculate  a  goal  function  value 
from the template’s result. In our application, we optimize S-Parameters for which we 
can use the build-in results. Hence we do not need to define any post-processing tasks. 
To add a new goal, click on the Add New Goal… dialog button. From a drop-down list 
you can select a specific result that is to be used for the goal definition. We keep the 
default result name since we want to define optimization goals on S1,1.
The  prefix  1DC  in  the  result  name  indicates  that  the  task’s  S-Parameters  are  of  the 
complex  1D  Result  type.  The  appearing  dialog  box  allows  us  to  complete  the  goal 
definition. 
 
In  the  Type  frame  the  type  of  result  which  the  goal  definition  should  act  on  can  be 
specified.  We  want  to  define  goals  on  the  magnitude  of  S1,1  and  leave  this  frame 
untouched. 
In  the  Conditions  frame  you  may  assign  an  objective  for  the  selected  data.  We  will 
describe the proper definition of such a target in detail later on. Furthermore, you can 
specify a weight for the goal. 
In  the  Range  frame  you  can  specify  the  abscissa  interval  (range)  within  which  the 
condition should be satisfied. There are three options: You may optimize either at a single 
value  at  a  specific  abscissa  value  (select  Single),  at  a  given  abscissa  range  (select 
Range) or for the total abscissa range (select Total). The default option is Total. In many 
cases the abscissa values will be frequencies. 
 
 
Let us take a closer look at the definition of a condition by considering some examples. 
  Specifying constraints:  
  If  you  want  the  selected  data  not  to  exceed  a  certain  value,  perform  the  following  settings: 
Choose the operator ‘<’ from the Operator list and specify the maximum value of the chosen 
result inside the Target edit field.  
  For the specification of a lower data limit just select the operator ‘>’ and perform the same steps.  
  Use the operator ‘=’ to optimize the parameters such that the template result equals the target 
value.   Moving 
the  minimum  or  maximum  value 
to  a  specific  abscissa  value:  
To move the minimum value of the goal function to a specific abscissa value, select the 
operator move min and specify the abscissa value, where you want the minimum to be 
moved to. in the  Target field. Because  a  value  will  be moved along the  abscissa, the 
Single  setting  in  the  Range  frame  will  be  disabled  for  this  type  of  goal.  You  can 
analogously move the maximum value to a certain location using the operator move max. 
If  there  is  more  than  one  goal,  you  may  adjust  their  influence  on  the  optimization  by 
specifying a weight. It can be any positive number. 

For our example, we need to define three goals specifying constraints for certain ranges.  
Description 
Stop band 
Frequency range 
400 < f / MHz < 550 
Transition region  550 < f / MHz < 610 
610 < f / MHz < 790 
Transition region  790 < f / MHz < 850 
Pass band 
Stop band 
850 < f / MHz < 
1000 
The first goal definition should look like this: 
Condition 
|S11| maximal 
- 
|S11| minimal 
- 
|S11| maximal
The  check  boxes  in  the  first  column  of  the  table  can  be  used  to  enable/disable  the 
defined goals. In our case all goals need to be enabled.  
Now press the Start button. As soon as the optimizer is started, the solver run Info page 
will  be  available,  displaying  some  information  about  the  optimization  process.  To 
visualize the optimization process, click on the Opt1\S-Para2\S-Parameters tree item.  
When  the  calculations  are  performed,  the  Info  page  reports  the  progress  of  the 
optimization. Among the values displayed are the number of evaluations (some of them 
are based on a calculation, while others are reloaded), the first, the last and the best 
goal function values and the best parameter values thus far.  
After  successful  completion  of  the  optimization  the  Info  page  displays  the  results  as 
shown below: During the optimization, the goal function value decreased by a considerable amount, 
indicating that the optimizer was able to improve the filter’s characteristic.  
Now  that  we  have  an  optimized  result,  it  would  be  interesting  to  see  a  comparison 
the  Tasks\Opt1\Result 
between 
the 
Curves_SPara2_S-Parameters_S1,1 tree item to visualize these curves. 
the  optimized  and 
initial  S11.  Select
Inside this plot the goal definitions are also shown. The selected S-Parameter S1,1 is 
not indicated in the title but in the associated result tab of the plot. 
To get a plot in dB please change the plot scaling to Magnitude in dB and slightly change 
the y-axis range: Open the 1D Plot Properties dialog box via the context menu of the 
schematic view ( Plot Properties…), disable the Auto range for the y-axis and set its 
min value to -14. 
You can verify that the insertion loss throughout the pass band could be improved by
Chapter 3 – System Assembly and Modeling 
This chapter introduces the system simulation capabilities of CST Design Studio. 
The first section describes how planar circuits can be simulated with different accuracy 
levels. It starts with a schematic representation in which each block is described by an 
analytical model. This is followed by a full 3D field simulation that is performed on a 3D 
model derived from the original schematic. 
The second section describes how a complete 3D model can be derived from schematic 
blocks. The assembly view is used to align the components to each other. Simulation 
projects are used to create partial results and combine them into the final results for the 
whole structure. 
The third  section  describes  how  variations  of  a master  project  may be  simulated and 
compared.  For  this  purpose,  simulation  projects  are  derived  from  the  master  project. 
Results  of  the  variants  are  compared  by  using  a  post-processing  task  in  the  master 
project. 
Planar Circuits 
When  working with  distributed  elements  such  as  microstrip  and  stripline waveguides, 
CST Design Studio combines the advantages of having a pure schematic and a full 3D 
representation of such elements. 
To  show  this  ability  we  will  use  an  already  prepared  project.  Please  open  the  3D 
Component Library by choosing Home: Components  3D Component Library  
 . You 
can  find  the  S-Parameter  Lowpass  Geometry  Only  project  by  using  the  Search 
components field to filter the available components. Once you have located the correct 
component, hover the mouse over its preview area and click Download a copy of the 
latest revision 
Alternatively, an entirely set up and simulated version of this example can be found with 
the name S-Parameter Lowpass. 
, followed by Open as a project 
.The  circuit  consists  of  three  microstrip  T-junctions  and  three  microstrip  open-ended 
stubs. Since two of the T-junctions and open-ended subs are identical, one of each is 
represented as a clone block. Clone blocks refer to other, already defined blocks and 
behave identically to them.
The blocks have the following properties (length units are in mm): 
Reference Block 
Height 
Thickness 
Epsilon 
Tandelta 
0.71 
0.035 
3.5 
0.006 
  MSOPEN 1, 2 
  Length 
  Width 
L1, L3 
W1, W3 
  MSTEE 1,2 
  Width1 
1.56, W2 
  Width2  W2, W2 
  Width3  W1, W3 
  Length1  6, 0.0 
  Length2  L2, 0.0 
  Length3  0.0, 0.0 
The parameters are defined as follows in the global parameter list: 
L1 
L2 
L3 
W1 
W2 
W3 
6.5 
8.1 
8.6 
1.7 
2.0 
1.5 
In many cases it is important to check if the resulting 3D structure, i.e. the layout of the 
circuit, is correct. It may happen that the resulting structure overlaps or that distances 
between elements are too small, such that unwanted coupling may occur. Choose NT: 
Assembly  or  Home:  Edit    Assembly 
.  A  new  view  will  open,  showing  the  3D 
structure:The  assembly  view  automatically  snaps the  components at  their  port  locations to get 
proper positioning of each block. However, as you can see, some orientations that are 
not relevant for the circuit simulation but relevant for the 3D coupling may not be defined 
correctly yet. Whether all blocks are oriented as desired or not depends on the creation 
order of the individual blocks. Therefore, manual adjustments  may be needed. In our 
case  we  want  to  have  all  three  fingers  at  one  side  to  make  the  3D  geometry  more 
compact. Select the block that has the wrong orientation (MSTEE1_CLONE1 if you used 
the  Geometry  Only  project).  To  do  so,  select  Layout  Flip  in  the  Settings  tab  of  the 
Parameter List of the block and check the associated checkbox:
The assembly view is updated with the new geometry automatically. If needed, repeat 
the step for other blocks with wrong orientation. Now the desired result is obtained:For the later 3D simulation it is useful to enlarge the substrate in the transverse direction. 
Most field simulators need some space between the structure and the boundary of the 
simulation domain. Select the microstrip reference block MSREF1 in the assembly view 
by  double-clicking  on  it  and  change  Substrate  Ymin  and  Substrate  Ymax  to  6  in  the 
Settings tab of the Block Parameter List.
Again, the geometry is updated right away:  
To simulate the S-Parameters, an S-Parameter task needs to be set up as described in 
the previous sections. The frequency range should be between Fmin = 0 and Fmax = 7 
GHz. The results can be seen in the following graph:Of course, these are the results of the circuit simulation based on the analytical models 
of the used blocks. To obtain the results of the entire structure in 3D, some additional 
steps need to be done.  
To set up a 3D model, a so-called Simulation project needs to be created.  
A simulation project is a complete .cst project that is automatically created by using the 
assembly information of the schematic. Additionally, all necessary solver settings and 
possibly further structure modifications can be done there.  
Note: Generally, the created 3D structure of a simulation project is linked to the blocks 
of  the  schematic  such  that  parametric  changes  of  the  blocks  are  propagated  to  and 
reflected by the simulation project as well. 
From either the schematic view or the assembly view, choose Home: Simulation  New 
  and  double  click  on  Simulation  project.  Alternatively,  just  press  the 
Task 
corresponding button in the Ribbon (Home: Simulation  Simulation Project  Select 
). Some guiding text will appear and the schematic view will be 
Block Representation
colored  in  a  light  yellow,  indicating  that  the  simulation  project  mode  is  active  and  a 
Simulation Project tab will be shown in the Ribbon.  
When in simulation project mode, the following buttons of the Simulation Project Ribbon 
tab are available: 
3D Model  Schematic 
Model 
Ignore in 
Simulation 
Create 
Simulation 
Project 
Close 
Simulation 
Project 
Mode 
The buttons are grouped in different tabs as follows: 
  Simulation Project: Model Representation  3D Model 
as 3D 
: Considers the selected blocks 
  Simulation  Project:  Model  Representation    Schematic  Model 
:  Considers  the 
selected blocks as schematic elements 
  Simulation  Project:  Model  Representation    Ignore  in  Simulation 
:  Ignores  the 
selected blocks 
  Simulation Project: Create Project  Create Simulation Project 
: Ends the simulation 
project mode by creating a simulation project 
  Simulation  Project:  Close   Close  Simulation  Project  Mode 
:  Exits  the  simulation 
project mode without creating a simulation project 
Note:  Only  blocks  that  will  be  represented  as  3D  elements  are  linked  to  the  master 
project. Blocks that are created as schematic elements are copied. 
Since we want to add all blocks into a full 3D simulation press Ctrl+A in the schematic 
view to select all elements. If you are in the assembly view, the easiest way to select all 
blocks is to click the uppermost block in the Navigation Tree: Blocks folder and then hold 
Shift  while  clicking  the  lowermost  block.  Afterwards,  press  Simulation  Project:  Select 
Block Representation  3D Model 
. End the simulation project mode with Simulation 
Project: Create Project  Create Simulation Project 
. 
We could also have used the short cut  Home: Simulation  Simulation Project  All 
Blocks as 3D Model 
 instead of individually selecting all blocks. 
The appearing dialog box allows the specification of some simulation project properties. 
Please choose Full_3D as Name and select High Frequency as Project type. Since we 
want to simulate a planar microstrip filter structure we should define a template that sets 
several solver settings specific to this kind of structure. Select Select template… in the 
Project template drop down box. A new dialog box opens that allows either to select an 
already existing template or to create a new one. Let us quickly create an appropriate 
new template: 
  Press New Template… 
  Click on the MICROWAVES & RF / OPTICAL piece in the pie chart 
  Double click on Circuit & Components 
  Double click on Planar Filters 
  Double click on Frequency Domain (Fast Reduced Order) 
  (If the FD-Solver is not included in your license, you may choose any other listed solver) 
  Leave all unit settings unchanged and click Next 
 
  Specify My Planar Filter as template name and press OK to leave this dialog box
You  will  find  more  information  on  project  templates  in  the  CST  Studio  Suite  Getting 
Started document. 
Select  My  Planar  Filter and press  OK to return  to the  Create  New  Simulation  Project 
dialog box.  
Make sure  that the  Frequency  Domain  solver  is selected  and then finalize  the  dialog 
settings by choosing Task: SPara1 as Reference model for global settings. While the project template ensures that the 3D simulation project gets the appropriate 
settings for background material and boundary conditions, the Reference model setting 
takes  care  that  the  same  frequency  range  as  in  the  S-Parameter  task  is  set.  The 
frequency range of the reference task will overwrite any frequency range definition in the 
selected project template 
Press OK to create the new simulation project.
Finally everything is in place to start the simulation. The newly created simulation project 
task Full_3D has been added to the navigation tree of the schematic. 
In  the  schematic  or  assembly  view  of  the  main  project,  select  Home:  Simulation  
Update 
. Now both the regular S-Parameter task as well as the simulation project are 
simulated. After the simulations are finished, all results can be found in the result tree. 
To view the simulation project results, select NT: Tasks  Full_3D  3D Model Results 
 1D Results  S-Parameters:As you can see, the results from schematic and from 3D agree very well. The approach 
to compose the structure of different elements was reasonable in this case. 
Assemblies 
In the previous section we have seen how a full 3D model can be created from microstrip 
and stripline blocks. These blocks were almost automatically aligned in the  assembly 
view.  The  assembly  view  can  also  be  used  to  assemble  a  compound  structure  from 
individual 3D components. To demonstrate this functionality, we would like to create a 
horn-reflector antenna. If you do not want to create the structures yourself, you can find 
the  already  set  up  and  simulated  example  Reflector  Antenna  Assembly  in  the 
Component Library. 
As the name already suggests, a horn-reflector antenna consists of a horn antenna that 
illuminates  a  reflector  dish.  We  will  now  import  predefined  examples  for  these  two 
components.
Please close all open projects and create a new project of Type Circuits & Systems  
Assembly. Save it as Assembly.cst. 
To add the reflector dish to the project, open the 3D Component Library by choosing 
Home: Components  3D Component Library 
. Please find the Reflector Dish project, 
for  instance  by  using  the  Search  components field to filter the  available  components. 
Once you have located the correct component, hover the mouse over its preview area 
and click Download a copy of the latest revision 
, followed by Add as a Block 
. 
Next, repeat the same steps to add another CST Studio Suite block, this time selecting 
the Horn Antenna project to import the horn antenna as well. 
Your  assembly  should  now  contain  two  blocks  with  the  3D  geometry  of  the  imported 
components. You can select any block by double-clicking on it. A selected block can be 
edited by right-clicking it and selecting Edit to view the full 3D structure of the block in 
the 3D EM simulation environment.In  the  assembly  view,  all  included  3D  projects  are  automatically  scaled  to  the  units 
chosen in the assembly project. 
It can be seen that the horn antenna is very small in size in contrast to the reflector dish. 
We have to adjust the dimensions of the antenna to make it match the reflector’s size 
better. In the main view, double-click on the horn antenna (or choose NT: Blocks  Horn 
Antenna_1) to select the respective block and bring up the Block Parameter List.
In the Settings tab, you can see that the geometry of the block is fully parameterized 
and can easily be adjusted.  
The following illustration outlines the parameters in a top-down perspective (when using 
waveguide_width) or side perspective (waveguide_height). 
Modify the block parameters such as in the following screenshot:Since we have just changed the geometry, the assembly model needs to be updated. 
Select  Home:  Edit   Parametric  Update  or  press  F7  to  trigger  the  update.  Now,  the 
dimensions of the two components match well. 
Still, there is no information about how to automatically align the two structures; they are 
positioned relative to the origin in the same way as they were in the original projects. To 
place them correctly, we need to transform the horn antenna manually. 
We will introduce a parameter for the slant angle with which the antenna is aligned to 
the reflector dish. Switch to the Parameter List window and add a parameter slant_angle 
with the value of 45: 
Transformations can be done by selecting the desired block (the horn antenna in our 
case) and choosing Assembly Modeling: Manual Transform  Absolute Transform 
or pressing Ctrl+T on the keyboard. Set a value of -400 for Translation: W to define the 
distance  between  horn  antenna  and  reflector,  and  a  value  of  180+slant_angle  for
Rotation: X°, using the parameter we just defined. As the translation is specified in the 
local U/V/W coordinate system, the translation vector is rotated together with the block, 
such that the antenna is properly aligned to illuminate the center of the reflector dish. 
Now the assembly is ready:The shown structure is a 3D representation of all elements comprised in the schematic 
as well. It is not yet a project that can be simulated in 3D. For this purpose, a Simulation 
project  needs  to  be  created.  This  time  we  use  the  shortcut:  Home:  Simulation   
Simulation Project  All Blocks as 3D Model 
 from the ribbon menu.
Adjust all settings in the Create New Simulation Project dialog box as shown below: 
When a block is chosen in the Reference model for global settings drop down box, the 
simulation project will be generated in a way that most of its model settings are the same 
as  defined  in  the  reference  model.  Reference  model  settings  can  extend  or  override 
potential settings given by a project template, allowing to further customize the model 
behavior. You can click on Select… to choose which settings shall be considered. This 
option is very useful since in many cases it will save you a lot of configuration time. 
Another important option is the  Use reference block’s coordinate system checkbox. If 
activated, it ensures that the coordinate system of the new project is the same as the 
one used in the reference model. All other structure elements are imported relative to 
this coordinate system. This is necessary if the used solver has some constraints on the 
orientation  of  some  solver  features.  For  instance,  the  time  domain  solver  we  have 
chosen requires all wave guide ports to be aligned perpendicular to the global coordinate 
system. Since this is the case for the reference model, its coordinate system should be 
preserved, while all other structure elements need to be transformed accordingly.  
After  pressing  OK  in  the  dialog  box,  a  new  CST  Microwave  Studio  project  with  the 
correctly assembled structure is created, nearly ready for simulation. You can click and 
drag the mouse while holding Shift or Ctrl to get a better view of the model. Visualization 
of the working plane can be toggled via View: Visibility  Working Plane or by pressing
The  only  settings that  need  adjustment  are the symmetry  planes.  Currently  there  are 
two  symmetry  planes:  One  in  the  YZ  plane  and  one  in  the  XZ  plane.  For  the  horn 
antenna these settings were correct, but for the assembled project the XZ plane is not 
a symmetry plane anymore. 
In the simulation project please select Simulation: Settings  Boundaries 
, go to the 
Symmetry Planes tab and remove the electric symmetry in the XZ plane. Press OK to 
close the dialog box. 
Now  switch  back  to  the  Assembly  project  and  update  all  tasks  by  choosing  Home: 
Simulation  Update 
. The field solver will start, and after some time, list its results in 
the result tree.To visualize the resulting farfield just click on the corresponding tree item.
For this plot the Farfield Plot: Visibility  Show structure option was switched on and the step 
size was set to 1 degree (Farfield Plot: Resolution and Scaling  Step Size). 
Managing Variations 
A common task is to simulate variations of an already assembled structure. Additionally, 
all these variations should be automatically maintained or managed by a master setup 
in order to keep track of the entire project. 
Let us have a further look at the example above. There are several possible scenarios 
for it. For instance, one might want to: 
  Do parametric studies. 
  Simulate  the  dish  with  the  I-Solver,  using  the  farfield  result  of  the  horn  antenna  as 
illuminating source. 
Include some fixture that connects the horn with the dish. 
 
  And many more… 
Unfortunately, within this document we can give you only a very brief introduction to this 
large  variety  of  possibilities.  Therefore,  we  will  concentrate  on  the  first  mentioned 
workflow.  
A detailed description of the second application using the Hybrid Solver workflow can 
be found in the help page of the tutorial example "Reflector Antenna Hybrid Solver" in 
the component library. 
Parametric Changes 
Doing  investigations  concerning  parametric  changes  is  very  easy.  Please  find  the 
Parameter List window in the Assembly project, and change the value of slant_angle to 
0. The Assembly view is immediately updated to the new geometry:Save the project to confirm your change. If you switch to the simulation project SP1, you 
will  see  the  message  Imported  sub-project  has  been  modified.  Press  ‘Home:  Edit-
>Parametric Update (F7)’. (Press ESC to cancel). When a parameter is modified, the 
changes are propagated to each derived project, which is indicated by this notification.
Switch back to the Assembly project and press Home: Simulation  Update 
the simulation again. Our sub-project SP1 will automatically simulate. 
 to start 
Once the simulation of all tasks has finished, we can again have a look at the farfield 
results. Select NT: Tasks  SP1  Farfields  farfield (f=5) [1] to activate the plot. 
Result of Full Simulation (SP1) 
For this plot, the structure was set to transparent by activating Farfield Plot: Visibility  
Structure Transparent.  
As for the Lumped Filter example, you have the possibility to automatize such parameter 
studies  by  moving  the  simulation  project  into  a  parameter  sweep  task.  After  having 
defined a sweep task and relocating the simulation project task, the task list looks like 
this.Double clicking on the sweep task again lets you define the sequences you would like 
to run. To reproduce the manual steps we did so far, define a sequence that varies the 
parameter slant_angle from 0 to 45 degrees in two steps.  
Now, Home: Simulation  Update 
for all defined sequences automatically. 
 will update the geometry and run the simulation 
Remarks 
Since the shown example was chosen to explain the principle workflows, the geometries 
do not represent a ‘real world design’. In addition, some solver settings of the 3D solvers 
have  been  chosen  to  run  fast  but  possibly  less  accurate.  Please  have  a  look  at  the 
corresponding CST MWS documentation for proper solver settings.
Chapter 4 – Schematic View 
For all CST Studio Suite modules that offer 3D simulations2, two fundamentally different 
views on the structure exist. A 3D view that is visible by default and a schematic view, 
showing an abstract, terminal oriented representation of the structure. The schematic 
view  allows  embedding  the  structure  in  a  more  complex  environment.  Several 
components may be added, such as resistors, capacitors, transistors, transmission line 
models or even other 3D CST Studio Suite projects. 
This  chapter  addresses  CST  Studio  Suite  users  who  are  mainly  dealing  with  field 
simulation but who also need the capabilities of a powerful circuit simulator that is tightly 
coupled with the 3D world. 
To  demonstrate  the  main concepts  of the  schematic  view,  we will  use  the  Connector 
project from the  CST  Studio  Suite for  High  Frequency  simulation examples.  You  can 
find  it  in  the  Component  Library  (Home:  Components   3D  Component  Library 
), 
searching  for  the  name  Connector.  Use  the  one  tagged  with  High  Frequency  and  S-
Parameter. 
Main Concepts 
Download a copy of the latest revision 
, followed by Open as a project 
. 
After having opened the project, the schematic view can be activated by selecting the 
corresponding tab on the bottom of the main view: Schematic 
In the beginning, the schematic view shows only one single CST Studio suite schematic 
block (MWS block). It represents the 3D structure with its terminals. 
2 CST MICROWAVE STUDIO®, CST EM STUDIO®, CST MPHYSICS® STUDIO, CST PARTICLE STUDIO®, CST PCB STUDIO®, CST 
CABLE STUDIO®
MWS block 
Component / Block parameter list 
Block selection tree 
The terminals (pins) have a one-to-one correspondence to the 3D structure’s waveguide 
or  discrete  ports.  The  schematic  view  now  allows  easy  addition  of  external  blocks  or 
circuit elements to the terminals of the 3D structure.  
Adding  blocks  or  circuit  elements  to  the  schematic  view  is  straightforward,  simply 
navigate to the block selection tree, select one of the available blocks within the selected 
folder, and drag it onto the schematic view. Please refer to the corresponding chapters 
at the beginning of this document to get more information on how to place blocks onto 
the schematic. 
The  following  picture  shows  an  exemplary  external  circuit  where  the  original  8-port 
structure has been reduced to a 2-port device. This is done by connecting two pins to 
external ports (the yellow, rectangular symbols) that define the terminals of the circuit
We  want  to  perform  an  S-Parameter  simulation.  In  the  example  above,  the  resulting 
scattering matrix will be a 2x2 matrix since only two external ports have been defined. 
In CST Design Studio, analysis options are organized into simulation tasks. To define a 
new simulation task, choose Home: Simulation  New Task 
, select S-Parameters
The newly created S-Parameter task SPara1 is now visible in the navigation tree. At the 
same  time,  the  Task  Parameter  List  shows  all  properties  and  settings  of  it.The MWS block is the only block with frequency limits in the schematic. By default, the 
S-parameter task applies the maximum frequency range, which is the frequency range 
of the MWS block in our case.  
Most circuit tasks have excitation- and/or impedance settings at the external ports which 
can be individually defined for each task in the Excitations or Terminations tab of the 
Task Parameter List.  
The S-Parameter task only has impedance settings but no excitation settings. By default, 
they are on Block Dependent. That means the connected port impedances of the MWS 
block MWSSCHEM1 are taken as reference impedances for the S-Parameter task. This 
is exactly what we want. This can be verified by switching to the Terminations tab. 
We are satisfied with default settings here and leave the Task Parameter List as it is.  
Once all task settings have been defined, you can run an S-Parameter circuit simulation 
by choosing Home: Simulation  Update 
. This will start the S-Parameter simulation 
of the coupled EM and circuit problem. If all simulation results of the 3D EM simulation
are  already  present,  the  circuit  simulation  will  only  take  a  few  seconds  to  complete. 
Otherwise, the missing EM simulation data will be automatically computed first. 
Once the simulation is complete, the results will be added to the navigation tree.  
The  schematic  view  also  supports  the  parameterization  of  the  3D  model  in  a 
straightforward  way.  Both  the  schematic  view  and  the  3D  view  use  the  same  project 
parameters.  
The tight integration of the 3D and the schematic modules also allows another type of 
coupled simulation: The transient EM/circuit co-simulation. 
Transient EM/Circuit Co-Simulation 
The  transient  EM/circuit  co-simulation  is  an  alternative  to  the  standard  EM/circuit  co-
simulation  that  is  available  for  coupled  circuit  CST  Studio  Suite  high-frequency 
problems. The standard EM/circuit co-simulation uses S-Parameters to describe CST 
Studio Suite high frequency blocks. The computation of S-Parameters by CST Studio 
Suite for high frequency simulations requires either a frequency sweep of the frequency 
domain solver, or one simulation per port of the time domain solver. The resulting S-
Parameters describe the block for any combination of port excitations. 
The transient EM/circuit co-simulation uses a different approach. Only one simulation of 
the coupled circuit-EM problem is performed, with exactly the excitation that is defined 
in  the  circuit.  Both  the  circuit  and  the  EM  problem  are  solved  simultaneously.  This 
approach may be faster than the standard EM/circuit co-simulation (especially for large 
numbers of ports), since no general S-Parameters need to be calculated. 
The setup of a transient EM/circuit co-simulation is very similar to the setup of the S-
Parameter  simulation  described  above.  Open  the  Home:  Simulation   New  Task
The newly created transient task Tran1 is now visible in the navigation tree and its Task 
Parameter List is preselected after adding the new task.   
To perform a transient EM/circuit co-simulation, stay with the Transient tab of the Task 
Parameter List and select CST transient co-simulation as Circuit Simulator. In addition, 
set the total simulation time (Tmax) to 5 ns. Leave the Sampling setting to Automatic, 
which is the default. The number of samples (Samples) is inactive, since it defines the 
plot resolution of the result curves only if the Manual sampling mode is selected. Next, the transient excitations need to be defined. Leave the Transient tab and change 
to the Excitations tab of the Task Parameter List. 
The excitations are organized such that for each external port (1 and 2) there are two 
rows: The first row describing the excitation settings and the second row describing the 
impedance settings at the port. The second row can always be made visible by clicking 
on the small arrow (>) to expand. 
By  default,  the  ports  are  non-excited  (indicated  by  the  keyword  Load),  and  they  are 
terminated by the block-dependent port impedance of the MWS block, similar as for the 
S-Parameter task we defined earlier.
To define an excitation at the first port, expand the corresponding drop-down list of 
port 1 and select Define Excitation … 
A new dialog for defining the excitation signal at port 1 will then appear. Here the Use reference Fmin/Fmax is selected. This means that the frequency range of 
the Gaussian signal will be taken from the task’s Reference Frequency Range setting. 
It corresponds to the frequency range of the MWS block, here. Press OK to apply the 
signal definition of the excitation signal. 
In the Task Parameter List you see that port 1 is now excited by an ideal voltage source, 
characterized by an inner resistance of zero. The parameters of the Gaussian excitation 
source can be seen as a tooltip.
The setup of the transient simulation task is complete now. The only missing bit is to 
define in which transient results of the circuit you are interested. This is done by probes: 
A  probe  can  be  attached  to  any  connector  in  your  design  which  and  will  record  the 
associated voltage and current for visualization or further processing. To insert a probe, 
first click onto the connector to be probed and then click on Home: Components  Probe 
 or press o. In our simple example we are interested in the voltages and currents at 
the ports and at pins 3 and 7 of the MWS block. The time signals at the external ports 
are monitored automatically, so we need to define only two probes:Now the setup of the transient EM/circuit co-simulation is complete and 
you may start the simulation with Home: Simulation  Update 
. After 
the simulation has finished, the results appear below the task item NT: 
Tasks  Tran1.  
In this simple example you will notice the Gaussian pulse travelling from port 1 to port 2 
causing some cross talk in probes P1 and P2. More realistic examples may of course 
use  any  of the  excitation signals  available from the  excitation  signal  library  (including 
user defined signals). The excitation of more than one port is of course also possible.
For further information about transient simulation in general and transient EM/circuit co-
simulation in particular, please refer to the online help. 
Chapter 5 – Schematic View in CST Cable Studio / CST PCB Studio 
This chapter covers the specific aspects of the schematic view of CST Cable Studio and 
CST PCB Studio 
Schematic view in CST Cable Studio 
CST  Cable  Studio  (CST  CS)  is  a  tool  especially  designed  for  simulating  cable 
harnesses. The basis of CST CS is a CST MWS module, tailored to the needs of cable 
modeling.  
CST  Cable  Studio  not  only  simulates  the  behavior  of  cable harnesses  themselves.  It 
may also simulate the effects of a 3D environment on the harness. Such an environment 
may  be  a  chassis  or,  even  more  complex,  an  antenna  imposing  a  3D  field  onto  the 
harness. Generally, a CST CS project may contain a cable harness with terminals, and 
a 3D structure with field excitations like 3D ports.  
As for the other modules, the schematic view shows a schematic block that represents 
the electrical model of the project. It shows pins for all defined 3D and cable ports. In the 
example below, you can see a simple single wire on a ground plane illuminated by a 
dipole  antenna.  The  dipole  is  excited  by  a  discrete  3D  port.  Correspondingly,  the 
schematic view shows a CS block with two pins for the two cable ports and one for the
Cable studio blocks offer two different ways to represent the cable model. Either the full 
3D structure including the cable is simulated, like the connector in chapter 4, or only the 
cable model itself, without 3D interactions is considered. The latter applies to all circuit 
tasks,  like  for  instance  a  transient  task  or  an  AC  task.  In  this  case,  an  equivalent 
transmission line circuit model is created from the cable harness. 
For more information about CST Cable Studio please have a look into the CST Cable 
Studio – Workflow and Solver Overview document. 
Schematic View in CST PCB Studio 
CST PCB Studio (CST PCBS) is a tool especially designed for simulating printed circuit 
boards. Since the analysis of a PCB has many different aspects, CST PCB Studio also 
offers a variety of different modeling/solver modules that cover the different simulation 
needs. For instance, you will find modules for solving SI-TD problems as well as IR-Drop 
or PI analyses.  
Many  of  the  CST  PCBS  solver  modules  heavily  use  the  schematic  view.  They 
automatically set up a circuit that not only contains an equivalent electrical model of the 
PCB  but  also elements and excitations  defined by  the  imported  layout. This  circuit  is 
then simulated by an appropriate simulation task to gain the desired results. CST PCBS 
heavily uses SAM to create several simulation projects that cover and manage different 
simulation aspects of the entire board. 
For more information about CST PCBS please have a look into the CST PCB Studio –
Chapter 6 – CST Studio Suite Projects in CST Design Studio 
This section explains how CST Studio Suite projects3 (CST 3D projects), simulating 3D 
fields, can be added to a CST Design Studio (CST DES) design.  
Whenever you want to incorporate a CST 3D project into your CST DES design, you 
have the choice to use either a parameterized block or a file reference block.  
Parameterized block:  
  Maintains a copy of the original project. 
  Allows parametric control from within CST Design Studio. 
File Reference block:  
  Maintains a reference to the original project. 
  Recognizes project changes to provide up-to-date results. 
To  give  you  an  idea  of  the  capabilities  offered  by  these  blocks,  we  will  construct  an 
example and demonstrate the key features in this chapter. Since the main concepts are 
the same for all CST 3D projects, we will explain them exemplarily for a CST Microwave 
Studio project. 
Example Introduction 
The model to be used in this example is shown in the image below. A rectangular patch 
antenna with two feeds having impedances of approximately 100  is connected to two 
impedance transformers. If you do not want to set up the model manually, you can find 
the setup and the already simulated Matched Antenna project in the Component Library. 
The  individual  parts  of  the  antenna,  the  Transformer  project  and  the  Patch  Antenna 
project,  can  be  found  in  the  Component  Library  as  well.  For  convenience,  they  are 
tagged with Matched Antenna.Transformer No.1 
Patch Antenna 
100  
1 
50  
100  
2 
50  
Transformer No. 2 
We  assume  a  fixed  antenna  design  with  no  parameterization.  The  antenna  radiation 
frequencies are as follows: 
3 CST MICROWAVE STUDIO®, CST EM STUDIO®, CST MPHYSICS® STUDIO, CST PARTICLE STUDIO®, CST PCB STUDIO® (only file 
blocks), CST CABLE STUDIO®, FEST3D
f1= 7.0 GHz for excitation at port No.1 
f2= 7.5 GHz for excitation at port No.2 
The transformers consist of two microstrip step discontinuities with a microstrip line of 
length l and width w in between: 
l 
100  
w 
50  
To distinguish between the line widths of transformer 1 and 2, we call their widths w1 
and w2, respectively. The other line widths are established by the patch antenna’s port 
impedances, of approximately 100 , and the 50  of the feeding line.  
Our  design  goal  is  a  typical  matching  problem  and  can  be  formulated  as  follows: 
Determine  values for  l1, l2, w1  and w2  to  obtain minimal  reflection  at the  transformers’ 
input ports (50 ) for the original antenna radiation frequencies. 
To simplify this task, we reduce the number of degrees of freedom by fixing l1=l2=7mm. 
Thus, w1 and w2 remain as the only parameters to optimize.  
CST Studio Suite for High Frequency Simulation models 
First, we set up the high frequency simulation models that we will use within our CST 
Design Studio project. If you are not familiar with CST Studio Suite 3D EM solvers, you 
may  read  through  the  CST  Studio  Suite  Getting  Started  and  CST  Studio  Suite  High 
Frequency Simulation manuals first. 
For both the antenna and transformer models, the substrate and the metallization will 
be described by the following values:Value 
Name 
Dielectric constant r  2.2 
Substrate height 
Metallization 
thickness 
Metallization 
material 
PEC 
0.794 mm 
0.05 mm 
The hexahedral transient field solver will be used.
Antenna 
The image below shows the rectangular patch antenna.  
The dimensions are the following: 
Name 
Size 
hadd 
Microstrip line width 
ladd 
Distance from patch to 
port 
Value 
12.6mm x 13.6 mm 
0.5 mm 
0.7 mm 
4 mm 
8 mm 
The patch is elevated from the substrate by the additional hadd. The space between the 
patch  and  the  substrate  is  also  filled  with  substrate  material.  Therefore,  the  resulting 
substrate height below the patch is hpatch = 1.294 mm. 
The  feeding  microstrip  lines  are  located  on  the  original  substrate  and  end  below  the 
patch. The length ladd defines the distance between the patch’s edge and feeding line’s 
end (as shown in the image below). The frequency range is set to 5 ≤ f / GHz ≤ 10. To get decent mesh and solver settings 
for this project, a project template for planar antennas has been used.  
The S-Parameters S1,1 and S2,2 of the patch antenna show minima at the antenna’s 
radiation frequencies f1 and f2:
As we can see, these frequencies are approximately f1 =7 GHz and f2 =7.5 GHz, and 
thus  two  farfield  monitors  have  been  defined  at  these  frequencies  to  perform  a  final 
antenna calculation from within CST Design Studio.  
Transformer 
Although  CST  Design  Studio  provides  an  analytical  model  for  a  microstrip  step 
discontinuity, a CST Microwave Studio model of the transformer is used to demonstrate 
the parametric control of CST MWS projects from within CST DES. 
Two parameters are defined for the model of the transformer: w for the transformer's 
width and l for the transformer's length. The widths of the input and output microstrip 
lines  are  defined  by  their  impedances  of  50    and  100 .  Considering the  substrate 
defined above, we obtain the following dimensions: 
Name 
w100  
w50 
l 
winitial 
Value 
0.7 mm 
2.4 mm 
7 mm 
1 mm 
To get reasonable accuracy quickly, a project template for planar filters has been used 
but  with  mesh  adaption  disabled.  To  enhance  optimization  performance,  in  order  to  
speed up the calculation, a magnetic symmetry plane is defined to take advantage of 
the symmetry of our 3D model and the excited Port. 
CST Design Studio Modeling 
As mentioned in the introduction to this chapter, CST DES provides two types of CST 
3D  project  blocks.  In  this  section,  we  will  give  a  more  detailed  overview  over  the 
properties  and  usage  of  these  blocks.  We  will  also  introduce  the  clone  block  as  an 
efficient substitute for topologically equivalent MWS blocks.
CST Studio Suite File Block 
A  block  of  this  type  holds  a  reference  to  a  CST  3D  project.  You  find  it  in  the  Field 
Simulators  folder  of  the  Block  Selection  Tree.  If  the  underlying  project  is  a  CST 
Microwave Studio project, a CST MWS file block will be created. This block is basically 
represented  by  the  S-Parameters  of  the  referenced  project4.  Additionally,  the  block 
keeps track of modifications of the project such that CST Design Studio makes sure that 
it uses up-to-date results. If some required results are missing in the CST MWS project 
– e.g. the project has not been simulated yet or only a subset of all existing ports have 
been excited – the required CST MWS simulation is automatically started from CST DES 
before the circuit simulation is performed.   
The usage of a CST STUDIO SUITE file block is quite simple: After dropping 
this type of block from the Block Selection Tree into the schematic, the Import 
CST Studio Suite File dialog box is opened where you may browse for a CST 
3D project file. Alternatively, a CST Studio Suite file block may be created by 
dragging a CST 3D project from a file browser onto the schematic while pressing the 
Ctrl key. 
There are two additional properties that can be set while inserting the block or can also 
be modified later by customizing the block’s property dialog box: 
  Store  relative  path:  You  can  either  store  the  relative  path  from  the  current  CST  DES 
project or the absolute path to the selected CST 3D project. This option is disabled if the 
CST DES project has not yet been saved (as there is no path for this project at all). Then, 
the absolute path will automatically be stored. Both options make sense, depending on 
how you wish to deal with the project in the future. If there is a project repository on a 
server it is useful to provide absolute paths because you just need to send the CST DES 
project file to a colleague who may also access the server. On the other hand, if you want 
to send a project file to someone who cannot access the server, perhaps by e-mail, it is 
more  useful  to  copy  the  CST  project  to  a  local  folder  and  provide  the  relative  path. 
NOTE: The relative  path option is  available only  if both files  are located on the  same 
drive. 
  Use AR filter whenever possible (only for CST MWS projects): Use the AR filter function 
of CST MWS to extract the S-Parameters from the time domain calculation via the AR 
filter method.A CST Studio Suite file block is represented by a small image of the 3D 
model and a small arrow on the lower left indicating that it is a file block. 
The number of (block) ports corresponds to the number of (waveguide or 
discrete) ports5 defined in the CST MWS model.  
Let us examine the content of a CST MWS file block’s parameter list. The initial page 
shown is the General page.  
4 Other modules may represent different results: A CST EMS project for instance will provide an impedance matrix. 
5 Other modules may define different terminal types than waveguide or discrete ports.
A CST MWS file block is always frequency bound. As usual, the limits are displayed in 
the  General  page  as  shown  above.  Furthermore,  the  file  that  the  block  refers  to  is 
displayed there. You can again choose between an absolute path and a relative path. If 
the  CST  DES  project  has  not  yet  been  saved,  this  option  will  be  disabled  and  the 
absolute path will be considered. 
The File name row contains a button with an ellipsis (…). Pressing the button opens the 
Import  CST  Microwave  Studio  File  dialog  box  where  you  can  browse  for  a  different 
project. Frequency bounds and the number of ports will be changed according to the 
new file’s contents. Connections will be kept if there are some ports with identical names 
contained in the new project, otherwise the links will be deleted. 
The  Patch  antenna’s  CST  MWS  project  can  be  opened  in  a  new  tab  by 
selecting Edit… in the block’s context menu. CST Studio Suite Block 
A  CST  Studio  Suite  block  allows  you  to  parametrically  deal  with  a  CST  Studio  Suite 
project.  You  find  it  in  the  Field  Simulators  folder  of  the  Block  Selection  Tree.  After 
dropping this block into the schematic, the Import CST Studio Suite File dialog box will 
be opened where you can browse for the project. Alternatively, a CST Studio Suite block 
may be created by dragging a CST 3D project from a file browser onto the schematic. 
In contrast  to  the  CST  Studio Suite file  block, this  type  of  block  does  not  refer  to  the 
selected  project.  Instead,  the  essential  project  files  will  be  stored  by  the  block.  To 
recalculate  the  results  or  to  open  this  project  in  a  corresponding  CST  Studio  Suite 
module,  these  project  files  will  be  copied  into  a  sub-folder  of  the  current 
project’s  folder  and  opened  from  there.  However,  you  cannot  open  this 
project in a standalone CST Studio Suite module, since it is controlled by 
the CST DES project.  
A CST Studio Suite block is represented by a small image of the 3D model (without the 
small arrow on the lower left) indicating that it is a parameterized block. The number of
(block) ports corresponds to the number of (waveguide or discrete) ports6 defined in the 
CST MWS model. 
The  most  relevant  feature  supported  by  this  type  of  block  is  the  control  of  the  CST 
project’s parameters from within CST DES. Whenever you select a CST Studio Suite 
block, the Block Parameter List window shows all parameters defined in the associated 
project. 
Clone Block 
A  clone  block  refers  to  another  block’s  model  and  data  in  order  to  replace 
redundant copies of blocks. You find it in the Miscellaneous folder of the Block 
Selection Tree. Clones of CST MWS blocks can even be parameterized with 
different  values  after  disabling  the  Inherit  parameter  values  option  on  the 
General page in the block parameter list, as shown below.6 Other modules may define different terminal types than waveguide or discrete ports.
Block properties shown on the Settings page of the block parameter list can be edited 
as long as Inherit parameter values is disabled. The frequency bounds, however, are 
always inherited. 
A clone block is represented by an image that looks like the cloned block 
except for the gray squares in the lower rigth corner. 
CST Design Studio Simulation  
The CST Design Studio model of our example consists of three blocks:  
  A CST Studio Suite file block is used for the antenna because it is a fixed model and 
does not have varying parameters. 
  A CST Studio Suite block is used to create an independent copy of the previously created 
transformer  model.  It  offers  the  parameter  w  that  will  be  used  to  optimize  each 
transformer from within CST Design Studio. 
  A Clone block is used to represent the other transformer, which differs from the former 
only by the values of geometric parameters. 
Add these blocks to your (initially empty) project, and connect them as shown below. 
The 100  ports of the transformers are connected to the antenna, while two external
Now some parameters need to be defined. These parameters will be used to optimize 
the match between the antenna and the external ports. Use the docked Parameter List 
control as explained during the Quick Tour, and create the parameters width1 = 1.0 and 
width2 = 1.0.Whenever  a  CST  Studio  Suite  block  is  selected,  its  parameters  are  displayed  in  the 
Settings tab of the docked Block Parameter List control: 
The transformer blocks show two parameters: w = 1 mm and l = 7 mm. They are initially 
set  by  the  corresponding  CST  Microwave  Studio  project.  Modify  the  parameter  w  as 
follows: 
Transformer No. 1: (The one connected to the antenna’s port No.1) w = width1. 
Transformer No. 2: (The one connected to the antenna’s port No.2) w = width2. 
To  obtain  an  initial  S-Parameter  result,  an  S-Parameter  simulation  task  needs  to  be 
defined. Choose Home: Simulation  New Task 
 to open the Select Simulation Task 
dialog  box,  and select  S-Parameters. The following  Task  Parameter  List displays  the 
setting of the new task.
Since frequency  ranges are  specified for  CST Microwave Studio  projects,  the  blocks’ 
valid  frequency  ranges  are  limited  as  well.  Therefore,  the  Maximum  frequency  range 
option can be chosen inside the Simulation settings frame as well. In this example we 
keep all default settings.  
Update the results now by choosing Home: Simulation  Update 
. 
Look at the S-Parameter results of the circuit now by selecting the corresponding item 
in the navigation tree:Obviously,  this  initial  result  is  quite  good.  The  relatively  low  reflections  indicate  a 
reasonable match. However, let us try to obtain even better results via optimization.  
Optimization 
The  goal  of  this  optimization  example  will  be  to  improve  the  matching  of  the  patch 
antenna at the resonance frequencies, that is: 
Minimize S1,1 (in dB) at f = 7.0 GHz. 
Minimize S2,2 (in dB) at f = 7.5 GHz. 
How to set up an optimization task has already been presented in detail during the ‘Quick 
Tour’. Therefore, the following list just briefly summarizes how to set up the optimization 
task:
  Create the optimization task using Home: Simulation  New Task 
  Duplicate the already existing S-Parameter task and move it into the optimization task 
After the task creation, the task structure should look like this: 
To  properly  set  up  the  optimizer,  open  the  optimizer  properties  dialog  box  by  double 
clicking on NT: Tasks  Opt1. On this page all important settings for the optimization 
can  be  made.  The  most  important  one  is  the  choice  for  an  appropriate  optimization 
algorithm. In our case we will choose the Trust Region Framework. For more information 
about  this  algorithm  please  have  a  look  at  the  online  help.  The  page  also  lists  all 
parameters that will be taken into account during the optimization. For each parameter 
the  range  in  which  it  is  allowed  to vary  and,  depending  on the  optimizer  algorithm,  a 
number of samples can be set.The  global  parameters  “width1”  and  “width2”  are  assigned  to  the  properties  w  of  the 
transformer  blocks.  The  parameter  range  0.7  ≤  w  ≤  2.4  should  be  set  for  these 
properties, as these values are the fixed characteristic widths of the transformer lines. 
Please disable the Use current as initial value to be able to repeat the simulation with 
the same initial conditions. 
Setting up the goals is straightforward. Switch to the Goals tab and press the Add New 
Goal button to define the first goal.  
We want to minimize S1,1 at 7 GHz. This is reflected by the following dialog settings: 
  Select 1DC: SPara2\S-Parameters\S1,1 as Result Name 
  Choose Mag. (dB) 
  Specify min as operator  
  Change the range to Single at 7
Having done that please proceed then to create a second goal for S2,2 (in dB) at 7.5 
GHz. The Goals page now displays a list of both defined goals:The  optimization  setup  is  now  complete.  Start  the  optimization  by  clicking  the  Start 
button.  The  Info  page  displays  information  about  the  goal  values  and  the  optimized 
parameters. After the optimization is complete, a message appears in the  Info tab as 
follows:
As  the  difference  of the first  and the  best goal  values  indicates, the  optimization was 
successful. The following plot shows that both, S1,1 and S2,2 could be improved at the 
desired frequencies: Antenna Calculation 
If  your  model  contains  a  CST  Microwave  Studio  schematic  block,  a  CST  Microwave 
Studio block or a CST Microwave Studio file block, CST Design Studio allows you to 
calculate  field  values  as  a  result  of  the  excitation  coming  from  the  network  on  the 
schematic.  
Let us now perform a final antenna calculation with the optimized parameters of our CST 
DES  model.  To  do  so,  an  AC-task  needs  to  be  created.  Once  again,  go  to  Home: 
Simulation  New Task 
. In 
the displayed Task Parameter List (AC1) change to the Combine Results tab where all 
settings for farfield calculations from within CST DES can be accessed. 
 and create a new AC, Combine results simulation task
By  default,  the  Combine  Results  calculation  is  disabled.  Select  the  Combine  Results 
option to switch it on. Moreover, the block describing the antenna needs to be selected 
in the Block selector box.  
Select, within the Task Parameter List (AC1), the Excitations Tab so we can proceed 
now to define the excitations.  
Right now, no excitations have yet been defined for the AC, Combine results simulation 
task. Open the combo box currently showing Load for the first port and select the Define 
Excitation… item. This will open the Define AC-Excitation dialog. Specify a Signal source 
type of amplitude 1:Similarly, specify a Signal source type of amplitude 0 for port No. 2.
The two field monitors at 7 GHz and 7.5 GHz have been specified for the antenna’s CST 
MWS  project.  Because  the  task’s  frequency  range  is  wide  enough,  then  the  driven 
farfield will be computed for both frequencies. 
Now, ensure that the AC-task tree item is still selected and select Update in its context 
menu to start the simulation. You will see the following output in the message window: 
Note:  No  3D  simulation  is  performed  because  the  transformer's  results  and  the 
antenna’s results are already available. Before the task is successfully completed, the 
farfields are calculated for the defined excitation. 
The  results  of  the  farfield  calculations  are  now  available  in  the  antenna  block’s  CST 
MWS project. You can access them by selecting the block and choosing Edit from its 
context menu which will open the project. 
The  navigation  tree’s  Farfields  folder  contains  additional  entries  labeled  with  [AC1]. 
These items contain the farfields for the excitation as defined in the simulation task.  
For  instance,  selecting  the  item  NT:  Farfields    farfield  (f=7)  [AC1]  leads  to  the
Chapter 7 – Finding Further Information 
After carefully reading this manual, you will already have a basic understanding of how 
to use CST Design Studio efficiently for your own problems.  However, you may have 
additional questions once you start creating your own designs. In this chapter, we will 
give you an overview of the available documentation and help systems. 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by selecting File: Help  Help Contents or simply 
by  clicking  on  the 
  icon  on  the  right  hand  side  of  the  Ribbon  bar.  The  online  help 
system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties. 
When  no  specific  information is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system. 
Please  have  a  look  into  the  CST  Studio  Suite  -  Getting  Started  manual  to  find  more 
detailed explanation about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  A collection of macro examples.  
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software described in this document is furnished under a license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a 
retrieval system, or transmitted in any form or any means electronic 
or mechanical, including photocopying and recording, for any 
purpose other than the purchaser’s personal use without the written 
permission of Dassault Systèmes. 
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Chapter 1 – Introduction 
Welcome 
Welcome to CST Studio Suite for Particle Dynamics Simulation, the powerful and easy-
to-use  electromagnetic  field  and  charged  particle  dynamics  simulation  software.  This 
program combines a user-friendly interface with high simulation performance. 
Please  refer  to  the  CST  Studio  Suite  Getting  Started  manual  first.  The  following 
explanations  assume  that  you  have  already  installed  the  software  and  familiarized 
yourself with the basic concepts of the user interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite - Getting Started manual. 
2.  Work  through  this  document  carefully.  It  provides  all  the  basic  information 
necessary to understand the advanced documentation. 
3.  Look  at  the  examples  provided  in  the  Component  Library  (File:  Component 
Library    Examples).  Especially  the  examples  which  are  tagged  as  Tutorial 
provide detailed information of a specific simulation workflow. Press the Help 
button  of  the  individual  component to get to  the  help  page  of  this  component. 
Please note that all these examples are designed to give you a basic insight into 
a particular application domain. Real-world applications are typically much more 
complex and harder to understand if you are not familiar with the basic concepts. 
4.  Start with your own first example. Choose a reasonably simple example, which 
will allow you to quickly become familiar with the software. 
5.  After you have worked through your first example, contact technical support for 
hints  on  possible  improvements  to  achieve  even  more  efficient  usage  of  the 
software. 
CST Studio Suite for Particle Dynamics Simulation 
CST Studio Suite for Particle Dynamics Simulation is a fully featured software package 
for the design and analysis of electromagnetic components for accelerating and guiding 
charged  particle  beams.  It  simplifies  the  structure generation  by  providing  a  powerful 
solid modeling front end based on the industry-standard ACIS modeling kernel. Strong 
graphical  feedback  simplifies  the  definition  of  your  device  even  further.  After  the 
component has been modeled, a fully automatic meshing procedure (based on an expert 
system) is applied for the electromagnetic computation before the simulation engine is 
started. 
The  simulators  support  the  Perfect  Boundary  Approximation  (PBA)  feature,  which 
increases the accuracy of the electromagnetic simulation significantly in comparison to 
conventional  simulators.  To  calculate  electromagnetic  fields  and  analyze  particle 
dynamics  this  software  contains  four  different  solvers:  a  time  domain  Wakefield 
simulator,  a  time  domain  Electromagnetic  Particle-in-Cell  solver,  an  Electrostatic 
Particle-in-Cell solver and a Particle Tracking solver. 
Additionally,  CST  Studio  Suite  for  Thermal  and  Mechanical  Simulation  allows 
subsequent multiphysical analysis. 
If you are unsure which solver best suits your needs, contact your local sales office for 
further assistance. 
Each  solver's  simulation  results  can  be  visualized  with  a  variety  of  different  options. 
Again,  a  strongly  interactive  interface  will  help  you to  achieve the  desired insight  into
The last – but not least – outstanding feature is the full parameterization of the structure 
modeler,  which  enables  the  use  of  variables  in  the  definition  of  your  component.  In 
combination with the built-in optimizer and parameter sweep tools, CST Studio Suite for 
Particle  Dynamics  Simulation  is  capable  of  both  the  analysis  and  design  of  particle 
accelerating devices. 
Who Uses CST Studio Suite for Particle Dynamics Simulation? 
Anyone who has to deal with electromagnetic problems that involve the effect of charged 
particle  dynamics  will  greatly  benefit  from  using  CST  Studio  Suite.  The  program  is 
especially suited to the fast, efficient analysis and design of components like electron 
guns, deflecting devices, guiding configurations and more. Since the underlying method 
is a general 3D approach, CST Studio Suite for Particle Dynamics Simulation can solve 
virtually any field problem that involves interaction with charged particles. 
The  software  is  based  on  an  electromagnetic  solving  method,  which  requires  the 
discretization of the entire calculation volume; for this reason the applications are limited 
only by the complexity of the structure. 
Key Features for Particle Dynamics Simulation 
The following list gives you an overview of the main features for this part of CST Studio 
Suite.  Please  note  that  not  all  of  these  features  may  be  available  to  you  because  of 
license restrictions. Please contact a sales office for more information. 
General 
  Native  graphical  user  interface  based  on  Windows  10,  Windows  Server  2016 
and Windows Server 2019 
  The structure can be viewed either as a 3D model or as a schematic. The latter 
allows a parametrized approach of coupled simulation with our System Assembly 
and Modeling workflow. 
  Various  independent  solver  strategies  allow  accurate  results  with  a  high 
performance 
  For  specific  solvers,  highly  advanced  numerical  techniques  offer  features  like 
Perfect  Boundary  Approximation (PBA) ® for  hexahedral grids  and curved  and 
higher order elements for tetrahedral meshes 
Structure Modeling 
  Advanced  ACIS-based,  parametric  solid  modeling  front  end  with  excellent 
structure visualization  
  Feature-based hybrid modeler allows quick structural changes 
  Import of 3D CAD data from ACIS SAT (e.g. AutoCAD®), ACIS SAB, Autodesk 
Inventor®,  IGES,  VDA-FS,  STEP,  Pro/ENGINEER®,  CATIA®,  Siemens  NX, 
Parasolid,  Solid  Edge,  SolidWorks,  CoventorWare®,  Mecadtron®,  NASTRAN, 
STL or OBJ files 
  Import of 2D CAD data from DXF™, GDSII and Gerber RS274X, RS274D files 
  Import of EDA data from design flows including Cadence Allegro® / APD® / 
SiP®, Mentor Graphics HyperLynx®, Zuken CR-5000® / CR-8000®, IPC-2581 
and ODB++® (e.g. Altium Designer, Mentor Graphics Expedition / PADS / 
Boardstation®, CADSTAR®, Visula®) 
  Import of PCB designs originating from CST PCB Studio® 
  Import of 2D and 3D sub models 
  Import of Agilent ADS® layouts 
  Import of Sonnet® EM models
  Export  of  CAD  data  to  ACIS  SAT,  ACIS  SAB,  IGES,  STEP,  NASTRAN,  STL, 
DXF™, GDSII, Gerber or POV files 
  Parameterization for imported CAD files 
  Material database 
  Structure templates for simplified problem setup 
Particle Tracking Simulator 
  Arbitrary shaped particle source surfaces  
  Circular particle sources with spatially inhomogeneous current distribution 
  Particle interfaces for coupling of tracking/tracking or tracking/PIC simulations 
  ASCII emission data imports based on particle interfaces 
  Static-, eigenmode- and multiple external field distributions as source fields 
  Support for hexahedral as well as linear and curved tetrahedral meshes 
  Import of tetrahedral and hexahedral source fields into simulations 
  Space  charge  limited,  plasma-sheath,  thermionic,  fixed  and  field-induced 
emission model 
  Oblique emission 
  Secondary electron emission induced by ions or electrons as material property 
  Optically stimulated electron emission  
  Definable material transparency of sheets for particles 
  Consideration of space charge via gun iteration 
  Consideration of self-magnetic fields in gun iteration 
  Analysis of extracted particle current and space charge 
  Monitoring  of  beam  cross-section,  phase-space  diagram  and  other  statistical 
data of the beam 
  Emittance calculation 
  Thermal coupling (export of thermal loss distribution from crashed particles) 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for remote computations 
  Coupled simulations with the Thermal Solver from CST Studio Suite 
  Support of Linux batch mode 
Note:  some  solvers  features  may  be  available  for  hexahedral  or  tetrahedral  meshes 
only. 
Electrostatic Particle-in-Cell Simulator 
  Arbitrary shaped particle source surfaces  
  Circular particle sources with spatially inhomogeneous current distribution 
  Volumetric particle source featuring Maxwellian distribution 
  Particle interfaces for coupling of tracking/tracking or tracking/PIC simulations 
  ASCII emission data imports based on particle interfaces 
  Static-, eigenmode- and multiple external field distributions as source fields 
  Support for hexahedral as well as linear and curved tetrahedral meshes 
  Import of tetrahedral and hexahedral source fields into simulations 
  Gaussian-, DC-, field induced- and explosive emission model 
  Oblique emission 
  Secondary electron emission induced by ions or electrons as material property
o  Volume ionization due to electron impact 
o  Volume ionization due to ion impact 
o  Neutral atom excitation due to electrons 
o  Elastic collisions between electrons and neutral gas 
o  Elastic collisions between ions and neutral gas 
  Definable material transparency of sheets for particles 
  Analysis of extracted particle current and space charge 
  User defined excitation signals and signal database 
  Monitoring  of  beam  cross-section,  phase-space  diagram  and  other  statistical 
data of the beam 
  Particle Monitors on Solids or Boundaries including Energy Histogram 
  Phase space monitoring 
  Thermal coupling (export of thermal loss distribution from crashed particles) 
  Online visualization of intermediate results during simulation 
  Periodic boundary conditions for particles and the hexahedral field solver 
  Particle merging 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for remote computations 
  Coupled simulations with the Thermal Solver from CST Studio Suite 
  Support of Linux batch mode 
  Single-GPU  acceleration  for  hexahedral  meshes  (not  all  solver  features  are 
supported) 
Note:  some  solvers  features  may  be  available  for  hexahedral  or  tetrahedral  meshes 
only. 
Particle-in-Cell Simulator 
  Arbitrary shaped particle source surfaces 
  Circular particle sources with spatially inhomogeneous current distribution 
  Circular particle source in open boundaries 
  Volumetric particle source featuring Maxwellian distribution 
  Gaussian-, DC-, field induced- and explosive emission model 
  Oblique emission 
  Particle interfaces for coupling of tracking and PIC simulations 
  ASCII emission data imports based on particle interfaces 
  Selection of active Particle Sources 
  Static-, eigenmode- and multiple external field distributions as additional source 
fields 
  Import of tetrahedral source fields 
  Automatic detection of multipaction breakdown 
  Thermal coupling (export of thermal loss distribution from crashed particles) 
  Periodic boundary conditions for particles 
  Support for Single- / Multi-GPU acceleration 
  Single node parallelization 
  Support of Linux batch mode 
  Online visualization of intermediate results during simulation 
  Calculation  of  field  distributions  as  a  function  of  time  or  at  multiple  selected 
frequencies from one simulation run 
  Time domain monitoring of particle position and momentum 
  Particle Monitors on Solids or Boundaries including Energy Histogram 
  Time domain monitoring of output power
  Phase space monitoring 
  Emittance calculation 
  Secondary electron emission induced by ions or electrons as material property 
  Volume ionization based on Monte-Carlo collision model 
  Definable material transparency of sheets for particles 
  Isotropic and anisotropic material properties 
  Frequency dependent material properties with arbitrary order for permittivity and 
permeability as well as a material parameter fitting functionality 
  Field-dependent  microwave  plasma  and  gyrotropic  materials  (magnetized 
ferrites) 
  Non-linear material models (Kerr, Raman) 
  Surface impedance models (tabulated surface impedance, Ohmic sheet, lossy 
metal, corrugated wall, material coating) 
  Frequency  dependent  multilayered 
thin  panel  materials 
(isotropic  and 
symmetric) 
  Time dependent conductive materials 
  Port mode calculation by a 2D eigenmode solver in the frequency domain 
  Efficient calculation of higher order port modes by specifying target frequency 
  Automatic waveguide port mesh adaptation 
  Multipin ports for TEM mode ports with multiple conductors 
  User defined excitation signals and signal database 
  Charge absorbing open boundaries for CPU solver 
  High performance radiating/absorbing boundary conditions 
  Conducting wall boundary conditions 
  Calculation  of  various  electromagnetic  quantities  such  as  electric  fields, 
magnetic  fields,  surface  currents,  power  flows,  current  densities,  power  loss 
densities,  electric  energy  densities,  magnetic  energy  densities,  voltages  or 
currents in time and frequency domain 
  Calculation of time averaged power loss volume monitors 
  Calculation of time averaged surface losses 
  Discrete edge and face elements (lumped resistors) as ports 
  Ideal voltage and current sources 
  Discrete edge and face R, L, C, and (nonlinear) diode elements at any location 
in the structure 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for remote computations 
  Support for Transient Co-Simulation with CST Design Studio™ 
  Coupled simulations with the Thermal Solver from CST Studio SuiteWakefield Simulator 
  Particle beam excitation for ultra-relativistic and non-relativistic beams 
  Transmission line injection scheme (improved dispersion characteristics) 
  Arbitrary particle beam shapes for ultra-relativistic beams 
  Automatic wake-potential calculation 
  Automatic wake-impedance, loss and kick factor calculation 
  Wakefield postprocessor allows to recompute wake impedances 
  Mesh settings for particle beams 
  Direct and two indirect wake-integration methods available
  MPI Cluster parallelization via domain decomposition 
  Support of Linux batch mode 
  Efficient calculation for loss-free and lossy structures 
  Calculation  of  field  distributions  as  a  function  of  time  or  at  multiple  selected 
frequencies from one simulation run  
  Adaptive mesh refinement in 3D  
  Isotropic and anisotropic material properties 
  Frequency dependent material properties  
  Gyrotropic materials (magnetized ferrites) 
  Surface impedance model for good conductors 
  Port mode calculation by a 2D eigenmode solver in the frequency domain 
  Automatic waveguide port mesh adaptation 
  Multipin ports for TEM mode ports with multiple conductors  
  High  performance  absorbing  boundary  conditions  also  for  charged  particle 
beams 
  Conducting wall boundary conditions 
  Calculation  of  various  electromagnetic  quantities  such  as  electric  fields, 
magnetic  fields,  surface  currents,  power  flows,  current  densities,  power  loss 
densities,  electric  energy  densities,  magnetic  energy  densities,  voltages  or 
currents in time and frequency domain 
  Calculation of time averaged power loss volume monitors 
  Calculation of time averaged surface losses 
  Discrete edge and face elements (lumped resistors) as ports 
  Ideal voltage and current sources 
  Discrete edge and face R, L, C, and (nonlinear) diode elements at any location 
in the structure 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and multiple 
port/mode excitations 
  Support for Transient Co-Simulation with CST Design Studio™ 
  Coupled simulations with the Thermal Solver from CST Studio SuiteEigenmode Simulator 
  Calculation of modal field distributions in closed loss-free or lossy structures 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Isotropic and anisotropic materials  
  Multithread parallelization 
  Adaptive mesh refinement in 3D using eigenmode frequencies as stop criteria, 
with True Geometry Adaptation 
  Periodic boundary conditions including phase shift 
  Calculation of losses and internal / external Q-factors for each mode (directly or 
using perturbation method)  
  Discrete L,C elements at any location in the structure  
  Target frequency can be set (calculation within the frequency interval) 
  Calculation of all eigenmodes in a given frequency interval  
  Sensitivity analysis with respect to materials and geometric deformations defined 
by face constraints (with tetrahedral mesh) 
  Automatic Lorentz force calculation 
  Introduction of a General (Lossy) solver
  Support of Open Boundary conditions for accurate internal / external Q-factors 
calculation 
  Support Tetrahedral mesh only with automatic Adaptive mesh refinement 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations and parameter sweeps 
  Coupled simulations with the Thermal Solver from CST Studio Suite 
Electrostatics Simulator 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Sources: potentials, charges on conductors (floating potentials), uniform volume- 
and surface-charge densities 
  Force calculation 
  Capacitance calculation 
  Electric  /  magnetic  /  tangential  /  normal  /  open  /  fixed-potential  boundary 
conditions 
  Periodic boundary conditions for hexahedral meshes 
  Perfect conducting sheets and wires 
  Discrete edge capacitive elements at any location in the structure 
  Adaptive mesh refinement in 3D 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Coupled simulations with the Mechanical Solver from CST Studio Suite 
Magnetostatics Simulator 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Nonlinear material properties 
  Laminated material properties 
  Sources:  coils,  permanent  magnets,  current  paths,  external  fields,  stationary 
current fields 
  Discrete edge inductances at any location in the structure 
  Force calculation 
  Inductance calculation 
  Flux linkages 
  Electric / magnetic / tangential / normal / open boundary conditions  
  Adaptive mesh refinement in 3D 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Coupled simulations with the Mechanical Solver from CST Studio Suite 
Visualization and Secondary Result Calculation 
  Multiple 1D result view support 
  Import and visualization of external xy-data 
  Copy / Paste of xy-datasets 
  Fast access to parametric data by interactive tuning sliders 
  Automatic parametric 1D result storage 
  Displays port modes (with propagation constant, impedance, etc.) 
  Various field visualization options in 2D and 3D for electric fields, magnetic fields,
  Animation of field distributions  
  Particle and secondary electrons vs. time 1D plots (PIC) 
  Collision event monitors for Monte-Carlo collisions 
  Current/Power 1D plot of emitted and absorbed particles (PIC) 
  Wave-Particle Power Transfer (PIC) 
  Animation of 2D and 3D particle positions / momenta (PIC) 
  Visualization of 3D particle trajectories (Tracking) 
  Combined Visualization of 2D/3D fields and particle positions (PIC) 
  Visualization of thermal loss distribution due to particle collisions with solids 
  Display of source definitions in 3D 
  Display of nonlinear material curves in xy-plots  
  Display of material distributions for materials with nonlinear permeability  
  Animation of field distributions 
  Display and integration of 2D and 3D fields along arbitrary curves 
  Integration of 3D fields across arbitrary faces 
  Hierarchical  result  templates  for  automated  extraction  and  visualization  of 
arbitrary results from various simulation runs. These data can also be used for 
the definition of optimization goals. 
Result Export 
  Export of result data such as fields, curves, etc. as ASCII files 
  Export of particle data as ASCII files 
  Export screen shots of result field plots 
Automation 
  Powerful  VBA  (Visual  Basic  for  Applications)  compatible  macro  language 
including editor and macro debugger 
  OLE  automation  for  seamless  integration  into  the  Windows  environment 
(Microsoft Office®, MATLAB®, AutoCAD®, MathCAD®, Windows Scripting Host, 
etc.) 
About This Manual 
This manual is primarily designed to enable a quick start with CST Studio Suite. It is not 
intended to be a complete reference guide to all the available features but will give you 
an overview of key concepts. Understanding these concepts will allow you to learn how 
to use the software efficiently with the help of the online documentation. 
The main part of the manual is the Simulation Workflow (Chapter 2) which will guide you 
through  the  most  important  features  of  CST  Studio  Suite  for  Particle  Dynamics 
Simulation. We strongly encourage you to study this chapter carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the Ctrl key while pressing the S key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the 
command.  
Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item. 
  Example: NT: 1D Results  Port Signals  i1 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support
Chapter 2 – Simulation Workflows 
CST Studio Suite for Particle Dynamics Simulation is designed for ease of use. However, 
to get started quickly, you need to know a few things. The main purpose of this chapter 
is to provide an overview of the software’s capabilities. Read this chapter carefully, as 
this may be the fastest way to learn how to use the software efficiently. 
This chapter covers three different workflow examples for Particle Tracking, Particle in 
Cell (PIC) and Wakefield computations: 
1.  Workflow Example: Particle Tracking 
1.1. Model and simulate a simple electron gun, including a particle simulation (static 
approximation) 
1.2. Parameter studies of the model and automatic optimization of the structure 
2.  Workflow Example: Electromagnetic Particle in Cell 
2.1. Model and simulate a simple output cavity 
3.  Workflow Example: Wakefield 
3.1. Model and simulate a simple pillbox cavity 
Simulation Workflow: Particle Tracking 
In the following example, it is shown how to set up and run a simple Particle Tracking 
simulation. Studying this example carefully will allow you to become familiar with many 
standard operations that are necessary to perform a Particle Tracking simulation within 
CST Studio Suite. For more information on the physics that can be modelled with the 
Tracking  solver,  an  overview  is  provided  in  Chapter  3  –  Solver  Overview  :  Particle 
Tracking Solver. 
Go through the following explanations carefully even if you are not planning to use the 
software for Particle Tracking simulations. Only a small portion of the example is specific 
to this particular application type since most of the considerations are general and apply 
to all solvers and application domains. 
At  the  end  of  this  example,  you  will  find  some  remarks  concerning  the  differences 
between  the  typical  simulation  procedures  for  electrostatic  and  magnetostatic 
calculations and some useful hints for setting up the Particle Tracking and gun algorithm. 
The following explanations always describe the menu-based way to open a particular 
dialog box or to launch a command. Whenever available, the corresponding toolbar item 
is displayed next to the command description. Due to the limited space in this manual, 
the  shortest  way  to activate a particular  command  (i.e.  by  pressing  a  shortcut key  or 
activating the command from the context menu) is omitted. You should regularly open 
the context menu to check available commands for the currently active mode. 
The Structure 
Usually  an  electron  gun  is  only  one  part  of  a  complex  device,  for  example  a  particle 
accelerator. The gun is used to create a collimated particle beam, so that other parts of 
the device are driven with a beam of good quality. 
The  way  this  gun  works  is  quite  simple.  Electrons  are  emitted  from  a  cathode  by  a 
particle source based on space charge limited emission. These particles are accelerated 
and focused by an anode. Additional focusing is realized by a set of magnets behind the 
anode. 
The  following  picture  shows  the  structure  of  interest.  It  has  been  sliced  open  to  aid
whereas  the  magnetic  structure  above  the  anode  consists  of  iron  and  permanent 
magnets. 
Before you start modeling the structure, let us spend a few moments discussing how to 
describe this structure efficiently.  
At  first,  CST  Studio  Suite  allows  to  define  the  properties  of  the  background  material. 
Anything  you  do  not  fill  with  a  particular  material  will  automatically  be  filled  with  the 
background material. For this structure it is sufficient to model anode, cathode, two iron 
discs and three permanent magnets of the electron gun. The background properties will 
be set to vacuum. 
Your method of describing the structure should therefore be as follows: 
1.  Model cathode and anode of the electron gun. 
2.  Model the two iron discs. 
3.  Model the three permanent magnets. 
Create a New Project 
After launching the CST Studio Suite, you will enter the start screen showing a list of 
recently  opened  projects  and  allowing  to  specify  the  application  that  suits  your 
requirements  best.  The  easiest  way  to  get  started  is  to  configure  a  project  template, 
which  defines  the  basic  settings  that  are  meaningful  for  your  typical  application. 
Therefore, click on the New Template button in the New Project from Template section 
within the New and Recent tab. 
Next,  you  should  choose  the  application  area,  which  is  Particle  Dynamics  for  the 
example  in  this  tutorial  and  then  select  the  workflow  by  double-clicking  on  the
For  the  electron  gun,  please  select  Vacuum  Electronic  Devices    Particle  Gun   
Particle Tracking 
. 
Finally,  you  are  requested  to  select  the  units,  which fit  your  application best.  For  this 
example, please select the dimensions as follows: 
Dimensions:  mm 
Frequency:  Hz 
Time: 
s 
For the specific application in this tutorial the other settings can be left unchanged. After 
clicking the Next button, you can specify a name for the project template and review a 
summary of your initial settings:Finally click the Finish button to save the project template and to create a new project 
with  appropriate  settings.  CST  Studio  Suite  for  Particle  Dynamics  Simulation  will  be
launched  automatically  due  to  the  choice  of  this  specific  project  template  within  the 
application area Particle Dynamics. 
Please note: When you click again on the File: New and Recent you will see that the 
recently  defined  template  appears  below  the  Project  Templates  section.  For  further 
projects  in  the  same  application  area  you  can  simply  click  on  this  template  entry  to 
launch CST Studio Suite for Particle Dynamics Simulation with useful basic settings. It 
is  not  necessary  to  define  a  new  template  each  time.  You  are  now  able  to  start  the 
software with reasonable initial settings quickly with just one click on the corresponding 
template. 
Please note: All settings made for a project template can be modified later during the 
construction of your model. For example, the units can be modified in the units dialog 
box  (Home:  Settings   Units 
)  and  the  solver  type  can  be  selected  in  the  Home: 
Simulation  Setup Solver drop-down list. 
Open the Tracking QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
you can open this assistant by selecting QuickStart Guide from the dropdown list next 
to the Help button 
 in the upper right corner. 
The  following  dialog  box  should  then  be  visible  at  the  upper  right  corner  of  the  main 
view:As the project template has already set the solver type, units and background material, 
the Particle Tracking Analysis is preselected and some entries are marked as done. The 
red arrow always indicates the next step necessary for your problem definition. You do 
not have to follow the steps in this order, but we recommend to follow this guide at the 
beginning to ensure that all necessary steps have been completed.  
Look at the dialog box as you follow the various steps in this example. You may close 
the assistant at any time. Even if you re-open the window later, it will always indicate the 
next required step. 
If you are unsure of how to access a certain operation, click on the corresponding line. 
The  QuickStart  Guide  will  then  either  run  an  animation  showing  the  location  of  the 
related menu entry or open the corresponding help page. 
Define the Units 
The Particle Gun template has already applied some settings for you. The defaults for 
this  structure type  are geometrical  units  in mm and time  in s.  You  can change these 
settings by entering the desired settings in the units dialog box (Home: Settings  Units
), but for this example you should just leave the settings as specified by the template. 
Additionally, the used units are also displayed in the status bar: 
Define the Background Material  
As discussed above, the structure will be described within vacuum. The material type 
Normal  is  set  as  default  background  material  in  the  Particle  Gun  template.  For  this 
example, you do not need to make any changes as the default properties of the material 
type Normal are those of vacuum. In case you need to change the properties, you may 
do so in the corresponding dialog box Simulation: Settings  Background 
. 
Model the Structure 
The basic settings have been made, now we are able to set up the structure. Since the 
electron gun is rotationally symmetric, a special but very efficient technique can be used 
to design the structure. First of all, the cathode is created. 
1.  Open the Rotate Profile dialog box Modeling: Shapes  Rotate Face 
 to create 
the cathode. 
2.  Press the ESC key to show the dialog box. Do not click a point in the working plane.3.  Enter the name "cathode" and choose Z as axis of rotation. Set the material to PEC. 
Now enter the polygon data as shown in the table below. 
x 
1.5 
7.0 
7.0 
6.5 
6.5 
1.5 
z 
0.0 
0.0 
6.0 
6.0 
0.5 
0.5 
4.  You  may  click  the  Preview  button  during  the  construction  to  get  a  preview  of  the 
solid. This makes it easy to detect any possible mistakes when entering the data.
The  dialog  box  should  now  look  like  in  the  picture  above.  Click  the  OK  button  to 
confirm your settings and to construct the cathode. 
5.  The structure is displayed in the working plane and now your cathode should look 
like this: 
One part of the cathode is still missing, the inner cylinder. We will need this inner 
cylinder to define the particle source. To create this cylinder, open the Cylinder dialog 
Modeling: Shapes  Cylinder 
. Press the ESC key to show the dialog box.Change  the  name the  name to  "cathode_inner",  enter  an  Outer  radius  of  1.5  and 
Zmax of 0.5. Click the OK button to confirm your changes. The cylinder should fit 
perfectly into the hole of the solid cathode: 
6.  The construction of the cathode is completely finished and now we will construct the 
anode in the same way as we constructed the outer cathode. Open the Rotate Profile 
dialog box Modeling: Shapes  Rotate Face 
. 
7.  Press the ESC key to show the dialog box. Do not click a point in the working plane.
8.  Enter the name "anode" and choose z as axis of rotation. The material PEC should 
be automatically selected. 
Your dialog box should now look like in the picture above. Now enter the polygon 
data as shown in the following table: 
x 
20.0 
40.0 
40.0 
2.1 
2.1 
20.0 
z 
25.0 
25.0 
31.0 
31.0 
30.0 
30.0Click the OK button to confirm your changes. The creation of the anode is complete 
and the whole structure should look like this (rotated for better visibility): 
9.  As you might have noticed, the magnetic part of the structure is still missing. First, 
we will construct the three vacuum discs that will serve as permanent magnets. To 
create  one  disc,  open  the  Cylinder  dialog  box  Modeling:  Shapes   Cylinder 
. 
Press the ESC key to show the dialog box. 
10. Enter the name "magnet", outer radius 32.8 and the inner radius 5.8. The  z range 
extends from 31 to 37.9 mm. Change the material to vacuum. Click the OK button to 
confirm your changes.
11. Since the same cylinder exists three times, we will use the transform dialog box to 
create the missing two cylinders. First select the solid "magnet" in the navigation tree 
NT: Components  component 1  magnet. 
12. Open the Transform Selected Object dialog box Modeling: Tools  Transform 
copy the cylinder.
Enable the checkbox Copy. Then enter a translation of 10 in z-direction. Change the 
Repetition factor to 2 and click the OK button to confirm your changes. The structure 
should now look like this: 
13. Before the iron discs will be defined, we create a new and simple iron material. To 
do  this,  open  the  material  dialog  box  Modeling:  Materials    New/Edit    New 
Material. Change the Material name to "Iron", the Color to red and value of Mu to 
100 like in the picture below. Now we have quickly defined a simple iron material.
14. The iron discs are created in the same way as the magnets. Open the cylinder dialog 
Modeling: Shapes  Cylinder 
. Press the ESC key to show the dialog box. 
15. Enter the Name "iron", an Outer radius of 32.8 and Inner radius of 5.8. The z range 
extends from 37.9 to 41 mm. Change the material to the new material "Iron". Your 
dialog box should now look like the picture above. 
16. Finally click the OK button and confirm your changes. To create the second iron disc, 
we will use the transform mechanism again. Select the solid "iron" in the navigation 
tree.17. Open the Transform Selected Object dialog box Modeling: Tools  Transform 
copy the cylinder. 
 to 
18. Select  Copy  and  enter  a  translation  of  10  in  z-direction.  Click  the  OK  button  to 
confirm your changes. Now the structure should look like this:
19. The structure creation part is finished and we can start to define the sources, i.e. 
potentials, magnets and particle sources. 
Congratulations! You have just created your first particle tracking structure within CST 
Studio Suite. 
Define Potentials and Magnets 
With  all  components  for  the  electrostatic  part  of  the  configuration  defined,  the 
appropriate potentials can be set. First define the potentials of the cathode and anode: 
1.  Select Simulation: Sources and Loads  Static Sources  Electric Potential 
 and 
double-click  on  the  surface  of  the  “cathode”  solid  in  the  working  plane.  Press  the 
Return key to finish your selection and to open the Define Potential dialog box.2.  Enter the name "cathode_pot" and a value of -3e4 V. As usual, click the OK button 
to confirm your changes. 
3.  In the same way the potential for the anode is defined. Select Simulation: Sources 
and Loads  Static Sources  Electric Potential 
 and double-click on the surface 
of the anode. Press the Return key to finish your selection and to open the Define 
Potential dialog box. 
4.  Enter the name "anode_pot" and a value of 0 V. Click the OK button to confirm your 
changes.
5.  If you now select the potential folder in the navigation tree your structure should look 
like the picture below: 
Note: As the solids "cathode" and "cathode_inner" are in direct contact, both have 
the same potential. That means "cathode_inner" also has a potential of -30 kV. 
6.  After the potential definition is finished, we will create three permanent magnets for 
the three vacuum discs. To define the first magnet select Simulation: Sources and 
Loads  Static Sources  Permanent Magnet 
. 
7.  Then select the solid that should become a permanent magnet. Thus double-click 
on the vacuum disc named "magnet".8.  The Permanent Magnet dialog box opens. Ensure that the vectorial components are 
set to X: 0, Y: 0, Z: 1 and Inverse direction is not checked. Enter a value of 0.02 T 
for the remanent flux. Leave other settings unchanged and click OK to confirm.
9.  In the same way define magnets for the vacuum solids "magnet_1" and "magnet_2" 
in z-direction. The solid "magnet_1" should be the vacuum disc in the middle of the 
three discs. 
solid 
name 
X  Y  Z 
magnet 
magnet1 
magnet_1  magnet2 
magnet_2  magnet3 
0 
0 
0 
0 
0 
0 
1 
1 
1 
Inverse 
direction 
 
 
 
Br (T) 
0.02 
0.01 
0.01 
10. If you now select the Permanent Magnets folder in the navigation tree you should 
see the following picture:11. Potential and magnet definitions are finished now. 
In practice it is advisable to visualize and refine the mesh before the particle source is 
defined.  The  reason  is  that  the  number  of  emission  points  of  the  particle  source  can 
depend  on  the  mesh  settings.  This  matter  is  discussed  in  detail  in  the  later  chapter 
Define Particle Sources.
Visualize and Refine the Mesh 
By  default,  the  particle  tracking  solver  uses  a  hexahedral  mesh  for  computing 
electrostatic  and  magnetostatic  fields.  This  is  the  optimal  choice  for  axis-aligned 
structures as used in this example. However, especially when surfaces in the vicinity of 
the particle trajectories are curved, their representation by tetrahedral mesh cells might 
be better-suited and will deliver more accurate results. In order to keep the focus on the 
simulation  workflow  itself,  we  will  deal  with  tetrahedral  meshes  in  a  later,  specialized 
section. 
The mesh generation for the structure’s analysis is performed automatically based on 
an expert system. However, in some situations it may be helpful to inspect the mesh to 
improve the simulation speed by changing the parameters for the mesh generation.  
The mesh can be visualized by entering the mesh view Home: Mesh  Mesh View 
For this structure, the mesh information will be displayed as follows: 
.One 2D mesh plane is visible at a time. You can modify the orientation of the mesh plane 
by adjusting the selection in the Mesh: Sectional View  Normal dropdown list or just 
by pressing the X/Y/Z keys. Move the plane along its normal direction using the Up/Down 
cursor keys. The current position of the plane will be shown in the Mesh: Sectional View 
 Position field. 
There are some thick mesh lines shown in the mesh view. These mesh lines represent 
important  planes  (so-called  snapping  planes)  at  which  placement  of  mesh  lines  is 
considered necessary by the expert system. You can control these so-called snapping 
planes in the Special Mesh Properties dialog by selecting Simulation: Mesh  Global 
Properties 
  Specials  Snapping. 
In a lot of cases the automatic mesh generation will produce a reasonable initial mesh, 
but  in  our  case  we  will  refine  the  mesh  in  the  cathode  region  to  have  a  finer  mesh 
resolution for the particle beam. 
1.  Make  sure  you  are  in  the  mesh  view  mode.  Select  the  solid  cathode  in  the 
navigation tree NT: Components  component1  cathode. 
2.  Open the dialog box Mesh: Mesh Control  Local Properties 
 to modify the 
local mesh settings of the cathode. In the General tab, choose Absolute value
from the Volume refinement drop-down list. This brings up the Use same setting 
in all three directions checkbox. Uncheck that box and change the step width in 
x and y to a value of 0.4. 
3.  Confirm  your  changes  as  usual  by  clicking  on  the  OK  button.  The  dialog  box 
closes and you can see the modified mesh.The  number  of  mesh  cells  should  be  497,536.  You  can  get  this  information  from  the 
status bar. 
You can now leave the mesh inspection mode via Mesh: Close  Close Mesh View 
. 
Define Particle Sources 
A particle source is a shaped surface of a component where charged particles enter the 
computational domain under a specific emission condition, which is determined by the 
emission model settings. Such a source is often located on the surface of a PEC solid, 
but it can also be defined on the surface of any arbitrary material. In our case the particle 
source will be placed on the inner cathode. To facilitate the selection of the surface of 
the inner cathode, some solids will be hidden.
1.  Select "cathode" and "cathode_inner" in the  navigation tree. Use the  Shift key 
for multi-selection. Select the option View: Visibility  Hide  Hide Unselected. 
Now we are able to define the particle source. 
2.  Select  Simulation:  Sources  and  Loads    Particle  Sources    Particle  Area 
Source 
 and select the inner surface of the solid "cathode_inner" by double-
clicking  onto  it.  Make  sure  that  the  surface  is  highlighted  when  you  move  the 
mouse cursor away from the surface.3.  After  selecting  the  emission  surface,  press  the Return key  to  open the Define 
Particle Area Source dialog box. Here, the particle type and particle density at 
the previously selected surface are adjustable. Change the  Tracking emission 
model  to  Space  charge.  The  blue  points  in  the  preview  visualize  the  particle 
emission points. Their density can be influenced using the Number of emission 
points slider. An increase of the number of emission points leads to a smoother 
current density. The checkbox Adjust density to mesh should be enabled if the 
emission  model  Space  charge  is  chosen.  Otherwise  the  number  of  emission 
points might be too low to obtain good simulation results and has to be increased 
manually when refining the mesh.
Note:  As  seen  in  the  lower  part  of  the  dialog  box,  standard  or  user-defined 
particle types can be specified. A particle definition library allows you to export 
such user-defined particle definitions to a database and also to import them. This 
library  is  accessible  through  the  Load  and  Save  buttons.  In  this  example,  we 
keep the default particle type electron. 
4.  Move  the  Number  of  emission  points  slider  until  the  number  is  375.  For  fine-
control,  you  can  use  the  left/right  arrow  keys  while  the  slider  is  focused.  To 
change the emission model settings, click the Edit button next to the emission 
model drop down list. The SCL Emission Settings dialog box opens:5.  An emission model describes the conditions particles need to fulfill in order to be 
emitted into free space. For instance, the space charge emission model allows 
particles to be emitted as long as an electric field perpendicular to the emitting 
surface  is  present. If  not  already  preselected, make  the following  adjustments 
inside  the  dialog  box  on  the  Potentials  tab:  Change  the  emitting  potential  to 
"cathode_pot" and the reference potential to "anode_pot". Click the OK button to 
confirm your changes. The particle source should now look like this:
Note: 
The red triangular mesh shows the discretization of the cathode surface, while 
the blue points visualize the start positions of the particles for the simulation. In 
this case the emission model Space charge limited requires the start positions 
to  be  shifted  a  little  bit  away  from  the  cathode  surface.  This  shifting  is  done 
automatically depending on the mesh close to the cathode. 
6.  We  finished  the  particle  source  definition  and  leave  the  Define  Particle  Area 
Source dialog box by clicking the OK button again. 
7.  Since some solids are currently hidden, we have to unhide them to see the whole 
structure again. Select View: Visibility  Show (dropdown list)  Show All. It is 
often helpful to hide some solids in order to select faces inside a structure. 
The particle source is now defined and ready for emission. Before you continue, have a 
look at the QuickStart Guide to see the next steps.The  point  “Set  boundary  conditions”  already  has  been  set  to  be  finished  as  the 
boundaries  were  defined  by  the  Particle  Gun  template.  Nevertheless,  the  boundary 
conditions will be discussed in the next section to illustrate the basics of the boundary 
condition setup. 
Define Boundary Conditions 
The simulation will be performed only within the bounding box of the structure, the so-
called  computational  domain.  You  can  specify  certain  boundary  conditions  for  each 
plane  (Xmin,  Xmax,  Ymin,  Ymax,  Zmin,  Zmax)  of  the  computational  domain.  These 
boundary conditions reflect the appropriate behavior of the surrounding world.  
The boundary conditions are specified in a dialog box which can be opened by choosing 
Simulation: Settings  Boundaries 
.
While the boundary dialog box is open, the boundary conditions are visualized in the 
structure view as shown in the next picture. 
You can change boundary conditions from within the dialog box or interactively in the 
view. Select a boundary by double-clicking on the boundary symbol within the view and 
select the appropriate type from the context menu.The following table gives an overview of available boundary conditions and their effect 
on the tangential and normal component of the electric and magnetic fields: 
Boundary 
type 
Electric field 
component 
Magnetic field 
component 
tangential 
component 
0 
exists 
exists 
0 
exists 
normal 
component 
exists 
0 
0 
exists 
exists 
tangential 
component 
exists 
0 
exists 
0 
exists 
normal 
component 
0 
exists 
0 
exists 
exists 
electric 
magnetic 
tangential 
normal 
open 
In our case, we want to use open boundaries in all directions. As we use the Particle 
Dynamics template, the default boundaries are already set to open. 
Furthermore,  some  extra  space  is  added  between  the  structure  and  the  open 
boundaries. Click the button Open Boundary to check this setting.
The size of this extra space is the length of the bounding box diagonal times the user 
defined  factor,  in  our  case  0.1.  This  value  is  also  defined  in  the  Particle  Dynamics 
template. Click Cancel to leave this setting unchanged. Click Cancel again to leave the 
Boundary Conditions dialog box. 
Note:  There  are  two  ways  to  create  some  space  (background  material)  between 
structure  and  boundaries. The first  way  is  described above.  Alternatively,  some extra 
space can be defined in the Background Properties dialog box. You can have a look in 
the paragraph Define the Background Material. 
Start the Simulation 
After  having  defined  all  necessary  parameters,  you  are  ready  to  perform  your  first 
simulation. The simulation is started from within the particle tracking solver control dialog 
box: Simulation: Solver  Setup Solver
In this dialog box you can specify the settings of the Particle Tracking Solver and start 
the simulation process. If multiple particle sources are defined, you can choose between 
a simulation where all sources emit particles and a simulation where only a single source 
is active. Enable the Gun iteration option to activate the iterative gun solver algorithm, 
set the Relative accuracy to be -20 dB and the Max. number of iterations to 20. Thus the 
Tracking Solver does not just track the particles once through the computational domain. 
Instead,  the  solver  iteratively  repeats  an  electrostatic  calculation  and  then  tracks  the 
particles  until  the  desired  accuracy  of  the  space  charge  deviation  between  two 
successive iterations is reached. 
The Tracking fields box lists all electromagnetic fields that are available for the particle-
tracking solver. In order to consider a specific field type for the tracking process, check 
the respective Active checkbox, in our case for the E- and the M-Static field. 
Now you can start the simulation procedure by clicking the Start button in the particle 
tracking  dialog  box.  A  few  progress  bars  will  appear  to  keep  you  up  to  date  with the 
solver’s progress. 
As you can see in the next paragraph, the complete solving procedure consists of three 
to four parts, depending upon the selected post processing steps. In this example, part 
two (electrostatic solver) and part three (particle tracking) are repeated iteratively until 
the relative accuracy condition specified in the gun iteration section is reached. 
1.  Magnetostatic Solver 
1.1. Checking model: During this step, your input model is checked for errors such 
as invalid overlapping materials, etc. 
1.2. Calculating  matrices:  During  these  steps,  the  system  of  equations,  which  will 
subsequently be solved, is set up. 
1.3. Magnetostatic  solver  is  running:  During  this  stage  a  linear  equation  solver 
calculates the field distribution inside the structure. 
2.  Electrostatic Solver 
2.1. Calculating  matrices:  During  these  steps  the  system  of  equations,  which  will 
subsequently be solved, are set up. 
2.2. Electrostatic  solver  is  running:  During  this  stage  a  linear  equation  solver 
calculates the field distribution inside the structure. 
3.  Particle Tracking 
3.1. Initializing  Tracking  Solver:  The  data  structure  for  the  collision  detection  of 
particles with solids is constructed. 
3.2. Tracking Solver is running: The particles are emitted and tracked through the 
computational domain. 
4.  Post Processing 
4.1. From  the  field  distribution,  additional  results  like  the  inductance  matrix  or  the
After a few repetitions of steps two and three, the desired accuracy of -20 dB of the gun 
iteration is reached, i.e. the relative difference of the space charge distribution between 
two consecutive solver runs is less than -20 dB. The algorithm of the iterative gun solver 
and its convergence condition are explained by the following diagram: 
START 
Calculate magnetostatic 
field distribution 
Calculate electrostatic 
field distribution 
Update space charge 
distribution 
Track particles and 
monitor space-charge 
no 
Converged? 
yes 
END 
Analyze the Results 
In  tracking  applications,  users  are  often  interested  in  the  particle  beam  behavior.  To 
have  an  overview  of  the  particle  movement,  a  3D  visualization  of  the  trajectories  is 
available  in  the  navigation  tree  NT:  2D/3D  Results    Trajectories.  The  trajectories
Colors indicate the particle energy. There are lots of options to modify this plot using the 
Particle Plot properties dialog box 2D/3D Plot: Plot Properties  Properties 
. 
Open the dialog box and change some settings, for example the Display type. Click the 
Start  button  on  the  Animation  tab  to  see  the  movement  of  the  particles.  Detailed 
explanations can  be  obtained from the  online  help.  Click the  Help  button  to  open the 
online help in your browser. If you like to close this dialog box, click the Close button. 
Field plots are also available in the navigation tree. To obtain the current density of the 
particle  beam  select  NT:  2D/3D  Results   Particle  Current  Density  in  the  navigation 
tree.  To  enable  logarithmic  scaling  check  the  respective  box  at  2D/3D  Plot   Color
Further  plot  settings  can  be  changed  in  the  3D  Vector  Plot  dialog  box.  This  can  be 
opened as usual via 2D/3D Plot: Plot Properties  Properties 
. 
To create the field plot above, the  Density slider on the Arrows and Bubbles tab was 
shifted to the right. Try to change some settings. Click the OK button to leave this dialog 
box. 
In the case of gun simulations with space charge limited emission, the emitted current 
is an important parameter. The 1D result plot emitted current versus gun iteration NT: 
1D  Results   Particle  Sources   Current  vs. Iteration   particle1  is  available in the 
navigation tree:This 1D result offers you the possibility to control the emission process. Thus, it is very 
helpful that this plot is already available during the gun iteration. 
Another plot is also available during the gun iteration, the gun code accuracy. If the user 
defined accuracy  is  reached, the  iterative gun  solver  stops. To get  this  1D  result  plot
select the folder NT: 1D Results  Convergence  Gun Iteration Charge Accuracy in 
the navigation tree: 
Apart from these 1D graphs, the development of the emitted charge and the perveance 
during the gun iteration process are also available via NT: 1D Results  Particle Sources 
  Charge  vs.  Iteration  and  NT:  1D  Results    Particle  Sources    Perveance  vs. 
Iteration. 
The collision information under NT: 1D Results  Total Collision Information can also 
be very interesting, because these graphs contain e.g. information about the power that 
is absorbed by a solid. Precise numbers can easily be read from these graphs via the 
entry Show Axis Marker from the context menu:In this case the background consists of vacuum, thus all particles are absorbed by the 
boundary of our calculation domain. 
Parameterization of the Model 
The previous steps demonstrated how to enter and analyze a simple structure. However, 
structures are usually analyzed to improve their performance. This procedure may be 
called “design” in contrast to the “analysis” done before. 
After you get some information on how to improve the structure, you will learn how to 
optimize the structure’s parameters. This could be done by modifying each parameter
manually,  but  this  of  course  is  not  the  best  solution.  CST  Studio  Suite  offers  various 
options to describe the structure parametrically in order to change the parameters easily. 
Let  us  assume  you  are  interested  in  the  dependency  of  the  emitted  current  on  the 
cathode's  potential.  To  obtain  this  dependency,  first  of  all  the  potential  has  to  be 
parameterized. Thus double click on the potential NT: Potentials  cathode_pot in the 
navigation tree. 
The Edit Potential dialog box opens and the potential can be edited. Instead of a number 
type the string "phi" in the Potential value field. 
If you click the OK button, you will be asked to delete the current results. Just click the 
OK button to delete the results. Then the dialog box New Parameter opens to define the 
value of your parameter "phi".Enter a value of -3e4 and click the OK button. You have successfully defined your first 
parameter. The values of your parameter can be edited and checked in the Parameter 
List window that is usually located in the lower left part of the main window:
Since we did not change the value of the cathode's potential, the results of the simulation 
would be the same. We will now change the setup to run a so called Parameter Sweep 
to get the emitted current for potentials in the range from -32 kV to -28 kV. To do this, 
open the Particle Tracking solver dialog box Simulation: Solver  Setup Solver 
.To save some time during the parameter sweep disable the checkbox Gun iteration. The 
tracking  solver  will  now  run  only  one  calculation  and  will  not  operate  in  the  iterative 
mode. 
Click the button Par. Sweep to open the dialog box Parameter Sweep and to configure 
the parameter range and also the expected results of the parameter sweep.
In  this  dialog  box  you  can  specify  calculation  sequences  that  consist  of  various 
parameter combinations. To add such a sequence, click the New Seq. button now. Then 
click the New Par button to add a parameter variation to the sequence:In the resulting dialog box you can select the name of the parameter to vary in the Name 
field. Then you can specify different sweep types to define the sampling of the parameter 
space (Linear sweep, Logarithmic sweep, Arbitrary points). Depending on this selection 
the sampling can be defined further, e.g. the linear sweep option allows us to define the 
lower (From) and upper (To) bounds for the parameter variation as well as the definition 
of either the number of samples or the step width. 
In this example you should perform a linear sweep from -32 kV to -28 kV in 5 steps. Click 
the OK button to confirm your changes. The definition of the sequence is finished but 
we still need to configure the expected result, the emitted current. The parameter sweep 
dialog box should look as follows: 
After  a  successful  simulation  run,  many  simulation  results  are  already  generated 
automatically  under  NT:  1D  Results  and  saved  in  the  parametric  storage.  For  more 
detailed investigations and customized evaluations, Template Based Postprocessing is 
available.  Often,  the  parametric  results  are  already  sufficient  to  analyze  the  results.
However, the general procedure of defining and handling Result Templates is outlined 
below. 
In order to evaluate a particular quantity of interest during the parameter sweep, it needs 
to be defined in advance. Here, the current emitted from the particle source should be 
monitored. 
As can be seen above, this quantity is available as a plot versus gun iteration number 
under NT: 1D Results  Particle Sources  Current vs. Iteration  particle1. For finding 
the  final  value  obtained  during  the  gun  iteration,  we  have  to  extract  the  value  that 
corresponds  to  the  rightmost  point  in  the  plot.  Note  that  this  approach  is  also  valid  if 
Perform gun iteration is deactivated, as we did above, since then the plot only contains 
a single point. 
In  order  to  define  the  results  of  interest,  click  on  the  button  Result  Template.  The 
Template  Based  Postprocessing  dialog  box  opens.  Templates  are  separated  into 
several Template Groups.Choose the template 0D or 1D Result from 1D Result (Rescale Derivation, etc) in the 
General  1D  group.  This  very  powerful  template  is  intended  for  postprocessing  or 
extracting data from any 1D plot. Once you choose this template, a dialog box opens 
where the data source and the operation have to be entered.
Under Specify Action select y at x-Maximum. Under 1D Results, the data source has to 
be  selected  –  in  our  case  Particle  Sources\Current  vs.  Iteration\particle1.  Leave  the 
dialog by pressing OK. 
The  Template  Based  Postprocessing  dialog  box  should  be  still  open  and  contain the 
following row:The  Result  name  can  be  changed  by  clicking  onto  the  respective  cell.  You  should 
change  it  to  something  more  recognizable  since  this  will  become  the  result  plot  title, 
choose, “Emitted Current”: 
Click the Close button to return to the parameter sweep. Now start the parameter sweep 
by clicking the Start. After confirming the request to delete existing results with OK, the 
calculation may take a few minutes. After the solver has finished, leave the dialog box 
by clicking the Close button. The navigation tree contains a new item called Tables from 
which  you  can  select  the  item  NT:  Tables   0D  Results   Emitted  Current.  The  1D 
result plot should look like in the picture below and gives you the relation between input 
voltage and emitted current of the electron gun:
Automatic Optimization of the Structure 
Let us assume that you wish to adjust the emitted current to a value of -0.22 A (which 
can  be  achieved  within  the  parameter  range  of  -32 kV  to  -30 kV  according  to  the 
parameter sweep). Figuring out the proper parameter may be a lengthy task that can 
also be performed automatically. 
CST  Studio  Suite  offers a very  powerful  built-in optimizer feature for  such parametric 
optimizations.  
To use the optimizer, open the tracking solver control dialog box Simulation: Solver  
 in the same way as before, or directly via Simulation: Solver  Optimizer 
Setup Solver 
. Click the Optimizer button to open the optimizer control dialog box.First, activate the desired parameter(s) for the optimization in the  Settings Tab of the 
optimization dialog box, here the parameter "phi" should be checked. Next specify the 
minimum  and  maximum  values  for  this  parameter  during  the  optimization.  From  the
parameter sweep, we already know that the searched potential is greater than -32 kV 
and  lower  than  -30 kV.  Therefore,  you  can  enter  a  parameter  range  between  -32 kV 
and -30 kV. Deactivate Use current as initial value and set the initial start value for the 
optimization, e.g. to -31.5 kV. 
For this simple example, the other settings can be kept as default. Refer to the online 
documentation for more information on these settings. You can specify a list of goals 
you  wish to achieve during the optimization. In this example the objective is to find a 
parameter  value  for  which  the  emitted  current  becomes  -0.22 A.  The  next  step  is  to 
specify this optimization goal. Switch to the Goals Tab and click Add New Goal.Now you can define the goal for the emitted current. Since you would like to find a value 
of -0.22 A, you should select the equal operator in the conditions frame. Then set the 
Target to -0.22. After you click OK, the optimizer dialog box should look as follows: 
Note:  The  optimizer  is  capable  of  optimizing  multiple  parameters  at  once.  Detailed 
information can be obtained from the online help. 
Up to now, you have specified which parameters to optimize and set the goal that you 
want to achieve. The next step is to start the optimization procedure by clicking the Start 
button. As shown in the next picture, the optimizer will display its progress in an output 
window  in  the  Info  tab  which  is  activated  automatically.  After  the  whole  process  has 
finished,  the  optimizer  output  window  contains  the  best  parameter  values  in  order  to 
achieve the desired goal.
Note  that,  due  to  sophisticated  optimization  technology,  only  five  solver  runs  are 
necessary to find the optimal solution with very high accuracy. 
Click the Close button to leave the dialog box. Now look at the final result of the emitted 
current for the optimal parameter setting phi = -30405.6 V by clicking NT: 1D Results  
Particle Sources  Current vs. Iteration. You should obtain the following result:As you can see, the final emitted current for the optimized voltage parameter is -0.22 A 
as it was previously defined by the setting of the optimization goal. 
Additional Information: More settings for the Particle Tracking Solver 
The Particle Tracking and the Particle Tracking Specials dialog boxes offer many more 
options to change the solver properties. The latter is available by selecting Simulation: 
Solver  Setup Solver 
 and clicking the Specials button.
The  Particle  dynamics  frame  offers  the  possibility  to  change  specific  settings  of  the 
particle tracking algorithm. The setting Max. timesteps defines the maximum number of 
simulated  steps  performed  by  the  tracking  algorithm.  The  Min. pushes per cell  value 
determines the spatial sampling rate of the particle trajectories. The Timestep dynamic 
parameter specifies the variation of the time step between two pushes and introduces a 
dynamic  adaptation  of  the  time  step  to  the  highest  particle  velocity.  Activating  the 
checkbox Monitor charge and current results in monitoring the space charge and current 
density  generated  by  the  particles.  This  is  automatically  activated  for  gun  iteration 
simulations. 
In the Gun iteration frame, in addition to the desired Relative accuracy, the maximum 
number  of  iterations  of  consecutive  electrostatic  simulations  and  particle  tracking 
computations is defined. The Relaxation parameter describes the influence of the last 
obtained space charge distribution to the overall charge distribution, which is considered 
in  the  next  electrostatic  computation.  By  checking  Consider  self-magnetic  field,  the 
magnetic field generated by the particles can be included in the gun iteration. 
In order to save disk space, usually not all time steps are written to the trajectory data. 
Instead, a subsampling is performed. The sampling method and its parameter can be 
set in the Trajectory sampling section of the Particle Tracking Specials dialog. 
Additional Information: Treating PEC as Normal Material for Magnetostatic 
Computations 
Simulation  Setups  used  for  Particle  Tracking  or  PIC  simulations  often  consist  of  a 
metallic beam pipe or similar enclosing structure. If these structures are modeled using 
PEC  material,  they  effectively  cannot  be  penetrated  by  magnetic  fields,  which  is 
physically correct within the simulation model but usually not desired.
This is why it is possible to treat PEC as a normal material for the Magnetostatic Solver 
via a setting in its Specials dialog. 
The  option  Consider  PEC  as  Normal  is  default  only  when  a  Particle Tracking  or  PIC 
project template is used - otherwise this checkbox is disabled by default. If you want to 
change or check this setting, open the Special Settings dialog box of the Magnetostatic 
Solver  Parameters  via  Home:  Simulation  Setup  Solver  (dropdown  list)  M-Static 
Solver, Home: Simulation Setup Solver 
  Specials.If the checkbox Consider PEC as Normal is enabled, PEC materials are considered like 
normal materials with a permeability µ which can be defined in the material properties 
of  the  PEC material.  In case  the  solver  is  started from  problem  class “Tracking”,  this 
setting is activated automatically. 
Please note that in stand-alone Magnetostatic simulations using the Problem Type “Low 
Frequency”, different results compared to Problem Type “Particle” are obtained despite 
otherwise identical settings due to the different defaults regarding the consideration of 
PEC type materials. 
Additional Information: Using tetrahedral meshes in the Tracking Solver 
Especially  for  models  with  curved  surfaces  in  the  vicinity  of  the  particle  beam,  a 
representation of  the  structure by  a  hexahedral mesh may  require  a large number  of 
cells.  In  these  cases,  it  can  be  helpful  to  use  a  tetrahedral  mesh  that  will  model  the 
structure’s surfaces more naturally and thus can yield more accurate surface fields. 
You  can  either  switch  to  the  tetrahedral  mesh  type  by  selecting  Simulation:  Mesh  
 (dropdown list)  Tetrahedral and pressing OK in the appearing 
Global Properties 
Mesh Properties dialog or alternatively via the option the solver setup dialog Simulation: 
Solver  Setup Solver 
  Mesh  Tetrahedral. 
When  changing  the  mesh,  you  will  be  informed  that  any  existing  results  have  to  be 
deleted. Confirm the deletion of the results by clicking OK. 
Before  starting  a  new  simulation  based  on  a  tetrahedral  mesh,  a  few  settings  in  the 
model  setup  have  to  be  changed,  part  of  which  can  be  seen  as  general 
recommendations for using the tetrahedral tracking solver: 
  Open boundaries are not supported. They are automatically replaced by magnetic 
 
boundaries (Ht = 0) upon solver start. 
In many cases, the automatically generated mesh will be a good starting point for 
performing your simulations. However, in order to obtain a mesh well adapted to the 
simulation type, some settings should be changed.
o  For modifying the global mesh resolution, you can set the mesh properties via 
. In the mesh properties dialog, enter 10 under Cells 
Mesh  Global Properties 
per max model box edge for Model and 15 for Background. 
o  As the particles interact with the electromagnetic fields in the vacuum regions, a 
mesh refinement of the permanent magnets is not of highest priority in the first 
place. Therefore, you may disable the checkbox Consider material properties for 
refinement in the Specials dialog. Moreover, the value in the edit field Smooth 
mesh with equilibrate ratio should be changed to 1.3 in order to avoid generating 
a too large number of tetrahedrons for this example.Due to using the project template for setting up the simulation project, most of these 
settings already have been applied automatically. 
The mesh can be visualized by entering the mesh view Home: Mesh  Mesh View 
and then pressing Mesh: Mesh  Update 
 to invoke the tetrahedral mesher. In case 
you do not trigger the mesh generation manually, the mesh is automatically constructed 
upon  solver  start.  After  a  few  seconds,  the  mesh  appears.  For  the  structure  in  this 
example, it looks as follows:
The right image has been generated using  Mesh: Visibility  Background and Mesh: 
Sectional View  Cutting Plane 
. It includes a visualization of the background mesh 
cells, i.e., the free-space region where finally the particle trajectories will be computed. 
Naturally, the mesh quality in the beam region is important for achieving accurate results. 
Please note that particle tracking simulations using a tetrahedral mesh will in general be 
slower  than  simulations  with  the  same  number  of  hexahedral  cells.  However,  since 
tetrahedral meshes yield a more precise surface representation, a considerably smaller 
number of cells will often be sufficient for getting accurate results. 
Press  Update  in  the  Mesh  Properties  dialog. This  requests the tetrahedral  mesher to 
update the  mesh representation. The  total  number  of tetrahedrons  is  close to  55,000 
now, as can be seen in the status bar: 
As in the hexahedral case, a more local control of the mesh resolution can be reached 
via the local mesh properties of the respective component. 
After leaving the mesh inspection mode via Mesh: Close  Close Mesh View 
, you 
could start the simulation as before using the particle tracking solver control dialog box: 
Simulation: Solver  Setup Solver 
  Start. However, due to some restrictions that 
apply  to  the  tracking  solver  when  used  with  tetrahedral  meshes,  the  following 
preparations  have  to  be  performed  (if  you  omit  these  steps,  the  solver  will  emit 
respective messages to guide you towards solving possible issues): 
  While being relative to the mesh dimensions in the hexahedral case, the emission 
distance for the space charge limited emission model has to be an absolute value 
when using a tetrahedral mesh. In general, it is a good idea to review all settings of 
the particle source after switching the mesh type. 
In order to do so, right-click onto the particle source in the navigation tree NT: Particle 
Sources  particle1 and select Edit Properties… from the context menu.This will open the Edit Particle Area Source dialog again. Here you should increase 
the  Number  of  emission  points  to  a  value  around  400  again  by  setting  the  Scale 
Factor to 10 and adjusting the slider appropriately.
Furthermore, open the settings of the emission model using the  Edit button in the 
Tracking emission model frame, check the settings and press OK twice to close both 
dialogs. 
Finally, you can now run the particle tracking solver with a tetrahedral mesh via its solver 
control dialog box: Simulation: Solver  Setup Solver 
  Start. 
The results should look similar to the ones obtained using a hexahedral mesh for the 
workflow example described earlier in this section (here for phi = -30 kV and active gun 
iteration again):Summary 
This example gave you a basic overview of the key concepts of the Tracking Solver of 
CST Studio Suite. You should now have a good idea of how to do the following: 
1.  Create a structure using the solid modeler 
2.  Specify the solver parameters, check and modify the mesh and start the tracking 
simulation 
3.  Visualize the electromagnetic field distributions and the particles trajectories
4.  Define a structure using parameters 
5.  Use the parameter sweep tool for parameter studies 
6.  Perform automatic optimizations 
If you are familiar with all these topics, you have a very good starting point for further 
improving your usage of CST Studio Suite. 
For more information on a particular topic, we recommend that you look at the contents 
page of the online help manual, which can be opened via File: Help  Help Contents – 
Get Help using CST Studio Suite 
. If you have any further questions or remarks, do 
not  hesitate  to  contact  our technical  support team. We also  strongly  recommend that 
you  participate  in  one  of  our  special  training  classes held  regularly  at  a  location  near 
you. Please ask us for details. 
Simulation Workflow: Electromagnetic Particle-in-Cell 
The basic procedure of running the electromagnetic (EM) particle-in-cell (PIC) solver is 
very similar to the one demonstrated in the tracking simulation workflow. In contrast to 
the  tracking  solver,  particles  and  electromagnetic  fields  are  computed  in  a  self-
consistent way using a time integration scheme. For more information on the physics 
that can be modelled with the EM PIC solver, an overview is provided in Chapter 3 – 
Solver Overview: Particle-in-Cell Solver. 
The  following  example  demonstrates  how  to  perform  a  PIC  calculation  for  a  simple 
output  cavity  of  a  klystron.  Studying  this  example  carefully  will  allow  you  to  become 
familiar with many standard operations that are necessary to perform a PIC simulation 
within CST Studio Suite.  
Go through the following explanations carefully even if you are not planning to use the 
software  for  PIC  simulations.  Only  a  small  portion  of  the  example  is  specific  to  this 
particular application type since most of the considerations are general to all solvers and 
application domains. 
The following explanations always describe the menu-based way to open a particular 
dialog box or to launch a command. Whenever available, the corresponding toolbar item 
is displayed next to the command description. Due to the limited space in this manual, 
the  shortest  way  to activate  a particular  command (i.e.  by  pressing  a  shortcut key  or 
activating the command from the context menu) is omitted. You should regularly open 
the context menu to check available commands for the currently active mode. 
The Structure 
This workflow example demonstrates how to build up the output cavity of a klystron for 
a PIC  simulation.  A klystron  is  a  device  to amplify microwave and/or  radio  frequency 
signals. The output resonator is the last stage (cavity) of a klystron. The amplified signal 
can be extracted using waveguide ports. 
Since  only  the  output  resonator  as  a  part  of  the  klystron  is  simulated,  a  Gaussian
CST  Studio  Suite  allows  you  to  define  the  properties  of  the  background  material. 
Background material is considered for the space in which no shape is defined. For this 
structure,  it  is  sufficient  to  use  vacuum  for  the  klystron  cavity  and  perfect  electrical 
conductor (PEC) for the surrounding background space. 
Create a New Project 
After launching the CST Studio Suite you will enter the start screen showing you a list 
of recently opened projects and allowing you to specify the application which suits your 
requirements  best.  The  easiest  way  to  get  started  is  to  configure  a  project  template, 
which  defines  the  basic  settings  that  are  meaningful  for  your  typical  application. 
Therefore, click on the New Template button in the New Project from Template section. 
Next,  you  should  choose  the  application  area,  which  is  Particle  Dynamics  for  the 
example  in  this  tutorial  and  then  select  the  workflow  by  double-clicking  on  the 
corresponding entry.Please then select the following workflow: Vacuum Electronic Devices  Klystron  Hot 
Test  Particle in Cell 
. 
You are then requested to select the units that fit your application best. For this example, 
please select the dimensions as follows: 
Dimensions:  mm 
GHz 
Frequency: 
ns 
Time: 
Temperature:  Kelvin
For the specific application in this tutorial the other settings can be left unchanged. After 
clicking  the  Next  button,  you  can  give  the  project  template  a  name  and  review  a 
summary of your initial settings: 
Finally click the Finish button to save the project template and to create a new project 
with  appropriate  settings.  CST  Studio  Suite  for  Particle  Dynamics  Simulation  will  be 
launched  automatically  due  to  the  choice  of  this  specific  project  template  within  the 
application area Particle Dynamics. Save the newly created “Untitled” project on your 
hard disk using a name of your choice. 
Please note: When you click again on the File: New and Recent you will see that the 
recently  defined  template  appears  below  the  Project  Templates  section.  For  further 
projects  in  the  same  application  area  you  can  simply  click  on  this  template  entry  to 
launch CST Studio Suite for Particle Dynamics Simulation with useful basic settings. It 
is  not  necessary  to  define  a  new  template  each  time.  You  are  now  able  to  start  the 
software with reasonable initial settings quickly with just one click on the corresponding 
template.  
Please note: All settings made for a project template can be modified later on during 
the construction of your model. For example, the units can be modified in the units dialog 
box  (Home:  Settings   Units 
)  and  the  solver  type  can  be  selected  in  the  Home: 
Simulation  Setup Solver drop-down list.Open the PIC QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an  electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
 in the 
you can open this assistant by selecting QuickStart Guide from the Help button 
upper right corner. 
The  following  dialog  box  should  then  be  visible  at  the  upper  right  corner  of  the  main 
view:
As the project template has already set the solver type, units and background material, 
the PIC Analysis is preselected and some entries are marked as done. The red arrow 
always indicates the next step necessary for your problem definition. You do not have 
to follow the steps in this order, but we recommend you follow this guide at the beginning 
to ensure that all necessary steps have been completed.  
Look at the dialog box as you follow the various steps in this example. You may close 
the assistant at any time. Even if you re-open the window later, it will always indicate the 
next required step. 
If you are unsure of how to access a certain operation, click on the corresponding line. 
The  QuickStart  Guide  will  then  either  run  an  animation  showing  the  location  of  the 
related menu entry or open the corresponding help page. 
Define the Units 
The Klystron Hot-Test template has already made some settings for you. The defaults 
for  this  structure  type  are  geometrical  units  in  mm  and  times  in  ns.  You  can  change 
these settings by entering the desired settings in the units dialog box (Home: Settings 
 Units 
), but for this example you should just leave the settings as specified by the 
template. Additionally, the used units are also displayed in the status bar:Define the Background Material 
As discussed above in the Structure section, the klystron cavity is surrounded by perfect 
electrical conductor (PEC). The material type PEC is already set as default background 
material in the Klystron Hot-Test template. You may change the background material in 
the corresponding dialog box (Simulation: Settings  Background 
). For this example, 
no change of the background material is needed. 
Model the Structure 
Having defined the initial general settings, the 3D view window is now visible and the 
working plane is shown therein. The working plane can be turned off (and on) by clicking 
on View: Visibility  Working Plane 
. 
Then, you can start building the 3D structure. First, create a vacuum cylinder along the 
z-axis of the coordinate system using the following steps: 
1.  Select the cylinder creation tool Modeling: Shapes  Cylinder 
2.  Press the ESC key to open the dialog box. Do not click a point in the working plane. 
3.  Enter "cavity" as name. 
.
4.  Enter the parameters "Rcav" as outer radius and "Lcav" as Zmax. Set the Material 
to "Vacuum". Click the OK button to confirm the changes. 
5.  The "New Parameter" dialog box appears. Enter 38.8 as value for Rcav. Press the 
Return key to confirm. It is also possible to add a description of the parameter. 
6.  Another "New Parameter" dialog box appears. Enter 22 as value for Lcav. Press the 
Return  key  to  confirm.  The  defined  parameters  are  shown  in  the  Parameter  List 
window of the CST Studio Suite. To view the newly created shape, click on View: 
Change View Reset view 
.7.  Activate and move the working coordinate system to the center of the upper cylinder 
face: Select Modeling: WCS  Align WCS 
 and pick the face in the maximum z-
direction  with  a  double-click.  This  setting  is  used  in  the  following  step  (step  8)  to 
define a vacuum cylinder based on the axes of the working coordinate system.
8.  Define a second vacuum cylinder: select the cylinder creation tool Modeling: Shapes 
 Cylinder 
. Press the ESC key to open the dialog box.9.  Enter the parameters "Rtub" as outer radius and "Ltub" as Wmax. Press the Return 
button to confirm the changes. 
10. The "New parameter" dialog boxes appear again. Choose 15.9 for Rtub and 55 for 
Ltub. Press the Return button to confirm. 
11. In the same way as before move the origin of the working coordinate system to the 
center of the lower face of the cavity cylinder. Select Modeling: WCS  Align WCS 
 and pick the face in the minimum z-direction with a double-click.
12. Define a third vacuum cylinder. Select the cylinder creation tool Modeling: Shapes 
 Cylinder 
. Press the ESC key to open the dialog box.  
13. Enter the parameters "Rtub" as outer radius and "Ltub" as Wmax. Press the Return 
button to confirm the changes. 
In the 3D structure view, the structure below should be visible now:14. Rotate  the  local  coordinate  system  180°  around  the  v-axis:  open  the  Transform 
 and select the Rotate button. 
dialog box from Modeling: WCS  Transform WCS 
Enter 180° for the V-direction. Then click the Apply button. 
15. Move the local coordinate system about Rcav in v-direction: Select the Move button 
and enter Rcav for the DV shift. Click OK to confirm.
The  origin  of  the  local  coordinate  system  should  now  have  been  shifted  to  this 
position: 
16. Define a vacuum brick. Select the brick creation tool Modeling: Shapes  Brick 
. 
Press the ESC key to open the dialog box. 
17. Enter the values as shown in the picture above. For Umax enter the length "WW" 
and for Umin the length "-WW". Click the OK button. The "New Parameter" dialog 
box will appear again. Enter 36.1 as length for WW and click OK. 
18. Since  the  structures  intersect,  the  "Shape  Intersection"  dialog  box  shown  below 
appears. Select "None" and click OK.19. Switch  to the global  coordinate  system  by  disabling  the WCS:  Modeling: WCS  
Local Coordinate System 
. 
20. Select "solid3" in the navigation tree.
21. Open 
the  "Transform  Selected  Object"  dialog  box:  Modeling:  Tools    
Transform 
. 
22. Enable "Mirror" and "Copy". Choose “Y” as mirror plane normal. Click the OK button. 
23. Since the structures intersect, the "Shape Intersection" dialog box appears again. 
Select "None" and click OK. Your structure should now look like this:24. Select all existing solids in the navigation tree. Transform all selected solids into one 
vacuum solid: Modeling: Tools  Boolean  Add 
.
25. Finally the structure should look like this: 
Congratulations! You have just created your first PIC structure within CST Studio Suite. 
Define the Particle Source 
We use an electron source as particle source. The emission is based on a Gaussian 
emission model. Since the beam has a circular cross section, the circular particle source 
 can be used. 
1.  Define  a  circular  particle  source  on  the  beam  tube  at  the  lower  z-coordinate: 
Simulation:  Sources and  Loads   Particle Sources   Particle Circular Source 
. 
Select the following edge (lower z-direction) of the beam tube with a double-click:2.  The dialog box "Define Particle Circular Source" opens where you can modify the 
settings of the particle source:
3.  Deselect the checkbox “Use pick”, enter an Outer Radius value of Rtub*0.3 and a 
Znormal value of 1. Click the Preview button to check these settings.In the PIC emission model section, the Gauss emission model is already selected 
from  the  drop-down  list.  Click  the  Edit  button  to  define  the  parameters  of  the 
Gaussian emission model. The Gauss emission settings are organized in two tabs: 
“General” and “Kinetic Settings”. Enter the values shown in the following table:
General 
Kinetic 
Setting  
Value 
Setting  
Value 
Charge (abs) 
50e-9 
Kinetic type 
Gamma 
Bunches 
15 
Kinetic value 
2 
Time / Length 
Length 
Sigma 
0.5*Lcav 
Cutoff Length 
1.25*Lcav 
Offset 
1.25*Lcav 
Bunch distance 
87 
After configuring the emission settings, the dialog boxes should look as follows: Click OK  to  confirm  the changes  and click  OK  again to close  the  "Define  Particle 
Circular Source" dialog box. 
Note: For more information about emission models and appropriate settings please 
refer to the online manual. 
Define the Ports 
In our example waveguide ports are used to extract the energy  out of the cavity. The 
ports are not used for excitation. 
1.  Pick the following face of one brick and double-click to define a port on it: Modeling: 
Picks  Picks   Pick Points, Edges or Faces.
2.  Open the "Waveguide Port" dialog box to define a waveguide port on the picked face 
(upper y-direction): Simulation: Sources and Loads  Waveguide Port 
.3.  Change the number of port modes to 4 and click OK to confirm. 
4.  For the other brick define a port on the opposite face (lower y-direction) in the same 
way: Pick the face, enter the Waveguide Port dialog box and change the Number of 
modes to 4.
5.  Confirm the settings with the OK button. The port definition is finished now. 
Simulation Setup 
The  solver  parameters  can  be  set  up  within  the  PIC  solver  dialog  box.  A  maximum 
simulation frequency must be defined. The PIC solver results are only valid in the defined 
frequency range. The mesh generation depends on the maximum frequency. 
1.  Define  the  maximum  frequency  within  the  Frequency  Range  Settings  dialog  box 
Simulation: Settings  Frequency 
. 
2.  Enter a frequency of 10 for Fmax and click the OK button. 
3.  Open the PIC solver dialog box: Simulation: Solver  Setup Solver 
.4.  Change the simulation time to 5 and enable the checkbox Analytic Field.
5.  To define the analytic field, click the Settings button of the analytic fields. The Define 
Analytic Magnetic Source Field dialog box appears. 
6.  Change the z-component of the "Constant B Vector" to -0.2 and click the OK button 
to confirm.  This will apply a homogeneous magnetic flux density of 0.2T along the 
–z direction to focus the particle beam. 
Before leaving the Particle in Cell Solver Parameters dialog box we want to draw your 
attention to the Excitation List button that might be important if ports or other HF-sources 
are defined:If the ports are excited, one can define the amplitude and the time shift for a previously 
defined  excitation  signal.  For  example,  applications  like  traveling  wave  tubes  feature 
driven ports. 
Note:  The  amplitude  value  is  the  amplitude  of  the  port  signal  (units  sqrt(W)),  which 
represents  the  square  root  of  the  peak  power  applied  to  the  port.  For  simplicity,  the 
corresponding average power of the exited port is shown in the column Power avg. 
No  changes  need  to  be  made  for  this  example,  so  you  can  leave  the  dialog  box  by 
clicking Cancel.
Now  the  solver  can  be  started.  But  before  that,  the  mesh  will  be  modified  and  some 
particle monitors will be defined. First, click the Apply and then the Close button in the 
main solver dialog box. 
Refine the mesh 
Appropriate mesh settings for this example are already specified by the Klystron Hot-
Test template. However, in some cases the mesh has to be adjusted manually, as the 
mesh  does  not  know  anything  about  the  particle  movement.  To  change  the  mesh 
settings, proceed as follows: 
1.  Click on Simulation: Mesh  Global Properties 
 to open the dialog box of the mesh 
properties.2.  Play a little bit with the settings. E.g. set Cells per wavelength – Near to model to 20, 
click Apply to observe the change in the number of mesh cells. 
3.  Undo your changes and click OK to leave the dialog box.
Define Particle Monitors 
To understand the interaction of particles with electromagnetic fields, it is often useful to 
gain an insight into the particle distribution. In this example, it may be interesting to see 
how particle bunches are deformed when moving through the beam tube. 
The particle distribution can be recorded with an equidistant sampling in time. You may 
need  to  switch  back  to  the  modeler  mode  by  selecting  the  Components  folder  in  the 
navigation tree before the monitor definition can be activated. 
For this example a 3D PIC Position Monitor will  be defined. Select and open  the PIC 
Position Monitor dialog box: Simulation: Monitors  PIC Position Monitor 
. 
Enter a Step width of 0.1 and create the monitor by pressing the OK button. 
In addition to the 3D PIC position monitor, a phase space monitor will be set up. Select 
Simulation: Monitors  PIC Position Monitor  PIC Phase Space Monitor 
 to open 
the PIC Phase Space Monitor dialog box:For the abscissa select the z-position and for the ordinate select Gamma. Enter a Step 
width  of  0.1 for the  time  sampling.  As  the  beam  moves parallel  to the  z-axis,  we are 
interested in monitoring the particle γ as a function of the z-position. 
Apart from the 3D PIC position monitor and the phase space monitor, a PIC 2D monitor 
is available as well. Please refer to the online help for further details.
Start the Simulation 
All necessary parameters have been now defined and you are ready to perform your 
first  PIC  simulation.  You  can  start  the  solver  directly  by  clicking  Home:  Simulation  
Start Simulation . Alternatively, you can reopen the PIC solver dialog box, Simulation: 
Solver  Setup Solver 
In the progress window, a progress bar will be shown which informs you on the solver's 
status. Information regarding the operation will be displayed next to the progress bar. 
The most important stages are listed below: 
, and start the solver by clicking the Start button.  
1.  Calculating matrices: Processing CAD model: During this step, the input model 
is checked and processed. 
2.  Calculating matrices: Computing coefficients: During these steps, the system of 
equations, which will subsequently be solved, is set up. 
3.  Data  rearrangement:  Merging  results:  For  larger  models  the  matrices  are 
calculated in parallel and the results are merged at the end. 
4.  Transient analysis: Calculating port modes: In this step, the solver calculates the 
port mode field distributions if any ports were defined. This information will be used 
later in the time domain analysis of the structure. 
5.  Transient analysis: Processing excitation / transient field analysis: During this 
stage, the particles are emitted into the calculation domain and the time integration 
of  the  fields  and  particle  movement  takes  place.  The  solver  stops  when  the 
previously defined Simulation time has been reached. 
For this simple structure, the entire analysis takes a few minutes to complete. 
Note: During the simulation, the position of the particles can be watched by selecting 
NT: 2D/3D Results  PIC Position Monitors  Particle preview in the Navigation Tree. 
The view of particles can be then updated by pressing the F5 key or by clicking on 2D/3D 
Plot: Plot Properties  Update Results 
. 
Analyze the Simulation Results 
The results of the PIC simulation can be analyzed in several ways. By clicking on NT: 
2D/3D  Results    PIC  Position  Monitors   Particle  preview,  the  last  sample  of  the 
simulation can be visualized in the default monitor “Particle preview”. The  charged  particle  motion  can  be  visualized  by  selecting  the  result  entry  for  the 
.  Select  NT:  2D/3D  Results   PIC  Position 
previously  defined  3D  particle  monitor
Monitors  position monitor 1. Open the Plot Properties dialog box by double clicking 
inside the 3D view window or by selecting 2D/3D Plot: Plot Properties  Properties 
and click on the tab Animation. 
You can enter a time to plot another time sample. Another way to move back and forth 
in the time sample sequence is to use the left and right arrow keys, after having clicked 
somewhere  in  the  3D  view  window.  To  start  an  automatic  animation,  click  the  Start 
button in the 2D/3D Plot Properties dialog box. This dialog box allows several other plot 
modifications, described in more detail in the online help. Close the dialog box by clicking 
the OK button. 
The phase space plot monitor result can be accessed by selecting NT: 1D Results  
PIC Phase Space Monitor  pic phase space monitor 1:This result  illustrates the  gamma  (proportional  to  energy)  variation  in time versus  the 
longitudinal  position.  The  results  can  be  visualized  as  an  animation:  select  Home: 
Macros   Macros  Report and Graphics  Save Video. Set the Framerate to 5 Hz 
and then click OK. The animation is saved by default in the folder where the .cst project 
lies and starts to be executed automatically. It takes less than a minute to create the 
video. For a specific time instance of the space phase, you can select a single frame in 
the Navigation Tree:
In  addition  to  the  results  of  the  previously  defined  monitors,  the  PIC  solver  creates 
several  other  entries  in  the  result  tree.  Below  you  can  find  a  selection  of  interesting 
results:  
Port Signals (NT: 1D Results  Port signals) 
If  ports  are  defined,  the  output  signals  at  these  ports  are  added  automatically  to  the 
results.  In  this  example,  the  signal  at  port  1  shows  that  the  bunched  particle  beam 
creates high power radio waves. As mentioned earlier, the output signals correspond to 
the square root of the peak power, which means that the average output power extracted 
from the beam amounts to 0.5*3000*3000 = 4.5 MW. 
Particle Number (NT: 1D Results  Solver Statistics [PIC])This 1D result shows the total number of macro particles inside the calculation domain 
vs.  time.  The  curve  increases  when  new  particles  are  emitted  by  the  source.  It 
decreases, when particles are absorbed by solids and/or the background. Especially if 
a multipacting event is expected, this type of plot can be very useful.
Emitted Current (NT: 1D Results  Emission Information  Current  [Sources]) 
This  1D  result  shows  the  amount  of  emitted  current  for  all  particle  sources  vs.  time. 
Especially for field based emission models, like explosive emission, this result is very 
important. 
Wave-Particle-Power Transfer (NT: 1D Results  Power)The wave-particle power transfer is the power (loss or gain) that is transferred from the 
electromagnetic fields to the particles. In case of oscillators, this quantity can be very 
interesting.  Superposed fields,  i.e.  analytic fields and field  imports,  are  not  taken  into 
account for this plot. 
There are even more possibilities for monitoring the particle data during the simulation 
and  for  analyzing  the  results,  but  the  previously  presented  methods  provide  a  good 
starting basis. For further options, we would like to refer to the online help. 
Summary 
This example should have given you an overview of the key concepts of  CST Studio 
Suite. You should now have a basic idea of how to do the following: 
1.  Model the structures by using the solid modeler 
2.  Specify the solver parameters, check the mesh and start the simulation 
3.  Define particle and field monitors 
4.  Visualize the particle distribution and use the PIC solver statistics
If you are familiar with all these topics, you have achieved a very good starting point for 
further improving your usage of the PIC solver inside CST Studio Suite. 
For more information on a particular topic, we recommend that you browse through the 
online help system which can be opened by pressing the F1 key or clicking on Help  
Help Contents – Get Help using CST Studio Suite 
. If you have any further questions 
or  remarks,  do  not  hesitate  to  contact  your  technical  support  team. We also  strongly 
recommend that you participate in one of our special training classes held regularly at a
Simulation Workflow: Wakefield 
The following example demonstrates how to perform a wakefield calculation for a simple 
resonator cavity. Studying this example carefully will allow you to become familiar with 
many standard operations that are necessary to perform a wakefield simulation within 
CST Studio Suite. For more information on the physics that can be modelled with the 
Wakefield solver, an overview is provided in Chapter 3 – Solver Overview : Wakefield 
Solver. 
Go through the following explanations carefully even if you are not planning to use the 
software for wakefield simulations. Only a small portion of the example is specific to this 
particular application type since most of the considerations are general to all solvers and 
application domains. 
The following explanations always describe the menu-based way to open a particular 
dialog box or to launch a command. Whenever available, the corresponding toolbar item 
is displayed next to the command description. Due to the limited space in this manual, 
the  shortest  way  to activate  a  particular  command (i.e.  by  pressing  a  shortcut key  or 
activating the command from the context menu) is omitted. You should regularly open 
the context menu to check available commands for the currently active mode. 
The Structure 
This workflow example considers a particle beam passing through a pillbox cavity. Since 
only the vacuum parts of the structure need to be modeled, it is very easy to set up the 
geometrical description. It consists only of two added cylinders with a couple of blended 
edges. The following picture shows the structure of interest. It is shown in a transparent 
way, in order to see the particle beam axis.CST  Studio  Suite  allows  you  to  define  the  properties  of  the  background  material. 
Anything  you  do  not  fill  with  a  particular  material  will  automatically  be  considered  as 
background material. For this structure, it is sufficient to model only the vacuum space. 
The background properties will be set to PEC (Perfect Electric Conductor). 
The model will be created in three simple steps: 
1.  Model the cylindrical vacuum parts of the resonator and the beam tube. 
2.  Blend the circular edges of the cavity. 
3.  Define the beam parameters (axis, charge, velocity). 
Create a New Project 
After launching the CST Studio Suite you will enter the start screen showing you a list 
of recently opened projects and allowing you to specify the application which suits your
requirements best. The easiest way to get started is to configure a project template that 
defines  the  basic  settings  that  are  meaningful  for  your  typical  application.  Therefore, 
click on the New Template button in the New Project from Template section. 
Next,  you  should  choose  the  application  area,  which  is  Particle  Dynamics  for  the 
example  in  this  tutorial  and  then  select  the  workflow  by  double-clicking  on  the 
corresponding entry.For the pillbox cavity, please select Accelerator Components  Cavities  Wakefields 
 Wakefield 
. 
At  last,  you  are  requested  to  select  the  units  that  fit  your  application  best.  For  this 
example, please select the dimensions as follows: 
Dimensions:  cm 
Frequency:  GHz 
Time: 
ns 
For the specific application in this tutorial the other settings can be left unchanged. After 
clicking  the  Next  button,  you  can  give  the  project  template  a  name  and  review  a 
summary of your initial settings: 
Finally click the Finish button to save the project template and to create a new project 
with  appropriate  settings.  CST  Studio  Suite  for  Particle  Dynamics  Simulation  will  be 
launched  automatically  due  to  the  choice  of  this  specific  project  template  within  the 
application area Particle Dynamics.
Please note: When you click again on the File: New and Recent you will see that the 
recently  defined  template  appears  below  the  Project  Templates  section.  For  further 
projects  in  the  same  application  area  you  can  simply  click  on  this  template  entry  to 
launch CST Studio Suite for Particle Dynamics Simulation with useful basic settings. It 
is  not  necessary  to  define  a  new  template  each  time.  You  are  now  able  to  start  the 
software with reasonable initial settings quickly with just one click on the corresponding 
template.  
Please note: All settings made for a project template can be modified later on during 
the construction of your model. For example, the units can be modified in the units dialog 
box  (Home:  Settings   Units 
)  and  the  solver  type  can  be  selected  in  the  Home: 
Simulation  Setup Solver drop-down list. 
Open the Wakefield QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
you can open this assistant by selecting QuickStart Guide from the Help button 
 in the 
upper right corner. 
The  following  dialog  box  should  then  be  visible  at  the  upper  right  corner  of  the  main 
view:The project template has already automatically set the Solver type appropriately. Units 
and background settings have been predefined by the project template.
The red arrow always indicates the next step necessary for your problem definition. You 
may not have to process the steps in this order, but we recommend you follow this guide 
at the beginning in order to ensure all necessary steps have been completed. 
Look at the dialog box as you follow the various steps in this example. You may close 
the assistant at any time. Even if you re-open the window later, it will always indicate the 
next required step. 
If you are unsure of how to access a certain operation, click on the corresponding line. 
The  QuickStart  Guide  will  then  either  run  an  animation  showing  the  location  of  the 
related Ribbon entry or open the corresponding help page. 
Define the Units 
The Wakefields template has already made some settings for you. The defaults for this 
structure  type  are  geometrical  units  in  cm  and  times  in  ns.  You  can  change  these 
settings by entering the desired settings in the units dialog box (Home: Settings  Units 
), but for this example you should just leave the settings as specified by the template. 
Additionally, the used units are also displayed in the status bar: 
Define the Background Material 
As  previously  discussed  in  the  Structure  section,  the  pillbox  cavity  is  surrounded  by 
perfect  electrical  conductor  (PEC).  The  material  type  PEC  is  already  set  as  default 
background  material  in  the  Wakefields  template.  You  may  change  the  background 
material in the corresponding dialog box Simulation: Settings  Background 
. For this 
example, no change of the background material is needed. 
Model the Structure 
First,  create  a  cylinder  along  the  z-axis  of  the  coordinate  system  using  the  following 
steps: 
1.  Select the cylinder creation tool: Modeling: Shapes  Cylinder 
2.  Press  the  Shift+Tab  key,  and  enter  the  center  point  (0,0)  in  the  xy-plane  before 
. 
pressing the OK key to store this setting. 
3.  Press Esc to show the dialog box. 
4.  In the shape dialog box, enter “beamtube” in the Name field. 
5.  Press the Tab key twice, enter the Outer radius as 5. 
6.  Press the Tab key five times, enter the height by defining Zmax as 80. 
7.  Set the Material to “Vacuum”.
Since  the  material  type  “Vacuum”  is  already  predefined,  you  can  create  the  cylinder 
without defining a new material by clicking OK. Your result should look like the picture 
below. Press the Space bar to zoom the cylinder to window size. 
To create the cavity, you will now construct another vacuum cylinder with the help of the 
working coordinate system (WCS): 
1.  Activate the working coordinate system Modeling: WCS  Local WCS 
2.  Choose Modeling: WCS  Transform WCS 
, enter a shift of 25 in the DW direction 
and click on OK. 
3.  Again select the cylinder creation tool: Modeling: Shapes  Cylinder 
4.  Press  the  Shift+Tab  key,  and  enter  the  center  point  (0,0)  in  the  uv-plane  before 
. 
pressing the Return key to store this setting. 
5.  Press Esc to show the dialog box. 
6.  In the shape dialog box, enter “cavity” in the Name field. 
7.  Press the Tab key twice, enter the outer-radius as 23.
Confirm your setting by pressing OK. The automatic intersection check detects that both 
cylinders are intersecting and ask how to resolve the overlap:It is important for the following construction steps to add both shapes to one. In order to 
do so, select “Add both shapes” and confirm with OK. 
The  final  construction  step  is  to  blend  the  outer  circular  edges  at  the  cavity  and  the 
intersection edges between the cavity and the beam-tube. Since four edges have to be
blended in one step you can activate the Keep Pick Mode tool Modeling: Picks  Picks 
  Pick  Modes    Keep  Pick  Mode 
  before  picking  the  four  edges.  Now  activate 
Modeling: Picks  Pick Points, Edges or Faces 
 to pick the first edge – you might also 
use the keyboard shortcut e: 
Cavity edges 
By moving the mouse cursor to the first edge and performing a double-click you select 
the  appropriate  edge.  Repeat  this  operation  for  the  other  three  circular  edges  on  the 
cylindrical cavity. You have to rotate the model to pick all four edges. 
Now press the Return key to store all picks. Deactivate Modeling: Picks  Picks  Pick 
Modes  Keep Pick Mode 
 by selecting it once more. To activate the blend tool finally 
select Modeling: Tools  Blend  Blend Edges 
 and enter the value 2 for the blend 
radius.Confirm with OK. Now the work of defining the geometric part is done, and your model 
should  look  as  follows  (after  switching  off  the  visualization  of  the  working  plane  by 
pressing the Alt+W keys): 
Congratulations! You have just created your first wakefield structure within CST Studio 
Suite.
Define the Particle Beam Source 
A  wakefield  computation  is  always  driven  by  a  particle  beam  source,  which  will  be 
defined  in  this  section.  The  beam  definition  consists  of  the  axis  settings  and  the 
description of a charged bunch of particles with a Gaussian shape. 
1.  Select Modeling: Picks  Pick Point  Pick Circle Center 
2.  Double-click on the lower circular edge of the beam tube with respect to the z axis. 
. 
The center point will be highlighted:  
3.  Open the particle beam dialog box by selecting Simulation  Sources and Loads 
 Particle Beam 
:Enter a value of 10 (cm) for the longitudinal spatial width of the Gaussian pulse, and 
a total bunch charge of -1e-12 C. Confirm the settings with the OK button and the 
beam source is created. Since the structure is hiding the source visualization, you 
might select NT: Particle Beams to take a look at the beam source:
Note: The blue arrows indicate the beam position, whereas the orange arrows 
indicate the position of the wake integration path. For more information, please visit 
the respective section in the Online Help. 
Define Boundary and Symmetry Conditions 
The simulation of this structure will only be performed within the bounding box of the 
structure.  However,  you  may  specify  certain  boundary  conditions  for  each  plane 
(Xmin/Xmax/Ymin/Ymax/Zmin/Zmax) of the bounding box.  
The  boundary  conditions  are  specified  in  a  dialog  box  which  opens  after  choosing 
Simulation: Settings  Boundaries 
.While the boundary dialog box is open, the boundary conditions will be visualized in the 
structure view as in the picture above. 
In this simple case, the structure is embedded in perfect conducting material, so all x- 
and y- boundary planes may be specified as “electric” planes (which is the default). The 
z-boundaries are defined as “open” planes, such that eventual scattering fields traveling 
along the beam tube can be absorbed at the lower and upper z-boundaries. 
In  addition  to  these  boundary  planes,  you  can  also  specify  “symmetry  planes."  The 
specification of each symmetry plane will reduce the simulation time by a factor two. 
In our example, the structure is rotationally symmetric with respect to z-axis, therefore 
the yz-plane and the xz-plane can be set to be symmetry planes. The excitation of the 
fields will be performed by the particle beam source for which the magnetic field is shown 
below:
Plane of structure symmetries (yz- and xz-
planes) illustrated by means of the 
magnetic field. 
The  magnetic  field  has  no  component  tangential  to  the  planes  of  the  structure’s 
symmetry (the entire field is oriented perpendicular to this plane). If you specify these 
planes  as  “magnetic”  symmetry  planes,  you  can  direct  CST  Studio  Suite  to  limit  the 
simulation  to  one  quarter  of  the  actual  structure  while  considering  the  symmetry 
conditions. 
For the yz- and xz-symmetry planes, you can choose magnetic either by selecting the 
appropriate  option  in  the  dialog  box  or  by  double-clicking  on  the  corresponding 
symmetry  plane  visualization  in  the  view  and  selecting  the  proper  choice  from  the 
context menu. Once you have done so, your screen will appear as follows:Symmetry Planes tab in the boundary conditions dialog box. 
Finally click OK in the dialog box to store the settings. Then the boundary visualization 
will disappear. 
Visualize the Mesh 
The  mesh  generation  (hexahedral  mesh)  for  the  structure’s  analysis  is  performed 
automatically based on an expert system. However, in some situations it may be helpful 
to inspect the mesh to improve the simulation speed by changing the parameters for the 
mesh generation.  
The mesh can be visualized by entering the mesh view Home: Mesh  Mesh View 
For this structure, the mesh information will be displayed as follows: 
.
One 2D mesh plane is in view at a time. Because of the symmetry setting, the mesh 
plane extends across only one half of the structure. You can modify the orientation of 
the  mesh  plane  by  adjusting  the  selection  in  the  Mesh:  Sectional  View    Normal 
dropdown  list  or  just  by  pressing  the  X/Y/Z  keys.  Move  the  plane  along  its  normal 
direction using the Up/Down cursor keys. The current position of the plane will be shown 
in the Mesh: Sectional View  Position field.  
There are some thick mesh lines shown in the mesh view. These mesh lines represent 
important  planes  (so-called  snapping  planes)  at  which  the  expert  system  finds  it 
necessary to place mesh lines. You can control these snapping planes in the Special 
Mesh  Properties  dialog  by  selecting  Simulation:  Mesh    Global  Properties 
   
Specials  Snapping. 
For  wakefield  computations  the  minimization  of  dispersion  due  to  the  mesh  is  very 
important,  especially  in  the  longitudinal  beam  direction.  Therefore,  the  particle  bunch 
has  to  be  sampled  adequately  in  space.  Open  the  mesh  properties  dialog  box  by 
selecting Home: Mesh  Global Mesh Properties 
.This example is driven by quite a long bunch (compared to the structure’s dimensions), 
therefore the sampling rate can be increased by entering a value of 25 for the Cells per 
wavelength setting. The new settings are applied by clicking Apply. In case the bunch 
length is very short, this might increase the number of mesh cells significantly. However, 
a simulation is still possible using cluster simulation via MPI. Please refer to the Online
Help->Simulation Acceleration -> MPI Computing. Leave the dialog box by clicking OK 
and have a look at the refined mesh: 
Leave the mesh inspection mode by clicking Mesh: Close  Close Mesh View 
. 
Define a 2D Time Domain Field Monitor 
In order to understand the behavior of an electromagnetic device, it is often useful to get 
insight into the electromagnetic field distribution. In this example, it may be interesting 
to see where the particle bunch creates electric fields. 
The fields can be recorded at arbitrary frequencies or with a given sampling rate in the 
time  domain.  Since  storing  all  computed  field  data  would  require  a  large  amount  of 
memory only specific samples are stored. In order to obtain these field samples so called 
monitors have to be defined. 
Monitors can be defined in a dialog box that opens after choosing Simulation: Monitors 
 Field Monitor 
. You may need to switch back to the modeler mode by selecting the
After selecting the proper Type for the monitor, you may specify its time settings in the 
Specification field. Clicking Apply stores the monitor while leaving the dialog box open. 
All  time  settings  use  the  active  time  unit,  which  was  previously  set  to  “ns”.  For  this 
analysis, you should enter the following settings: 
E-Field 
Time 
0 
0.5 
Field type 
Specification 
Start time 
Step width 
Use Subvolume  Activate on 
Orientation 
Position 
X 
0 
Finally  leave the  dialog box  by  clicking  OK.  All  defined monitors  are  listed  in the  NT: 
Field Monitors folder. Within this folder, you may select a particular monitor to reveal its 
parameters in the main view. 
Note: After the simulation has finished, you can visualize the recorded field by choosing 
the corresponding item from the navigation tree. The monitor results can then be found 
in  the  NT:  2D/3D  Results  folder.  The  results  are  ordered  according  to  their  physical 
quantity E-Field / H-Field / Currents / Power flow. 
Start the Simulation 
After  having  defined  all  necessary  parameters,  you  are  ready  to  start  the  wakefield 
simulation. Start the simulation from the Wakefield Solver control dialog box: Simulation: 
Solver  Setup Solver 
.
In  this  dialog  box,  you  can  specify  the  maximum  wakelength  behind  the  bunch  that 
should be calculated. Enter a value of 200 (cm) in this field.  
The accuracy of the results mainly depends on the discretization of the structure and 
can be improved by refining the mesh. In case a resonant structure is observed, a short 
simulated wakelength introduces a truncation error in the wake potential. This could lead 
to ripples in the wake impedance. 
You can now start the simulation procedure by clicking the Start button. A progress bar 
will appear in the status bar that will inform you on the solver's progress. Information text 
regarding the operation will appear next to the progress bar. The most important stages 
are listed below: 
1.  Calculating matrices, preparing and checking model: 
During this step, your input model is checked for errors such as invalid or overlapping 
materials. 
2.  Calculating matrices, normal matrix and dual matrix: 
During these steps, the system of equations, which will subsequently be solved, is 
set up. 
3.  Transient analysis, calculating the port modes: 
In this step, the solver calculates the port mode field distributions if any ports were 
defined.  This  information  will  be  used  later  in  the  time  domain  analysis  of  the 
structure. 
4.  Transient analysis, processing excitation: 
During  this  stage,  the  particle  beam  is  injected  into  the  calculation  domain.  The 
solver then calculates the resulting field distribution inside the structure as well as 
the wakefields. 
5.  Transient analysis, transient field analysis: 
After the beam pulse has been injected, the solver continues to calculate the field 
distribution  and  the  wake  potentials  until  the  requested  wakelength  has  been 
computed. 
For this simple structure, the entire analysis takes only a few seconds to complete. 
Analyze the Simulation Results 
After the solver has completed the wake computation, you can view the results. In order 
to  look  at  the  wake  potential,  choose  the  solution  from  the  navigation  tree.  You  can
visualize them by selecting NT: 1D Results  Particle Beams  ParticleBeam1  Wake 
potential. If you open this subfolder, you will see all signals assigned to that folder.  
After selecting the folder, you should see the following plot:The Reference Pulse graph is shown only for orientation purposes. As expected due to 
the symmetry of structure and beam, only the longitudinal z–wake potential is different 
from zero. 
If  you  select  the  electric  field  result  from  the  previously  defined  monitor  NT:  2D/3D 
Results  E-Field  e-field (…)[pb], you may obtain a plot showing no arrows at all. 
This is because the first time-sample has been selected automatically at a time where 
the  beam  has  not  yet  entered  the  calculation  domain.  Since  the  transparent  mode 
(accessible  via  2D/3D  Plot:  Plot  Properties    Structure  Transparent 
)  is  already 
activated, you can select another time frame by using the left / right cursor keys when 
the focus is in the main window.
There are several other plot and visualization options. Please refer to the Online Help 
for  more  details.  The  different  view  options  can  be  selected  using  the  dropdown  list 
under 2D/3D Plot: Plot Type. 
The  following  gallery  shows  some  possible  plot  options  for  the  absolute  electric  field 
values. Can you reproduce them? 
Isoline plot of the absolute E-fieldContour plot of the absolute E-field 
Carpet plot of the absolute E-Field 
Hint:  In  order  to  see  the  absolute  field  values  recorded  by  the  monitor,  switch  from 
Arrows to, e.g., Contour, and also try the other possible selections, such as deactivating 
the logarithmic scale. 
Hint:  As  the  time  monitor  contains  multiple  frames,  try  stepping  through  those  while 
trying to reproduce the pictures shown above. When selecting frame 22 at 10.5 ns the 
results should look alike. 
Additional Information: Wakefield Postprocessing 
During the solver run, complex-valued wake impedances are computed by dividing the 
wake  potential  by  the  charge  distribution  of  the  beam  in  frequency  domain.  These 
impedances  are accessible from the  navigation tree. The following  picture shows  the 
real  part  of  the  Z-impedance  for  the  previous  example  with  a  Simulated  Wakelength 
setting of 2000:
Real part of the z-wake impedance for the previous example using a Simulated 
Wakelength of 2000. 
This impedance shows the typical truncation error (ripples) for a time signal that has not 
decayed to zero before the simulation was completed. In this particular case, the wake 
potential is truncated in the time domain. 
It  is  possible  to recalculate  the  impedance  spectra  after  a  simulation  has  finished  by 
selecting Post Processing: 2D/3D Field Post Processing  Wakefield Postprocessing 
:This post processing option allows recomputing of the wake impedances. Additionally, 
a  low-pass  filter  can  be  applied  to  the  impedance  in  order  to  smooth  the  signal. 
Moreover, it is possible to recompute certain frequency intervals with a given sampling 
rate (only for the DFT transformation type). For a very fast computation of the complete 
spectrum, use the FFT transformation type. The impedance spectra can be accessed 
by selecting NT: 1D Results  Particle Beams  ParticleBeam1  Wake impedance 
[Name]  Z:
Real part of the z-wake impedance computed with a cos²- filter and the FFT 
transformation type. 
The wake impedance describes the behavior of the cavity in the frequency domain. For 
this type of impedance the beam serves as a current source and the wake potential as 
voltage.  Thus,  this  impedance  can  be  used  to  detect  the  modes  where  beam  and 
structure interact. 
Note: The DFT transformation type is helpful when computing only a few samples within 
a specified frequency range, while the FFT type computes a full spectrum very fast. 
Summary 
This example should have given you an overview of the key concepts of  CST Studio 
Suite. You should now have a basic idea of how to do the following:1.  Model the structures by using the solid modeler 
2.  Specify the solver parameters, check the mesh and start the simulation 
3.  Visualize the wake potentials and impedance profiles 
4.  Define field monitors 
5.  Visualize the electromagnetic field distributions 
If you are familiar with all these topics, you have a very good starting point for further 
improving your usage of CST Studio Suite. 
For more information on a particular topic, we recommend that you browse through the 
online help system which can be opened by selecting File: Help  Help Contents – Get 
Help using CST Studio Suite 
. If you have any further questions or remarks, please do 
not hesitate to contact your technical support team. We also strongly recommend that 
you  participate  in  one  of  our  special  training  classes  held  regularly  at  a  location  near 
you. Please ask your support center for details.
Chapter 3 – Solver Overview  
Particle dynamics take place in a vast range of time scales: from the nanosecond regime 
in  high-frequency  vacuum  electronic  devices,  across  microseconds  in  breakdown 
phenomena, up to milliseconds in plasma chambers and quasi-static particle guns. For 
each application, CST Particle Studio offers an optimal solution.  
Particle Tracking Solver 
The Particle Tracking Solver and its gun-iteration mode are used for quasi-static particle 
dynamics. A typical application for this solver is a quasi-static electron gun. The solver 
is  based  on  a  simplification  of  the  complex  interaction  of  electromagnetic  fields  and 
charged particles. Electrostatic and magnetostatic fields dominate the charged particle 
dynamics.  The  influence  of  the  particle’s  charge  and  induced  current  on  the 
electromagnetic fields is neglected. This leads to a quasi-static problem. The charged 
particles  move  according  to  the  standard  equations  of  motion  for  charges  in 
electromagnetic fields. Each particle with the same initial condition will follow the same 
trajectory  through  static  electric  and  magnetic  fields.  It  is  sufficient  to  sample  the 
trajectory of a limited number of particles per source to describe the particle dynamics. 
Regarding  the  numerical  computation  details,  the  particle  movement  is  integrated 
through the static fields. The trajectory is the sample of particle positions from the initial 
position  until  the  particle  collides  with  either  the  structure  or  the  bounding  box  of  the 
setup. The solver can use either hexahedral or tetrahedral mesh. 
In the gun-iteration  mode, the quasi-static  space-charge  effect  of the  particles  on  the 
static  electric  field  is  considered.  This  approximation  is  useful  when  a  weak  coupling 
between the charged particles and the electromagnetic fields exists. For every iteration, 
the particle trajectories and electric fields are computed. The iteration loop stops when 
the  convergence  criterion  is  met.  The  gun-iteration  mode  is  shown  in  the  following
In  certain  applications,  for  example  when  particles  are  relativistic,  the  particles  carry 
such a significant amount of current, that the self-induced magnetic field has an effect 
on  their  trajectories.  In  these  cases,  there  is  the  possibility  of  considering  the  self-
induced magnetic field. 
Particle-in-Cell Solver  
The  electromagnetic  (EM)  Particle-in-Cell  (PIC)  solver  offers  the  most  detailed  and 
complete view of the charged particle dynamics in electromagnetic fields. It is best suited 
for the interaction of fast charged particles and high-frequency electromagnetic fields. 
Typical  applications  include  high-frequency  vacuum  electronic  devices,  such  as 
oscillators like magnetrons and amplifiers like traveling wave tubes. The solver performs 
transient  simulations  ranging  in  the  nanosecond  regime  up  to  microseconds.  The 
interaction of electromagnetic fields and charged particles is computed by considering 
the  two-way  coupling  between  the  charged particles  and  the  computational  grid.  The 
solver consists of a grid-based EM solver and a particle pusher. 
The  whole  system  is  integrated  in  time  using  a  leapfrog  time-integration.  One  single 
time-step consists of integrating the fields and particles in time. In the first step, the EM 
fields  are  integrated;  this  step  considers  the  current  density  induced  by  the  moving 
charged  particles.  Next,  the  equations  of  motion  for  each  simulated  particle  are 
integrated in time by interpolating the updated EM fields to the particle’s position. This 
self-consistent cycle is repeated until the final simulation time is reached. The time-integration of the EM PIC solver is restricted by the requirement of resolving 
the  fastest  occurring  phenomena.  This  is  the  smaller  of  the  following  two  conditions. 
First,  there  is  the  stability  limit  of  the  Courant-Friedrich-Lewys  condition  for  the  EM 
solver.  This  requires  the  grid  to  be  fine  enough  to  resolve  the  propagation  of  all 
electromagnetic waves. Second, there is the requirement to resolve the highest gyration 
or plasma frequency of the electrons. 
Electrostatic Particle-in-Cell Solver 
Particle  dynamics  take  place  in  a  vast  range  of  time  scales.  The  fastest  particle 
dynamics, typically electron dominated, can be simulated with the electromagnetic (EM) 
Particle-in-Cell solver. Quasi-static dynamics can be treated with the Particle Tracking 
Solver  and  its  gun-iteration  mode.  For  the  intermediate  time  scales,  where  the 
interaction of both slow ions and fast electrons comes into play, the Electrostatic (ES) 
PIC Solver can be well suited. Compared with the EM-PIC solver, it is not limited by the 
typically  small  Courant time step  needed for  EM-wave propagation  in  a 3D geometry 
with small-scale variations. In the ES-PIC Solver, the time step can be larger and it is 
then only limited by the fastest particle dynamics, typically by the plasma frequency.
In  order  to  understand  the  necessity  of  the  ES-PIC  solver,  a  glance  into  physics 
modeling applied in the remaining solvers is useful. In the EM-PIC solver, the EM field 
and the particle dynamics are self-consistently described because all the terms in the 
Maxwell equations are retained in the equation scheme. This formulation is well-suited 
for  problems  where  the  interplay  between  particles  and  electromagnetic  waves  is 
dominant. This applies especially to light, highly-mobile electrons, which carry a particle 
current great enough to affect the EM wave propagation. However, in many applications, 
the effect of total particle current is negligible and therefore, the particles do not affect 
the  electromagnetic  wave  propagation  or  vice-versa.  Instead,  the  dominant  effect 
consists in modifying the electrostatic field via the particle space charge. Furthermore, 
ions are typically slow compared with the electrons and the EM waves. For these cases, 
the electromagnetic PIC solver represents excessive computational effort. On the other 
hand, the Particle Tracking Solver in the gun-iteration is not well-suited either, because 
the coupling between the charged particles and the electrostatic field is too strong to be 
sufficiently described by its formulation. These are the cases, where the ES-PIC solver 
has advantages and it is therefore the right choice to study electrostatic effects, such as 
breakdowns, sheath formation, space charge compensation and electrostatic waves. 
Regarding  the  numerical  computation  details,  similarly  to  the  EM-PIC  solver,  a  time 
integration  takes  place  and  the  particle  movement  is  calculated  using  the  standard 
equations  of  motion  for  charges  in  electromagnetic  fields.  In  contrary  to  the  EM-PIC 
solver, the particle current is assumed to be negligible in the ES-PIC solver. Instead, the 
particle distribution is used to calculate the space-charge density, which is then used to 
solve the Poisson problem for every time step. This allows the simulation of fast particle 
dynamics of electrostatic type. This is in contrast to the Particle Tracking Solver, where 
it  is  additionally  assumed  that  the  space  charge  varies  very  slowly  compared  to  the 
particle movement.Wakefield Solver 
In particle accelerators, the interaction of travelling particle bunches with the surrounding 
environment  leads  to  the  generation  of  electromagnetic  fields  in  their  “wake”.  For 
example, geometrical or material discontinuities in the surrounding accelerator structure 
cause  the  excitation  of  the  so-called  wakefields.  The  fields  can  adversely  affect 
subsequent  bunches  or  even  destabilize  the  originating  particle  beam.  The  wakefield 
solver can be used for the analysis of such electromagnetic effects. 
The main assumptions are the following: a) the particle beam is moving on a straight 
line  and  b)  the  particle  beam  is  not  affected  by  the  generated  wakefields.  An  infinite 
beam pipe is modeled by a special treatment at the beam entrance and exit, in which 
not only the particle current is considered but also the corresponding electromagnetic 
fields. 
The wakefield solver is a time-domain solver with a special particle beam excitation. The 
resulting wakefields are used to calculate the integrated force acting on a virtual particle 
along its way through the structure. To perform this integration, several techniques are 
available.  Standard  results  are  the  wake  potential  and  the  wake  impedance.    For
ultrarelativistic  beams,  these  results  are  a  property  of  the  structure.  For  non-
ultrarelativistic beams, the wake potential and impedance include the integrated effect 
of the space charge and thus, depend on the length of simulated tube.  
The  wakefield  solver  can  also  be  helpful  for  the  analysis  of  beam  position  monitors 
(BPMs), where the quantities of interest are the signals recorded at the BPM pick-ups. 
Arbitrary bunch shapes and bunch sequences can be modeled as well. 
Additional Features 
This section covers features supported by two or more solvers. The following features 
are available for Tracking, ES-PIC and PIC simulations. 
Particle interaction with materials 
Particles can not only interact with electromagnetic fields but also directly with materials. 
To activate and edit the settings of the particle-material interaction, you can open the 
  
dialog box of a previously selected material with Modeling: Materials  New/Edit 
Edit Material properties and click on the tab Particles. The following dialog box will then 
be  visible  for  PIC.  The  available  options  for  Tracking  and  Es-PIC  differ  slightly,  as 
explained in this section.  
It is implicitly assumed that in most of the applications particles move in vacuum space. 
Subsequently,  particles  can  collide  with  shapes  filled  with  any  material  other  than 
vacuum. In some cases, it is useful to model the space in which particles move using a 
material  with  non-vacuum  properties.  This  is  possible  using  the  volume  transparency
Via the drop-down list in the Property frame, you can select the kind of particle-material 
interaction. Several options are available: Secondary Emission (induced by electrons or 
ions), Sheet Transparency and Special Dispersion. 
Secondary  emission  occurs  when  primary  incident  particles  of  sufficient  energy  hit  a 
surface  and  induce  the  emission  of  secondary  particles.  In  the  frame  Secondary 
emission  model,  the  parameters  of  the  secondary  emission  model  can  be  specified. 
Options  include  a  phenomenological  probabilistic  model  (Furman),  a  heuristic  model 
(Vaughan) and a model based on an imported secondary electron yield (Import). The 
latter model is available for the ion-induced secondary emission. 
In some applications, very thin grids or foils are present, through which some particles 
are absorbed. This can be represented by an infinitely thin body, a so-called sheet, which 
can become transparent to particles. In the frame Sheet transparency, the transparency 
level can be specified, which can be either constant or energy-dependent.  
Under  certain  conditions,  PIC  simulations  can  be  corrupted  by  a  numerical  instability 
often  referred  to  as  Cerenkov  instability.  To  mitigate  its  effects,  a  special  dispersive 
material can be defined here using the Special Dispersion property. 
The Tracking and Es-PIC solver do not compute electromagnetic waves, therefore the 
option Special Dispersion is not available. Instead, Optically Induced Emission is offered 
as an option. This emission models the emission of electrons through the photoelectric 
effect.  
Monte-Carlo Collisions 
The Monte-Carlo Collisions (MCC) module models collisions between charged particles 
and neutral background gas particles. This model assumes a background gas of a much 
higher density than the plasma density. Therefore, the thermodynamic state of the gas 
is unaltered by the collisions. The collisions occur randomly and lead to a momentum 
and energy transfer. The Monte-Carlo collisions dialog is reached through Simulation: 
Setup Solver  Specials  Data Input.The  user  can  define  a  single  background  gas  in  a  constant  physical  state  and 
thermodynamic equilibrium. The gas occupies the complete simulation region in which 
particles can move. The dialog shows an example of the list of available options for the 
Es-PIC  solver.  This  set  of  collisions  include  elastic  scattering,  excitation  and  impact 
ionization for electrons and elastic scattering and impact ionization for ions. The MCC 
computations can be accelerated by using multithreading. This results in better solver
performance  and  optimized  simulation  times.  In  contrast,  the  PIC  solver  can  only 
consider a model for electron impact ionization.  
Particle Merging 
The Particle Merging module contains a model to combine four particles that are close 
to  each  other  in  phase-space,  into  two  new  particles  and  is  available  for  Es-PIC 
simulations.  During  a  merging  step,  the  algorithm  ensures  charge,  momentum  and 
energy  conservation.  The  algorithm  is  especially  useful  in  breakdown  simulations  in 
which the particle number increases exponentially. The settings dialog can be reached 
through Simulation: Setup Solver  Specials. 
Coupled Simulations 
CST  Studio  Suite  for  Particle  Dynamics  Simulation  offers  various  options  to  link 
electromagnetic  field  simulations  to  a  specific  particle  computation.  Furthermore,  the 
Particle Interfaces allow linkage of different tracking or PIC simulations. Finally, one can 
export losses from collided particles to a subsequent thermal analysis. Usually it is either 
possible to perform several simulations within a single project or connect two or more 
projects by using the import and export options. 
Considering Electromagnetic Fields 
CST  Studio  Suite  for  Particle  Dynamics  Simulation  is  dedicated  to  simulate  charged 
particles traveling through electromagnetic fields. To accomplish this task, one (or more) 
of three possible techniques can be used: 
1.  Computation of electromagnetic fields 
2.  Definition of analytic magnetic fields 
3.  Import of electromagnetic fields - ASCII or from other projects 
In general, all fields defined for a PIC or tracking simulation are superposed before being 
used for the particle update. Specifically, in case of the PIC solver, these fields are 
superposed to the self-consistent and time-dependent fields based on Maxwell’s 
equations. 
Computation of Electromagnetic Fields 
CST Studio Suite for Particle Dynamics Simulation has the ability to use fields from other 
CST  Studio  Suite  3D  EM  solvers  as  input,  particularly  CST  Studio  Suite  for  Low 
Frequency Simulation and CST Studio Suite for High Frequency Simulation. 
  Electrostatics Solver 
The Electrostatics Solver of CST Studio Suite for Low Frequency Simulation is used 
to calculate the accelerating fields for static guns, or the deflecting electrostatic fields 
of beam steering units in cathode ray tubes (CRT). 
  Magnetostatics Solver 
The Magnetostatics Solver of CST Studio Suite for Low Frequency Simulation pre-
calculates  the  fields  of  various  types  of  magnets  (such  as  solenoids,  dipoles, 
quadrupoles, etc.) for beam optics simulation. 
  Eigenmode Solver 
The particles can also be tracked through resonant fields in cavities calculated with 
the Eigenmode Solver from CST Studio Suite for High Frequency Simulation.
The particles can also be tracked through the frequency domain 3D field monitors 
provided  by  the  Time  Domain  Solver  from  CST  Studio  Suite  for  High  Frequency 
Simulation. A typical application is multipaction analysis. 
To get an introduction and/or further information to these electromagnetic field solvers, 
refer  to  the  Workflow  and  Solver  Overview  of  CST  Studio  Suite  for  Low  Frequency 
Simulation and CST Studio Suite for High Frequency Simulation. 
Definition of Analytic Magnetic Fields 
Besides the possibility of calculating fields before or during a particle simulation,  CST 
Studio  Suite  for  Particle  Dynamics  Simulation  offers  the  option  to  define  and  use 
analytical H- and B-field distributions for the Tracking-, Electrostatic PIC- and the PIC-
solver. 
Three different types of analytic magnetic field distributions are currently available: 
  A constant magnetic field throughout the computational domain 
  A constant magnetic flux density throughout the computational domain 
field  characterized  by  a  1D 
  A  rotationally  symmetric  magnetic 
tangential 
magnetization  vector  defined  along  the  Z-/  W-  axis  of  the  active  global  or  local 
coordinate system. The r-component of the rotationally symmetric magnetic field can 
only be calculated if the z-component of the magnetic field is not a function of the 
radius r: 
It is possible to define such a source by selecting Simulation: Sources and Loads  
Source field  Analytic Source Field 
. The corresponding dialog box allows you to 
define the magnetic field vector. Alternatively, a 1D description of the magnetic field 
along the axis of the currently active coordinate system can be defined:The picture above shows the “measured” tangential field along the z-axis and the 
rotationally symmetric field distribution of the resulting B-field.
Import of Electromagnetic Fields 
The third possibility to consider fields for a tracking or PIC simulation is to import them 
from an ASCII file or from another CST-project. Thus, it is easily possible to superpose 
multiple  fields.  In  order  to  define  one  or  more  field  imports,  open  the  dialog  box  by 
selecting Simulation: Sources and Loads  Source Field  Import External Field: 
This  feature  allows  importing  of  eigenmodes,  e-,  h-  or  b-fields  even  from  different 
projects  based  on  different  meshes.  When  creating  a  field  import  with  the  Add  from 
Project option, one can pick an existing field distribution from a CST project file. Fields 
based on hexahedral (HEX) and/or tetrahedral (TET) meshes can be imported. Add from 
File offers the possibility to import ASCII files or HEX mesh based monitor files. 
By  clicking  the  Preview  button,  the  overlapping  regions  of  the  imported  data  and  the 
current domain can be visualized with a magenta colored frame. 
It  is  possible to  combine fields from  different structures  with  a  particle  simulation,  but 
care  has  to  be  taken  since  the  program  does  not  check  the  consistency  of  fields  on 
material boundaries.Another nice aspect is that a recalculation of tracking or PIC problems does not require 
the recalculation of fields. This results in a simulation speed up. 
Particle Interfaces 
Particle interfaces allow you to connect tracking and/or PIC simulations from different 
CST Studio Suite projects. Two types of interfaces are available: 
  Export Interface 
Import Interface 

Assuming that you have a tracking or gun project, which has to be linked to a subsequent 
PIC or tracking project by using Particle interfaces, perform the following steps to define 
a proper connection: 
1.  Open the tracking or gun project. 
2.  Define one or more export interfaces: Simulation: Monitors  Particle 2D Monitor  
Particle Export Interface 
. 
3.  Run a tracking or gun simulation. After the simulation has finished, the particle data 
are automatically exported into a file with the extension .pio. This file is stored in the 
result folder of the project. 
4.  Open the PIC or tracking project. 
5.  Define  one  or  more  import  interfaces  by  importing  the  particle  interface  files: 
Simulation: Sources and Loads  Particle Sources  Particle Import Interface 
. It 
is possible to rotate and translate the interface plane.6.  Run the subsequent PIC or tracking simulation. 
Note:  An  ASCII  import  of  files  with  user  defined  particle  emission  information  is  also 
available. Further information about the file format can be obtained from the online help. 
Export of Particle Surface Losses 
The  particle  solvers  allows  computing  particle  surface  losses  caused  by  the  particles 
interacting  with  matter.  This  feature  is  available  for  Tracking,  ES-PIC  and  PIC.  For 
example,  this  might  be  an  interesting  option  for  medical  applications,  but  also  for 
collectors. It can be activated by opening Simulation: Solver  Setup Solver  Specials 
 PIC:
Since an averaged power is needed for the thermal coupling, the time period in that the 
power data are averaged has to be defined. Per default, this time period is set to the 
user  specified  simulation  time.  The  particle  surface  losses  are  calculated  during  the 
solver run and can be visualized in the result tree directly after the solver is finished. It 
is also possible to export thermal losses caused by electromagnetic fields. This is an 
interesting  option  for  wakefield  or  PIC  computations.  For  further  information  about 
thermal  coupling,  we  refer  to  the  CST  Studio  Suite  for  Thermal  and  Mechanical 
Simulation help. 
Acceleration Features 
Within  the  frame  of  charge  particle  simulation,  CST  Studio  Suite  offers  several 
hardware-related  possibilities  to  accelerate  simulations.  All  the  solvers  support  CPU 
acceleration using multithreading. In addition, the electromagnetic PIC solver supports 
multi-GPU acceleration, the electrostatic PIC solver supports single-GPU acceleration 
and the Wakefield solver supports MPI cluster parallelization. 
To access the acceleration settings, for example in the case of the PIC solver, select 
  Acceleration. If you have a GPU, you can try to 
Simulation: Solver  Setup Solver
Please  refer  to  the  online  help  (section  Simulation  Acceleration)  or  to  the  GPU 
computing guide for more detailed information about the different acceleration features 
as well as the required hardware. The GPU computing guide is available via the following
Chapter 4 – Finding Further Information 
After carefully reading this manual, you will already have some idea of how to use CST 
Studio  Suite  for  Particle  Dynamics  Simulation  efficiently  for  your  own  problems. 
However, when you are creating your own first models, many questions will arise. In this 
chapter, we give you a short overview of the available documentation. 
The QuickStart Guide 
The main task of the QuickStart Guide is to remind you to complete all necessary steps 
in order  to  perform  a  simulation successfully.  Especially  for  new  users  –  or for  those 
rarely using the software – it may be helpful to have some assistance. 
The QuickStart Guide is opened automatically on each project start, when the checkbox 
File:  Options   Preferences   Open  QuickStart  Guide  on  project  load  is  checked. 
Alternatively, you may start this assistant at any time by selecting QuickStart Guide from 
the Help button 
 in the upper right corner. 
When  the  QuickStart  Guide  is  launched,  a  dialog  box  opens  showing  a  list  of  tasks, 
where  each  item  represents  a  step  in  the  model  definition  and  simulation  process. 
Usually, a project template will already set the problem type and initialize some basic 
settings like units and background properties. Otherwise, the QuickStart Guide will first 
open a dialog box in which you can specify the type of calculation you wish to analyze 
and proceed with the Next button:As  soon  as  you  have  successfully  completed  a  step,  the  corresponding  item  will  be 
checked and the next necessary step will be highlighted. You may however, change any 
of your previous settings throughout the procedure. 
In order to access information about the QuickStart Guide itself, click the Help button. 
To obtain more information about a particular operation, click on the appropriate item in 
the QuickStart Guide. 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by choosing File: Help  Help Contents 
. The 
online help system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  directly  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties. 
When no  specific  information is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system.
Please refer to the CST Studio Suite - Getting Started manual to find some more detailed 
explanations about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given  when  following  the  Tutorials  and Examples  link 
  on  the  online  help system’s 
start page. We recommend that you browse through the list of all available tutorials and 
examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does  not  help  you  to  solve  your  problem,  you  can  find  additional  information  in  the 
Knowledge Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language 
  A description of all specific macro language extensions. 
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language. 
  Some documented macro examples 
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software  described  in  this  document  is  furnished  under  a  license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a retrieval 
system,  or  transmitted  in  any  form  or  any  means  electronic  or 
mechanical,  including  photocopying  and  recording,  for  any  purpose 
other than the purchaser’s personal use without the written permission 
of Dassault Systèmes. 
Trademarks 
icon, 
IdEM,  Spark3D,  Fest3D,  3DEXPERIENCE, 
CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
STUDIO,  CST  EMC  STUDIO,  CST  MICROWAVE  STUDIO,  CST 
PARTICLE  STUDIO,  CST  Studio  Suite,  EM  Studio,  EMC  Studio, 
Microstripes,  Microwave  Studio,  MPHYSICS,  MWS,  Particle  Studio, 
PCB  Studio,  PERFECT  BOUNDARY  APPROXIMATION  (PBA), 
Studio  Suite, 
the 
logo,  CATIA,  BIOVIA,  GEOVIA, 
Compass 
SOLIDWORKS, 3DVIA, ENOVIA, NETVIBES, MEDIDATA, CENTRIC 
PLM,  3DEXCITE,  SIMULIA,  DELMIA  and  IFWE  are  commercial 
trademarks or registered trademarks of Dassault Systèmes, a French 
"société  européenne"  (Versailles  Commercial  Register  #  B  322  306 
440), or its subsidiaries in the United States and/or other countries. All 
other  trademarks  are  owned by  their respective owners.  Use  of  any 
Dassault  Systèmes  or  its  subsidiaries  trademarks  is  subject  to  their 
express written approval. 
the  3DSDS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries. 
3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome to the CST Studio Suite® software package, the powerful simulation software 
for  all  kinds  of  electromagnetic  field  problems  and  related  applications.  The  program 
provides a user-friendly interface to handle multiple projects and views at the same time. 
One of the outstanding features of the environment is the seamless integration of various 
simulation methods and strong interoperability management especially when connected 
to the 3DEXPERIENCE® platform. The CST Studio Suite software provides the following 
simulation options: 
3D EM Technology 
CST Microwave Studio®: Fast and accurate 3D EM simulation tools 
for high frequency problems. It offers a variety of different solvers 
operating in time and frequency domains. 
CST  EM  Studio®:  3D  EM  simulation  of  static  and  low  frequency 
problems.  The  module  features  a  large  collection  of  solvers  for 
various applications. 
CST  Particle  Studio®:  Specializes  solvers  for  the  3D  simulation  of 
electromagnetic  fields  interacting  with  charged  particles.  The 
these 
software  contains  several  different  solvers  addressing 
challenging problems. 
Spark3D®:  A  general  software  tool  for  radio  frequency  (RF) 
breakdown  analysis.  It  uses  powerful  and  accurate  numeric 
algorithms  for  predicting  both  corona  (arcing)  and  multipactor 
breakdown onsets, which are two of the main high power effects that 
can severely damage a device. 
Cable | Circuit | Macromodels | Filters | PCB | ChipCST  Cable  Studio®:  Tools  for  the  analysis  of  SI,  EMC  and  EMI 
effects in cable systems including single wires, twisted pairs as well 
as complex cable harnesses. 
CST  Design  Studio™:  A  design  and  analysis  tool  for  system  level 
simulation. Its schematic view allows the connection of different 3D 
projects  and  circuit  elements.  It  is  the  entry  point  for  the  System 
Assembly and Modeling (SAM) workflows and our powerful circuit 
simulator. 
IdEM®/IdEM Builder  is  a  tool  for  the  generation  of  SPICE-ready 
macromodels  of  electrical  interconnect  structures.  Starting  from 
IdEM/IdEM Builder  provides 
their 
accurate,  proven,  passive  and  causal  broadband  computational 
models that can be used in any circuit simulation environment. 
Fest3D®:  An  efficient  software  tool  for  the  accurate  analysis  of 
passive components based on waveguide technology. Fest3D is 
the first commercial software capable to integrate high power effects 
in the design process. 
input-output  port  responses 
CST PCB Studio®: Tools for the investigation of signal and power 
integrity  and  the  simulation  of  EMC  and  EMI  effects  on  printed 
circuit boards (PCB) and for the design of 3D chips.
Multi-Physics 
CST MPhysics® Studio: A set of tools for solving thermal as well as 
mechanical stress problems. Use these solvers in conjunction with 
other simulation domains to address coupled simulation tasks. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Work  through  this  document  carefully.  It  provides  you  with  all  the  basic 
information necessary to understand further documentation.  
2.  Each of the solver modules mentioned above comes with a dedicated manual. 
Once  you  have  determined  which  modules  are  best  suited  to  solve  your 
problems, continue by reading the corresponding manual. The manuals provide 
valuable information to help you use the software quickly and efficiently. 
3.  Browse through the online help system and familiarize yourself with its content. 
As an entry point, you may follow the links on the online help system’s start page. 
4.  Do not hesitate to contact technical support if you encounter any problems or if 
any  questions  remain.  Since  a  variety  of  different  applications  exists,  the 
documentation may not be able to cover all special cases equally. The support 
team will be more than happy to assist you in solving your simulation problems 
as soon as possible. 
About This Manual 
This manual is primarily designed to enable a quick start to CST Studio Suite. It is not 
intended to be a complete reference guide to all available features, but it will give you 
an overview of the key concepts. Understanding these concepts will allow you to learn 
how to use the software efficiently with the help of the online documentation. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key  combinations  are  connected  with  a  plus  (+)  sign.  Ctrl+S  means  that  you 
should hold down the “Ctrl” key while pressing the “S” key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document, a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the  group  Group  name.  If  a  keyboard  shortcut  exists,  brackets  are  used  to 
highlight the command. Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item.
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support 
center: 3ds.com/support. 
Support 
Dassault  Systèmes  is  happy  to  receive  your  feedback.  If  you  have  any  questions 
concerning  sales,  please  contact  your  local  sales  office.  In  case  you  have  problems 
using  our  software,  see  the  information  provided  in  Chapter  6  –  Finding  Further
Chapter 2 – Installation 
Installing the CST Studio Suite software is simple. This chapter explains everything you 
need to know regarding installation. It covers the following sections: 
  Installation requirements 
  Licensing options 
  Installation instructions for Microsoft Windows 
  License Server 
  Starting the CST Studio Suite software 
Please  note:  This  document  deals  with  the  installation  on  a  Microsoft  Windows 
operating system. To install the software on Linux, please refer to the documentation 
shipped with the Linux package. 
Installation Requirements 
Software Requirements 
The software runs under Windows 10, Windows 11, Windows Server 2016, 2019 and 
2022. 
Hardware Requirements 
  CPU x86-64 processor (Intel or AMD) 
  OpenGL compatible graphics hardware 
  16 GB RAM 
  30 GB free disk space (60 GB recommended) 
Please refer to CST Studio Suite at 3ds.com/support/hardware-and-software/simulia-
system-information/ for more details. 
Licensing Options 
The software can be licensed either as a single PC (node locked) version or as a network 
version. The single PC license allows the software to run on a single PC only. In contrast, 
the network license allows the software to run on several PCs connected to a license 
server. 
Most of the steps of the installation procedure are the same for both types of licenses. 
We will therefore focus on the common procedures first and then explain the differences 
in setting up the license afterwards. 
Installation Instructions for Microsoft Windows 
You will normally need administrator privileges in order to install the software. If you do 
not  have  these  privileges  on  your  local  computer,  ask  your  system  administrator  for 
assistance. Once you installed the software successfully and it is running, you should 
close it and log back in as a standard user for security reasons. 
Please note:   Some  virus  detection  programs  may  interfere  with  the  setup  process 
and cause the installation to fail. We therefore strongly recommend  that you close all 
other  applications  and  turn  off  virus  scanning  before  proceeding  with  the  actual 
installation. 
Before installing the CST Studio Suite software, please download the current installer
installation  DVD,  you  can  skip  this  step.  However,  the  download  area  also  contains 
some  additional  packages  free  of  charge.  Please  consider  the  license  terms  of  each 
individual package. 
If you have downloaded, an installation package or the DVD installation does not start 
automatically  after  you  put  it  into  you  DVD  drive,  run  the  installer  by  double-clicking 
setup.exe in the root folder of the installation package. You will see the following screen: 
Depending  on  the  current  system  configuration,  the  next  step  will  be  to  install  some 
modules required by the CST Studio Suite software. If some or all of these requirements 
are already installed, then either some modules or even the entire dialog box may be 
skipped. 
Please press the Install button here to proceed to the actual software installation, which 
will then show the following screen:Next, follow the instructions on the screen, and make sure that you read every screen 
as you advance. We recommend using the Typical setup to ensure that you can access 
all examples which might be of interest to you.
Please  note  that  the  Typical  setup  now  also  includes  the  installation  of  Distributed 
Computing components, which can be activated afterwards. 
Now press Next and then Install.  
Once the installation is completed, the following dialog box appears:If you have a single-PC (node locked) license, skip the next section and continue to the 
Starting CST Studio Suite section. 
IdEM requires separate installation of MATLAB runtime (MCR) 
IdEM is automatically installed through the CST Studio Suite installation, but a separate 
installation  of  MATLAB  runtime  (MCR)  is  required.  Check  if  the  appropriate  Matlab 
Runtime R2018b (9.5) is already installed on your computer by looking in the Control 
Panel under Add/Remove Programs. 
You will get an error message when starting IdEM if the correct MCR is not installed. 
If the required version of the Matlab Runtime is missing: 
  Download the Windows 64-bit version of the Matlab Runtime R2018b (9.5) 
 
from the MathWorks web page by navigating to: 
mathworks.com/products/compiler/mcr/index.html 
Install the MCR by running the MCR_R2018b_win64_installer.exe executable 
file and follow the instructions in the installation wizard. This installation will 
need Administrator rights. 
Please note: IdEM is MCR version-specific and it is tied to the MCR version 9.5 only.
Multiple versions of the MCR can be installed simultaneously on your system. There is 
no need to uninstall previous versions. 
License Server  
The usage of a floating (or  network) license requires a license server running on one 
computer in your network that is accessible to all other computers, which will run CST 
Studio  Suite  software.  The  communication  between  the  license  server  and  the  other 
modules is done via TCP/IP. If you are using a firewall, make sure that the connections 
can be established properly. 
The individual installation of a license server is required only if you are going to use the 
license server on a computer which does not have the CST Studio Suite Program Files 
component installed on it. The Typical installation of the software package will always 
include the license server. If you already installed CST Studio Suite simulation software 
and the license server, skip the installation step and continue with the configuration of 
the license server. 
License Server Installation 
Installing the license server on a particular computer is easy. Simply run the installation 
program as shown on the previous pages and select License Server as installation type.  
License Server Configuration 
After  the  license  server  installation  is  completed,  you  need  to  configure  the  license. 
Access the CST Studio Suite modules from within the CST Studio Suite 2023 folder in 
the Windows Start menu. This folder contains an entry named CST License Manager. 
Select this entry to start the License Server control panel:Now press the New License File button. As a later step, you will be prompted to browse 
for the license file, which you should have received by email. Once properly selected, 
the new license file will be automatically copied to the correct location. Then you need 
to press the Start Service button to start the license server. The Licenses available on 
local server list will display a summary of currently available licensed features.
The  following  picture  shows  an  example  of  how  the  dialog  box  should  look  after  the 
license has been set up successfully: 
Please note: This dialog box also allows you to obtain information about who is currently 
using a particular license by pressing the Active Licenses button. 
Automated Installation 
For an automated and silent installation with default settings use the following command: 
start /wait setup.exe /s /v"/l*v C:\InstallCST.log REBOOT=REALLYSUPPRESS /qn 
More information on this topic is provided in QA00000062498.  
Starting the CST Studio Suite Software 
When you start the CST Studio Suite software for the first time or whenever the license 
has expired, a dialog box will appear:The following steps are slightly different depending on whether you are going to use a 
node locked or floating license. 
Node Locked License 
To install a node locked license, click the Import a CST license file option in the Specify 
License dialog box as shown above. Pressing the … button will then allow you to specify 
the location of the license file, which you should have received by e-mail. After pressing
OK, the license file will be automatically copied to the correct location, and you can start 
using the software. 
Floating License Using a License Server 
A  floating  license  requires  a  license  server  running  on  one  of  the  computers  in  your 
network.  We  assume  that  you  have  already  set  up  your  license  server  correctly  by 
following the instructions in the License Server section above. If not, please install the 
license server now before continuing with the next steps. 
For  floating  licenses,  you  can  choose  between  a  Flexnet-based  and  a  DSLS-based 
license server. If you select Point to an existing Flexnet-based CST Studio Suite license 
server system, the dialog box will then appear as follows: 
The only setting you need to specify here is the name of your license server in the Server 
field. The Port field optionally allows you to specify the license server’s TCP/IP port. By 
default,  the  port  will  be  detected  automatically,  so  you  can  normally  keep  the  default 
setting. Pressing OK will then store this setting and you can use the software. The DSLS-
Chapter 3 – User Interface 
After  successfully  installing  the  software,  remember  to  log  in  as  standard  user  rather 
than keeping administrator privileges for security reasons. 
Start  the  application  by  selecting  the  CST  Studio  Suite  entry  in  the  Windows  Start 
menu’s CST Studio Suite 2023 folder. You will see the main window of the CST Studio 
Suite user interface:If no project is open, this is the default view of the application. You can activate it at any 
time by selecting the File tab. 
On the left pane you have direct access to typical file related options like Open, Save, 
Print  and  Help.  In  addition  to  those  standard  controls,  the  following  four  pages  are 
provided: 
  Project: The Project page gives a brief overview of the currently active project 
and offers project related operations like Archive As or quick access to the project 
folder in the windows explorer. Please note: you can access this page only if a 
project is loaded. 
  New and Recent: The New and Recent page is the central place to a start a new 
project or quickly load one of the recent projects. 
  Component  Library:  On  the  Component  Library  page  you  can  manage  and 
share your reusable projects with your colleagues. For more information about 
the Component Library please refer to the online help system. 
  Manage Libraries: Manage additional packages that can you download from the 
same location where you get the main installer. 
Please  note:  The  button  Connect  to  3DEXPERIENCE 
the 
3DEXPERIENCE  platform  is  already  installed  on  your  system.  In  this  case,  you  can 
easily open projects or import CAD geometry from the platform.  
is  available, 
if
License Management  
Open the License Management dialog box by choosing File: License: 
The tree view shows a list of all potentially available features along with the number of 
licenses and their respective expiration date. Moving the mouse over one of the features 
shows a tool tip containing more information concerning the respective feature.  
Other text fields in the dialog box show the currently used License server and License 
server port as well as the Host ID. 
In case of a node locked license, you can also update the license file by pressing the 
License  button.  If  you  are  using  a floating  license,  we  recommend  using  the  License
Automatic Software Updates 
The automatic software update system helps you to keep your installation of CST Studio 
Suite up-to-date. 
Please  note:  Some  virus  scanning  tools  can  interfere  with  the  automatic  updating 
system.  We  strongly  recommend  either  to  turn  off  virus  scanners  while  installing  an 
update or to exclude the CST Studio Suite installation directory and its sub-directories 
from virus scanning. 
By  default,  the  system  is  configured  in  such  a  way  that  it  frequently  checks  on  the 
internet for new updates. You can change this by choosing File: Options  Automatic 
Updates:Here  you  can  specify  the  Update  mode  (Update  from  internet,  Update  from  local 
directory, No automatic updates) and optional proxy server information. The latter may 
be necessary if you need to provide authentication information when opening an internet 
connection. 
We strongly recommend using the automatic software updates in order to stay up-to-
date with the latest improvements of the software. Please refer to the online help system 
for more information about the software update system.
Version Information 
Sometimes the technical support team will ask you which software version you have. 
You can easily find this information by selecting File: Help: 
Opening a Project 
Use the File: Open command to open an existing project:Here you can select a project file with the extension .cst.  
If you want to open a project, which you have used recently, just activate File: New and 
Recent and select the project from the list of recent projects.
Creating a New Project 
Create a new project by clicking on the New Template button in the New and Recent 
page. This will start the template wizard, which guides you through a series of questions 
in order to specify the application area of your new project. 
This  ensures  that  the  appropriate  module  starts  automatically.  In  addition,  all  project 
settings are set correctly for the particular type of device you want to analyze. These 
settings are also stored as a project template for later use. Just click on this template in 
the list of project templates whenever you want to create another project of the same 
type.Besides the Template Wizard, you can use the buttons in the Modules and Tools group 
to create a new project. The Tools buttons offer quick access to additional applications. 
Now we want to create a new project. Press the button File: New and Recent  New 
Template to start the template wizard.
For this introduction, we do not rely on any specific project settings, so just select MW 
&  RF &  OPTICAL  and  Antennas  and  press  the  Next  button  multiple times  without  any 
change. In this document, we just introduce the common steps needed when using this 
wizard for project creation. Please refer to the other CST Studio Suite documents for 
more  details.  At  the  end  of  the  project  definition,  you  can  verify  your  choices  on  the 
summary page. On this page, change the name of the project template, if needed:Finally press the Finish button to start the appropriate module. In this case, this is the 
high frequency module CST Microwave Studio. 
Overview of the User Interface 
This section explains the controls and commands of CST Microwave Studio. Since the 
user  interface  concept  of  CST  EM  Studio,  CST  Particle  Studio,  and  CST  MPhysics 
Studio are identical, it should be straightforward to follow the explanations below in case 
you are using any one of these modules.
After the module has started, you will see the user interface of CST Microwave Studio. 
Now let us have a closer look at the various user interface elements: 
Navigation
Tree 
Active Project 
Schematic 
3D 
Ribbon 
Context Menu 
Drawing Plane 
Status Bar 
Parameter List, 
Result Navigator 
Messages, 
Progress 
Ribbon 
The Ribbon command bar organizes all user interface controls in a series of tabs. It is a 
replacement for the classical menus and toolbars: 
Quick Access Toolbar 
Tab 
Contextual Tab 
Search 
HelpGroup 
All commands in a Ribbon tab are organized in groups, which are labeled. Besides 
tabs and groups, the Ribbon consists of: 
  A  Quick  Access  Toolbar.  This  is  a  small  customizable  toolbar  that  displays 
frequently used commands. 
  Core  tabs  are  the  tabs,  which  are  always  visible. When  switching  from  3D  to 
Schematic  the  core  tabs  change,  because  each  mode  has  its  own  set  of 
individual controls. 
  Contextual tabs are activated only when a particular object is selected or special 
view is active. 
  The  File  tab  consists  of  a  set  of  commands  related  to  file  handling.  General 
application options and additional help can also be found here. 
  A Search field to quickly find commands, examples or search in the help.
  A Help 
 button to access the online help and the support account. In addition, 
the Quick Start Guide can be started here if a CST Microwave Studio project or 
a project of a similar type is active. 
  The Minimize the Ribbon (Ctrl+F1)
button can be used to hide all the Ribbon 
groups. Instead, only the tab labels are permanently visible. 
Use File: Options  Customize Ribbon to create your own tabs or add additional buttons 
or groups to the predefined tabs. 
A Ribbon tab can contain three different types of buttons:Push Button 
Menu Button 
Split Button 
  A Push button simply performs an action or switches a certain state. 
  The Menu button offers a set of choices, but does not directly trigger an action. 
  The Split button is a combination of the two other types. It shows a menu when 
clicking  on  the  lower  part  of  the  button.  If  the  upper  part  is  used,  the  default 
action of the control is performed. 
Other User Interface Elements 
Active Project: Use the tabs at the top of the central main window to switch between 
the currently loaded projects. 
Navigation Tree: The navigation tree is an important part of the user interface.  Here 
you can access structural elements as well as simulation results.
Context  Menu:  The  context  menus  are  a  flexible  way  of  accessing  frequently  used 
menu commands for the current context. The content of this menu (which can be opened 
by pressing the right mouse button) changes dynamically. 
Drawing Plane: Use the drawing plane to sketch the 2D part of 3D geometry. As the 
mouse  is  only  a  2D  locator,  even  when  defining  3D  structures,  the  coordinates  are 
projected onto the drawing plane in order to specify a 3D location. Since you may change 
the location and orientation of the drawing plane by means of various tools, this feature 
makes the modeling very powerful. 
3D, Schematic and Assembly: With the tabs at the bottom of the central main window 
you  can  switch  between  the  3D  modeling,  the  Schematic  and  the  Assembly  view. 
Besides  these  main  views,  you  also  have  access  to  additional  temporary  views,  e.g. 
results. The user interface for the Schematic and the Assembly view is explained in the 
CST Studio Suite - Circuit Simulation and SAM documentation. 
Parameter  List:  The  parameter  list  window  displays  a  list  of  all  previously  defined 
parameters together with their current values. 
Result Navigator: The result navigator window displays a list of all previously calculated 
parametric results. It allows you to browse all results available within the current result 
view. 
Messages and Progress: The messages window displays information text (e.g. solver 
output)  whenever  applicable.  In  the  progress  window,  a progress bar  is displayed  for 
every running simulation, even if another project is currently active. 
Status Bar: The status bar provides some useful information about the current project 
settings. You can click on the text for direct access to these values. In addition, you can 
alter  how  you  manipulate  the  view  with  the  mouse.  The  different  mouse  modes  are 
explained later in this document. 
Next Steps 
Now that you have been introduced to some basic concepts of CST Studio Suite, the 
next step in becoming familiar with the software is to carefully study the module specific 
manuals depending on the product you are planning to use. 
For simulations which are using CST Microwave Studio, CST EM Studio, CST Particle 
Studio,  CST  Cable  Studio,  or  CST  MPhysics  Studio  we  also  strongly  recommend
Chapter 4 – Structure Modeling 
CST Microwave Studio, CST EM Studio, CST Particle Studio, and CST MPhysics Studio 
share a common structure-modeling tool. The main purpose of this chapter is to provide 
an overview of the structure modeler’s many capabilities. Read this chapter carefully, as 
this is a fast and easy way to learn how to use the software efficiently. 
Please note: Most parts of this chapter are also part of the online help Getting Started 
Video. 
Create and View Some Simple Structures 
The  following  section  deals  with  the  procedure  of  creating  a  simple  structure.  Many 
complex structures are composed of very simple elements, or so called primitives. In the 
following, we will draw one such primitive, a brick. 
Create a First Brick 
1.  Use the Modeling tab and activate the Brick tool by using Modeling: Shapes  Brick 
. You are able to select the first point of the brick’s base in the drawing plane .  
2.  You may set a starting point by double-clicking a location on the drawing plane.  
3.  Now you can select the opposite corner of the brick’s base on the drawing plane by 
double-clicking on it. 
4.  Next, define the height of the brick by dragging the mouse. Double-click to fix the 
height of the brick. 
5.  Finally,  a  dialog  box  will  open  showing  the  numerical  values  of  all  coordinate 
locations  you  have  entered.  Click  OK  to  store  the  settings  and  create  your  first 
primitive! 
The  following  picture  gives  an  overview  of  the  three  double-clicks  used to  define  the 
brick:Point 1 
Point 2 
Point 3 
Before we continue drawing other simple shapes, let us spend some time on the different 
methods of setting a point.  
The  simplest  way  to set  a  point  is to  double-click  its  location  in the  drawing  plane as 
above. However, in most cases the structure coordinates have to be entered with high 
precision.  In  this  case,  the  snap-to-grid  mode  should  be  activated.  You  will  find  the
corresponding  option  dialog  box  under  View:  Visibility   Working  Plane   Working 
Plane Properties. The following dialog box will appear: 
Here you may specify whether the mouse coordinates should Snap to a raster (which is 
the  default)  or  not.  Furthermore,  you  may  specify  the  raster  Snap  width  in  the 
corresponding field. The raster Width entry influences only the size of the raster, which 
is drawn on the screen. The coordinate mapping is independent of this setting. 
Please note that selecting the Help button in a dialog box always opens a help page 
containing more information about the dialog box and its settings. 
Another  way  to  specify  a  coordinate  is  to  press  the  Tab  key  whenever  a  location  is 
expected. In this case, a dialog box will appear in which you may numerically specify the 
location. The following example shows a dialog box that appears when the first point of 
a shape must be defined: You may specify the position either in Cartesian or in Polar coordinates. The latter type 
is measured from the origin of the coordinate system. The Angle is between the x-axis 
and the location of the point, and the Radius is the point’s distance from the origin.  
When the first point has been set, the Relative option will be available. If you check this 
item, the entered coordinates are no longer absolute (measured from the origin of the 
coordinate system) but relative to the last point entered. The coordinate dialog boxes 
always show the current mouse location in the entry fields. However, often a point should 
be set to the center of the coordinate system (0, 0). If you press Shift+Tab, the coordinate 
dialog box will open with zero values in the coordinate fields. 
The third  way  to  enter  accurate coordinates  is  by  clicking  estimated  values  using the 
mouse and then correcting the values in the final dialog box. You may skip the definition 
of points using the mouse at any time by pressing the Esc key. In this case, the shape 
dialog box will open immediately.
Pressing the Esc key twice aborts the shape generation. Pressing the Backspace key 
deletes  the  previously  selected  point.  If  no  point  has  been  selected,  the  shape 
generation will also be aborted. 
Please note that another mode exists for the generation of bricks. When you are asked 
to pick the opposite corner of the brick’s base, you may also specify a line rather than a 
rectangle. In this case, you will be asked to specify the width of the brick as a third step 
before specifying the height. This feature is quite useful for construction tasks such as 
building a microstrip line centered on a substrate. 
To  facilitate  this,  a  feature  exists  which  allows  the  line  definition  to  be  restricted  to 
orthogonal movements from the first selected point. Simply hold down the shift key and 
move the mouse to define the next point. 
An Overview of the Basic Shapes Available 
The following picture gives a brief overview of all basic shapes that can be generated in 
a similar way to the brick (as described above). 
Sphere  
Cylinder  
Torus  
Cone 
RotationBrick  
Elliptical 
Cylinder  
Extrude  
At  this  stage,  you  should  play  around  a  bit  with  the  shape  generator  to  familiarize 
yourself  with  the  user  interface.  Use  the  shape  creation  tools,  which  are  located  in 
Modeling: Shapes. 
Select Shapes 
After a shape is defined, it is automatically cataloged in the navigation tree. You can find 
all  shapes  in  the  Components folder.  If  you  open  this folder,  you  will  find  a  subfolder 
called component1, which contains all defined shapes. The name for each primitive is 
assigned in the final shape dialog box when the shape is created. The default names 
start with “solid” followed by an increasing number: solid1, solid2, etc. 
You may select a shape by clicking on the corresponding item in the navigation tree. 
Note that after you select a shape, it will be displayed opaquely while all others will be 
drawn transparently . This is how the modeler visualizes shape
selection. A shape can also be selected by double-clicking on it in the main window. In 
this case, the corresponding item in the navigation tree will also be selected. Holding 
down the Ctrl key, while double-clicking a shape in the main view, allows you to select 
multiple shapes. You may also select ranges of shapes in the navigation tree by holding 
down the Shift key while clicking on the shapes’ name. 
Another  powerful  way  to  select  multiple  shapes  is  the  Rectangle  Selection  feature. 
Choose  View:  Selection   Rectangle  Selection  and  define  a  rectangular  area  in  the 
main view by clicking and dragging with the mouse. All shapes within this rectangle are 
selected.  Take  a  few  seconds  to  familiarize  yourself  with  the  shape  selection 
mechanism. 
solid1 
solid2You may change the name of a shape by selecting it and choosing Modeling: Edit  
Rename/Change   Rename  (F2).  You  can  then  change  the  name  of  the  shape  by 
editing the item text in the navigation tree. 
Group Shapes into Components and Assign Material Properties 
Now that we have discussed how to select an object, we should spend some time on 
the  grouping  of  shapes  into  components.  Each  component  is  a  subfolder  of  the 
Components folder in the navigation tree. Each individual component folder can contain 
an  arbitrary  number  of  shapes.  The  purpose  of  the  component  structure  is  to  group 
together  objects,  which  belong  to the  same  geometrical  component,  e.g.  connectors, 
antennae,  etc.  This  hierarchical  grouping  of  shapes  allows  simplified  operations  on 
entire components such as transformations (including copying), deletions, etc. 
You  can  change  the  component  assignment  of  a  shape  by  selecting  the  shape  and 
choosing Modeling: Edit  Rename/Change  Change Component (you find the option 
Change Component also in the context menu when a shape is selected). The following 
dialog box will open:
In this dialog box, you can select an existing component from the list or create a new 
one by simply typing its name in the edit field. You may also select [New Component] 
from  the  list.  In  the  latter  case,  the  newly  created  components  will  be  automatically 
named as component1, component2, etc. 
The  component  assignment  of  a  shape  has  nothing  to  do  with  its  physical  material 
properties.  In  addition  to  its  association  with  a  particular  component,  each  shape  is 
assigned to a material that also defines the color for the shape’s visualization. In other 
words, the material properties (and colors) do not belong to the shapes directly, but to 
the corresponding material. This means that all shapes made of a particular material are 
represented with the same color.  
To change the material properties or the color of an individual shape you can assign it 
to another material. This can be done by dragging the solid in the navigation tree to the 
target material or vice versa: 
Another method is to select the shape and choose Modeling: Materials  New/Edit  
Assign  Material  and  Color  (this  option  is  also  available  in  the  context  menu  of  the 
selected shape). The following dialog box will open:In this dialog box, you may select an existing material from the list or define a new one 
by selecting the item [New Material…] from the list. In the latter case, another dialog box 
will open:
In this  dialog  box,  you  have  to  specify  the  Material  name  and the  Material  type  (e.g. 
perfect electric conductor (PEC), normal dielectric (Normal), etc.). Note that the available 
material  types  as  well  as  the  corresponding  options  depend  on  the  currently  used 
module. You can also change the color of the material by clicking the Color button. Use 
the Material folder field to arrange the materials in different sub folders. After clicking the 
OK  button,  the  new  material  is  stored  and  appears  in  the  Materials  folder  in  the 
navigation tree. Selecting a particular material in the navigation tree also highlights all 
shapes that belong to this material. All other shapes will then be drawn transparently. 
In  order  to simplify  the  definition  of  frequently  used  materials,  a material  database  is 
available. Before you use a material definition from the available database, you have to 
add it to the current project by selecting Modeling: Materials  Material Library  Load 
from Library. This operation will open the following dialog box displaying the contents of
You may select an existing material from the list and click the  Load button to add the 
material  definition  to  the  Materials  folder  in  the  navigation  tree.  Once  the  material  is 
available in this folder, it can be used in the current project. You can also add a material 
that has been defined in the current project to the database by selecting the material in 
the navigation tree and then choosing Modeling: Materials  Material Library  Add to 
Library. 
Change the View 
So  far,  we  have  created  and  viewed  the  shapes  by  using  the  default  view.  You  can 
change  the  view  at  any  time  (even  during  shape  generation)  using  some  simple 
commands  as  explained  below.  The  view  will  change  whenever  you  drag  the  mouse 
while holding down the left button, according to the selected mode. You can select the 
mode by choosing View: Mouse Control  Zoom / Pan / Rotate / Dynamic Zoom / Rotate 
in Plane or by selecting the appropriate item from the status bar:Zoom  Pan  Rotate  Dynamic 
Zoom 
Rotate 
in 
Plane 
The mode setting affects the behavior as follows: 
  Zoom: In this mode, a zoom window can be defined by dragging the mouse. After 
you  release  the  left  mouse  button,  the  zoom  factor  and  the  view  location  will  be 
updated so that the rectangle fills up the main window. 
  Pan: The structure will be translated in the screen plane following the mouse cursor 
movement. 
  Rotate: The structure will be rotated around the two screen axes. The center of the 
rotation  will  be  the  point  on  the  structure  where  the  mouse  button  was  pressed, 
indicated by a red mark. If the selected location is outside the structure, the bounding 
box center point will be used as rotation center. 
  Dynamic  Zoom:  Moving  the  mouse  upward  will  decrease  the  zoom  factor  while 
moving the mouse downward will increase the zoom factor. 
  Rotate in Plane: The structure will be rotated in the screen’s plane. 
The dynamic view-adjusting mode ends when you release the left mouse button. You 
can reset the zoom factor by choosing View: Change View  Reset View (Space) or 
from  the  context  menu.  Press  View:  Change  View    Reset  View  to  Selection 
(Shift+Space) to zoom to the currently selected shape rather than the entire structure. 
Since changing the view is a frequently used operation that will sometimes be necessary 
even during the process of interactive shape creation, some useful shortcut keys exist. 
Press the appropriate keys, and drag the mouse while pressing the left button: 
  Ctrl: Same as “rotate” mode 
  Shift: Same as “plane rotation” mode 
  Shift +Ctrl: Same as “pan” mode 
A mouse wheel movement has the same effect as the Dynamic Zoom. By default, the 
origin  for  this  operation  is  located  at  the  current  mouse  pointer  location.  Optionally, 
pressing the Ctrl key while using the mouse wheel performs a zoom operation around 
the  center  of  the  screen.  This  behavior  can  be  altered  by  changing  Zoom  to  mouse 
cursor in File: Options  Preferences  User interface settings.
In  addition  to  the  options  described  above,  some  specific  settings  are  available  to 
change the visualization of the model. 
Axes (View: Visibility  Axes, Ctrl+A): This view option toggles the coordinate system 
visibility: 
 
Working plane (View: Visibility  Working Plane 
may specify whether the drawing plane is visible or not. 
, Alt+W): With this view option you 
 
Wireframe (View: Visibility  Wire Frame 
shapes are displayed as simple wire models or as solid shaded objects. 
, Ctrl+W): This option indicates whether all 
 
To change the colors of the scene or other specific view settings use View: Options  
View Options 
. 
Apply Geometric Transformations 
So far, you have seen how to model simple shapes and how to change the view of your 
model. This section focuses on applying geometric transformations to your model.  
We assume that you have already selected the shape (or multiple shapes) to which a 
transformation will be applied (e.g. by double-clicking on a shape in the main view). 
You  can  then  open  the  transformation  dialog  box  by  choosing  Modeling:  Tools   
Transform 
 or by choosing the item Transform from the context menu. In the dialog 
box, you are asked to select one of the following transformations: 
  Translate: This transformation applies a vector translation to the selected shape. 
  Scale:  By  choosing  this  transformation,  you  can  scale  the  shape  along  the 
coordinate  axes.  By  unchecking  Scale  uniform  you  may  specify  different  scaling
  Rotate: This transformation applies a rotation of the shape around a coordinate axis 
by a fixed angle. You may additionally specify the rotation center in the Origin field 
(click  on  More  if  the  option  is  not  immediately  available).  The  center  may  be  the 
center  of  the  shape  (calculated  automatically)  or  any  specified  point.  Specify  the 
rotation angle and axis settings by entering the corresponding angle in the entry field 
for the corresponding axis (e.g. entering 45 in the y field while leaving all other fields 
set to zero performs a rotation around the y-axis of 45 degrees). 
  Mirror: This transformation allows one to mirror the shape at a specified plane. A 
point in the mirror plane is specified in the Mirror plane origin field, and the plane’s 
normal vector is given in the Mirror plane normal input field. 
For all transformations above you may specify whether the original shape should be kept 
(Copy option) or deleted. Furthermore, you can specify in the Repetition factor field how 
many times the same transformation will be applied to the shape (each time producing 
a new shape when the Copy option is active). Once a particular type of transformation 
is  selected,  corresponding  handles  will  be  visualized  in  the  main  view.  The  actual 
transformation parameters can either be specified by entering numerical values in the 
input fields or by just dragging the handles with the mouse. Please note that you may 
need to press the More button in order to see all input fields. 
A final example will demonstrate the usage of the transformation feature. Assume that 
a brick has been defined and selected as depicted below. Open the transform dialog 
box  by  choosing  the  appropriate  item  from  the  context  menu  or  Modeling:  Tools  
Transform
Now the screen should look as follows: 
The next step is to apply a translation to the shape by setting a translation vector (7, 0, 
0), and to produce multiple copies as the transformation is applied twice. You can either 
enter the values into the dialog box or use the mouse and drag & drop the golden arrows 
in the main view:After pressing the OK button, you should finally obtain the following shapes: 
Solid1 
Solid1_1 
Solid1_
Note that for each transformation the name of the transformed shape is either kept (no 
Copy  option)  or  extended  by  extensions  _1,  _2,  etc.  to  obtain  unique  names  for  the 
shapes. 
Combine Shapes Using Boolean Operations 
Probably the most powerful operation to create complex shapes is to combine simple 
shapes using Boolean operations. These operations allow you to add shapes together, 
to subtract one or more shapes from another, to insert shapes into each other, and to 
intersect two or more shapes. 
Let  us  consider  two  shapes  –  a  sphere  and  a  brick  –  on  which  we  need  to  perform 
Boolean operations.  
This list names all available Boolean operations and shows the resulting body for each 
combination: 
Add brick to sphere 
Add both shapes together to obtain a 
single shape. The resulting shape will 
assume  the  component  and  material 
settings of the first shape. 
Subtract sphere from brick 
Subtract  the  second  shape  from  the 
first  to  obtain  a  single  shape.  The 
resulting  shape  will  assume 
the 
component  and  material  settings  of 
the first shape. 
Intersect brick and sphere 
Intersect two shapes to form a single 
shape.  The 
resulting  shape  will 
assume  the  component  and  material 
settings  from  the  first  shape  of  this 
operation. 
Trim sphere 
= Insert brick into sphere 
The first shape will be trimmed by the 
boundary  of  the  second  shape.  Both 
shapes  will  be  kept.  The  resulting 
shapes  will  have  no 
intersecting 
volume.
Insert sphere into brick 
= Trim brick 
The second shape will be inserted into 
the first one. Again both shapes will be 
kept.  The  resulting  shapes  will  have 
no intersecting volume. 
Note that not all of the Boolean operations  above are directly accessible. As you can 
see, some of the operations are redundant (e.g., a trimming operation can be replaced 
by an insertion operation when the order of the shapes is reversed). 
You can access the following Boolean operations by choosing the corresponding items: 
Modeling:  Tools    Boolean    Add  /  Subtract  /  Intersect  /  Insert.  Operations  are 
accessible only when a shape is selected (in the following referred to as “first” shape). 
After  the  Boolean  operation  is  activated,  you  will  be  prompted  to  select  the  “second” 
shape. Pressing the Return key performs the Boolean combination. The result depends 
on the type of Boolean operation: 
  Add  (+) 
:  Add  the  second  shape  to  the  first  one  –  keeps  the  component  and 
material settings of the first shape. 
  Subtract  (-) 
:  Subtract  the  second  shape  from  the  first  one  –  keeps  the 
 
 
component and material settings of the first shape. 
Intersect (*) 
and material settings of the first shape. 
Insert (/) 
changing the first shape only. 
: Intersect the first with the second shape – keeps the component 
: Insert the second shape into the first one – keeps both shapes while 
The trim operations are only available in a special “Shape intersection” dialog box which 
appears when a shape is created that intersects or touches areas with existing shapes. 
This dialog box will be explained later. 
When multiple shapes are selected, you can access the Boolean add operation to unite 
all selected shapes. You can also select more than one shape when you are prompted 
to specify the second shape for Boolean subtract, intersect or insert operations. 
Pick Points, Edges, or Faces from within the Model 
Many construction steps require the selection of points, edges, or faces from the model. 
The following section explains how to select these elementary entities interactively. For 
each  of  the  “pick  operations”,  you  must  first  select  the  appropriate  pick  tool  e.g. 
Modeling: Picks  Picks. 
Pick points, 
edges or 
faces 
Pick edge 
center 
Show point 
pick list 
Clear picks 
After  you  activate  a  pick  tool,  the  mouse  cursor  will  change  indicating  that  a  pick 
operation is in progress. In addition, all pickable elements (points, edges, or faces) will 
be  highlighted  in  the  model.  Now  you  can  double-click  on  an  appropriate  item. 
Alternatively, you can cancel the pick mode by pressing the Esc key.
Note:  You  cannot  pick  edges  or  faces  of  a  shape  when  another  shape  is  currently 
selected. In this case, you should either select the proper shape or deselect all 
shapes. 
As soon as you double-click in the main view, the pick mode will be terminated and the 
selected item will be highlighted. Note that if the Modeling: Picks  Picks  Keep Pick 
Mode option is activated, the pick operation will not terminate after double-clicking. In 
this case you have to cancel the pick mode by pressing the Esc key. This mode is useful 
when multiple items have to be selected and it would be cumbersome to re-enter the 
pick mode several times. 
The following  list gives an  overview  of  the  available  pick modes. Whenever  the main 
structure  view  is  active,  keyboard  shortcuts  (listed  in  parentheses)  can  be  used  to 
activate a particular pick mode. The main structure view can be activated by left clicking 
once on the main drawing window. 
  Pick Points 
  Pick  End  Point  (P) 
:  Double-click  close  to  the  end  point  of  an  edge.  The 
corresponding point will be selected. 
  Pick Edge Center (M) 
: Double-click on an edge. The mid-point of this edge 
will be selected. 
  Pick Circle Center (C) 
: Double-click on a circular edge. The center point of 
this edge will be selected. The edge need not necessarily belong to a complete 
circle. 
  Pick  Point  on  Circle  (R) 
:  Double-click  on  a  circular  edge.  Afterward  an 
arbitrary  point  on  the  circle  will  be  selected.  This  operation  is  useful  when 
matching radii in the interactive shape creation modes. 
  Pick Face Center (A) 
: Double-click on a planar face of the model. The center 
point of this face will be selected. 
  Pick Point on Face (O): Double-click on a point on the model to select it. 
  Picks 
  Pick  Points,  Edges,  or  Faces  (S) 
:  Double-click  close  to  an  edge,  an  end 
point of an edge, or a face. The corresponding item will be selected.: Double-click on a face of the model to select it. 
  Pick Face (F) 
  Pick Face Chain (Shift+F): Double-click on a face of the model. This function 
will automatically select all faces connected to the selected face. The selection 
stops at previously picked edges, if any. 
  Pick Similar  Faces (Ctrl+Shift+S) 
:  Pick face  or faces  which are  similar  to 
already picked face or faces. If the number of picked faces is less than ten, this 
option will pick faces similar to already picked faces. If the number of picked faces 
is more than ten, this option will enable the interactive pick mode. Hovering with 
the mouse over a face, will highlight all other similar faces in that shape, double- 
click will select all highlighted faces. 
  Pick  Faces by  Rectangle  Selection  (Ctrl+F):  Pick  all faces  within a  selected 
area. Start to drag a rectangle containing all faces of solids you want to pick. Only 
faces  are  selected  that  are  completely  within  the  given  rectangle.  You  may 
change this behavior by using the Shift-Key during dragging the rectangle. Now 
every face that is touched by the rectangle will be selected. This feature is limited 
to the visible parts of faces. 
: Double-click on an edge of the model to select it. 
  Pick Edge (E) 
  Pick Edge Chain (Shift+E): Double-click on an edge of the model. If the selected 
edge  is  a  free  edge,  a  connected  chain  of  free  edges  will  be  selected.  If  the 
selected edge is connected to two faces, a dialog box will appear in which you 
can specify which one of the two possible edge chains bounding the faces will be
selected. In both cases, the selection chain stops at previously picked points, if 
any. 
  Pick Blend, Pick Protrusion and Pick Depression: Allows selection of multiple 
faces at once which represent an individual feature: 
     Pick Blend            Pick Protrusion 
 Pick Depression 
The pick operations for selecting points from the model are also valid in the interactive 
shape  creation  modes. Here,  whenever  you  are  requested  to  double-click  in  order  to 
enter the next point, you may alternatively enter the pick mode. After leaving this mode, 
the picked point will be taken as the next point for the shape creation. 
Previously picked points, edges or faces can be cleared by selecting Modeling: Picks  
Clear Picks 
 (D). 
Chamfer and Blend Edges 
One of the most common applications for picked edges is the chamfer and blend edge 
operation. We  assume  you  have  created  a  brick  and  selected  some  of  its  edges,  as 
shown in the following picture:Now you can perform a chamfer edge operation by choosing Modeling: Tools  Blend 
  Chamfer  Edges 
.  In  the  following  dialog  box,  you  can  specify  the  width  of  the 
chamfer. The structure should look similar to the one depicted below: 
Alternatively, you can perform a blend edges operation by choosing Modeling: Tools  
Blend  Blend Edges 
. In the following dialog box, you can specify the radius of the 
blend. The result should look similar to the following picture:
Extrude, Rotate and Loft Faces 
The chamfer and blend tools are common operations on picked edges. Extrude, rotate 
and loft operations are equally typical construction tools for use on picked faces. In the 
following, we assume an existing cylinder with a picked top face: 
Top face 
Now  we can extrude this face by simply selecting  Modeling: Shapes  Extrusions  
Extrude 
. When a planar or cylindrical face is picked before this tool is activated, the 
extrusion refers to the picked face, and the dialog box opens immediately:If no face is picked in advance, an interactive mode will be entered in which you can 
define polygon points for the extrusion profile. However, in this example you should enter 
a height and click the OK button. Finally, your structure should look as follows:
The extrusion tool has created a second shape by extruding the picked face. For the 
rotation, you should start with the same basic geometry as before: 
The rotation tool requires the input of both a rotation axis and a picked face. The rotation 
axis can be a linear edge picked from the model or a numerically specified edge. In this 
example,  you  should specify the  edge  by  selecting  the  Modeling:  Picks   Pick  Edge 
from Coordinates 
. Afterwards you will be requested to pick two points on the drawing 
plane to define the edge. Please select two points similar to those in the following picture:In the numerical edge dialog box, click the OK button to store the edge. Afterward you 
can activate the rotate face tool by selecting Modeling: Shapes  Extrusions  Rotate 
.
The  previously  selected  rotation  axis  is  automatically  projected  into  the  face’s  plane 
(blue vector), and the rotation tool dialog box opens immediately. In this dialog box, you 
can  specify  an  Angle (e.g.  90  degrees)  and  click  OK. The final  shape  should look  as 
follows:Note that the rotate tool enters an interactive polygon definition mode similar to the one 
in the extrude tool if no face is picked before the tool is activated.
One  of  the  more  advanced  operations  is  generating  lofts  between  picked  faces.  To 
practice, construct the following model by defining a cylinder (e.g. radius=5, height=3) 
and transforming it along its axis by a certain translation (e.g. (0, 0, 8)) using the Copy 
option: 
Transformed 
cylinder 
Next select the transformed cylinder and shrink it by applying a scaling transformation 
along the x- and y-axes by 0.5 while keeping the z-scale at 1.0: 
Face A 
Face B 
Now  pick  the  adjacent  top  and  bottom  faces  of  the  two  cylinders  as  shown  above. 
Afterward you can activate the loft tool by selecting Modeling: Shapes  Extrusions  
Loft.  
In the following dialog box you can set the smoothness to a reasonable value and click 
the Preview button to get an impression of the shape. Drag the Smoothness slider such 
that the shape has a relatively smooth transition between the two picked faces before 
clicking OK. 
Note: You should select the corresponding shape before picking its face. Since all other 
shapes become transparent, it is easier to pick the desired face even “through” other
After pressing the OK button, your model should look like the following picture (note that 
the actual form of the lofted shape depends on the setting of the smoothness parameter). 
Face AFace B 
Finally, add all shapes together by selecting all three (holding down the Ctrl key) and 
using the Modeling: Tools  Boolean  Add (+) 
 operation. Now, pick the two planar 
top and bottom faces of the shape. Next, select the shape by double-clicking on it and 
initiate the Modeling: Tools  Shape Tools  Shell Solid or Thicken Sheet 
 tool. 
Note that the shell command will be accessible only if you select a shape. 
In the dialog box, you can specify a Thickness (e.g. 0.3) and click the OK button. Now,
your model should look similar to the following picture: 
Picking the two faces before entering the shell operation has the effect that the selected 
faces will later be openings in the shelled structure. If no faces are selected, the structure 
will be shelled to form a hollow solid. 
Local Coordinate Systems 
The  ability  to  create  local  coordinate  systems  adds  a  great  deal  of  flexibility  to  the 
modeler.  In  the  above  sections  we  described  how  to  create  simple  shapes  that  are 
aligned with the axes of a global fixed coordinate system. 
The aim of a local coordinate system is to allow the easy definition of shapes even when 
they  are  not  aligned  with  the  global  coordinate  system.  The  local  coordinate  system 
consists of three coordinate axes. In contrast to the global x-, y-, and z-axes, these axes 
are called as the u-, v-, and w-axes, respectively. The local coordinate system is also 
known as the Working Coordinate System (WCS). 
Either the local or the global coordinate system is active at any time. Any geometry data 
entered  is  stored  in  the  currently  active  coordinate  system.  You  may  activate  or 
deactivate the local coordinate system with Modeling: WCS  Local WCS 
 or from 
the WCS context menu item. This toggles the local coordinate system on or off. 
The most important operations on the local coordinate system are accessible directly in 
the Modeling tab:Toggle WCS 
on or off 
Transform 
WCS 
Align WCS 
Fix WCS 
The  most  common  way  to  define  the  orientation  of  a  local  coordinate  system  is  by 
selecting Modeling: WCS  Align WCS (W) 
. 
Hovering over the highlighted points, edges, or faces shows a preview of the new WCS. 
This WCS can be activated by double-clicking on the highlighted item:
Another option is to pick points, edges, or faces of the model in advance and align the 
WCS with these items by selecting Modeling: WCS  Align WCS (W) 
: 
  When a point is selected, the origin of the local coordinate system is moved to this 
point.  
  When three points are selected, the u/v plane of the WCS can be aligned with the 
plane defined by these points. Additionally this function will move the origin of the 
WCS onto the first selected point. 
  When  an  edge  is  selected,  the  u-axis  of  the  WCS  may  be  oriented  such  that  it 
becomes parallel to the selected edge.  
  Finally, a planar face can be selected with which the u/v plane of the WCS can be 
aligned. 
Together with the available shortcut keys for the pick mode, this is the most efficient way 
to change the location and orientation of the WCS. 
Besides aligning the WCS with items selected from the model, there are two more ways 
to define the local coordinate system: 
  Define local coordinate system parameters directly (Modeling: WCS  Local 
WCS  Local Coordinate System Properties): In this dialog box, you may enter 
the  origin  and  the  orientation  of  the  w-axis  (denoted  as  Normal)  and  the  u-axis 
directly. 
  Transform local coordinate system (Modeling: WCS  Transform WCS 
): In 
this  dialog  box,  you  can  translate  the  origin  of  the  local  coordinate  system  by  a 
specified translation vector. You can also rotate the local coordinate system around 
one of its axes by a specified rotation angle. 
The second option is especially powerful when combined with the pick alignment options 
described above. 
The following example should give you an idea of what can be done by efficiently using 
local coordinate system specifications: 
The first step is to create a brick in global coordinates. Then rotate the brick around the 
z-axis by 30 degrees using the transform dialog box:
1) 
2) 
Next activate the local coordinate system, and align it first with the top face of the brick 
and then with one of the corner points on the top face: 
3) 
4) 
Now align the coordinate system with one of the edges of the brick’s top face by rotating 
the  coordinate  system  300  degrees  around  its  w-axis,  and  then  rotate the coordinate 
system 30 degrees around its v-axis: 
5) 
6)Finally create a new cylinder in the local coordinate system. As soon as you have defined 
the  cylinder,  a  dialog  box  will  open  asking  for  the  Boolean  combination  of  the  two 
intersecting shapes. In this dialog box, choose Add both shapes and click OK:
7) 
The History List 
Up  to  now,  you  have  created  some  basic  structures  and  performed  some  geometric 
transformations. You can always correct mistakes made during the structure generation 
by using Undo 
 from the Quick Access toolbar to undo the most recent construction 
step. 
However,  sometimes  it  may  become  necessary  to  return  to  a  previous  step  in  the 
structure generation to change, delete, or insert some operations. This typical task is 
supported via the “History List". All relevant structural modifications are recorded in a list 
that can be opened by choosing Modeling: Edit  History List 
. 
In the following, we assume you have created  a structure consisting of a brick and a 
cylinder as shown above. In this case, the history list will look like in the following picture:The list shows all previous operations in chronological order. The markerindicates the 
current position of the structure creation in the history list. You may restore the structure 
creation to any step in the history list by selecting the corresponding line and clicking the 
Run to button. Clicking the Step button will take you to the next step in the history list. 
By  using  the  Continue  button,  the  history  list  is  processed  to  the  end.  You  can  now 
experiment a bit with this feature.  
Clicking the Update button completely regenerates the structure. The Edit button allows 
you to perform changes to previous operations. In this case, select the “rotate wcs” line 
and click the Edit button. The following dialog box will appear:
The  text  in  this  box  is  the  macro  language  command  that  corresponds  to  the  task 
performed  in  the  currently  selected  history  step.  Here,  the  first  argument  “v”  is  the 
rotation axis while the second argument specifies the rotation angle. Try to change the 
rotation angle to 10 degrees and click the OK button. Back in the history list, click the 
Update button to regenerate the structure. Your structure should now look similar to the 
following picture:In general, the history functionality allows you to perform changes to the model quickly 
and easily without having to re-enter the modified structure. However, some care has to 
be  taken  when  history  items  are  altered  since  this  may  result  in  strong  topological 
changes  appearing  in  the  model.  This  often  happens  when  some  history  items  are 
deleted or new items are inserted. In such cases, pick operations might select incorrect 
points, edges, or faces (sometimes because the originally picked items no longer exist).  
As an example, assume you have deleted the creation of the first brick from the history 
list. In this case, the pick of the brick’s top face in order to align the WCS with this face 
will obviously fail. 
In such cases, we recommend you work through the history list from the beginning in 
order  to  properly  adjust the  picks  when needed. Even  in this  extreme case,  the  work 
needed  to  change  the  model  takes  much  less  effort  than  completely  re-entering  the 
model. Please refer to the online documentation for more details. 
The History Tree 
The History Tree is another powerful tool to edit an already existing object. Assume that 
you want to change the radius of the cylinder in the previous example. One way to do
this would be to open the complete history list and edit the history step where the cylinder 
was created. However, you can also select the corresponding shape by double-clicking 
it in the navigation tree and then choosing Modeling: Edit  Properties 
 or Properties 
from the context menu. 
A dialog box (the History Tree) will open, showing the construction history of the selected 
shape: 
You can now simply click the “Define cylinder” item. As soon as you have selected an 
editable  operation  from  the  History  Tree,  the  corresponding  structure  element  will  be 
highlighted in the main view. Please note that subsequent transformations will not be 
considered by this highlighting functionality.  
After clicking the Edit button in the History Tree dialog box, the cylinder creation dialog 
box will open, showing the parameters of the cylinder:You  can  now  alter  the  cylinder  radius  and  click  the  Preview  button.  You  will  get  an 
impression of how the structural changes will influence your model. If you are happy with 
the result, click the OK button to update the structure.
Finally, your model should look as follows: 
Play around a little with the History Tree to get an idea of what changes can be applied 
to the existing structure using this functionality. Note that subsequent transformations 
will not be visualized by the Preview option in the shape dialog box but will be applied 
when you update the model. 
Curve Creation 
The previous chapters showed how a model can be generated from 3D primitives and 
how  they  can  be  modified  by  using  powerful  operations  such  as  blending,  lofting, 
shelling, etc.  
Another complex shape generation option is based on curves. A curve is typically a 2D 
line  drawn  on  the  drawing  plane.  After  a  curve  is  defined,  it  can  be  used  for  more 
advanced modeling operations. 
The following explanations give you only a basic introduction to the way curve modeling 
works.  A  detailed  description  of  all  possibilities  would  exceed  the  scope  of  this 
document. Please refer to the online documentation for more information. 
Before proceeding with the actual curve creation, use File: New and Recent and press
Use Modeling: Curves  Curves  Rectangle 
 to create a new curve item and draw 
a rectangle on the working plane. Creating curve items is similar to constructing solid 
primitives. 
Your result should look as follows: 
Next, draw a circle on the drawing plane, which overlaps with the rectangle. Activate the 
circle  creation  by  choosing  Modeling:  Curves   Curves   Circle 
.  Afterward,  your 
screen should look similar to the following: 
circle1rectangle1 
As a result of the previous steps, you now have two curve items – rectangle1 and circle1 
– in a subfolder named curve1. The navigation tree reflects this relationship. 
Now trim both curve items so that the resulting curve contains only the outlines of both 
curve items. First, select one of the curve items, e.g. rectangle1 (either in the navigation 
tree  or  by  double-clicking  on  it  in  the main view).  Afterward  activate  the  Trim  Curves 
operation by choosing Modeling: Curves  Curves  Trim Curves 
.  
You will be prompted to select the item to be trimmed with the rectangle. Select the circle 
and confirm your selection by pressing the Return key.
The next step will prompt you to double-click on any curve segments you wish to delete 
from  the  model.  When  you  move  the  mouse  across  the  screen,  all  selectable  curve 
segments  at  the  mouse  location  will  be  highlighted.  You  should  now  delete  two 
segments  so  that  the  result  will  look  similar  to  the  following  picture.  Press  Return  to 
complete the operation. 
Now you can activate the local coordinate system and rotate it around its u-axis. Your 
model should look as follows:The next action is to draw an open polygon consisting of three points on the drawing 
plane by using Modeling: Curves  Curves  Polygon 
.
Point 
1 
Point 
2 
Point 
3 
Based on these two disjoint curves, you can create a solid using the sweep curves operation, which can be 
initiated by choosing Modeling: Shapes  Sweep Curve 
: 
As soon as this operation is activated, you will be prompted to select the profile curve. 
Double-click on the curve consisting of the rectangle and the circle.  
After the profile is selected and confirmed by pressing Return key, you will be requested 
to double-click on the path curve given by the polygon’s curve here. After you close the 
resulting dialog box by clicking OK, the final shape should look as follows:This short introduction into curve modeling provides a very basic understanding of these 
powerful structure drawing tools. You should experiment a little with the curve modeling 
features to become more familiar with this kind of structure modeling. Please refer to the 
online documentation for more details.
Trace Creation 
The  next  section  focuses  on  a  rather  tedious  part  of  model  creation:  the  definition  of 
conducting  traces.  Some  structures  (e.g.  printed  circuit  boards)  require  many  traces, 
which often entail many time-consuming construction steps. A trace tool simplifies the 
creation of solid traces with finite width and thickness based on the definition of curves. 
To practice using this powerful tool, draw an open but otherwise continuous curve such 
as the following by selecting Modeling: Curves  Curves  Spline 
: 
Based on this curve, you can now easily create a trace by choosing Modeling: Shapes 
 Trace from Curve 
. As soon as this operation is activated, you will be prompted to 
select the trace’s curve.  
After you double-click on the previously defined curve, the following dialog box will open:In this dialog box, you can specify the metallization Thickness and the Width of the trace. 
You  can  also  specify  whether  the  trace  should  have  rounded  caps  (instead  of 
rectangular caps) at the start or end of the trace’s path. If Delete Curve is checked, the 
original curve will be deleted by the create trace operation. 
The resulting trace might look as follows (rounded cap at the end of the trace only):
Bond Wire Creation 
Since bond wires are frequently used structure elements, a dedicated bond wire tool is 
available.  The  easiest  way  to  define  a  bond  wire  between two points  is  to  pick  those 
points first as shown in the following picture:Once  the  points  are  picked,  you  can  open  the  bond  wire  dialog  box  by  choosing 
Modeling: Shapes  Bond wire 
.
You can also open the dialog box without having picked any points. In this case, you 
may specify the coordinates of the bond wire’s start and end points numerically. 
The  type  of  the  bond  wire  can  be  spline,  JEDEC4,  or  JEDEC5.  The  location  of  the 
spline’s maximum can be specified whereas the other two models accept standardized 
parameters.  
The following picture shows the three different types of bond wires: 
 Spline     
       JEDEC4   
             JEDEC5Please refer to the online documentation for more information about JEDEC parameters. 
You  may  also  assign  a  finite  radius  to the  wire by  specifying  a  non-zero  entry  in  the 
Radius field. The wire will still be modeled as infinitely thin, but the solver module will 
apply a special model to the wire in order to consider the finite radius. Please note, that 
solvers based on a tetrahedral mesh do not support this feature. 
In addition to this option of modeling the bond wire as an infinitely thin wire, the dialog 
box also supports the creation of solid bond wires by offering the Solid wire model option. 
As for every other solid, a solid bond wire needs to have a material assigned to it.  
The Termination of the bond wire can be set to any one of the following types:
  Natural: The wire will be a solid tube with perpendicular cuts at the end. 
  Rounded: The wire will be terminated by a part of a sphere.  
  Extended: This is the most powerful option. In this case, the software detects 
the plane in which the bond wire ends. Then the wire extends toward this plane 
in order to ensure an optimal connection with this plane. 
The following picture illustrates the three types of termination: 
Natural   
Rounded 
     Extended 
Local Modifications 
So far, we have focused on how to change a structure that has been entirely constructed 
within the built-in modeler. However, sometimes the model will consist of an imported 
geometry for which no information about the modeling process is available.  
This section will illustrate that, even in these cases, the structure can be parameterized 
using Local Modifications. To practice using these advanced modeling tools, go ahead 
and create a model similar to the following image (a brick combined with a cylinder and 
a chamfer operation applied to the cylinder’s top edge):In this structure you should first use the pick face tools in order to select the chamfer’s 
face (Modeling: Picks  Picks 
). Then you can initiate the Remove Feature command 
by selecting Modeling: Tools  Modify Locally  Remove Feature (Ctrl+R). 
Chamfer’s 
face 
Remove 
Feature 
As  you  can  see,  the gap  produced  by  simply  removing  the face  will  automatically  be 
closed by the Remove Feature operation. Afterward, pick the cylindrical face and select 
the Modeling: Tools  Modify Locally 
 command. A dialog box will open where you 
can modify the offset of the cylindrical face.
This can be done either by dragging the yellow arrow or by modifying the Offset edit field 
in the dialog box. The yellow arrow appears when the mouse is near the affected face.Press  Apply  to  confirm  the  change.  Now  you  can  select  the  top  face  and  modify  the 
height of the cylinder by dragging the yellow arrow again: 
After pressing the Apply button, the model finally looks like this:
The local modifications are powerful modeling operations. However, the modifications 
will fail if there is no unique solution for closing the gaps. You should play around a bit 
with these tools to get an impression of what is possible. 
Next Steps 
Now you are familiar with the general user interface and the 3D modeling capabilities of 
the software package. Before starting with the following chapter, which is about post-
processing, we recommend that you read the dedicated manual of the module, which is
Chapter 5 – Post-Processing 
Once a simulation is completed, result data will typically be shown in the navigation tree. 
CST Studio Suite contains powerful post-processing capabilities, which include various 
options for visualizing the results and calculating secondary quantities. Please refer to 
the module specific documentation and the online help system for more information. 
Parametric Result Storage 
In order to reduce the effort required for obtaining typical parametric results, all zero and 
one dimensional data points / result curves are stored parametrically by default. In the 
following,  we  will  introduce  this  functionality  briefly.  Please  refer  to  the  online 
documentation for more information. 
For  the  following  explanations,  we  assume  that  your  model  has  a  parameter  “offset’” 
defined  and  that  you  have  performed  multiple  simulations  for  different  values  of  this 
parameter. Furthermore, the examples show the results of an S-Parameter computation 
using  CST  Microwave  Studio,  but  the  concept  is  the  same  for  all  other  solvers  and 
modules. 
Once a computation has finished, selecting a result from the navigation tree will display 
the corresponding result curves for the current parameter values:Further results from all previously calculated parameter values are summarized in the 
Result Navigator window:
Here  you  can  change  the  parametric  result  selection  to  plot  more  results  within  the 
current result view:  
The Result Navigator offers an advanced filtering functionality to reduce the number of 
displayed results based on desired parameter values or plotted  0D results. Changing 
the selection in the navigation tree allows you to inspect other results based on the active 
parameter combination selection. 
The parametric plotting functionality allows for convenient access of typical parametric 
results  without  the  need  for  further  setting  up  more  advanced  post-processing 
operations.  The  automatically  stored  parametric  results  can  also  be  used  directly  for 
optimizations. Please refer to the online documentation for more information. 
Another very powerful feature, which is common to all modules of CST Studio Suite is 
the  concept  of  Post-Processing  Templates  which  will  be  introduced  in  the  following 
sections. 
Post-Processing Templates 
The  Post-Processing  Templates  allow  for  flexible  processing  of  2D/3D  Fields,  1D 
Signals, or scalar values (0D Results). 
All  defined  Post-Processing  Templates  are  evaluated  after  every  calculation  during 
parametric sweeps and optimizations. The calculated data is then stored parametrically 
to allow for flexible access to the entire data set. 
Typical examples for Post-Processing Templates are 1D results such as the following:  Z, Y versus frequency 
  Farfield 1D plots at a single frequency 
  Broadband farfield values 
  Group delay times 
  1D Plots of 2D/3D results along arbitrary curves 
  FFT of existing time signals 
  Exchange excitations and TDR functionality 
  Mixture of any of these 1D-results using an analytic formula 
  and more…
or 0D results (single real scalar values): 
  Min, max, mean, integral, and other values of existing 1D-results 
  Q-values, energies, losses, coupling coefficients of eigenmodes 
  Curve-, face-, or volume integrals of 2D/3D results 
  Mixture of any of these 0D-results using an analytic formula 
  and more… 
The following sections introduce the framework of this feature and present its application 
with an example. 
Framework to set up Result Templates 
The following picture shows the template-based post-processing dialog box, which can 
be opened by choosing Post-Processing: Result Templates  Template Based Post-
Processing 
 (Shortcut Shift+P):The list contains the currently defined sequence of post-processing tasks. You can add 
new tasks to the list by first selecting a template group and then selecting a particular 
item from the drop-down list below. The Type field indicates whether the result of a post-
processing task is a one-dimensional curve (1D) or a single data point (0D). 
You can easily rename a task by clicking on the corresponding line and directly changing 
its name in the list. 
If the currently selected task provides a settings dialog box, pressing the Settings button 
will open that box and allow you to change template parameters. 
Clicking the Duplicate button creates a copy of the currently selected item. Some post-
processing  operations  require  many  settings.  However,  most  of  the  time  one  is  only 
interested  in  investigating  the  results,  which  depend  on  varying  parameters,  leaving 
most  of  the  settings  unchanged.  In  such  a  case,  instead  of  repeatedly  entering  all 
settings, you may simply duplicate an existing entry and modify the settings of interest 
afterwards. 
The  Evaluate  button  executes  the  currently  selected  task  whereas  the  Evaluate  All 
button executes the entire list starting from the beginning.
All  Post-Processing  Templates  are  automatically  processed  after  each  solver  run, 
including parametric sweeps and optimizations. The execution takes place in the order 
shown  in  the  list.  You  may  need  to  change  the  order  (up  /  down  arrow  buttons), 
especially if tasks refer to previously obtained data. 
The template based post-processing results are managed as follows: 
  1D results are shown in the navigation tree under Tables  1D Results … 
  0D  results  are  shown  in  the  navigation  tree  under  Tables   0D  Results …  
Additionally, the latest result value is shown in the Value column of the task list. 
  Templates with a “-“ sign in front of their name do not add useful results to the 
navigation tree’s Tables folder, but store their results at other locations. Please 
refer to the corresponding template’s description for more information. 
Pre-Loaded Post-Processing Templates 
The  standard  installation  includes  an  extensive  list  of  pre-loaded  Post-Processing 
Templates. They can be mainly categorized as follows: 
1.  Load data into the post-processing chain. 
2.  Calculate secondary quantities. 
3.  Extract data from other post-processing results. 
Besides  operations  on  S-parameters,  a  variety  of  pre-loaded  Post-Processing 
Templates deal with the extraction of 1D or 0D data from fields (including farfields, etc.). 
We recommend you to browse through the list of available templates in the online help 
system  to get  an  overview  of  what  is  already  available.  Each  of  the  Post-Processing 
Template’s Settings dialog boxes contains a Help button, which will open an online help 
page providing more information. 
Since all Post-Processing Templates are written in the VBA programming language, you 
can  add  your  own  specific  post-processing  operations.  Please  refer  to  the  online 
documentation or contact technical support for more information.Example for Post-Processing Templates 
The following example shows a typical Post-Processing Template for CST Microwave 
Studio.  However,  even  if  you  are  using  another  module,  we  still  recommend  reading 
through this example since it describes general procedures common to all modules. 
Let  us  assume  that  you  have  simulated  a  device  and  that  you  want  to  calculate  the 
accepted  averaged  power  0.5*(1-|S11|^2)  as  well.  You  can  take  any  example  that 
calculates S-parameters.  
Please note that the accepted averaged power is available right away in the navigation 
tree NT  1D Results  Power  Excitation [1]  Power Accepted. Although there is 
no actual need for Post-Processing Templates here, it can still serve as a good example 
to illustrate the principle workflow. 
You should select the General 1D template group from the upper drop-down list in the 
dialog  box.  Once  a  particular  group  is  selected,  the  lower  drop-down  list  shows  all
available post-processing tasks within this group. Now we can calculate the accepted 
averaged power 0.5*(1-|S11|^2) by selecting the Mix Template Results template: 
Selecting this task from the list opens the following window, where arbitrary 1D results 
can  be  combined  using VBA  expressions,  several  predefined mathematical  functions 
and physical constants (cf. the Function List button). If we select A as a placeholder for 
the complex S11 result, our expression would be 0.5*(1-abs(A)^2).Please  note  that  this  and  some  other  result  templates  allow  selecting  primary  result 
curves  directly  without  the  need  for  loading  them  into  the  post-processing  system 
beforehand. 
Back in the Post-Processing Template dialog box, you can set the name of the newly 
created task by clicking on the corresponding item and changing its name to Accepted
Power. Clicking the button Evaluate will immediately add the corresponding result to the 
navigation tree’s Tables folder: 
Evaluate: 
You  can  change  the  definition  of  any  task  by  selecting  the  corresponding  line  and 
clicking on Settings. 
So  far,  you  have  seen  how  Post-Processing  Templates  can  be  a  very  flexible  and 
powerful tool to perform complex post-processing tasks. However, many useful results 
will be calculated and stored in a parametric way automatically, so please check what is 
available before setting up Post-Processing Templates. 
Once defined, a set of Post-Processing Templates will always be executed right after an 
individual  simulation  run  is  completed.  This  functionality  provides  an  efficient  way  to 
automate post-processing steps. This automation becomes most useful when running 
parametric sweeps or optimizations. 
Let  us  now  assume  that  we  have  a  model  where  “offset”  is  one  of  the  structure’s 
parameters. Each solver dialog box contains buttons named Optimizer and Par. Sweep:In  our  example,  we  assume  that  the  Accepted  Power  calculation  was  defined  as 
described above. Once a Parameter Sweep is performed, the Accepted Power results
can  be  visualized  as  a  function  of  the  structure’s  parameters  by  selecting  the 
corresponding template result: 
Let us now assume that you want to optimize the Accepted Power averaged over the 
entire simulation frequency band. This can be achieved by adding a  Post-Processing 
Template calculating the mean value of the Accepted Power. Therefore, switch to the 
General 1D template group again and select the task 0D or 1D Result from 1D Result
This will open the corresponding Post-Processing Template’s settings dialog box: 
The results of 0D Post-Processing Templates are also written to the Tables folder in the 
navigation tree after pressing the  Evaluate button. Once the evaluation of a 0D  Post-
Processing Template is performed, the latest results are shown directly in the task list’s 
Value column: The same 0D Post-Processing Templates that we used for parametric sweeps can be 
used  as  goal  definitions  for  the  optimizer.  The  ability  to  combine  various  templates 
together provides a very powerful way to define even complex post-processing tasks, 
which in turn allows for very flexible goal setups.
The following picture shows an example of such a 0D Result optimizer goal definition 
based on Post-Processing Templates. Choose Home: Simulation  Optimizer to access
Chapter 6 – Finding Further Information 
After carefully reading the Getting Started manuals, you should have some idea of how 
to use the CST Studio Suite modules efficiently for your own applications. However, you 
may have additional questions once you start creating your own models. In this chapter, 
we will give you an overview of the available documentation and help systems. 
Online Help System 
The online help system should generally be your primary source of information. You can 
access  the  help  system’s  overview  page  at  any  time  by  selecting  File:  Help   Help 
Contents or simply by clicking on the 
 icon on the right hand side of the Ribbon bar. Please note: By default the CST Studio Suite Help browser shows the help contents. 
By activating File: Options > Preferences > General settings > Use default browser to 
view help contents you can use your system Web browser. Currently Microsoft Internet 
Explorer, Microsoft Edge and Google Chrome are compatible.  
The help system’s overview page contains a collection of useful links, making it easy to 
access frequently requested information. The system also features a powerful full text 
search function, which provides fast access to the help system’s extensive content. 
The help system’s content is organized into a hierarchical structure of books and pages, 
which can be easily accessed from within the navigation tree. In each of the dialog boxes
there  is  a  specific  Help  button  that  directly  opens  the  corresponding  manual  page. 
Additionally  the  F1  key  gives  some  context  sensitive  help  when  a  particular  mode  is 
active.  For  instance,  by pressing the  F1 key  while a basic  shape generation  mode is 
active,  you  can  obtain  some  information  about  the  definition  of  shapes  and  possible 
actions. 
If no specific information is available, pressing the F1 key will open an overview page 
from which you may navigate through the help system. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Automation and Scripting > 
Visual Basic (VBA). The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  A collection macro examples.  
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, we suggest that you browse through these lists even if you are already familiar
Appendix – List of Shortcut Keys 
The following list gives an overview of available shortcut keys that may be very useful, 
especially for advanced users. 
General Shortcut Keys 
Alt 
F1 
F2 
F5 
Ctrl+F5 
F7 
F8 
Ctrl+O 
Ctrl+N 
Ctrl+S 
Delete 
Space 
Shows the key tips and enables to navigate through the Ribbon by 
using the keyboard 
Open context sensitive help 
Rename the currently selected shape in the navigation tree 
Update 1D results (while solver is running only) 
Start simulation 
Update parametric changes 
Open the component library 
Open new project file in current modeler window 
Switch to File: New and Recent 
Save current project  
Delete the currently selected object 
Reset view to contents 
Shift+Space 
Reset view to selection 
Shortcut Keys Available in 3D Modeling View 
You can activate this view by clicking on it with the left mouse button.Esc 
Alt+V 
Ctrl+C 
Ctrl+Alt+C 
Ctrl+V 
Alt+O 
Alt+W 
Ctrl+A 
Ctrl+W 
Shift+A 
Shift+C 
Shift+T 
x 
y 
z 
Tab 
Shift+Tab 
Numpad-(5) 
Numpad-(3) 
Numpad-(4) 
Numpad-(6) 
Numpad-(8) 
Numpad-(2) 
Numpad-(1) 
Numpad-(0) 
Cursor-Left 
Cursor-Right 
Cursor-Up 
Cursor-Down 
Page-Up 
Page-Down 
Alt+X 
Alt+Y 
Alt+Z 
Alt+A 
Alt+N 
Alt+T 
Ctrl+H 
Ctrl+Shift+H 
Ctrl+U 
W 
Cancel currently active mode 
Open view options dialog box 
Copy the currently displayed result curves to clipboard 
Copy the active view to clipboard 
Paste result curves from clipboard into the active result curve plot 
Toggle from outline off to colored and black outline 
Toggle working plane visualization on or off 
Toggle axis view on or off 
Toggle wireframe mode on or off 
Toggle field plot animation on or off 
Activate/deactivate cutting plane view 
Add to Report 
If the cutting plane view is active, the cut is made on the x-plane 
If the cutting plane view is active, the cut is made on the y-plane 
If the cutting plane view is active, the cut is made on the z-plane 
Open the numerical coordinate input box (also available in 1D plots 
for axis marker positioning) 
Open the numerical coordinate input box with zero defaults 
Front view 
Back view 
Left view 
Right view 
Top view 
Bottom view 
Nearest axis view 
Perspective view 
Decrement phase (2D/3D plots), move axis marker left (1D plots) 
Increment phase (2D/3D plots), move axis marker right (1D plots) 
Move cutplane or meshplane in positive normal direction 
Move cutplane or meshplane in opposite normal direction 
Increase  frequency  for  visualization  of  frequency  dependent  port 
modes 
Decrease  frequency  for  visualization  of  frequency  dependent  port 
modes 
Select vector component X (2D/3D Plot) 
Select vector component Y (2D/3D Plot) 
Select vector component Z (2D/3D Plot) 
Select vector component Abs (2D/3D Plot) 
Select vector component Normal (2D/3D Plot) 
Select vector component Tangential (2D/3D Plot) 
Hide selected shape or object 
Show selected shape or object 
Show all 
Align the WCS with a point, edge or face
Shift+U 
Shift+V 
Shift+W 
S 
P 
M 
A 
R 
C 
E 
F 
Ctrl+F 
Ctrl+Shift+S 
Shift+E 
Shift+F 
D 
Ctrl+E 
Ctrl+T 
Ctrl+Shift+A 
Ctrl+R 
Ctrl+Shift+D 
Ctrl+Shift+C 
Backspace 
+ 
- 
* 
 
% 
# 
Return 
Shift+P 
Mouse Wheel 
Rotate the WCS around its u-axis by 90 degrees 
Rotate the WCS around its v-axis by 90 degrees 
Rotate the WCS around its w-axis by 90 degrees 
Pick point, edge or face 
Pick point 
Pick edge midpoint 
Pick face center 
Pick point on circle 
Pick circle center 
Pick edge 
Pick face 
Pick faces by rectangle selection 
Pick similar faces 
Pick edge chain 
Pick face chain 
Clear picks 
Open history tree for selected shape 
Transform selected shape 
Align selected shape 
Remove the selected feature 
Delete the selected face 
Cover the selected edges 
Delete previous point in generation of basic shapes. 
Start Boolean add operation for selected shape 
Start Boolean subtract operation for selected shape 
Start Boolean intersect operation for selected shape, start trim 
curves operation for selected curve 
Start Boolean insert operation for selected shape 
Start Boolean imprint operation for selected shape 
Start trim curve operation for selected curve 
Perform Boolean operation (if active) 
Open result template post-processing dialog box 
Dynamic zoom view. By default the mouse wheel performs a zoom 
operation around the current mouse pointer location. Optionally,  by 
pressing  the  Ctrl  key  the  origin  for  this  operation  is  located  in  the 
center of the screen.  
The following shortcuts are  active when the mouse is dragged while pressing the left 
mouse button: 
Shift 
Ctrl 
Shift+Ctrl 
Restrict  mouse  movement  along  one  coordinate  axis  (in  shape 
creation) or Planar rotate view (otherwise) 
Rotate view 
Pan viewShortcut Keys Available in Edit Fields  
Copy selected text to clipboard 
Paste clipboard to current marker’s position 
Cut selected text 
Undo last editing operation 
Ctrl+C 
Ctrl+V 
Ctrl+X 
Ctrl+Z 
Shortcut Keys Available in Schematic View 
Ctrl+X 
Ctrl+C 
Ctrl+Alt+C 
Ctrl+V 
Ctrl+Z 
Ctrl+Y 
Ctrl+A 
Ctrl+E 
Esc 
Ctrl+Alt+Z 
Ctrl+Alt+P 
Space 
Shift+Space 
Shift+T 
Ctrl+Alt+Mouse
wheel 
Ctrl+Shift 
Cut selected component/text 
Copy selected component/text into clipboard 
Copy the active view to clipboard 
Paste clipboard into drawing/to current marker’s position 
Undo last editing operation 
Redo previously undone operation 
Select all 
Open property dialog of selected component 
Cancel currently active mode (and return to selection mode) 
Activate zoom mode 
Activate panning mode 
Reset view 
Reset view to selection 
Add to Report 
Zoom in/out (without switching to zooming mode) 
Pan (without switching to panning mode)
Ctrl+G 
A 
C 
G 
O 
P 
Shift+R 
Shift+L 
Shift+C 
D 
Left 
Right 
Up 
Down 
Page Up 
Page Down 
L 
R 
Ctrl+Alt+H 
Ctrl+Alt+V 
Ctrl+Left 
Ctrl+Right 
Ctrl+Up 
Ctrl+Down 
Shift+P 
Switch grid on or off 
Activate the insertion mode for a connection label 
Activate the insertion mode for a connector 
Activate the insertion mode for a ground element 
Activate the insertion mode for a probe 
Activate the insertion mode for an external port 
Activate the insertion mode for a resistor 
Activate the insertion mode for an inductor 
Activate the insertion mode for a capacitor 
Changes the direction of the selected probe  
Scroll to the left if no components are selected, otherwise move the 
selected components to the left 
Scroll to the right if no components are selected, otherwise move the 
selected components to the right 
Scroll up if no components are selected, otherwise move up the selected 
components  
Scroll down if no components are selected, otherwise move down the 
selected components  
Scroll up page by page 
Scroll down page by page 
Rotate left the selected components 
Rotate right the selected components 
Flip the selected components horizontally 
Flip the selected components vertically 
Select the component(s) to the selected component's left 
Select the component(s) to the selected component's right 
Select the component(s) to the selected component's top 
Select the component(s) to the selected component's bottom 
Open result template post-processing dialog box 
Shortcut Keys Available in Assembly View 
Esc 
Alt + V 
Alt + O 
Shift + C 
A 
B 
D 
E 
P 
R 
T 
Ctrl+T 
X 
Y 
Z 
Tab 
Shift+Tab 
Left 
Right 
Up 
Down 
Numpad-(5) 
Numpad-(3) 
Numpad-(4) 
Numpad-(6) 
Numpad-(8) 
Numpad-(2) 
Numpad-(1) 
Numpad-(0) 
Backspace 
Return 
Mouse-Wheel 
Ctrl+Mouse-
Wheel 
Cancel currently active mode 
Open the view options dialog box 
Toggle between outline off and black outline 
Activate cutting plane view 
Align 
Show bounding box 
Clear picks 
Edit part 
Pick point 
Rotate part 
Translate part 
Absolute transform 
If the cutting plane view is activated the cut is made in the x-plane 
If the cutting plane view is activated the cut is made in the y-plane 
If the cutting plane view is activated the cut is made in the z-plane 
Toggle between active modes 
Toggle between active modes 
Toggle between active modes 
Toggle between active modes 
Toggle between active modes 
Toggle between active modes 
Front view 
Back view 
Left view 
Right view 
Top view 
Bottom view 
Snap to closest aligned view 
Perspective view  
Go back to previous operation 
Perform operation 
Dynamic zoom around center or mouse position (according to mouse 
settings in Options - Preferences) 
Dynamic zoom around center or mouse position (according to mouse 
settings in Options - Preferences)
The following shortcuts are active when the mouse is dragged while pressing the left 
mouse button: 
Shift 
Ctrl 
Shift+Ctrl 
Planar rotate view 
Rotate view 
Pan view 
Shortcut Keys Available in VBA Editor  
Ctrl+N 
Ctrl+O 
Ctrl+S 
Ctrl+P 
Ctrl+F 
F3 
Ctrl+R 
Ctrl+Z 
Ctrl+Y 
Ctrl+X 
Ctrl+C 
Ctrl+V 
F1 
F5 
ESC 
F7 
F9 
Ctrl+F9 
Ctrl+Shift+F9 
Shift+F9 
Ctrl+F8 
Shift+F8 
F8 
File new 
File open 
File save 
Print 
Find 
Find again 
Replace 
Undo previous operation 
Redo previously undone operation 
Cut 
Copy 
Paste 
Context help for the word next to the caret position 
Run macro 
Pause macro 
Debug step to 
Debug break 
Add watch 
Clear all breaks 
Quick watch 
Debug step out 
Debug step over 
Debug step into 
More information about the VBA Language is provided in the Online Help. Especially the 
Overview  page  contains  a  short,  useful  introduction  to  the  most  important  language 
elements. In addition, there is also a Python interface for basic project handling and 1D 
result  access  available.  Please  refer  to  the  Automation  and  Scripting  section  in  the

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software  described  in  this  document  is  furnished  under  a  license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a retrieval 
system,  or  transmitted  in  any  form  or  any  means  electronic  or 
mechanical,  including  photocopying  and  recording,  for  any  purpose 
other than the purchaser’s personal use without the written permission 
of Dassault Systèmes. 
Trademarks 
icon, 
IdEM,  Spark3D,  Fest3D,  3DEXPERIENCE, 
CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
STUDIO,  CST  EMC  STUDIO,  CST  MICROWAVE  STUDIO,  CST 
PARTICLE  STUDIO,  CST  Studio  Suite,  EM  Studio,  EMC  Studio, 
Microstripes,  Microwave  Studio,  MPHYSICS,  MWS,  Particle  Studio, 
PCB  Studio,  PERFECT  BOUNDARY  APPROXIMATION  (PBA), 
Studio  Suite, 
the 
logo,  CATIA,  BIOVIA,  GEOVIA, 
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SOLIDWORKS, 3DVIA, ENOVIA, NETVIBES, MEDIDATA, CENTRIC 
PLM,  3DEXCITE,  SIMULIA,  DELMIA  and  IFWE  are  commercial 
trademarks or registered trademarks of Dassault Systèmes, a French 
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Dassault  Systèmes  or  its  subsidiaries  trademarks  is  subject  to  their 
express written approval. 
the  3DSDS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries. 
3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome  to  CST  Cable  Studio,  the  powerful  and  easy-to-use  package  for  analyzing 
conducted transmission, EMI (Electromagnetic Interference) and EMS (Electromagnetic 
Susceptibility) on complex cable structures.  
This  program  combines  transmission  line,  circuit  and  3D  “full-wave”  simulation  in  a 
convenient  and  sophisticated  way,  which  makes  it  highly  suitable  to  simulate  cables 
inside electrically large systems. 
CST Cable Studio is embedded into the design environment of CST Studio Suite, which 
is explained in the CST Studio Suite Getting Started manual. The following explanations 
assume that you have already installed the software and familiarized yourself with the 
basic concepts of the user interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite Getting Started manual. 
2.  Acquire a working knowledge of transmission lines. You should be familiar with two-
conductor and multi-conductor lines. 
3.  Work  through  this  document  carefully.  It  should  provide  you  with  all  the  basic 
information  necessary  to  understand  the  advanced  documentation  found  in  the 
online help. 
4.  Look at the examples provided in the  CST Studio Suite Component Library (File: 
Component  Library  >  Examples),  especially  the  examples  which  are  tagged  as 
Tutorial,  since  they  provide  detailed information  of  a  specific simulation  workflow. 
Press the Help 
 button of the individual component to get to the help page of this 
component.  
Please note that all these examples are designed to give you a basic insight into a 
particular  application  domain.  Real-world  applications  are  typically  much  more 
complex and harder to understand if you are not familiar with the basic concepts. 
5.  Start  with  your  first  own  example.  Create  your  first  CST Cable  Studio  model  and 
simulation.  Choose  a  reasonably  small  and  simple  harness  that  will  allow  you  to 
become familiar with the software quickly.What is CST Cable Studio? 
investigation  of 
CST Cable Studio is an electromagnetic simulation tool specially designed for the fast 
and  accurate 
in  complex  electromagnetic 
environments  of electrically large systems  by combining  transmission line, circuit  and 
3D full-wave simulation.  It  allows the investigation  of multi-scale  problems,  which  are 
otherwise difficult to solve with full-wave solvers. Typical multi-scale problems are for 
instance cables with dimensions down to the micrometer range built in towers, cars or 
aircraft with overall system dimensions in meter. 
real-world  cables 
CST Cable Studio offers a user interface that makes it easy to define a complex cable 
harness. The 3D topology can be defined either from scratch or by loading an existing 
harness via a NASTRAN or STEP AP212-KBL import filter.  
Several  dialog  boxes  allow  the  definition  of  four  basic  types  of  cables:  single  wires, 
twisted cables, ribbon cables and coaxial cables / shielded wires with compact, foil or 
braided shields.  
Any combination of these basic cable types can be set up as cable groups and can be 
stored in a user-defined library. A couple of dialog boxes allow the convenient definition 
of exact or random cable cross sections.
The transfer impedance of a shielded cable either can be defined directly or is calculated 
using the built-in transfer impedance calculator, which extracts the impedance from the 
geometric  characteristics  of  the  shield.  In  addition,  it  is  possible  to  load  and  assign 
measured transfer impedance curves. 
CST  Cable  Studio  generates  equivalent  circuits  from  the  cable  harness  based  on 
classical transmission line theory. It automatically meshes the cable harness along its 
length and calculates the transmission line parameters on these segments.  
Skin  effect  and  dielectric  loss  are  modeled  in  both  frequency  and  time  domain 
simulations. The equivalent circuits can be exported in several SPICE formats. 
It uses a powerful 3D solid modeling front end to set up or import arbitrary metallic 3D 
shapes, ranging from simple ground planes to complex chassis structures. Moreover, 
the 3D full-wave solvers from CST Microwave Studio calculate the electromagnetic field 
in the environments of cables.  
CST Cable Studio uses CST Design Studio’s easy-to-use schematic to define passive 
and active devices at cable terminations. The powerful built-in network simulator in CST 
Design  Studio  enables  the  simulation  of  a  whole  system  consisting  of  the  equivalent 
circuit of the cable harness and its terminations. 
CST Cable Studio controls the data exchange between the circuit simulation engine and 
the various 3D EM solvers for currents (on the cable harness) and electromagnetic fields 
(around the cable harness). This enables simulating both the effects of fields coupling 
into the cables and fields radiating from the cables.  
Applications 
  Transmission  and  crosstalk  simulations  of  extended  cable  structures  in  time  and 
frequency domains 
  E3: analysis of complex cables in electromagnetic environments of large systems 
  EMI: analysis of radiated electromagnetic fields from complex cables lying along and 
apart metallic structures 
  EMS: analysis of coupled electromagnetic fields into complex cables lying along and 
apart metallic structures 
CST Cable Studio Key Features 
An overview of the main features of CST Cable Studio is provided in the following list.  
For  the  circuit  simulator  only  some  selected  key  features  are listed  below.  Additional 
information can be found in the CST Studio Suite - Circuit Simulation and SAM (System 
Assembly and Modeling) manual and its Online Help. 
For the 3D solid modeling front end and the 3D full-wave simulation only some selected 
key  features  are  listed  below.  A  full  list  can  be  found  in  the  CST  Studio Suite  -  High 
Frequency Simulation manual. 
General  
  Native graphical user interface based on Windows operating systems. 
  Tight interface to CST Design Studio and CST Microwave Studio enabling cable 
modeling, circuit simulation and 3D full-wave analysis in one environment. 
  Transmission  line  modeling  method  for  fast  and  accurate  simulation  of  TEM  / 
Quasi-TEM propagation modes inside complex cable structures.
Harness Structure Modeling 
  Easy definition of complex harness topology. 
  Import of harness via NASTRAN and STEP AP212-KBL. 
  Interactive cable editing dialog boxes for all relevant types of cables. 
  Parameterization of cable position, cross section and material properties. 
Harness Electric Modeling 
  Automatic meshing and extraction of 2D transmission line parameters. 
  Modelling  of  all  relevant  cable  types  in  any  combination  (single  wire,  ribbon 
cables, twisted cables and shielded cables). 
  Consideration of skin and proximity effects as well as dielectric loss in time and 
frequency domains. 
  Consideration of transfer impedance for compact, foil or braided shields.  
  Impedance calculator for determination of characteristic line impedances. 
  Export of equivalent SPICE circuits. 
Circuit Simulator  
  Schematic editor enables the easy definition of passive and active devices on 
the cable’s equivalent circuit. 
  Fast circuit simulation in time and frequency domains. 
  Import of SPICE sub-circuits (Berkley SPICE syntax). 
  Support of IBIS models. 
  Import and Export of S-Parameter data via TOUCHSTONE file format. 
  Parameterization of termination circuitry and parameter sweep. 
3D Full-Wave Simulator 
  Automatic transfer of impressed common mode currents on cable bundles from 
circuit simulator to the 3D “full-wave” simulator.  
  Automatic transfer of induced voltages on cable bundles to circuit simulator. 
  Advanced solid modelling to define scattering or antenna structures. 
  Import  of  3D  CAD  data  by  SAT,  Autodesk  Inventor®,  IGES,  VDA-FS,  STEP, 
ProE®,  CATIA  4®,  CATIA  5®,  CoventorWare®,  Mecadtron®,  NASTRAN  or  STL 
files to define scatter and antenna structures. 
  Plane wave excitation (linear, circular, elliptical polarization). 
  Ideal voltage and current sources for antenna excitation. 
  Accurate  and  efficient  time  domain  solvers,  based  on  the  Finite  Integration 
Technique (FIT) and the Transmission-Line Matrix (TLM) method. 
  Fully  automatic  creation  of  hexahedral  grids  in  combination  with  the  Perfect 
Boundary Approximation (PBA), Thin Sheet Technique (TST) and Octree-based 
meshing. 
  Calculation  of  various  electromagnetic  fields  and  quantities  such  as  electric
About This Manual 
This manual is primarily designed to allow a quick start on the modeling capabilities of 
CST  Cable  Studio.  It  is  not  intended  as  a  complete  reference  guide  to  all  available 
features, but rather as an overview of the key concepts. Understanding these concepts 
will allow to learn the software efficiently with help of the online documentation. 
To learn more about the circuit simulator, please refer to the CST Studio Suite - Circuit 
Simulation and SAM (System Assembly and Modeling). 
To learn more about the 3D full-wave simulator, please refer to the CST Studio Suite - 
High Frequency Simulation manual. 
The  next  chapter,  Overview,  is  dedicated  to  explaining  the  general  concepts  of  CST 
Cable  Studio  and  to  show  the  most  important  objects  and  related  dialog  boxes.  The 
Chapter  Examples  will  guide  you  through  three  important  examples,  which  provide  a 
good overview of the capabilities of CST Cable Studio. We strongly recommend studying 
both chapters carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key  combinations  indicated  by  a  plus  (+)  sign.  Ctrl+S  means  that  you  should 
hold down the Ctrl key while pressing the S key. 
  Many of the program’s features can be accessed through a Ribbon command 
bar at the top of the main window. The commands are organized in a series of 
tabs within the Ribbon.  
  In this document, a command is marked as follows: Tab name: Group name  
Button name  Command name. This means that you should activate the proper 
ribbon tab first and then press the button Command name, which belongs to the 
ribbon group ‘Group name’. If a keyboard shortcut exists, it is shown in brackets 
after the command. Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item.Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments regarding  the  documentation,  please send  them to  your support 
center: 3DS.com/Support.
Chapter 2 – Overview  
CST Cable Studio is designed for ease of use. However, to get started quickly you will 
need to know the basic concepts behind it. The main purpose of this chapter is to provide 
an overview of the most important objects and dialog boxes. 
User Interface 
Launch CST Studio Suite from the Start menu or by clicking on the desktop icon. In the 
Modules and Tools list under New and recent click on 3D Simulation -> Cable.  
A new CST Cable Studio project opens with an empty Main View.  
Main Frame 
Ribbon  
Main View 
Cable / 3D 
Navigation Tree 
Cross Section 
Window  
Parameter List 
Window  
Message 
Window 
The user interface consists of five sub-windows: 
  The Main View allows the 3D visualization of the harness and its surrounding metallic and 
insulator shapes.  
  The Cross Section window shows the 2D visualization of cable cross sections. 
  The Cable/MWS Navigation Tree frame enables switching between the Cable 
Navigation and the MWS Navigation Tree.  
The Cable Navigation Tree allows access to all objects necessary to define a complete 
cable assembly in 3D. When selecting an item, it will be shown in the Main View, Cross 
Section View or in both depending on the object’s characteristics. The MWS Navigation 
Tree allows access to all MWS related objects, thereby allowing full access to solid 
modeling and 3D full-wave simulation technology. When selecting an item, it will be 
highlighted in the Main View. 
  The Messages  window  shows  general  information,  solver  progress,  warnings  and  errors 
during project set up or simulation. 
  The  Parameter  List  window  allows  defining  parameters  that  render  parameterized
Interface to CST Design Studio 
Below the Main View, there are two separate tabs: 
Initially  the 3D view is  active. Selecting  the  Schematic tab changes the view to CST 
Design Studio. This provides access to the schematic editor and the circuit simulator. 
The following list gives an overview on the meaning and usage of the two different tabs:  
  The 3D tab presents all objects and dialog boxes necessary to define and edit cable 
bundles  inside  a  3D  metallic  and  insulator  environment.  It  includes  the  solver 
technology to generate equivalent circuits, which are passed to the Schematic tab 
as model blocks. It further enables the hybrid methods for radiation and irradiation 
by  exchanging  the  common  mode  currents  and  voltages  of  a  cable  between  the 
circuit simulator and the 3D transient solvers. 
  The Schematic tab is used to define and edit loads on the equivalent circuit of the 
cable  harness  with  the  help  of  a  schematic  editor.  It  further  enables  the  circuit 
simulation of the whole system in time and frequency domains, while maintaining a 
tight interface with the 3D transient solvers to easily exchange impressed currents
How to Define a Cable Assembly 
This section will explain how to set up a complete cable assembly. It is a basic procedure 
that  we  recommend  reading  carefully  before  starting  with  the  examples  in  the  next 
chapter.  
In order to set up a cable assembly, cable bundles through nodes and segments must 
be defined first. Into those different cable types can be placed later on. 
Cable bundle creation can be done by using either any existing curve (Cables: Curves 
 Curves) or by using the following two objects: Nodes and Segment, which can be 
seen as separate sub-folders in the Cable Navigation Tree. 
The Trace of a Cable Bundle 
Nodes and Segments define a 3D graph, which is used for defining signal paths. Such 
paths are called Traces and they contain any number of different cables. 
Splices can be created as well. 
All cables on a Trace make up a Cable Bundle, and all those cables are automatically 
coupled with each other (through the mutual inductances and capacitances between the 
individual cables).  
There is one restriction: a trace of a cable bundle cannot build a closed loop. 
We start with the definition of six nodes, which we will use later on to define two separate 
traces. We double-click on Cable Navigation Tree: Nodes (or Cables: Edit Cabling  
New Node  Edit Nodes) and see the following dialog box:To define the first node, we select the marked New Node button and enter -200.0 for x 
and 200.0 for y.
We repeat this five more times to get additional nodes like in the list below: 
The  snap  buttons 
shape or to a picked point. In addition, nodes can be imported 
  allow  changing  the  position  of  a  node  to  either  the  nearest 
 from a text file.
In order  to  define  a  trace  along  the  nodes  N1  -  N2  -  N3  -  N4  we  select  Cables:  Edit 
Cabling  Cable Bundles  Edit Cable Bundles (or alternatively NT   Cable bundles 
  New Cable Bundle) as shown in the figure below:  
The following dialog box will appear: 
We click on the New Cable Bundle button on the top left of the dialog box and get the
To define the trace N1 - N2 - N3 - N4, we multi-select (mouse + shift/control) the first 
four nodes and move them to the right by using the arrow in the center of the dialog box 
or just dragging them with the mouse 
After moving the four nodes, they will disappear from the list of Available Nodes and will 
be in the default trace of the cable bundle:We name the Cable Bundle “first” in the Display name field as shown in the figure above 
and press the Ok button. We have generated the first trace as can be seen in the Main 
View:
We can now start adding cables to it. 
After double-clicking on Cable Bundles in the Cable Navigation Tree the following dialog 
box will appear. Here we select the item “first” in the list of available cable bundles: 
Inserting Cables 
In order to insert a cable in the predefined trace “first”, we select the cable bundle “first” 
and press the “Add Cable” button. 
The following dialog box will appear:Since there is no cable type in the current project yet, we select the  Library tab and 
see a list of predefined cable types: 
From Single wires we select the wire type LIFY_0qmm25 and press the Add button.
We repeat this procedure, add the wire type LIFY_0qmm75 and press Close.  
The dialog box should now look like the image below:By  default,  the  Random  bundling  box  in  the  bottom  right  is  enabled;  the  overlap 
between  wires  will  be  taken  care  of  automatically  and  the  meshing  process  will 
randomly bundle the wires in the bundle on each individual run.
To demonstrate the Auto Bundle feature, we uncheck the Random bundling flag. 
Both wires are initially at position x=0, y=0. After pressing ‘Apply’ a warning message 
will appear, indicating that the conductors of the two wires are overlapping: 
To define correct geometrical positions, there are two possibilities.  
One way is to enter suitable coordinates manually for each wire or to shift a wire in the 
cross section view using the mouse. Another way is to press the button Auto Bundle for a single random configuration.
Auto Bundle generates a simple arbitrary configuration for a physically correct bundle. 
In many cases, such an arbitrary cross section is sufficient because the exact position 
of  wires  inside  a  bundle  is  undefined  in  most  real-world  configurations  and  cross 
sections will vary.  
After  pressing  ‘Auto  Bundle’,  the  Cross  Section  View  will  show  the  corresponding
As long as a segment between two nodes is only used by a single cable bundle, the 
representative cross section is identical to that single cable bundle.  
This can be seen if we select the Segments tab on the right side of the dialog box: 
If we click on any of the three segments in the list, we will see the same bundle cross 
section in the Cross Section window as for the bundle above.  
When double-clicking on a segment a dialog box will appear showing the same x-y
This is no longer true if there are two or more cable bundles that are using a common 
segment. To show this, we will define a second cable bundle on path N5-N2-N3-N6.  
In order to show the arrangement of the existing nodes, we select Cables: Options  
View Options. The following dialog box will appear: 
We check Label visible and close the dialog box. After this the names of the nodes can 
be seen in the Main View. 
To generate the second cable bundle, we select Cable Navigation Tree: Cable Bundles 
 New Cable Bundle using the right mouse menu:The New Bundle dialog box will appear.  
We enter “second” as Name for the new cable bundle. Then, we select and add the 
nodes N2, N3, N5 and N6. The trace will consist of the correct nodes but the incorrect 
sequence N2 - N3 - N5 - N6 may appear:  
In order to get the correct node sequence N5 - N2 - N3 - N6, we have to move N5 to 
the first position. This is done by selecting the node and moving it up by using the Move 
Up button or dragging it up with the mouse.  
In the end, the trace definition should look like in the figure below:
After pressing Ok, the dialog box changes and we can insert cables along the trace. In 
order to do this we switch to the Cables tab. There we activate the Library tab to select 
and add one NYFAZ_2x1qmm50 from the cable type group Ribbon cables: 
The second view is visible if the Edit Bundle dialog is switched to “Less” mode. 
We press Ok for closing the dialog box.  
The new cable will be displayed in blue along N5 - N2 - N3 - N6 in the Main View. In 
addition, the ribbon cable can be seen in the Cross Section window:Now we want to investigate the cross section in segment N2-N3 used by both cable 
bundles. To do this, we select the corresponding segment (by double-click with the left 
mouse button) in the Cable Navigation Tree.
A new dialog box appears and the overlapping wires in the segment can be seen in the 
Cross Section window: 
The  overlap  can  be  resolved  by  either  manual  editing  the  cable  positions  or  by 
automatic bundling.  
To  resolve  the  overlaps,  we  can  either  drag  and  rotate  selected  cables,  enter  an 
appropriate coordinate for the new ribbon cable or simply press Auto Bundle. If Random bundling is inactive, the program will use the exact position values later on 
in the meshing and modeling process. 
The second  option  would  be  to  ignore  the  overlapping  wires  and to let the  program 
resolve  the  overlap  automatically  before  starting  the  2D-TL  solver.  In  this  case,  the 
Random bundling check box has to be on.  
The advantage of this function may not be obvious for such a simple configuration, but 
it is a powerful function if one has to deal with a complex cable harness consisting of 
many segments and overlaps.
Cable bundle from Curve 
For more complex routing, it is possible to create any curves (without loops) that can be 
turned into a cable bundle for simulation in CST Cable Studio. The first step is to define 
a curve by selecting e.g. Cables: Curves  Curves  Spline. Then double-click to create 
a series of intermediate points. Finally press ESC and close the dialog using Ok. 
The next step creates a cable bundle from this curve. Use Cables: Edit Cabling  Cable 
Bundles  Cable Bundle from Curve, and then pick the curve just created using a double 
mouse click.  
The Edit Cable Bundle dialog box appears with a default name for the cable bundle and 
the user is able to add cable types (as mentioned in the previous section). 
Cable splices or splits 
In some cases, it is not enough to have a 2-point connection in a cable. With a few steps, 
it is possible to create such a spliced cable setup. 
We start a new bundle from some nodes that will represent such a spliced configuration:First, we add the nodes of the main trace, move N2 to the start of the trace and leave 
the separate node N5 for now:
Next, we press New Trace and select the node N1 from the left list where the split is to 
be located. Then we add the node to the new trace Trace_2: 
As a last step, we add the remaining node N5 to the new trace and end up with a spliced 
bundle (note the green splice node N1) in which all cables are present in all three parts
We finish this section by explaining the remaining terms that have not been introduced so far 
but will be used in later chapters: 
       Cable Types 
          A specific cable has one of the following cable types:  
        Signals 
Every wire inside a cable carries an individual electrical signal. For each of these signals 
a signal path is generated.  
In the case of shielded cables a signal path for every shield will be created as well. Every 
signal path starts and ends at a terminal where electrical loads or cable ports can be 
defined.  
        Terminals 
A terminal is the electrical input or output of a signal path. 
        Connectors 
Connectors are virtual representations of actual physical connectors from a real cable 
assembly. Each connector can contain a list of plug-ins with a number of pins, where 
each pin can be connected to a wire terminal.  
Plug-in  
A  plug-in  is  part  of  a  connector  and  is  a  collection  of  pins.  There  is  no  electrical 
functionality. 
Pins (Connector Pins) 
A connector pin can be linked to a wire terminal. It is part of a plug-in and as such a part 
of a connector. It is possible to link more than one terminal to a connector pin.        Junctions 
Terminals can be connected to other terminals and connector pins can be connected to 
other connector pins. This is possible by means of junctions.  
        Current Monitors 
Current  monitors  allow  probing  the  current  of  any  wire  or  screen  of  a  cable  at  any 
location within a segment except at a location where a terminal exists. 
        Cable Ports 
A cable port offers the possibility to define an excitation in 3D. Cable ports are always 
of  type  S-parameter.  They  can  be  defined  as  single-ended  port  from  a  terminal  or 
connector pin to the reference. Alternatively, they can be differential ports between two 
terminals or between two connector pins. 
At the same time, these ports are used as block pins in Schematic. There you can also 
define excitations or loadings. Finally, they are used in Schematic tasks as described at 
the end of this chapter. 
In our example, let us define a single-ended port at each cable terminal.
We select Cables: Edit Cabling  Cable Ports  Cable Ports... as shown in the figure 
below: 
The Cable Port Manager dialog box appears. It shows all cable terminals in the tree at 
the left hand side.  
You can collapse and expand the second tree by clicking the symbols 
Select all terminals by pressing the left mouse button anywhere inside the frame 
Terminals and the typing Ctrl+A. Pressing the button New Cable Port to REFERENCE 
defines a single-ended port for all selected terminals. 
 & 
. The cable ports are of type S-Port and have per default a fixed default impedance 
value of 50 Ohms. The port impedance can be changed. 
        Components  
So  far,  we  have  generated  cables  in  the  3D  space  and  CST  Cable  Studio  has   
interpreted each single conductor inside a cable as a potential carrier of a signal. 
Every signal path starts and ends at a terminal where electrical loads or sources can be 
defined. The user has to provide a current return path for each signal.  
This can be done either by defining a separate wire conductor or by defining a reference 
conductor using 3D components. 
In  many  cable  configurations,  one  can  find  an  additional  conducting  body  acting  as 
reference conductor for the return current or for shielding purposes. In order to define 
such  metallic  3D  bodies,  the  whole  range  of  CST  Microwave  Studio  solid  modeling 
possibilities  are  available.  For  a  detailed  explanation  on  solid  modeling  the  user  is 
referred to the CST Studio Suite - Getting Started manual.  
For the  purpose  of this  manual,  the  definition  of two important metallic  bodies  will  be 
explained: a simple ground plane and the import of a complex car chassis.
To define a simple ground plane select Modeling: Shapes Brick. Press ESC in order 
to show the dialog box for inserting the coordinates by hand. Inside the dialog box, enter 
the values as shown in the next figure: 
Note  that  the  data  field  Material  is  set  to  PEC  by  default,  because  only  perfect 
conductors or other metallic materials are acting as a current return path. The 2D(TL) 
modeling  process  will  consider  both  metallic  materials  and  normal  (insulator  type) 
materials.  
After pressing OK, the new object is visible in the Main View:In the (MWS) Navigation Tree, the new object shows up as component: 
Note, that the red cubes in the 3D view indicate the cable ports. 
As a final step, we set up a simple S-Parameter analysis.
For this, we switch to the Schematic tab and start the Macro Macros  Construct  Add 
Ports to all pins of a block. The purpose of this step is to use all the cable ports as ports 
for any task in Schematic.  
Next,  we  create  an  S-Parameter  task  by  clicking  on  Tasks   New  Task.  The  port 
impedances defined in the cable ports are automatically passed to the Schematic ports 
for  the  S-Parameter  task  in  case  you  use  Block  Dependent  as  the  Reference 
Impedance. 
We  set  the  maximum  frequency  to  100MHz  (switch  project  units  if  necessary) 
corresponding to  the  default in the  2DTL settings  and  the  number  of samples  to  e.g. 
500. Then we press Simulation  Update and wait for the calculation to finish. 
The results in Tasks SPara1 show the S-Parameters of the selected system that looks
Chapter 3 – Examples 
Having given a short introduction into the theoretical background, the user interface and 
how to set up a cable harness, this chapter will present three insightful examples on the 
capabilities  of  CST  Cable  Studio.  The  first  two  examples  deal  with  the  simulation  of 
typical transmission line effects in cables. The third example explains how to proceed 
when radiation from cables or susceptibility into cables has to be investigated.  
Transmission on a Coax Cable  
The intention of this example is to acquaint you with the  
  Cable library and the definition of materials and cable shields 
  2D modeling dialog box and the generation of an equivalent circuit 
  AC- and Transient circuit simulation with preparation of result curves 
The Structure  
In this example a single coaxial cable without any additional reference conductor will be 
modeled.  
Cable Definition 
Create an empty CST Cable Studio project and save it as coax cable. The geometric 
and electrical units of the project can be set with Home  Settings  Units: The default units are correct for our example and should be kept as they are.
We  create  a  straight  coax  cable  with  a length  of  1m.  To  quickly  define  the  cable  we 
select Cable Navigation Tree: Cable Bundles  New Cable Bundle by using the right 
mouse button. The Create New Cable Bundle dialog box will appear where we generate 
the following end nodes: 
We  select  both  nodes  (by  Ctrl+left  mouse  button)  and  shift  them  to  the  right  side  by 
using the add arrow in the middle of the dialog box. 
The cable bundle dialog box should look like the figure below: 
After pressing Ok, the dialog box will change to the Edit Cable Bundle dialog. Here, we
Note: if you don’t see the full dialog box above (but only a reduceded version) you can 
press the “More”-button. Both forms of the dialog box work the same way: 
You should deselect “Random bundling” to avoid a random rotation of the cable in the 
bundle cross-section. 
After pressing Ok, the  generated cable  bundle  will  be  displayed in  the  Cross-Section 
Window:In order to see the characteristics of the cable, we pay a short visit to the Cable Types 
folder.  
We go into Cable Navigation Tree: Cables Types  Coaxial cables and double-click on 
the RG58 cable which has been loaded from the Library.  
A dialog box will appear, listing the structure of a coax cable with the inner  Wire, the 
Insulator Inside (inside the screen), the Screen and the Insulator Outside (outside the 
screen).
On the right side of the dialog box, the corresponding values can be seen: 
When selecting the content Insulator Inside the dialog box shows PE as material used 
for the insulator:  
If we want to check the characteristics for this material, we can open the materials list 
by pressing the Material button. If we right click on any material an Edit option opens a 
dialog box showing the values of the important characteristics (which can also be 
edited affecting all PE used in the project): Permittivity with Loss angle tan() and 
Frequency as well as Permeability:CST  Cable  Studio  performs  a  broadband  approximation  of  the  loss  angle.  This 
approximation  guarantees  a  constant  value  of  the  defined  loss  angle  within  the 
frequency  range  where  the  corresponding  equivalent  circuit  of  a  cable  (including  the 
material) is valid.
We  finish  the  introduction  of  the  characteristics  of  the  RG58  cable  by  looking  at  the 
characteristics of the screen. 
The dialog box shows that the type of the screen is a braided shield. This means, the 
screen  does  not  consist  of  one  solid  conductor  but  is  composed  of  many  single 
conducting  and  weaved  wire  strands.  This  affects  the  shielding  quality,  which  is 
described  by  the  transfer  impedance  of  the  screen,  displayed  as  Basic/Fitted  T.  In 
addition, the impedance of the screen affects the shielding effectiveness that the plot 
calls Basic/Fitted R.In order to calculate the transfer impedance using an analytical formula (Kley’s model), 
five parameters  of the  braided screen have  to  be set. Any change  of the  parameters 
below will result in an update of the impedance curve: 
  The inner diameter of the screen: this is automatically defined by the Insulator 
inside definition of the inner dielectric . 
  Strand diameter 
  Number of strands in one carrier: a carrier is a package composed of a certain 
number of filaments 
  Number of carriers: the number of carriers that is used for the braid 
  Braid angle: the angle with which the carriers are woven. As an alternative, the 
Optical coverage or the Picks per unit length can be defined instead of the 
Braid angle.
2D Modeling 
Before we generate an equivalent circuit, let’s have a look at the folder Signals in the 
Cable Navigation Tree. 
The inner wire and the outer screen of the coax cable are listed as two different signals. 
The names of those signals are automatically generated by the program. In addition, for 
each signal two terminals are created and can be distinguished by the prefix N1_ and 
N2_. These terminal names are used for the port labels when we define cable ports. 
The  cable  ports  are  necessary  to  add  excitations  and  loadings  directly  to  the  cable. 
Therefore, we use the Cable Ports Manager. In case there are connectors defined and 
all cable terminals end within connector pins, the Connector Pin Ports Manager allows 
adding ports directly to connector pins. 
We open the Cable Ports Manager in Cables: Edit Cabling  Cable Ports  Cable PortsWe create a port between each cable terminal and its reference. This allows the pinwise 
definition of loadings in the schematic. To do so, we click in the left tree of terminals and 
press CTRL-A. Now all cable terminals are selected. 
In the second step, we press the button New Cable Port to REFERENCE on the right of 
the  dialog  box.  This  creates  all  not  yet  defined  ports  between  the  selected  cable 
terminals and their reference. 
The new ports have a default port impedance of 50 Ω. This impedance can be changed 
by double clicking on the value. It is used in the both circuit simulation in Schematic or 
3D simulation. The cable ports are managed and used similar as 3D discrete ports. 
If you switch to the tab Schematic, you will notice that for each cable port a pin is created 
in the default cable block. 
To generate the cable equivalent circuit, we choose Cables: 2D (TL) Modeling. A new 
dialog  box  appears  where  we click  on the  Selection tab  and see the  two signals that 
were automatically selected:
We change to the Modeling tab and set up the dialog box as follows: 
We check Ohmic losses and Dielectric losses on to consider metallic losses and with it 
the skin-effect and dielectric of the inner insulator. We then press Apply. 
An important setting is the maximum frequency up to which the model should be valid. 
In this example, we want the maximum frequency to be 500MHz. We close the dialog 
box, go to Simulation: Settings  Frequency and enter the frequency range 0…500MHz 
as shown in the figure below:1.  We  recommend  setting  the  frequency  range  just  as  high  as  needed  for  your 
application, for a reason: The maximum frequency range affects the complexity of 
the equivalent circuit - the higher the frequency, the more complex the calculated 
circuit is.  
2.  Every configuration has its own natural frequency limit and once above this limit, a 
model  can’t  be  produced  reliably  because  of  the  modeling  method  used  by  the 
program . The 
limiting factor is the cross section size of the cable bundle – the larger the size of the 
cross section the lower the maximum possible frequency range.  
If we open the 2D (TL) Modeling again, we see that the frequency parameter “Model 
valid  up  to  frequency”  in  the  “Modeling”  tab  has  been  changed.  To  see  the  resulting 
circuit and to set up a simulation we have to change to the Schematic tab.
Circuit Simulation and Results 
In the Schematic tab,  the schematic symbol  with its  automatically  generated  terminal 
pins of the cable model is displayed in the Main View.  
Sometimes, the layout of the block pins is not as you like. You can re-arrange the pins 
by right-mouse clicking on the block and selecting “Changing Pin Layout…”  
The  options  “Layout  Type”  “Automatic  Grouping  (Cable  connectors)”  may  already  be 
good enough. 
Now we can prepare the circuit for an AC-task. For a detailed explanation on how to use 
the schematic editor, please refer to the CST Studio Suite - Circuit Simulation and SAM 
(System Assembly and Modeling) manual.  
We begin putting a resistor on either side of the cable block. Next, we place a yellow 
external port symbol to the left of the left resistor. We need to select “Differential” in the 
Block Parameter List. 
Next, we can complete the schematic as shown in the figure below:We have to put two differential probes on either side of the cable block. This gets done 
by selecting both nets on the left (using <Ctrl> left mouse click) and selecting  Home: 
Components  Probe  Add Probe.  
We repeat this on the right side. We have to make sure that both probes have the correct 
orientation with the positive pole on the upper and the negative pole on the lower side, 
as shown in the figure below:
If this is not the case, we select the probe, right-mouse click and choose “Change Probe 
Direction” from the corresponding pull-down menu.  
To set up an AC-task we select Navigation Tree: Tasks  New Task and choose “AC, 
Combine results” as shown in the figure below. 
After pressing Ok, a Task Parameter List will appear where we select the “Excitations” 
tab, click on the “Load” parameter and choose “Define Excitation” as shown in the figure
A new dialog box will appear as shown in the figure below: 
We leave the default values and close the dialog again by pressing the  OK button. In 
the  “Frequencies”-tab  of  the  Task  Parameter  List  we  define  0  Hz  as  the  minimum 
frequency and 500 MHz as the maximum frequency as shown in the figure below.Now we can start the simulation by pressing Home: Simulation  Update. In order to 
compare  the  two  differential  voltages  on  both  sides  of  the  cable,  we  generate  a  new 
result folder and name it “curves on both sides” as shown in the figure below:
Next, we drag P1 Diff and P2 Diff from the result folder FD Voltages into the new 
generated result folder. The results should look like in the figure below: 
In order to perform a Transient task, a similar procedure is applied as described for the 
AC-task.  
We  select  Navigation  Tree:  Tasks    New  Task  (using  the  right  mouse  button)  and 
select a Transient task. Again, a Task Parameter List will appear when we select the 
“Excitations” tab and define a pulse in the appearing dialog box as shown in the figure
After pressing Ok, we select the “Transient” tab from the Task Parameter List.  
First, we click on “Local Units” and change the time unit to “ns” in the appearing dialog 
box:  
In a final step, we can now set the maximum simulation time to 80 ns: 
Now,  the  Transient  task  is  defined  and  we  are  able  to  select  Update  and  start  the 
simulation of the transient task.  
After a few seconds, the task will be completed. We create a new result folder named 
Transient Voltage and drag the two results P1 Diff and P2 Diff from the result folder TD 
Voltages into the new generated folder. We should see something similar to the following 
result:We  want  to  finish the  example  with  a  special  note  on  a  general  characteristic  of  this 
cable  model.  As  mentioned  at  the  beginning  of  the  example,    the  model  was  generated  without  the  presence  of  an  additional  reference 
conductor.
It therefore makes sense to put a pure differential termination on the model’s pins as in 
our example. Any termination that forces currents to an imaginary ground  is actually allowed by the schematic editor but wouldn’t lead to any reasonable 
results, neither in the simulation nor in the real world.  
Note: the picture shows the way not to do the loading in case of a non-ground 
referenced structure! 
Crosstalk between two Wire Bundles  
The aim of this example is to acquaint you with the  
  search distance to couple cable bundles lying in different segments  
  S-Parameter analysis 
  difference between lumped models and modal models 
Cable Definition  
In this chapter,  we want to set  up  a simple cable  harness consisting  of two separate 
cable bundles. All cables in a cable bundle are automatically coupled by their mutual 
capacitances  and  mutual  inductances.  Electromagnetic  coupling  between  different 
cable bundles taking place depends on the given search distance during meshing. 
We create an empty project and save it as two cables. The geometric units are left at 
the  default.  We  start  with  the  definition  of  four  nodes  by  double-clicking  on  Cable 
Navigation Tree: Nodes. After the dialog box appears, we create the nodes by assigning 
the co-ordinates as shown in the figure below:Next, we create a cable bundle with name B1 between N1 and N2 and put two single 
wires into it as shown in the next dialog box: 
:
We press Auto Bundle (setting a fixed position of the two wires) and then place another 
cable bundle B2 between N3 and N4 by pressing the New Cable Bundle button. We put 
a single wire into it as shown in the dialog box below: 
We press Ok and close the dialog box. 
Next, we select Cables: Options  View Options and change the settings for nodes as 
shown in the following dialog box:Then we select Cables: Options  Real Thickness 
The structure defined so far can be seen in the Main View:
To finish the harness definition, we have to add a ground plane. We select Modeling: 
Shapes  Brick.  After  pressing  ESC,  the  following  dialog  box  will  appear  where  we 
complete the settings as shown below: 
Finally, we change to Simulation: Settings Frequency and set the maximum frequency 
to 500MHz as shown in the figure below:
Meshing and Simulation with two Different Search Distances 
To generate a first model, we select Cables: 2D (TL) Modeling.  
In the Meshing tab of the dialog box, we set Search distance for coupling of different 
bundles to 2 mm. 
We change to the Modeling tab and see that the value for “Model valid up to frequency” 
is set to 500MHz, according to the maximum frequency setting in Simulation: Settings 
Frequency. Now we press the Apply button on the top right. 
Next we go back to tab Meshing and press the Show Mesh button. If the button is greyed 
out, press Start Meshing first. A new dialog box will appear showing two separate cross 
section items. We select “Show in 3D” and “Cut plane view mode”. The Main View now 
changes its perspective in a way that matches the Cross Section Window:For each selected item, the corresponding cross-section appears in the Cross Section 
window. Each cable bundle is modeled individually and this means there will not be any 
coupling between the cable bundles. 
We define some loadings in the next step. Therefore, we select Cables: Edit Cabling 
Junctions Connect Terminals... to open the Cable Junctions Manager.
We create three 50 Ω resistors as shown in the figure below: 
We add cable ports at the rest of the cable terminals, each port between a terminal and 
its reference.  
First, we need to select Cables: Edit Cabling Cable Ports Cable Ports... to open the 
Cable Ports Manager. The figure below shows how the ports look after creating them:Now let us change to the Schematic tab and set up an S-Parameter-task. We load the 
cable block according to the figure below: 
Note:  define loading  elements  like  ports  between  a  cable terminal  and  circuit  ground 
(reference)  does  make  sense  in  this  case,  because  the  equivalent  circuit  behind  the 
schematic  symbol  includes  the  information  of  an  existing  reference  conductor  (the 
ground plane). 
It is now time to set up the S-Parameter task. We select Navigation Tree: Tasks New 
Task by using the right mouse button.
In  the  dialog  box,  we  select  S-Parameters  and  press  OK.  In  the  appearing  Task 
Parameter  List,  we  set  the  parameters  the  minimum  and  the  maximum  frequency 
according to the figure below: 
Now,  we  start  the  simulation  by  selecting  Home:  Simulation    Update.  After  a  few 
seconds, the task is completed. To show the results on port 2 and port 3, we create a 
new result folder with name crosstalk and drag curve S2,1 and S3,1 from the result folder
After switching the Plot Type (Result Tools: Plot Type) from dB to Linear, the two 
result curves should look like in the figure below: 
In a second step we go back to the 3D tab, open the Cables: 2D (TL) Modeling) dialog 
box  once  again,  select  the  Meshing  tab  and  set  the  Search  distance  for  coupling  of 
different cable bundles to 20 mm and press Apply.We will be prompted to confirm the change. Next, we switch to the Schematic tab and 
start the simulation task again. Note that the cable model is updated automatically. 
After the simulation has completed the result can be seen by again selecting the result 
folder crosstalk. As expected, there is also coupling into pin N4_SW_3 now.
In order to see the reason for this, we change back to the 3D tab and reopen the 2D 
Meshing tab (inside Cables: 2D (TL) Modeling).  
After pressing the Show Mesh button, a single cross section item will be shown instead 
of the two in the previous one. 
By selecting the cross section item and looking at the Cross Section window we see that 
there are three wires inside the cross section, and this confirms that both cable bundles 
have been coupled during the modeling:We want to finish this example by going back to the 3D tab and selecting Cables: 2D 
(TL) Modeling once again.
We check Allow Modal Models in the Modeling tab and press Apply. The difference between lumped and modal is best explained by using a simple, single 
transmission line.  
Using the lumped modeling approach, a transmission line is approximated by a series 
of discrete (or lumped) R, L, C devices as shown in the next figure: 
Each  R-L-C-combination  models  a  short  section  of  the  transmission  line.  The  valid 
frequency  range  for  the  whole  model  is  therefore  limited  by  the  length  of  this  unit 
because  the  length  of  the  section  must  be  considerably  smaller  than  the  shortest 
wavelength of the propagating signal.  
The advantage of the lumped approach is its flexible usage inside a circuit simulation 
and  its  suitability  for  modeling  non-uniform  transmission  lines  like  twisted  pairs. 
Disadvantages arise when dealing with overall lengths of transmission lines much larger 
than  the  wavelength  of  its  transmitted  signal.  In  this  case,  the  number  of  necessary 
sections  is  large  and  this  causes  a  large  number  of  lumped  elements  inside  the 
equivalent circuits. 
Using  the  modal  modeling  approach,  a  transmission  line  is  defined  by  its  secondary 
transmission line characteristics like wave impedance Z and propagation delay . The 
size of the model does not depend on the length of transmission line or on the maximum 
frequency and this is a big advantage when dealing with long uniform transmission lines. 
Using this approach for non-uniform transmission lines like twisted pairs requires some 
simplifications by the program and this may slightly influence the accuracy.  
The modal approach can’t be used if the models use hybrid field-to-cable coupling. 
When checking Allow modal models the program automatically looks for electrically long 
sections along the cable assembly and models these sections by modal models instead
of lumped models. Note: electrically long means a length that is considerably longer than 
the wavelength for the maximum frequency set in the same dialog box.  
To see how these modal models work we change to the Schematic tab. Before starting 
a new simulation, we first save the results of the previous run. In order to do this, we 
select the existing result curves in folder crosstalk and uncheck Update Automatically 
by using the right mouse button (do this for both curves). 
Now we run a new simulation and notice that the simulation takes less time than before. 
After completion of the simulation, we create a new result folder and name it crosstalk 
modal as in the figure below: 
We add curve S2,1 and S3,1 to compare it with the results in folder crosstalk and notice
Coaxial Cable Simulation in 3D 
The aim of this example is to acquaint you with 
  The bi-directional cable to field coupling method 
  Connecting cable to 3D metal to close the common mode current loop 
  Using parameterized geometry definition 
3D Structure Definition 
In this chapter, we want to set up a coaxial cable running between two 3D connectors on a 
metallic table. The size of the table and some other geometric numbers are defined as 
parameters. 
We create an empty Cable project and save it as ”coax cable cosimulation”. We keep the 
geometric units at their defaults. 
We start with the definition of the table. We define a 3D brick with the following parameters: 
  Name: top 
  Xmin / Xmax: -0.5*length / 0.5*length 
  Ymin / Ymax: -0.5*width / 0.5* width” 
  Zmin / Zmax: height-40 / height 
  Component: table 
  Material PEC 
We set the parameters with the following initial values: 
 
length: 1600 
  width: 0.5*length 
  height 700 
We define another brick with these parameters to start with the table legs:   Name: panel 
  Xmin / Xmax: -0.5*length / -0.5*length+40 
  Ymin / Ymax: -0.5*width / -0.5* width+40 
  Zmin / Zmax: 0 / height-40 
  Component: table 
  Material PEC 
Now we use the Transform to copy this panel: 
  Select Copy option 
  Translation vector x / y / z: length-40 / 0 / 0 
To complete the table we use again the feature transform on both panel and on the just 
created copy panel_1. For both transformations, we use the same settings: 
  Select Copy option 
  Translation vector x / y / z: 0 / width-40 / 0
The 3D view should now show the complete table setup as shown in the figure below:We define the next component that will represent the connection to the cable. The first part 
of it is a cone (Modeling: Shapes  Cone) with these settings: 
  Name: tmpcone 
  Orientation: X 
  Bottom radius / Top radius: 60 / 16 
  Ycenter / Zcenter: 0 / height + 100 
  Xmin / Xmax: 40 - 0.5 * length / 40 - 0.5 * length + cone_length  (use 100) 
  Segments: 12 
  Component: connection 
  Material: Zinc (loaded from the material library)  
We need a further brick with these parameters:  
  Name: connection 
  Xmin / Xmax: -0.5 * length / -0.5 * length + base_length  (use 40) 
  Ymin / Ymax: -60 / 60 
  Zmin / Zmax: height / height + 200 
  Component: connection 
  Material: Zinc 
We perform a Boolean operation and combine the shapes “connection” and “tmpcone”. This 
is done by selecting both shapes and selecting Modeling: Tools  Boolean. 
We need another cone to cut a hole into the connection and fill it with insulator material: 
  Name: insulator 
  Orientation: X 
  Bottom radius / Top radius: 20 / 5 
  Ycenter / Zcenter: 0 / height+100 
  Xmin / Xmax: -0.5 * length / -0.5 * length + base_length + cone_length 
  Segments: 12 
  Component: connection 
  Material: Polyimide (loss free) (loaded from the material library)
The next step is a Boolean operation.  
Select the shape connector and press Modeling: Tools  Boolean  Insert. We select the 
shape insulator. This operation cuts a hole into the shape connector and keeps the insulator 
in this hole. 
Finally, we define another cone that will be the core conductor. We use the following 
settings: 
  Name: core 
  Orientation: X 
  Bottom radius / Top radius: 4 / 2 
  Ycenter / Zcenter: 0 / height + 100 
  Xmin / Xmax: -0.5 * length / -0.5 * length + base_length 
  Segments: 12 
  Component: connection 
  Material: Zinc 
With these steps, we have completed the connection. We copy and mirror the entire 
component “connection” to the other side of the table and use the following transform
The 3D view should now look like this: 
Cable Definition 
In this setup, the cable between the two connectors is split into three parts. One is a coaxial 
cable in the middle. On each side of it, there are wires that connect the core of the coaxial 
cable to the cores of the 3D connectors. 
We start with the coaxial cable in the middle. To do this, we define a cable bundle:We put an RG58 cable from the library into this cable bundle and deselect random bundling: 
In a next step, we define the wires at the left-hand side and at the right-hand side. We add 
two more nodes:
We insert two new cable bundles as shown below: 
Next, we add a new single wire into each of these cable bundles:Simulation Setup 
We now connect the cables we just set up. We define several shorts as follows: 
 
 
 
the single wire on both sides at the nodes N1 and N2 to the coaxial core 
the coaxial screen on both sides at the nodes N1 and N2 to reference 
the single wire on both sides at the nodes NStart and NEnd to reference 
A short between a cable conductor to reference means that it is connected to the 3D 
conductors, if there is only one cable conductor connected at a certain position. If there are 
more than one cable conductors that end at the same position, you need to split them in any 
way and connect them individually to 3D.
The list of junctions needs to be defined in the Cable Junctions Manager available from 
Cables: Edit Cabling  Junctions  Connect Terminals: 
In addition, we need two metal sheets to complete the connection of the cable screen to the 
3D connector. Such sheets are necessary as if you want to continue a coaxial cable defined 
as cable bundle with a coaxial structure in 3D. 
We create a 3D cylinder available in Modeling: Shapes  Cylindrical Shapes Cylinder as 
shown in the figure below:Note that it is a sheet because it has no extension in the x direction.
In the 3D view it should look like this: 
Finally, we copy and mirror this sheet to the other connection as well. The figure below 
shows the parameters for this transformation:The mirror plane origin is 0 / 0 / 0 which is exactly in the middle of the whole structure.
In the next step, we define the 3D ports that we need as scattering parameter ports. In order 
to do this, we pick these two edge chains at the left connector as shown in the figure below 
and define a new discrete port: 
We add a similar port to the right connector. You can find the picking features in Modeling: 
Picks  Pick Edge Chain. 
We define a new current monitor in the middle of the cable segment “N1 – N2” as shown in 
the figure below. You can do so from Cable Navigation Tree  Current Monitors. Use the 
context menu and select New Current Monitor:Now, we set the frequency range as shown here: 
In the next step, we slightly reduce the complexity of the example. We edit Simulation: 
Settings  Boundaries settings and set the minimum distance to structure to the value 8 
(Fraction of wavelength) like shown below:
Next, we modify some very important solver and mesh settings.  
First, we select “Use-multi-stranded cable route” in Simulation: Solver  Setup Solver 
Specials: 
We change the Accuracy in the Solver settings to -60 dB. We only choose Port 1 to be
We change the global mesh settings for the hexahedral (TLM) mesh as shown below: 
In addition, we should also deselect the “Snapping: Axial edges” as shown here: 
Edge snapping might lead to unwanted effects, if a cable is placed into a 3D mesh. 
Finally, we set the local mesh properties / volume refinement for the shapes 
‘connection:insulator’ and ‘connection_1:insulator’ like shown in the figure below:This improves the mesh at the edge ports and effects the accuracy of the whole simulation.
With the setup is complete, we start the simulation by pressing Home: Simulation  Start 
Simulation. After a couple of minutes, the TLM solver simulation has finished. 
Note, that if the mesh is too coarse, the TLM solver might stop with errors. So please, do all 
the settings above as described. 
The S-parameter results look like in the chart below: 
The current monitor signals look like this: 
The current signals at the ports look like this:The transmission through the structure is present. This means that the signal is created in 
the 3D port at the left-hand side and propagates along the coaxial 3D cone structure. It runs 
along the coaxial cable that is simulated as a cable equivalent model. The fields next to the 
cable screen interact with the signals in the cable (bidirectional cosimulation). At the right-
hand side, the signal moves back into the 3D connection and reaches the second port. 
It is very important that the energy decays from the cable as well as from the 3D structure. 
This seems to be the case here. If you like to improve this energy decay, you can further 
increase the solver accuracy from -60dB to e.g. -80dB.
62
Field Coupling from and into a Twisted Pair  
The aim of this example is to acquaint you with the  
  hybrid method for radiation (current substitution method) 
  hybrid method for irradiation (field substitution method)  
  difference between a balanced and un-balanced termination on a twisted pair 
Cable Definition 
In this chapter, we want to set up a simple configuration of a straight 2m long twisted 
pair cable placed 50mm over a ground plane. We create an empty Cable project and 
save it as twisted pair. We keep the geometric units their defaults.  
We start with the definition of the ground plane as shown in the dialog box below:Next, we change to Simulation: Settings Frequency and set the maximum frequency 
to 200 MHz as shown in the figure below: 
Now we right-mouse click at Cable Navigation Tree: Cable Bundles and choose New 
Cable Bundle from the pull-down menu. The Create New Cable Bundle dialog box 
appears where we define a trace between nodes N1 and N2 as shown in the dialog 
box below:
Note that the z-position of the nodes is 50mm. We press Ok and see the Edit Cable 
Bundles dialog box where we add the standard twisted pair cable from the library into 
the trace: 
We finish with pressing the OK button. 
In the following examples, we want to connect both cable ends with the ground plane by 
using capacitors. In order to inform the 3D field solver of such a connection of the cable 
nodes to the 3D objects, both cable ends have to be marked in a special way.  
We select the Nodes tab on the left side of the dialog box and press the Connection to
A new dialog box appears which allows selecting both end nodes of the cable bundle.  
We see that both nodes are prepared for a (common mode) connection with the ground 
plane by default.  
Note: Nodes prepared for a 3D connection appear in yellow color in the Main View, all 
other nodes will be displayed in blue color. 
We  close  the  Connect  to  3D  dialog  box,  open  the  2D  (TL)  Modeling  dialog  box  and 
activate Ohmic losses and Dielectric losses as shown in the figure below: We press Apply to update the settings. 
Now we define cable ports. We use single-ended ports from each cable terminal to its 
reference. This allows us to set up the schematic in an asymmetric manner, which would 
not be possible in case of using differential ports between the two cable ends. We need 
this asymmetry to excite the common mode in this structure. Later in this chapter, we 
will see that a symmetric setup will not result in much interaction between the 3D fields 
and the cable and thus the common mode will be very low. 
Note:  The  current  implementation  of  the  cable  coupling  between  the  cable  circuit 
simulation and the 3D field simulation even does not allow to simulate these very small 
common mode that exists for the symmetric setup.
We  select  Cables:  Edit  Cabling  Cable  Ports  Cable  Terminal  Ports...  to  open  the 
Cable Ports Manager. The figure below shows how the ports look after creating them: 
Hybrid Method for Radiation from a Cable 
To simulate the radiation of the cable we now change to the Schematic tab and see the 
generated schematic symbol.  Before  we set  up  the schematic ,  we 
make sure that both pins of node N1 are arranged on the left side and both pins of node 
N2 are arranged on the right side (“Change Pin Layout”). We start on the left by adding two capacitors (both with a value of 1 pF), two resistors 
(both with value of 50 Ohm) and a differential port between the resistor terminals.  
On the right, we add a resistor of 100 Ohm and two capacitors with different values. The 
upper one has a value of 1pF, but the lower one has a value of 100pF. This difference 
causes an imbalance that will affect the radiation result. To finish the schematic, we add 
a differential probe on the right side of the cable block.
Next, we create an AC-task and do the following settings for Fmin, Fmax and Samples 
in the “Frequencies”-tab of the appearing Task Parameter List: 
The 3D field solvers are able to perform a calculation in a broad frequency range, but 
since we are only interested in a field distribution plot at a single frequency point, we 
reduce the number of frequencies to three.  
Finally, we define a voltage source in the ”Excitations”-tab 
with the following settings:Before we start the simulation, we have to prepare the circuit simulation to write out the 
common mode current along the cable path for the 3D field calculation. To do this, we 
change  in  the  “Cable  Field  Coupling”-tab  of  the  Task  Parameter  List  and  select  Uni-
directional Radiation as shown in the figure below:
Now we can close the Task Parameter List and change to the 3D tab to see that Units, 
Background Material, Boundary Conditions and Frequency are already set.  
In  order  to  get  a  distribution  of  the  radiated  field,  we  have to set  a  field  monitor. We 
select Navigation Tree: Field Monitors and choose New Field Monitor by using the right 
mouse button: 
A dialog box will appear where we select monitor type H-Field and Surface current:We leave the Frequency at the proposed value of 100MHz, and press OK. We now see 
a field monitor item in the Navigation Tree and a corresponding frame in the Main View:
There  are  two  transient  field  solver  techniques  (FIT  and  TLM).  We  choose  “TLM”  by 
choosing “Mesh type” “Hexahedral TLM” in Solver:  Setup Solver dialog box. 
We select Special Time Domain Solver Parameters: Solver  Special settings  Use 
multi-stranded cable route. We recommend to always select this option. It helps to avoid 
accuracy issues with fine 3D meshes in combination with larger cables. 
We open the dialog box by selecting Simulation: Mesh  Global Properties to define the 
following global mesh properties:We switch back to the Schematic tab and start the simulation by pressing the Update 
button. You may see warnings about “floating nodes” during the simulation. The reason 
is that at DC there is no circuit ground connected. However, this is OK.
To display the radiated magnetic field we change back to the 3D tab, select Navigation 
Tree: 2D/3D Results  H-Field  h-field (f=100) [AC1] and finally we select Contour in 
2D/3D Plot:  Plot Type. 
To  better  see  the  magnetic  field  distribution  on  a  2D  plane  we  select  2D/3D  Plot:  
Sectional View  Fields on Plane switch the Normal to Z in 2D/3D Plot:  Sectional 
View and display the magnetic field at Position 50 mm (the position where the cable is 
located): 
After rotating the whole structure according to the figure below and clamping the Color 
Ramp to 0.0002…0.03 A/m (logarithmic), we see something like the following magnetic 
field distribution:Note: Depending on the setup of this example, the field distribution can differ slightly. 
The contributing factors are geometry (cross section, path), twist/lay settings of the cable 
and  the  actual  resonance frequency  of  the  system.  One  resonance  frequency  of  this 
example is at or close to 100MHz, which we use for this example.
To demonstrate the influence of a better-balanced termination on the twisted pair, we 
change to the Schematic tab and modify the 100pF capacitor to 1pF: 
Now the termination is fully balanced and we repeat the whole simulation by updating 
the AC-task once more.  
After a few seconds, the simulations will be complete. Again, we plot the magnetic field 
distribution and clamp Color Ramp to 0.0002…0.02A/m as was done before. We see 
that the magnetic field distribution is gone:We have observed how the signals inside a cable and the termination on the cable’s 
ends  can  influence  the  3D  field  around  it.  In  the  next  section,  we  will  investigate the 
influence of the 3D field on the cable signals.
Hybrid Method for Irradiation into a Cable 
To see, how external fields can be coupled into the existing twisted pair cable, we first 
create a plane wave excitation in CST Cable Studio. In order to do this, we go into the 
Navigation  Tree,  close  the  2D/3D  Results  folder,  select  the  Plane  Wave  folder  and 
choose New Plane Wave by using the right mouse button.  
In the following dialog box, we change the settings as shown in the figure below: 
After pressing OK we are prompted to confirm the deletion of the old results:We press OK and select the new plane wave item in the Navigation Tree.
After doing so you will see the plane wave in the Main View: 
Next, we call the T-Solver dialog box (by selecting Home: Simulation  Setup Solver) 
and select Plane Wave as Source type and select Superimpose plane wave excitation 
as shown in the figure below:Next, we press Apply, close the dialog box and change to the Schematic tab where we 
make three modifications.  
First, we change the value of the bottom capacitor back to 100pF:
Next, in order to force the 3D solver to calculate the induced voltages along the cable 
path, we pick the task AC1 in the Navigation tree and open the Task Parameter List. We 
select the Cable Field Coupling tab and choose Uni-directional Irradiation as shown in 
the figure below: 
Now  we change to  the  Frequencies tab  and set the  number  of frequency samples  to 
200: As a final step, we change to the Excitations tab  
Here we set the value of the voltage source to 0 (zero): 
Now  we  press  OK  and  start  the  simulation.  We  notice  that  the  3D  field  simulation  is 
executed first, followed by the circuit simulation with the AC task. The whole sequence 
takes only a few seconds.
To display the induced voltage on the right side of the twisted pair cable, we select P1Diff 
in  the  FD  Voltages  result  folder  and  get  a  result  like  this  (the  magnitudes  may  vary 
slightly): 
Next,  we  force  the  scaling  to  fixed  values.  In  order  to  do  this,  we  go  with  the  mouse 
pointer  into  the  Main  View  and  choose  Plot  Properties  by  pressing  the  right  mouse 
button.  
In the dialog box, we uncheck Auto range of the Y Axis field like in the figure below and
In order to see the changes when we balance the termination network on the right of the 
cable, we will now change the 100pF capacitor to 1pF:
Chapter 4 – General Methodology 
CST Cable Studio is designed for ease of use. However, to work with the tool in the most 
efficient way the user should know the principal method behind it. The main purpose of 
this chapter is to explain the theoretical concepts and the constraints on its use. 
The central method of CST Cable Studio is based on classical transmission line theory. 
In this method,  the  geometric  and material characteristics  of a cable  are  transformed 
into an equivalent circuit that can be simulated in time and frequency domains.  
Standard Workflow 
In  the  first  step,  a  complex  cable  harness  is  divided  into  a  finite  number  of  straight 
segments. For each segment, the program checks for any metallic and insulator shapes 
surrounding the cables. All cables in a segment - in combination with additional metallic 
and  insulator  shapes  from  the  3D  environment  -  define  its  cross  section.  This  whole 
process is called Meshing. 
In the second step the primary transmission line parameter per unit length (R’, L’, C’, G’) 
is calculated from each segment by a static 2D field solver. Afterwards each segment 
will  be  transformed  into  an  equivalent  circuit.  Finally,  all  circuits  will  be  connected 
together into one single electrical model representing the whole cable. This process is 
called Modeling. 
The second step implies that only TEM propagation modes can be considered and this 
fact causes the following constraints, which are described below:  
  TEM propagation mode means that there are at least two separate conductors 
necessary to enable one single propagation mode (to enable forward and return 
current).  In  general,  N  conductors  are  necessary  to  enable  N-1  propagation 
modes.  One  single  wire  inside  open  space  without  any  reference  (typical 
antenna structure) will not be modeled correctly for a frequency higher than DC. 
  The generated equivalent circuits are only valid within a frequency range from 
DC  to  the  maximum  frequency.  This  is  because  the  primary  transmission  line 
parameters  are  static  parameters  and  only  valid  if  the  geometric  dimensions 
behind the calculation are significantly smaller than the shortest wavelength of 
the propagating wave. 
  Discontinuities like bends, deviations or cable ends will not be considered when 
using the standard workflow. 
In the third step the electrical model of the cable can be further processed in the Circuit 
Simulation. To make this possible the model will be automatically transferred to a circuit 
simulator where the user is able to define several loadings (passive/active, linear/non-
linear)  and to calculate  the  transmission  behavior  of  the  cable  in time  and frequency 
domains. 
Additional Workflow for Uni-and Bi-Directional Cable-to-Field Coupling 
Many industrial applications deal with cables inside an additional metallic environment 
(e.g. ground planes in laboratory setups, car chassis). In the presence of such reference 
conductors, one propagation mode is of special interest. This mode is called common
the  corresponding  return  current  back  through  the  reference  conductor.  Significant 
common mode currents are often the reason for considerable EMI/EMS problems. 
If  a  reference conductor  is  part  of  the  configuration,  the  method  used  by  CST  Cable 
Studio is able to calculate the common mode by summing up all currents in the cable 
bundle during  an AC task.  The “common mode  current”  along the cable  path can  be 
automatically  passed to  a  3D full-wave solver  where it can  be  used  as  an impressed 
field source. This method is called a uni-directional cable-to-field coupling.  
If the cable  was modeled for  uni-directional coupling, the cable itself is not  physically 
present during the 3D full wave simulation. Because of this, the reaction of the generated 
field  (generated  by  the  impressed  current)  back  to  the  cable  will  be  neglected.  This 
approach limits the range of applications to configurations where most of the radiated 
energy will not be scattered back to the cable. This is true for many configurations with 
cables along open metallic chassis. The assumption is not true in case of a resonant 
cable  inside  a  nearly  closed  metallic  enclosure.  Therefore,  when  using  this  current 
substitution  method,  the  user  has  to  check  if  the  application  fulfills  the  necessary 
assumption. 
Note:  If  there  is  no  reference  conductor,  CST  Cable  Studio  will  always  assume  a 
common mode current of zero. Any oscillating antenna modes, which may exist in the 
higher frequency range (when dimension of lambda equals length of cable), will not be 
considered because the basic method is only able to simulate TEM-modes. 
The  procedure  described  above  can  also  be  used  for  evaluating  the  common  mode 
impact of an external electromagnetic field onto a cable. Here, the 3D full-wave solver 
will calculate the tangential electric field along the cable path (while the cable itself is not 
physically present). In a next step, the solver will automatically convert these values to 
voltages  and  finally  pass  the  voltages  to  a  circuit  simulator.  During  an  AC-task,  the 
voltages can be used to calculate the induced currents on the cable. The limitation of 
this field substitution method is identical to the current substitution method. 
If the described uni-directional coupling methods are not sufficient, CST Cable Studio 
also offers the most general method, namely the bi-directional coupling between cable- 
and field-solver in  time-domain.  In  this case, currents  and voltages  are  exchanged in 
every time step between the 3D full-wave field simulator and the circuit simulator cables 
and loadings. This method can (and has to) be applied in case of resonating structures,
Chapter 5 – Finding Further Information 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by choosing  File: Help  Help Contents 
. The 
online help system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button  which  directly  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties. 
When  no specific information is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system. 
Please refer to the CST Studio Suite - Getting Started manual to find some more detailed 
explanations about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  Some documented macro examples.  
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software described in this document is furnished under a license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a 
retrieval system, or transmitted in any form or any means electronic 
or mechanical, including photocopying and recording, for any 
purpose other than the purchaser’s personal use without the written 
permission of Dassault Systèmes. 
Trademarks 
icon, 
IdEM,  Spark3D,  Fest3D,  3DEXPERIENCE, 
CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
STUDIO,  CST  EMC  STUDIO,  CST  MICROWAVE  STUDIO,  CST 
PARTICLE  STUDIO,  CST  Studio  Suite,  EM  Studio,  EMC  Studio, 
Microstripes,  Microwave  Studio,  MPHYSICS,  MWS,  Particle  Studio, 
PCB  Studio,  PERFECT  BOUNDARY  APPROXIMATION  (PBA), 
Studio  Suite, 
the 
Compass 
logo,  CATIA,  BIOVIA,  GEOVIA, 
SOLIDWORKS, 3DVIA, ENOVIA, NETVIBES, MEDIDATA, CENTRIC 
PLM,  3DEXCITE,  SIMULIA,  DELMIA  and  IFWE  are  commercial 
trademarks or registered trademarks of Dassault Systèmes, a French 
"société  européenne"  (Versailles  Commercial  Register  #  B  322  306 
440), or its subsidiaries in the United States and/or other countries. All 
other  trademarks  are  owned by  their respective owners.  Use  of  any 
Dassault  Systèmes  or  its  subsidiaries  trademarks  is  subject  to  their 
express written approval. 
the  3DSDS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries. 
3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome  to  CST  EM  Studio®,  the  powerful  and  easy-to-use  electromagnetic  field 
simulation software. This program combines a user-friendly interface with unsurpassed 
simulation performance. 
CST  EM  Studio  is  part  of  CST  Studio  Suite®.  Please  refer  to  the  CST  Studio  Suite 
Getting  Started  manual  first.  The  following  explanations  assume  that  you  already 
installed  the  software  and  familiarized  yourself  with  the  basic  concepts  of  the  user 
interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
1.  Read the CST Studio Suite Getting Started manual. 
2.  Work  through  this  document  carefully.  It  provides  all  the  basic  information 
necessary to understand the advanced documentation. 
3.  Look at the examples provided in the Component Library (File: Component 
Library  Examples). Especially the examples which are tagged as Tutorial 
provide  detailed  information  of  a  specific  simulation  workflow.  Press  the 
Help 
 button of the individual component to get to the help page of this 
component. Please note that all these examples are designed to give you a 
basic  insight  into  a  particular  application  domain.  Real-world  applications 
are typically much more complex and harder to understand if you are not 
familiar with the basic concepts. 
4.  Start with your own first example. Choose a reasonably simple example, which will 
allow you to become familiar with the software quickly. 
5.  After you have worked through your first example, contact technical support for hints 
on possible improvements to achieve even more efficient usage of the software. 
What is CST EM Studio? 
CST EM  Studio is  a fully featured  software  package for  electromagnetic analysis  and 
design of electrostatic, magnetostatic, stationary current and low-frequency devices. It 
simplifies the process of creating the structure by providing a powerful graphical solid 
modeling front end, which is based on the ACIS modeling kernel. After the model has 
been constructed, a fully automatic meshing procedure is applied before a simulation 
engine is started. 
A key feature of CST EM Studio is the Method on Demand approach, which allows using 
the solver or mesh type that is best suited to a particular problem. Most solvers support 
two different meshing strategies:  
  Classic  tetrahedral  meshes,  which  provide  an  explicit  representation  of  the 
geometry and material interface by a surface mesh. Thus, material interfaces are 
explicitly resolved by the mesh. Curvilinear mesh elements are especially suited 
to discretize curved geometries. The geometry resolution is continually improved 
during  an  adaptive  mesh  refinement  using  the  True  Geometry  Adaptation 
technique.  
  Hexahedral  grids  in  combination  with  the  Perfect  Boundary  Approximation 
(PBA®)  feature.  With  hexahedral  (Cartesian)  meshes,  interfaces  of  materials 
and solids are not represented by surface mesh cells. Therefore, the meshing
CAD  geometries.  The  PBA  feature  significantly  increases  the  accuracy  of  the 
simulation in comparison to conventional Cartesian mesh simulators.  
The software contains five different solvers that best fit their particular applications:   
  Electrostatic solver 
  Magnetostatic solver 
  Stationary current solver 
  LF Frequency Domain solver  
o  magnetoquasistatic 
o  electroquasistatic 
o 
full-wave 
  LF Time Domain solver  
o  magnetoquasistatic 
o  electroquasistaticIf you are unsure which solver best suits your needs, please consult the online help or 
contact your local sales office for further assistance. 
Simulation results from each solver can be visualized with a variety of different options. 
Again, a strongly interactive interface will help you quickly achieve the desired insight 
into your device. 
The last – but certainly not least – outstanding feature is the full parameterization of the 
structure  modeler,  which  enables  the  use  of  variables  in  the  definition  of  your 
component. In combination with the built-in optimizer and parameter sweep tools, CST 
EM Studio is capable of both the analysis and the design of electromagnetic devices. 
Who Uses CST EM Studio? 
Anyone  who  is  looking  for  a  solution  for  a  static  or  low-frequency  electromagnetic 
problems, can use CST EM Studio. The program is especially suited to the fast, efficient 
analysis  and  design  of  components  like  actuators,  insulators,  shielding  problems, 
sensors,  transformers,  electrical  machines,  etc.  Since  the  underlying  method  is  a 
general 3D approach, CST EM Studio can solve virtually any static and low-frequency 
field problem. 
CST EM Studio Key Features 
The following list gives you an overview of CST EM Studio's main features.  Note that 
not all of these features may be available to you because of license restrictions. Contact 
a sales office for more information. 
General 
  Native  graphical  user  interface  based  on  Windows  10,  Windows  Server  2016 
and Windows Server 2019 
  The structure can be viewed either as a 3D model or as a schematic. The latter 
allows for easy coupling of EM simulation with circuit simulation. 
  Various independent types of solver strategies (based on hexahedral as well as 
tetrahedral meshes) allow accurate results with a high performance for all kind 
of low frequency applications. 
  For  specific  solvers,  highly  advanced  numerical  techniques  offer  features  like 
PERFECT  BOUNDARY  APPROXIMATION  (PBA)®  for  hexahedral  grids  and 
curved and higher order elements for tetrahedral meshes. 
Structure Modeling 
  Advanced  ACIS-based,  parametric  solid  modeling  front  end  with  excellent 
structure visualization
  Feature-based hybrid modeler allows quick structural changes. 
  Import of 3D CAD data from ACIS SAT (e.g. AutoCAD®), ACIS SAB, Autodesk 
Inventor®,  IGES,  VDA-FS,  STEP,  Pro/ENGINEER®,  CATIA®,  Siemens  NX, 
Parasolid,  Solid  Edge,  SolidWorks,  CoventorWare®,  Mecadtron®,  NASTRAN, 
STL or OBJ files 
  Import of 2D CAD data from DXF™, GDSII and Gerber RS274X, RS274D files 
  Import of EDA data from design flows including Cadence Allegro® / APD® / 
SiP®, Mentor Graphics HyperLynx®, Zuken CR-5000® / CR-8000®, IPC-2581 
and ODB++® (e.g. Altium Designer, Mentor Graphics Expedition / PADS / 
Boardstation®, CADSTAR®, Visula®) 
  Import of OpenAccess and GDSII-based integrated-circuit layouts via CST Chip 
Interface 
  Import of PCB designs originating from CST PCB Studio® 
  Import of 2D and 3D sub models 
  Import of Agilent ADS® layouts 
  Import of Sonnet® EM models 
  Import of a visible human model dataset or other voxel datasets 
  Export of CAD data by ACIS SAT, ACIS SAB, IGES, STEP, NASTRAN, STL, 
DXF™, GDSII, Gerber or POV files 
  Parameterization for imported CAD files 
  Material database 
  Structure templates for simplified problem setup 
Electrostatic Solver 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Sources: potentials, charges on conductors (floating potentials), uniform volume- 
and surface-charge densities, capacitive field grading 
  Force calculation 
  Capacitance calculation 
  Electric  /  magnetic  /  tangential  /  normal  /  open  /  fixed-potential  boundary-
conditions 
  Perfect conducting sheets and wires 
  Discrete edge capacitive elements at any location in the structure 
  Adaptive mesh refinement in 3D 
  Higher order representation of the solution with tetrahedral mesh 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Coupled simulations with Mechanical Solver from CST MPhysics Studio® 
  Equivalent Circuit EMS/DS Co-Simulation for constant material properties 
Magnetostatic Solver 
  3D- and 2D1- problem support.  
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Nonlinear ferromagnetic material properties 
  Laminated material properties 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Sources:  coils,  coil  segments,  including  those  created  from  solids,  linear  and 
non-linear  permanent  magnets,  current  paths,  external  magnetic  fields, 
stationary current fields, current ports 
  Force and force density calculation
  Apparent and incremental inductance calculation 
  Flux linkages 
  Electric / magnetic / tangential / normal / open / cylindrical subvolume boundary-
conditions 
  Rotational periodicity for 2D and 3D problems 
  Adaptive mesh refinement for 2D and 3D solver 
  Higher  order  representation  of  the  solution  with  tetrahedral  and  triangular 
meshes 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Coupled simulations with Mechanical Solver from CST MPhysics Studio 
  Equivalent  Circuit  EMS/DS  Co-Simulation  for  constant  and  nonlinear  material 
properties 
Stationary Current Solver 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Nonlinear electrical conductivity properties 
  Temperature dependent materials with coupling to CST MPhysics Studio 
  Electric contact resistance 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Sources: current paths, potentials, current ports, coil segments, including those 
created from solids 
  Conductance calculation 
  Discrete edge resistances at any location in the structure 
  Perfect conducting sheets and wires 
  Electric  /  magnetic  /  normal  /  tangential  /  cylindrical  subvolume  boundary-
conditions 
  Adaptive mesh refinement in 3D 
  Higher order representation of the solution with tetrahedral mesh 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations 
  Uni- and bi-directionally coupled simulations with the Thermal and CHT Solvers 
from CST MPhysics Studio 
  Equivalent Circuit EMS/DS Co-Simulation for constant material propertiesLF Frequency Domain Solver 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Nonlinear  material  properties  (B(H))  and 
linear  equivalent  permeability 
computation 
  Temperature  dependent  nonlinear  (B(H))  and  linear materials  with  coupling  to 
CST MPhysics Studio 
  Support of hexahedral meshes as well as linear and curved tetrahedral meshes 
  Electroquasistatic analysis 
  Magnetoquasistatic analysis (eddy current approximation) 
  Magnetoquasistatic broadband analysis (eddy current approximation) 
  Full wave analysis 
  Sources for electroquasistatic analysis: potentials 
  Sources for full wave and magnetoquasistatic analysis: coils, coil segments, 
including those created from solids, current ports, current paths, voltage paths, 
external magnetic source fields 
  Impedance calculation
  Sources for magnetoquasistatic broadband analysis: coils, coil segments, 
including those created from solids, current ports 
  Fast and stable broadband calculation from zero frequency to given maximal 
frequency for: 
o 
impedance, inductance, resistance, DC-resistance and conductance 
matrices  
o  source parameters including flux linkages and induced voltages  
o  energies and losses 
  Authoring of Reduced Order Models as Functional Mockup Units according to 
FMI standard 
  Fast frequency sweep in the broadband solver regime 
  Force calculation 
  Perfectly conducting sheets and wires 
  Lumped R, L, C elements at any location in the structure 
  Surface impedance model for good conducting metals 
  Electric / magnetic / tangential / normal / open boundary-conditions 
  Adaptive mesh refinement in 3D 
  Higher order representation of the solution with tetrahedral mesh 
  Automatic parameter studies using built-in parameter sweep tool 
  Automatic structure optimization for arbitrary goals using built-in optimizer 
  Network distributed computing for optimizations, parameter sweeps and remote 
calculations  
  Uni-directionally  coupled  simulations  with  the  Thermal  and  CHT  solvers  from 
CST  MPhysics  Studio  for  both  magnetoquasistatic  and  electroquasistatic 
analysis 
  Bi-directionally coupled simulations with the Thermal and CHT solvers from CST 
MPhysics Studio for magnetoquasistatic analysis 
  Coupled simulations with SIMULIA Abaqus 
LF Time Domain Solver 
  Isotropic and (coordinate-dependent) anisotropic material properties 
  Magnetoquasistatic analysis (eddy current approximation), 3D- and 2D2-problem 
support 
  Electroquasistatic analysis 
  Nonlinear material properties (B(H), E(J), J(H, T)) 
  Recoil  model  for  nonlinear  hard  magnetic  material  properties  (permanent 
magnets) 
  Iron Loss computation 
  Support of linear and curved tetrahedral meshes 
  Sources  for  the  magnetoquasistatic  analysis:  coils,  coil  segments,  including 
those created from solids, current ports, current paths, voltage paths, permanent 
magnets, external magnetic source field 
  Sources for electroquasistatic analysis: potentials 
  Magnetoquasistatic analysis: perfect conducting sheets and wires 
  Electric / magnetic / tangential / normal / open / cylindrical subvolume boundary-
conditions 
  Higher order representation of the solution with tetrahedral mesh 
  User defined excitation signals and signal database 
  Adaptive time stepping 
  Dedicated time stepping algorithm for time periodic problems 
  Automatic source parameter monitors for current ports  and coils including  flux 
linkages and induced voltages
  Rigid body motion for 2D and 3D models with nested rotations and translation 
  Steady state detection for 2D models 
  Periodic boundary condition (translation) and cylindrical subvolume (rotation) 
  Demagnetization monitors 
  Network distributed computing remote calculations 
  Uni-directionally  coupled  simulations  with  the  Thermal  and  CHT  solvers  from 
CST MPhysics Studio 
  Coupled simulations with SIMULIA Abaqus 
Partial RLC Solver  
  Calculation  of  equivalent  circuit  parameters  (partial  inductances,  resistances, 
and capacitances) and optional SPICE export  
  For a detailed description consult the online documentation 
Drift-Diffusion Solver  
  Calculation of stationary electron and hole distribution within a semiconductor  
  Calculation of mid-gap potential 
  Solid constant doping densities 
  Computation of derived quantities: quasi-Fermi potentials, plasma frequency 
  Adaptive mesh refinement 
  Computation of junction capacitance 
  Carrier generation & recombination models 
  Import of 3D power loss fields 
  Improved current density visualization 
  Support of multi-materials  
  For a detailed description consult the online documentation 
Note: some solvers or features may be available for hexahedral and some may be available 
for tetrahedral meshes only. 
CST Design Studio View 
  Schematic view that shows the circuit level description of the current CST EM 
Studio project 
  Allows additional wiring, including active and passive circuit elements as well as 
more complex circuit models coming from measured data (e.g. Touchstone or 
IBIS  files),  analytical  or  semi-analytical  descriptions,  or  from  simulated  results 
(e.g. CST Microwave Studio, CST Cable Studio or CST PCB Studio projects) 
  Offers many different circuit simulation methods 
  All schematic elements as well as all defined parameters of the connected CST 
EM Studio project can be parameterized and are ready for optimization runs. 
  Geometry creation by assembling the components on the schematic in 3D 
  Flexible and powerful hierarchical task concept offering nested parameter sweep 
/ optimizer setups 
SAM (System and Assembly Modeling) 
  3D representations for individual components 
  Automatic project creation by assembling the schematic’s elements into a full 3D 
representation 
  Manage project variations derived from one common 3D geometry setup 
  Coupled multi-physics simulations by using different combinations of coupled 
Circuit/EM/thermal/mechanical projects 
Visualization and Secondary Result Calculation 
  Multiple 1D result view support 
  Online visualization of intermediate results during transient simulations
  Copy & paste of xy-datasets 
  Fast access to parametric data via interactive tuning sliders 
  Automatic parametric 1D result storage 
  Various field visualization options in 2D and 3D for electric fields, magnetic fields, 
potentials, current densities, energy densities, etc. 
  Animation of field distributions 
  Display of source definitions in 3D 
  Display of nonlinear material curves in xy-plots  
  Display of material distribution for nonlinear materials 
  Display and integration of 2D and 3D fields along arbitrary curves 
  Integration of 3D fields across arbitrary faces 
  Hierarchical  result  templates  for  automated  extraction  and  visualization  of 
arbitrary results from various simulation runs. These data can also be used for 
the definition of optimization goals. 
Result Export 
  Export of result data such as fields, curves, etc.  
  Export of result data as ASCII files 
  Export screen shots of result field plots 
Automation 
  Powerful  VBA  (Visual  Basic  for  Applications)  compatible  macro  language 
including editor and macro debugger 
  OLE  automation  for  seamless  integration  into  the  Windows  environment 
(Microsoft Office®, MATLAB®, AutoCAD®, MathCAD®, Windows Scripting Host, 
etc.) 
About This Manual 
This  manual  is  primarily designed  to  enable  a quick  start  of  CST EM  Studio. It  is  not 
intended to be a complete reference guide to all the available features but will give you 
an overview of key concepts. Understanding these concepts will allow you to learn how 
to use the software efficiently with the help of the online documentation. 
The main part of the manual is the Simulation Workflow (Chapter 2), which will guide 
you through the most important features of CST EM Studio. We strongly encourage you 
to study this chapter carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the “Ctrl” key while pressing the “S” key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document, a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the command.
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item.  
Example: NT: 2D/3D Results  E-Field [Es]  Abs 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support
Chapter 2 – Simulation Workflow 
The  following  example  shows  a  fairly  simple  magnetostatic  simulation.  Studying  this 
example carefully will allow you to become familiar with many standard operations that 
are necessary to perform a simulation within CST EM Studio.  
Go through the following explanations carefully even if you are not planning to use the 
software for magnetostatic computations. Only a small portion of the example is specific 
to  this  particular  application  type.  Most  of  the  considerations  are  quite  general  to  all 
solvers and application domains. 
At  the  end  of  this  example,  you  will  find  some  remarks  concerning  the  differences 
between  the  typical  sources  and  simulation  procedures  for  electrostatic,  stationary 
current, magnetostatic, and low-frequency calculations. 
The following explanations always describe the “long” way to open a particular dialog 
box or to launch a particular command. Whenever available, the corresponding toolbar 
item will be displayed next to the command description. In order to limit the space in this 
manual,  the  shortest  way  to  activate  a  particular  command  (i.e.  either  by  pressing  a 
shortcut key or by activating the command from the context menu) is omitted. You should 
regularly  open  the  context  menu  to  check  the  available  commands  for  the  currently 
active mode. 
The Structure 
In the example, you will model a simple sealed transformer consisting of two coils and 
an  iron  core  in  a  cylindrical  box.  Then  you  will  set  up  the  simulation  to  compute  the 
magnetic field distribution and the inductances. The following picture shows the current 
structure of interest (it has been sliced open purely to aid visualization). The picture has 
produced using the POV export option in CST EM Studio.Before you start modeling the structure, let us spend a few moments discussing how to 
describe this structure efficiently. 
CST EM Studio allows you to define the properties of the background material. Anything 
you  do  not  fill  with  a  particular  material  will  automatically  be  considered  as  the 
background material. For this structure, it is sufficient to model only the cylinder box, the 
iron core and the two coils. The background properties will be set to vacuum. 
Your method of describing the structure should therefore be as follows: 
1.  Create the cylindrical box. 
2.  Model the iron core inside the box. 
3.  Define the coils.
Create a New Project 
After launching the CST Studio Suite, you will enter the start screen showing you a list 
of recently opened projects and allowing you to specify the application which suits your 
requirements  best.  The  easiest  way  to  get  started  is  to  configure  a  project  template, 
which sets the basic settings that are meaningful for your typical application. Therefore, 
click on the New Template button in the New Project from Template section. 
Next, you should choose the application area, which is Statics and Low Frequency for 
the  example  in  this  tutorial  and  then  select  the  workflow  by  double-clicking  on  the 
corresponding entry. For the sealed transformer, please select Power Electronics  Transformers/Chokes  
M-Static 
. 
At  last,  you  are  requested  to  select  the  units  which  fit  your  application  best.  For  the 
sealed  transformer  all  dimensions  will  be  given  in  cm.  Therefore,  select  cm  from  the 
Dimensions drop-down list. For the specific application in this tutorial, the other settings 
can be left unchanged. After clicking the Next button, you can give the project template 
a name and review a summary of your initial settings.
Finally, click the Finish button to save the project template and to create a new project 
with  appropriate  settings.  CST  EM  Studio  will  be  launched  automatically  due  to  the 
choice of the application area Statics and Low Frequency. 
Please  note:  When  you  click  again  on  File:  New  and  Recent  you  will  see  that  the 
recently defined template appears below the New  Project from Template section. For 
additional projects in the same application area, you can simply click on this template 
entry to launch CST EM Studio with useful basic settings. It is not necessary to define a 
new template each time. You are now able to start the software with reasonable initial 
settings quickly with just one click on the corresponding template.  
Please note: All settings made for a project template can be modified later on during 
the construction of your model. For example, the units can be modified in the units dialog 
box  (Home:  Settings   Units 
)  and  the  solver  type  can  be  selected  in  the  Home: 
Simulation  Setup Solver drop-down list. 
Open the QuickStart Guide 
An interesting feature of the online help system is the QuickStart Guide, an electronic 
assistant that will guide you through your simulation. If it does not show up automatically, 
you can open this assistant by selecting QuickStart Guide from the Help contents drop-
down menu 
 in the upper right corner. 
The following dialog box should be positioned in the upper right corner of the main view:As the project template has already set the solver type, units and background material, 
the Magnetostatic Analysis is preselected, and some entries are marked as done. The 
red arrow always indicates the next step necessary for your problem definition. You do 
not have to follow the steps in this order, but we recommend you follow this guide at the 
beginning to ensure that all necessary steps have been completed.  
Look at the dialog box as you follow the various steps in this example. You may close 
the assistant at any time. Even if you re-open the window later, it will always indicate the 
next required step. 
If you are unsure of how to access a certain operation, click on the corresponding line. 
The  QuickStart  Guide  will  then  either  run  an  animation  showing  the  location  of  the 
related menu entry or open the corresponding help page.
Define the Background Material 
As discussed above, the structure will be described within a vacuum world with some 
surrounding space. The project template has set some typical default values already. 
Select Modeling: Materials  Background 
 to check or modify the background material 
settings. For this example enter 3 cm for all directions by checking Apply in all directions 
and enter the Distance value.  
Confirm  by  clicking  the  OK  button.  (Remember:  according  to  the  predefined  unit,  all 
geometric settings are in cm.)Model the Structure 
First, create a cylinder along the z-axis of the coordinate system by the following steps: 
1.  Select the cylinder creation tool from Modeling: Shapes  Cylinder 
2.  Press  the  Shift+Tab  key,  and  enter  the  center  point  (0,0)  in  the  xy-plane  before 
. 
pressing the Enter key to store this setting. 
3.  Press the Tab key again, enter the radius 5 and press the Enter key. 
4.  Press the Tab key, enter the height as 7 and press the Enter key. 
5.  Press Esc to create a solid cylinder (skip the definition of the inner radius). 
6.  In the shape dialog box, enter “cylinder box” in the Name field. 
7.  Select component1 from the Component drop-down list. 
8.  Select  [New  Material]  from  the  Material  drop-down  list.  The  Material  dialog  box 
opens  where you  should enter the material  name  “Iron”,  select  Normal  properties 
(Type) and set the material properties Epsilon = 1.0 and Mu = 1000. Now you can 
select a color and close the dialog box by clicking OK. 
9.  Back in the cylinder creation dialog box, click OK to create the cylinder. 
10. Finally, save the structure by selecting File: Save (Ctrl+S) and entering a name, e.g. 
"Transformer.cst" in a folder of your choice. 
The result of all these operations should look like the picture below. You can press the 
Space bar to zoom to a full screen view.
Please note that you can switch on or off the multicolored axes or the axes at the origin 
in the View Options dialog box (View: Options  View Options (Alt+V) 
). 
The  next  step  is  to  shell  the  cylinder.  Select  the  cylinder  in  the  navigation  tree  (NT: 
Components   component1   cylinder  box)  and  open  the  shell  dialog  by  selecting 
Modeling: Tools  Shape Tools  Shell Solid or Thicken Sheet. Enter the Thickness 
0.5 and select Inside as the direction.To observe the result, activate the cutting plane view via View: Sectional View  Cutting 
Plane  Cutting Plane (Shift+C) 
. You can adjust the cutting plane settings either by 
using the Up/Down arrow keys or by entering the Cutting Plane Properties dialog box 
(View: Sectional View  Cutting Plane  Cutting Plane Properties 
). 
To look into the box, you might have to rotate the view. Activate the rotation mode by 
selecting View: Mouse Control  Rotate  Smart (Mouse Pointer) 
. Then press the 
left mouse button and move the mouse until the view looks like this: 
It is also possible to hold down the Ctrl button to activate the rotation mode for as long 
as Ctrl is pressed.
The  next  step  is  to  create  a  second  cylinder  inside  the  box.  The  center  of  the  new 
cylinder’s base should align with the center of the box's inside face. To this end, first 
align the local coordinate system (WCS) with the lower inside z face of the box: 
.  
1.  Select Modeling: Picks  Picks 
2.  Double-click on the box’s lower inside z-plane. Note: Pickable faces or edges are 
automatically  highlighted,  when  the  mouse  is  in  an  appropriate  position.  They 
sometimes hide other objects. With the Tab key it is possible to switch through the 
relevant objects until the desired face is marked for picking. The selected face should 
now be highlighted: 
3.  Now choose Modeling: WCS  Align WCS 
 (Shortcut: W).  
4.  Select the cylinder creation tool Modeling: Shapes  Cylinder 
5.  Press the Shift+Tab key and enter the center point (0,0) in the uv-plane and press 
. 
the Enter key. 
6.  Press the Tab key again and enter a radius of 0.8 and press the Enter key. 
7.  Select Modeling: Picks  Pick Points  Pick Circle Center 
8.  Set the cylinder's height by picking the highlighted circle of the upper inner face of 
the box with a double-click. You might have to rotate the structure a little bit to get a 
better view: 
.9.  Press Esc to create a solid cylinder (skip the definition of the inner radius). 
10. In the shape dialog box, enter “iron core” in the Name field. 
11. Select the component “component1” from the component list. 
12. Select the material “Iron” from the material list.
13. Click the OK button. 
The result of these operations should look like this:Sharp edges are, in general, responsible for field singularities. Therefore, we will blend 
the edges of the iron core and the cylinder box. Before we can do this, the two bodies 
have  to  be  united.  Thus,  select  the  cylinder  box  (either  in  the  navigation  tree  or  by 
double-clicking on it in the main view). Then choose Modeling: Tools  Boolean  Add 
 and select the iron core. Confirm the operation by pressing the Enter key. The iron 
core entry will vanish from the navigation tree and only the cylinder box remains in the 
NT: Components  component1 folder. 
Now you can select the edges to blend. All inner edges shall be blended with radius 1, 
the outer edges of the cylinder box with radius 0.5. Hence, activate the pick edge tool 
Modeling: Picks  Picks  Pick Edge 
 (Shortcut: E) and pick all inner edges (multiple 
activations of the pick edge tool might be necessary, you can see the selected edges in 
the lower left corner):
Finally, enter the Blend Edges dialog box via Modeling: Tools  Blend  Blend Edges 
 and enter the radius 1.0. Confirm this setting by pressing OK. Next, pick the two outer 
edges of the cylinder box.  
Open the Blend Edges dialog again and enter the radius 0.5. Leave the dialog via the 
OK button. The cylinder box should look now as depicted below:Looking at the QuickStart Guide, you will see that now it is time to define the sources for 
the magnetic field simulation. 
Define Coils 
In  CST  EM  Studio,  a  coil  can  be  defined  as  an  a-priori  known  current-  or  voltage-
distribution which is constant over the cross-section of the coil body for this example. 
Consequently, the coil represents the equivalent distribution of the current in a realistic 
coil with many turns, where small-scale variations are averaged out. 
The creation of a coil is quite similar to the definition of a solid by curves. First, you have 
to move the working coordinate system to the right position:
1.  Select Modeling: Picks  Pick Points  Pick Face Center 
 (shortcut: A). 
2.  Double-click on the upper outside face of the box as highlighted. 
3.  Select Modeling: Picks  Pick Points  Pick Face Center 
 again. 
4.  Double-click on the lower outside face of the box as highlighted. 
5.  Select  Modeling:  Picks    Pick  Points    Mean  Last  Two  Points 
(Ctrl+Shift+M). 
6.  Select Modeling: WCS  Align WCS 
. 
Now, the working coordinate system should be placed as depicted in the next figure. At 
any time, the Working Plane can be enabled or disabled using View: Visibility  Working 
Plane (Alt+W).To define the path of the first coil, carry out the following: 
1.  Select Modeling: Curves  Curves  Circle 
2.  Press the Shift+Tab key and enter the center point (0,0) in the uv-plane. Then press 
. 
the Enter key to store this setting. 
3.  Press the Tab key again, and enter the radius 2.
4.  In the circle dialog box, enter “coil path 1” in the Name field. 
5.  Click OK to create the circle. 
The path for the second coil is created in the same way: 
1.  Select Modeling: Curves  Curves  Circle 
2.  Press the  Shift+Tab key,  and  enter  the  center  point  (0,0)  in the  uv-plane  before 
. 
pressing the Enter key to store this setting. 
3.  Press the Tab key again, and enter the radius 4. 
4.  In the circle dialog box, enter “coil path 2” in the Name field. 
5.  Select [New Curve] from the Curve drop-down list. 
6.  Click OK to create the circle. 
Please  note:  We  put  all  path  and  profile  curves  into  separate  Curve  folders  just  to 
simplify blending the coils’ edges afterwards. 
To define the profile paths of both coils, you first need to rotate the working coordinate 
system around the v-axis: 
1.  Press Shift+V or select Modeling: WCS  Transform WCS and activate the Rotate 
control in the Transform Local Coordinate System dialog box and enter 90 for the 
V component.For the definition of the first profile curve, perform the following steps: 
1.  Select Modeling: Curves  Curves  Rectangle 
2.  Press the Tab key, and enter the first point (-2.5, 1) in the uv-plane before pressing 
. 
the Enter key to store this setting. 
3.  Press the Tab key again, and enter the second point (2.5, 2.5) and press the Enter 
key. 
4.  In the rectangle dialog box, enter “profile path 1” in the Name field. 
5.  Select [New Curve] from the Curve drop-down list.
6.  Click OK to create the rectangle. 
The second profile can be created as follows: 
1.  Select Modeling: Curves  Curves  Rectangle 
2.  Press the Tab key, and enter the first point (-2, 2.7) in the uv-plane before pressing 
. 
the Enter key to store this setting. 
3.  Press the Tab key again, and enter the second point (2, 4.2) and press the Enter 
key. 
4.  In the rectangle dialog box, enter “profile path 2” in the Name field. 
5.  Select [New Curve] from the Curve drop-down list. 
6.  Click OK to create the rectangle. 
Now your model should look like the one depicted below. You may need to click on the 
components folder in the navigation tree if only the curve that was created last is still 
highlighted. 
Like for the cylinder box, it is meaningful to blend the coil edges as well. This can be 
done by blending the corners of the profile paths. Select NT: Curves curve3 profile 
path 1 and pick its four corners (Modeling: Picks  Picks 
. (shortcut: P)). Now choose 
Modeling: Curves  Curves  Blend Curve 
. The Blend Curve dialog box will pop up. 
Enter the radius 0.3 and confirm this setting by pressing OK.Next, the corners of the profile path 2 rectangle need to be blended in completely the 
same manner. Select NT: Curves curve4 profile path 2, choose Modeling: Picks  
Picks 
.repeatedly  and  pick  the  four  corners  of  the  selected  rectangle.  Next,  use 
Modeling: Curves  Curve Tools  Blend Curve 
 to blend the corners with the radius 
0.3. The profile curves should then look as depicted below:
Finally, the coils can be created from the profile and path curves: 
1.  Select Simulation: Sources and Loads  Coil  Coil 
2.  Move the mouse cursor to “profile path 1” until it the entire curve is highlighted (or 
select “curve3” in the navigation tree). Then double-click on it in the main view to 
select it (the inner profile curve). 
. 
3.  Move the mouse cursor to “coil path 1" and select it by double-clicking. 
4.  In  the  Define  Coil  dialog  box,  enter  “coil  1”  in  the  Name  field,  select  the  type 
Current, enter 1 A for the current value and 1000 in the Number of turns field. (Do 
not  change  the  Conductor  Type,  Phase  or  Resistance  values.)  Coils  can  be 
gathered into so-called coil groups. For more information about this, please refer 
to the online help.5.  Click OK to create the coil. 
Now your model should look like the one depicted below. You may need to click on the 
components folder in the navigation tree if the coil is not highlighted. 
The same procedure can be applied for the second coil: 
1.  Select Simulation: Sources and Loads  Coil  Coil 
 from the main menu.
2.  Move the mouse cursor to “profile path 2” until it is highlighted. Then double-click 
to select it. 
3.  Move the mouse cursor to “coil path 2,” and select it by double-clicking. 
4.  In the Define Coil dialog box, enter “coil 2” in the Name field, 1 A for the value of 
the current and 800 in the Number of turns field.  
5.  Click OK to create the coil. 
Congratulations! You have just created your first structure within CST EM Studio. The 
view should now look like this after the working plane (View: Visibility  Working Plane 
(Alt+W) 
) has been switched off:Please  note:  As  the  project  template  has  set  some  default  boundary  conditions 
applicable in most use cases, the corresponding entry in the QuickStart Guide is already 
checked. Nevertheless, you should always check if the model can be simplified, e.g. by 
symmetry conditions. We will discuss this in the next section.
The  following  gallery  shows  some  views  of  the  structure  using  different  visualization 
options: 
Shaded view,  
(deactivated working 
plane     iron material 
    50% 
properties: 
transparency) 
Shaded view, 
(cutting plane active) 
Wireframe view,  
(View: Visibility  
Wireframe 
) 
Define Boundary Conditions 
The simulation of this structure is performed only within the bounding box enclosing the 
structure together with some background material. The space occupied by the structure 
and background material is called the "computational domain" in the sequel. 
Note that the restriction to a bounded computational domain is artificial for our example 
(keeping in mind the transformer structure in open space). However, in this simple case, 
the magnetic flux is concentrated in the core material. Therefore, the artificial boundary 
will  not  considerably  disturb  the  solution  even  though  the  added  space  around  the 
structure is not very large. 
In order to get a well-defined problem, you must specify the behavior of the field at the 
boundary of the computational domain by setting a boundary condition for each plane 
(Xmin/Xmax/Ymin/Ymax/Zmin/Zmax). 
The  boundary  conditions  are  specified  in  a  dialog  box  which  you  can  bring  up  by 
choosing Simulation: Settings  Boundaries
While the boundary dialog box is open, the boundary conditions will be visualized in the 
structure view as in the picture above. You can change boundary conditions within the 
dialog box or interactively in the view by double-clicking on the corresponding boundary 
symbol, and then select the appropriate type from the context menu. 
The  project  template  has  already  set  "electric  (Et  =  0)"  boundary  conditions  in  every 
direction. You do not need to change the default setting. 
Background  information:  Electric  boundary  conditions  ("electric  (Et  =  0)")  force  the 
tangential electric field to be zero. For non-zero frequencies, Faraday's Law implies a 
zero  normal  component  of  the  magnetic  flux  density  B.  Viewing  magnetostatics  as  a 
static  limit  of  Maxwell's  equations  justifies  this  implication  even  for  the  magnetostatic 
case.  Consequently,  an  electric  boundary  condition  always  forces  a  zero  normal 
component of the magnetic flux density, i.e. the B-field is purely tangential, and no flux 
can  leave  the  computational  domain  at  this  face.  Note  that  this  also  applies  to  the 
boundary of perfect electric conductors (PECs), which play the role of interior boundary 
conditions. 
Another important boundary condition is the "magnetic (Ht = 0)"-condition, which forces 
a zero tangential magnetic field, i.e. the magnetic field is purely normal to a face defined 
as "magnetic." This consideration is used in the next sub-section. 
Define Symmetry Conditions 
In addition to the boundary planes, you can specify “symmetry planes". Each specified 
symmetry plane reduces the simulation time and the required memory by  (roughly) a 
factor of two. In our example, the structure is symmetric with respect to the Y/Z plane 
(perpendicular to the x-axis). A second symmetry plane applies to the X/Z plane.  
The excitation of the fields is performed by the currents in the coils for which the current
Y/Z plane 
X/Z plane 
The electric symmetry planes for the magnetic field can be applied if 
the current pattern is normal to the plane.  
The resulting magnetic field has no component normal to the X/Z and Y/Z planes (the 
entire  field  is  oriented  tangential  to  these  planes).  Moreover,  the  fields  have  no 
component tangential to the X/Y plane. If you specify X/Z and Y/Z planes as “electric” 
and  X/Y  as  “magnetic”  symmetry  planes,  you  can  advise  CST  EM  Studio  to  limit  the 
simulation  to  1/8  of  the  actual  structure  by  taking  these  symmetry  conditions  into 
account.  
To specify the symmetry condition, click on the Symmetry Planes tab in the Boundary 
Conditions dialog box. For the YZ- and XZ-plane symmetry, you can choose "electric 
(Et = 0)"  by  either  selecting  the  appropriate  choice  in  the  dialog  box,  or  by  double-
clicking on the corresponding symmetry plane visualization in the view and selecting the 
appropriate choice from the context menu. For XY-plane symmetry, choose "magnetic 
(Ht = 0)." Once you have done this, your model and the dialog box will appear as follows:Finally, click OK in the dialog box to store the settings. The boundary visualization will 
then disappear. 
As shown by the QuickStart Guide, the model is now completely defined, and you are 
ready to start the magnetostatic solver.
In order to get a discrete version of the defined model that can be solved numerically, a 
mesh  must  be  provided  for  the  computational  domain.  CST  EM  Studio  features  two 
independent solvers based on tetrahedral and hexahedral meshes, respectively. Let us 
start with the tetrahedral solver. 
Generate and Visualize a Tetrahedral Mesh 
The tetrahedral mesh generation for the structure is performed fully automatically when 
the tetrahedral magnetostatic solver is started.  
It is also possible to generate the mesh separately before starting the solver. This may 
be  helpful  in  order  to  get  an  impression  of  the  mesh  quality  and  mesh  resolution. 
Furthermore, it is possible to fine-tune the mesh before running the computation using 
a-priori knowledge about the solution. Let us use this second possibility and generate 
the mesh separately. First,  open  the  Mesh  Properties  dialog  by  selecting  Simulation:  Mesh    Global 
Properties   Tetrahedral 
. The dialog box “Mesh Properties – Tetrahedral” will open. 
In order to get a reasonable overall mesh resolution of the problem, you can increase 
the values for Maximum cell. In general, it is sufficient to refine the mesh locally, i.e. only 
at certain critical parts of the geometry, which can be achieved by running the solver 
with the fully automatic energy-based adaptive refinement. Thus, we start with a rather 
coarse mesh and leave the Cells per max model box edge at the value 10 for the model 
and at 5 for the background.  Additionally, press the Specials button and switch off the 
option Anisotropic Curvature Refinement in the Special Mesh Properties – Tetrahedral 
dialog box. 
Background information: The results are strongly influenced by the mesh resolution. 
The  automatic  mesh  generator  analyzes  the  geometry  and  tries  to  refine  the  mesh 
locally  taking  geometric  features  into  account  (e.g.  curvature-based  refinement  with 
tetrahedral  meshes  or  expert  system-based  approach  with  hexahedral  meshes). 
However, due to the complexity of electromagnetic problems, this approach may not be 
able to determine all critical domains in the structure. To circumvent this problem, CST 
EM  Studio  features  an  adaptive  mesh  refinement  that  uses  the  results  of  a  previous 
solver run in order to optimize the mesh. The adaptive mesh refinement can be activated 
by checking the corresponding option in the Solver Parameters dialog box.
Now  click  the  Update  button  in  the  Mesh  Properties  dialog  box  to  start  the  mesh 
generation.  You  will  see  a  progress  bar  displaying  the  current  status  of  the  mesh 
generation. 
When the mesh generation process has finished, the progress bar disappears. You will 
see that the entries in the Mesh summary frame of the Mesh Properties dialog box have 
been updated: In the Statistics frame, you can get information about the minimum and maximum mesh-
edge lengths, the number of tetrahedrons, and the maximum, minimum, and average 
mesh quality. The number of tetrahedrons and the edge lengths give you information 
about the size and resolution of the discretized model.  
Please note that the mesh size and  the  results might  differ  slightly  depending  on  the 
operating system and the architecture of the machine with which they are calculated. 
Background  information:  Generally,  due  to  the  finiteness  of  the  mesh  density,  the 
computed  results  differ  from  the  exact  solution.  The  introduced  error  is  called  the 
discretization error. Increasing the mesh density will usually lead to more precise results, 
yet the computation time and the necessary memory size will increase. 
The  quality  of  a  tetrahedron  is  positive  and  less  than  or  equal  to  one.  The  value  “1” 
indicates  the  highest  (equilateral  tetrahedron),  the  value  “0”  the  lowest  quality  (zero 
volume tetrahedron). Please refer to the online help for an exact definition of quality. 
Background information: Not only the mesh density but also the mesh quality has a 
strong  influence  on  the  results.  A  very  low  mesh  quality  may  lead  to  a  poor 
approximation of the model. Moreover, a low mesh quality may reduce the speed of an 
iterative solver. This is the reason why it is always meaningful to have a look at the mesh 
before running a simulation. 
Now close the Mesh Properties dialog box by clicking the OK button. You can visualize 
the mesh by entering the mesh view (Simulation: Mesh  Mesh View 
). The mesh 
should look similar to the illustration below. To inspect the mesh in the interior of the
structure, activate the cutting plane by selecting View: Sectional View  Cutting Plane 
Cutting Plane (Shift+C) 
. 
The automatic curvature refinement leads to a local refinement along the blended edges. 
By default, the mesh transition from the coarser to the finer mesh regions is very rapid. 
This  transition  can  be  smoothed  in  the  Specials  dialog-box  of  the  Global  Mesh 
Properties  dialog  box  (Mesh:  Mesh  Control   Global  Properties   Tetrahedral 
), 
which  may  also  improve  the  mesh  quality.  Please  refer  to  the  online  help  for  more 
details.  
Remember  that  you  have  reduced  the  computational  model  by  defining  symmetry 
planes. Therefore, only 1/8 of the computational domain is meshed. Nevertheless, the 
mesh is visualized for the complete structure by mirroring the missing parts. You can 
easily see the symmetry planes in the mesh-view. 
Finally, let us take a look at the mesh of the surrounding space. Activate the visualization 
of the background material by selecting View: Options  View Options (Alt+V) 
, and 
then select the Background material checkbox in the Draw frame of the General Tab. 
After you click OK, the displayed mesh should look similar to the following picture: Before you go on, you should deactivate the visualization of the background material by 
selecting View: Options  View Options (Alt+V) 
 again and un-checking Background 
material. Leave the mesh view by selecting Mesh: Close  Close Mesh View 
.
Run the Tetrahedral Magnetostatic Solver 
The simulation is started from the  Magnetostatic Solver Parameters dialog box which 
can be opened via Home: Simulation  Setup Solver 
:Make sure the Mesh Type "Tetrahedral" is selected. In the Accuracy drop-down list, a 
stopping criterion for the iterative linear equation system solver can be selected. For the 
example model, leave the Accuracy value at 1e-6.  
Background  Information:  While  the  solution  accuracy  mainly  depends  on  the 
discretization of the structure and can be improved by refining the mesh, the numerical 
error  of  the  linear  equation  system  solver  introduces  a  second  error  source  in  field 
simulations (iteration error). Choosing a small Accuracy value reduces this error at the 
expense of a longer calculation time. Usually, an Accuracy setting of “1e-6” is sufficient, 
but  in  some  cases  it  might  be  necessary  to  select  a  smaller  value,  particularly  if  you 
receive a warning that the results are not accurate. Furthermore, with increasing mesh 
density (i.e. smaller discretization error) you should also increase the solver accuracy 
by selecting a smaller Accuracy value.  
Furthermore,  activate  the  calculation  of  the  Apparent  inductance  matrix.  Please  note 
that the Adaptive mesh refinement is switched on already. This setting is meaningful as 
the initial mesh is rather coarse. During the solver run, several mesh refinement passes 
are  performed  automatically  until  the  energy  value  does  not  change  significantly 
between two subsequent passes. The default termination criterion is an energy deviation 
of 1% (or less). You can fine-tune these settings in the Adaptive Mesh Refinement dialog 
box. 
Click the Properties… button to enter the Adaptive Mesh Refinement dialog box. Change 
the Stopping criterion to 1e-5 and verify that the checkbox Snap new nodes to geometry 
is checked. This feature will ensure that new nodes that are generated on the surface 
mesh during the mesh adaption will be projected to the original geometry, so that the 
approximation of curved surfaces is improved after each adaption step. The dialog box 
should now look as follows:
Close the dialog with the OK button and finally start the simulation procedure by clicking 
Start.  
Several progress bars like the one depicted below will appear in the status bar informing 
you about the current solver status:These are the steps of the tetrahedral magnetostatic solver run: 
1.  Computing coil(s): This first calculation step must be performed to calculate the 
discrete representation of coil current patterns.  
2.  Initializing magnetostatic solver: During this step, your input model is checked 
for errors such as invalid overlapping materials, not well-defined sources, etc. 
3.  Assembling system: The linear system of equations is generated. 
4.  Constructing pre-conditioner: This includes construction steps for the pre-
conditioner of the solver, e.g. an LU-decomposition, a construction of hierarchy for 
a multigrid solver etc. 
5.  Solving linear system: During this stage, the equation system is solved yielding 
the unknown field. 
6.  Estimating error (only during mesh adaption pass): The local error for each 
element is estimated (error distribution). 
7.  Marking elements for refinement (only during mesh adaption pass): A certain 
number of elements will be marked for refinement, based on the computed error. 
8.  Adapting mesh (only during mesh adaption pass): The mesh is refined taking the 
marked elements into account. 
9.  Inductance computation (only if switched on): The apparent and/or incremental 
inductance matrix is calculated. 
10. Postprocessing stage: The field solution is used to compute other fields and 
additional results like the energy within the structure.
If the adaptive mesh refinement is switched on, some of the steps are repeated until a 
predefined stopping criterion is met. 
For  this  simple  structure,  the  entire  analysis  (including  adaptive  mesh  refinement) 
usually takes only a few minutes to complete on a modern standard computer. 
If you activate the mesh view (Home: Mesh  Mesh View 
) while the adaptive solver 
is running, you can observe how and where the mesh is refined after each pass. After 
the  solver  has  finished,  the  mesh  should  look  like  depicted  in  the  following  picture 
(deviations  are  possible  since  the  initial  mesh  can  differ  slightly  depending  on  the 
operating system and the architecture of the machine): 
Analyze the Results of the Tetrahedral Solver 
After the solver run you can access the results via the navigation tree, see below.  
While the adaptive solver is running, you can already watch the progress of the mesh 
refinement and the convergence behavior in the NT: 1D Results  Adaptive Meshing
Click, for instance, on NT: 1D Results  Adaptive Meshing  Error. This folder contains 
a curve that displays the change of the relative energy of two subsequent simulations. 
The curve below shows that the maximum difference of the relative change of the energy 
is below the desired stopping criterion of 1e-5.Additionally, 
NT: 1D Results  Adaptive Meshing  Energy. 
the  convergence  of 
the  energy  can  be  visualized  by  selecting
Please  remember that the  curves can  differ  slightly  when  computed  on machine  with 
different architecture. Furthermore, the number of passes needed for convergence can 
deviate also owing to the machine architecture. 
In practice, it often proves sensible to activate the adaptive mesh refinement to ensure 
convergence of the results. (This might not be necessary for structures with which you 
are  already  familiar  and  where  you  can  use  your  experience  to  refine  the  automatic 
mesh manually.) 
can 
You 
choosing 
NT: 2D/3D Results  B-Field [Ms]  to  get  an  impression  of  the  B-field  inside  the 
transformer. After you select this folder, a plot similar to the following should appear: 
magnetic 
visualize 
density 
flux 
the 
byIt might be necessary to adjust the size (scaling) and the density of the arrow objects to 
obtain  a  better  view.  You  can  modify  the  plot  properties  by  selecting  2D/3D Plot: 
Plot Properties  Properties 
 (or by selecting Plot Properties from the context menu 
in the main view). The following dialog box will open:
To decrease the number of arrows, move the Density slider slightly to the left.  
To get  an  even  better  view,  you  can  plot  the field on  a 2D  plane.  Select  2D/3D  Plot: 
Sectional View  Fields on Plane 
. Again, to adjust the plot quality, you can select 
2D/3D Plot: Plot Properties  Properties 
, and move the Density slider. Before you continue, ensure that the local coordinate system is not active. In order to 
deactivate the local coordinate system, deselect Modeling: WCS  Local WCS  Local 
WCS 
. Note that it may be necessary to click on the NT: Components folder first. 
After  reselecting  NT:  2D/3D  Results    B-Field  [Ms],  switch  off  the  “Structure 
Transparent” mode by clicking on 2D/3D Plot: Plot Properties  Structure Transparent 
. Furthermore, use the View tab to adjust the view properly:
1.  Select “Right” from the drop-down list in View: Change View  Select View. 
2.  Activate the Plane Rotation Mode (View: Mouse Control  Rotate in Plane 
3.  Turn the plot 90 degrees by holding the left mouse button and moving the mouse. 
4.  Select View: Change View  Reset View 
 to adjust the plot size. 
). 
A plot similar to the following should appear: 
Afterwards,  switch  on  the  “Structure  Transparent”  mode  again  via  2D/3D  Plot:  Plot 
Properties  All Transparent 
 and deactivate the 2D plot mode by deselecting 2D/3D 
Plot: Sectional View  Fields on Plane 
. 
Please note: At the right top corner in the main view, you can usually see a color ramp, 
which you can adjust by dragging its small markers, or in the plot properties. By default, 
it is scaled to the overall maximum of the 3D Field you are viewing. From time to time it 
may happen that, for example, the maximum of an active 2D cut plane is much smaller 
than the 3D maximum. In order to get a meaningful impression of the field then, it might 
be necessary to rescale the color ramp. This can be done, for example, in the context 
menu (right-click in the main view) by selecting Smart Scaling 
. To reset the view to 
the default, select Reset Scaling 
 from the context menu. 
The inductance matrix was computed after the last adaptive run. The results are located 
in NT: 1D Results  Ms Solver  Inductance Matrix and contain both, the self- and the 
mutual  inductances.  You  can  either  obtain  a  visual  representation  or  inspect  the 
numerical  values  in  the  Result  Navigator,  which  is  by  default  located  as  a  tab  in  the 
window below the main view. You can select multiple results within one folder by holding 
down the Shift key and then clicking them with the left mouse button.Note:  For  your  convenience,  you  can  move  around  and  detach  all  visual  tabs  and 
windows  by  Drag&Drop.  You  can  control  which  windows  are  visible  by  selecting  or 
deselecting them via the drop-down list accessible through View: Window  Windows.  
Finally,  let  us  take  a  look  at  the  total  magnetic  energy  in  the  computational  domain. 
Select all entries under NT: 1D Results  Ms Solver  Energy to obtain:
You  can  find  the  co-energy  in  a  similar  way  under  NT: 1D Results    Ms Solver   
Co-Energy: 
The energy and the co-energy are shown for each solid separately. Note that energy 
and co-energy are exactly the same since only linear materials have been used in the 
model. 
Remember  that  the  major  advantage  of  the  tetrahedral  mesh  is  the  explicit 
representation  of  the  geometry,  even  in  the  course  of  adaptive  refinement.  A  proper 
resolution of non-planar surfaces is very important, in particular, to model jumps in the 
field  components  at  material  interfaces.  For  very  complex  geometries,  however,  the 
generation of the tetrahedral mesh is sometimes rather time-consuming and requires a 
sufficient quality of the CAD data. An optional method is available, which combines the 
simplicity of hexahedral meshes with the Perfect Boundary Approximation technique. 
In the following subsections, let us compute the same model applying the hexahedral 
magnetostatic solver. Again, we will look at the mesh parameters and the visualization 
and then turn to the solver itself. 
Visualize a Hexahedral Mesh 
The  hexahedral  mesh  generation  for  the  structure  analysis  is  performed  fully 
automatically based on an expert system. As for tetrahedral meshes, it may be helpful 
in some situations to inspect the mesh before starting the solver in order to improve the 
simulation speed by changing the parameters for the mesh generation.  
Note that  in  CST  EM  Studio  generating hexahedral  meshes  is  very fast  compared  to 
generating  tetrahedral  meshes.  The  reason  is  that  by  applying  the  Perfect  Boundary 
Approximation feature,  hexahedral  meshes  do  not  need  to  resolve  the  geometry:  i.e. 
interfaces of materials and solids are not represented by a surface mesh as they are for 
tetrahedral meshes.  
First, you must switch from tetrahedral to hexahedral meshing. Select Home: Mesh  
Global  Properties   Hexahedral 
.  Then,  the  Global  Mesh  Properties  -  Hexahedral 
dialog box will open automatically. For the purpose of this tutorial, the Maximum cell -
When you click the OK button, you will be informed that the results have to be deleted: 
Confirm the deletion of the results by clicking OK. 
A hexahedral mesh will be generated automatically without any further action. You can 
visualize the mesh by entering the mesh view (Home: Mesh  Mesh View 
). For this 
structure, the mesh information will be displayed as follows:One 2D mesh plane will always be kept in view. Because of the symmetry settings, the 
mesh only extends across 1/8 of the structure (the mesh plane extends to 1/4). You can 
modify the orientation of the mesh plane by choosing Mesh: Sectional View  Normal:
X/Y/Z   (shortcut: X/Y/Z). You can move the plane along its normal direction with Mesh: 
Sectional View  Position or by pressing the Up / Down cursor keys.  
In  most  cases,  the  automatic  mesh  generation  produces  a  sufficient  mesh,  but  we 
recommend  that  you  spend  some  time  later  on  studying  the  mesh  generation 
procedures  in  the  online  documentation  once  you  feel  familiar  with  the  standard 
simulation procedure. 
Leave the mesh inspection view by Mesh: Close  Close Mesh View 
. 
Start the Hexahedral Solver 
After  you  have  defined  all  necessary  parameters,  you  are  ready  to  start  your  first 
simulation  using  the  hexahedral  solver.  Again,  start  the  simulation  from  the 
magnetostatic solver dialog box: Home: Simulation  Setup Solver 
. Within the solver 
dialog box, the "Hexahedral" mesh should be selected in the Mesh Type drop-down list. 
In order to compute inductances from the magnetic field, the box Apparent inductance 
matrix has to be checked. Ensure that the Adaptive mesh refinement is switched on (this 
is not the default for hexahedral meshes). Please recall the remarks on adaptive mesh 
refinement made in the section Generate and Visualize a Tetrahedral Mesh. They apply 
to hexahedral meshes as well. 
The  Accuracy  value  can  be  left  unchanged.  Please  note  that  what  is  mentioned 
concerning the accuracy value in the tetrahedral solver subsection (e.g. its dependence 
on  the  discretization)  also  applies  to  the  hexahedral  solver.  After  you  set  all  these 
parameters, the dialog box should look like this:Next enter the Properties dialog of the adaptive mesh refinement. The Error limit should 
be changed to 0.0005, the Minimum number of passes to 3, and the Maximum number 
of passes to 9. The other settings can be kept at their default values.
Confirm  your  setting  by  pressing  OK.  Now  start  the  simulation  procedure  by  clicking 
Start. A few progress bars will appear in the status bar to keep you up-to-date with the 
solver’s progress: 
1.  Calculating coil excitations: This first calculation step must be performed to 
calculate the discrete representation of coil current patterns. 
2.  Checking model: During this step, your input model is checked for errors such as 
invalid overlapping materials, etc. 
3.  Calculating matrix and dual matrix: During these steps, the system of equations 
is set up, which will be solved subsequently. 
4.  Solving linear system: During this stage, a linear equation solver calculates the 
field distribution inside the structure.  
5.  Postprocessing: The field solution is used to compute additional results like the 
inductance matrix or the energy within the calculation domain. 
As  for  the  tetrahedral  solver,  some  error  estimation  and  mesh  refinement  steps  are 
performed in the case of adaptive mesh refinement. Note that several linear systems will 
be solved during the computation in order to compute all entries of the inductance matrix. 
For this simple structure, the entire analysis takes only a few seconds per adaption pass. 
After the simulation the mesh (Home: Mesh  Mesh View
Analyze the Results of the Hexahedral Solver 
Now  you  can  generate  similar  result  plots  as  you  did  for  the  tetrahedral  solver-run: 
Visualize the magnetic flux density by choosing NT: 2D/3D Results  B-Field.  After you 
select this item a plot similar to the following should appear (possibly after some fine-
tuning of the plot properties in 2D/3D Plot: Plot Properties  Properties 
): 
Again,  you  can  switch  between  2D  and  3D-view  as  well  as  transparency  mode  via 
NT: 2D/3D  Results    Sectional  View    Fields  on    Plane 
  and  2D/3D  Plot:  Plot 
Properties  Structure Transparent 
, respectively. 
To observe field values at certain positions within a 2D plot, activate 2D/3D Plot: Tools 
 Field at Cursor. The field values will be displayed in the lower right corner of the main 
view. Note that for the scalar fields and for the vector fields projected on the plane you 
can add points to a List of Field Values with a double click in the main view.  
Several mesh refinement passes were performed automatically until the energy value 
did not change significantly between two subsequent passes. The default termination 
criterion is an energy deviation of 1% (or less).progress 
The 
the 
NT: 1D Results  Adaptive Meshing  folder.  This  plot  can  be  viewed  by  selecting 
NT: 1D Results  Adaptive Meshing  Error: 
the  mesh 
refinement 
checked 
can 
be 
of 
in 
This result shows that the maximum difference of the energy error is below 0.05 %, i.e. 
below the error limit prescribed in the adaptive mesh refinement properties.  
Additionally, 
NT: 1D Results  Adaptive Meshing  Energy: 
the  convergence  of 
the  energy  can  be  visualized  by  selecting
It can be seen that the hexahedral mesh generator already provides a good mesh for a 
first calculation. The small energy error shows that the adaptive mesh refinement is able 
to confirm that variations are reduced to a minimum. 
In practice, it often proves sensible to activate the adaptive mesh refinement to ensure 
convergence of the results. (This might not be necessary for structures with which you 
are already familiar where you can use your experience to manually refine the automatic 
mesh.) 
Now let us compare the magnetic energy computed by the hexahedral solver to the one 
computed by the tetrahedral solver. Select NT: 1D Results  Ms Solver  Energy to 
obtain the “Current Run” value for the total energy in the Result Navigator: 
This  is  very  similar  to  the  value  computed  by  the  tetrahedral  solver.  The  difference 
comes from the non-zero discretization errors. Moreover, fewer meshcells have been 
used for the hexahedral discretization.  
In the solver dialog box, you have chosen to calculate the inductance matrix. To view 
the values of the inductance matrix, select all entries in NT: 1D Results  Ms Solver  
Apparent Inductance Matrix to see them in the Result Navigator.
Create a Planar Mesh 
For axis symmetric structures or structures for which boundary effects for one spatial 
dimension can be neglected, the 2D solver can be applied. The structure is designed as 
a 3D model and cut by a user defined plane. Compared to the 3D solvers, choosing this 
option  might  save  a  lot  of  computation  time.  Even  if  your  model  is  not  perfectly 
symmetric, this solver can give good estimates when starting with a new design. 
First, you must switch from hexahedral to planar meshing. Select Home: Mesh  Global 
Properties  Planar 
. The cutting plane alignment description as well as the 2D mesh 
setting  are  available  then  in  the  Mesh  Properties  dialog  box,  which  will  open 
automatically.  Select  Rotational  for  the  symmetry  type  and  Z    for  the  axis.  The  axis 
should be centered in the 3D domain, therefore select Center  for the X- and Y-position. 
Finally,  select  Y  as  the  R  vector.  Also  change  the  Maximum  cell  –  Model  to  10  and 
Background to 1. The Preview button allows checking the settings in the main view: 
A first mesh can be created directly with the Update button: It will be shown a few seconds later:
Finally, leave the Mesh Properties dialog box by pressing OK.  
Start the Planar Solver 
After you have defined all the necessary parameters, you are ready to start your first 
simulation using  the  planar  solver.  Again,  start  the  simulation from the magnetostatic 
solver dialog box: Home: Simulation  Setup Solver 
. Within the solver setup menu, 
the  ”Planar“  mesh  should  be  selected  in  the  Mesh  type  drop-down  list.  In  order  to 
compute  the  apparent  inductances,  the  box  Apparent  inductance  matrix  has  to  be 
checked. Ensure that the Adaptive mesh refinement is switched on. The Accuracy value 
can be left unchanged. 
After you set all these parameters, the dialog box should look like this:Next, enter the Properties dialog of the adaptive mesh refinement and set the maximum 
number of passes to be equal to 8. If necessary, change the Stopping criterion to 1e-5. 
The other settings can be kept at their default values.
Finally, close the dialog with the OK button and start the simulation procedure by clicking 
on Start. Like in the case of the previous simulations, several progress bars will appear 
in the status bar informing you about the current solver status.  
These are the steps of the planar magnetostatic solver run: 
1.  Computing coil(s): This first calculation step must be performed to calculate the 
discrete representation of coil current patterns.  
2.  Initializing magnetostatic solver: During this step, your input model is checked 
for errors such as invalid overlapping materials, not well-defined sources, etc. 
3.  Assembling system: The linear system of equations is generated. 
4.  Constructing pre-conditioner: This includes construction steps for the pre-
conditioner of the solver, e.g. an LU-decomposition, a construction of hierarchy for 
a multigrid solver etc. 
5.  Solving linear system: During this stage, the equation system is solved yielding 
the unknown field. 
6.  Estimating error (only during mesh adaption pass): The local error for each 
element is estimated (error distribution). 
7.  Marking elements for refinement (only during mesh adaption pass): Based on 
the computed error, a certain number of elements will be marked for refinement. 
8.  Adapting mesh (only during mesh adaption pass): The mesh is refined taking the 
marked elements into account. 
9.  Inductance computation (only if switched on): The apparent and/or incremental 
inductance matrix is calculated. 
10. Postprocessing stage: The field solution is used to compute other fields and 
additional results like the energy within the structure. 
After the  solver  has finished, the  mesh should look similar  to the  one depicted  in  the 
following  picture  (deviations  are  possible  since  the  initial  mesh  can  differ  slightly
Analyze the Results of the Planar Solver 
Already during the planar solver run, you can watch the progress of the mesh refinement 
and the convergence behavior in the NT: 1D Results  Adaptive Meshing folder. 
Click, for instance, on NT: 1D Results  Adaptive Meshing   Error. This folder contains 
a curve which displays the change of the relative energy of two subsequent simulations. 
From this result, we can observe that the maximum difference of the relative change of 
the energy is below the desired stopping criterion 1e-5:Additionally, 
NT: 1D Results  Adaptive Meshing  Energy: 
the  energy  convergence  can  be  visualized  by  selecting 
in 
the
The  curves  can  slightly  differ  when  computed  on  a  32-bit  or  a  64-bit  machine.  The 
number of adaptation passes needed for convergence can also deviate depending on 
the machine architecture. 
you 
Now, 
choosing 
the  magnetic 
NT: 2D/3D Results  B-Field. After you select this item and fine-tune the plot properties 
in 2D/3D Plot: Plot Properties, a plot similar to the following one should appear: 
visualize 
density 
can 
flux 
by 
Completing the analysis of the planar solver results, let us compare the magnetic energy 
and the apparent inductance values computed by this solver to the ones computed by 
the 3D solvers.  
To view the magnetic energy result, select all the results in NT: 1D Results  Ms Solver 
 Energy and check them in the Result Navigator: The  co-energy  results  you  can  similarly  find  in  NT: 1D Results    Ms Solver   
Co-Energy: 
These results are very similar to the ones computed by the tetrahedral and hexahedral 
solvers.
The results for the apparent inductance computation can be found under NT: 1D Results 
 Ms Solver  Inductance Matrix:  
These results are also in good agreement with those computed with the 3D solvers.  
Accessing the Single-Value Results 
All  single-value  results  can  be  found  in  the  NT.  For  the  magnetostatic  solver,  result 
values  for  energy,  co-energy,  coil  characteristics,  flux  linkages  and  inductances  are 
quickly accessible from NT: 1D Results  Ms Solver  folder:The  same  data  and  more  complex  post  processing  results  are  also  available  via  the 
Template Based Post Processing tool. 
Parameterization and Automatic Optimization of the Structure 
The steps above demonstrate how to enter and analyze a simple structure. However, 
structures are usually analyzed to improve their performance. This procedure is called 
“design” in contrast to “analysis”. 
After you receive some information on how to improve the structure, you will need to 
change  the  structure’s  parameters.  This  could  be  done  by  simply  re-entering  the 
structure, but this is not the most efficient solution.  
CST EM Studio offers various options to describe the structure parametrically in order 
to change the parameters easily. The History List function, described in the CST Studio 
Suite  Getting  Started  manual,  is  a  general  option,  but  for  simple  parameter  changes 
there is an easier solution, which is described below. 
Let us assume you want to change the thickness of the transformer’s box. The easiest 
way  to do  this  is to  select the  box  by  clicking  on  NT:  Components   component1  
cylinder box. You may also need to rotate the structure in order to see a plot similar to 
the following (the cutting plane is still switched on):
You can now choose Modeling: Edit  Properties (Ctrl+E) to open a list showing the 
history of the shape’s creation:Select the “Shell” operation from the history tree . After you click Edit, the 
Shell  dialog  box  will  appear.  In  this  window,  you  will  find  the  thickness  of  the  box 
(Thickness = 0.5) as specified during the shape creation. Change this parameter to a 
value of 0.8 and click OK. 
Confirm the deletion of the results by clicking OK. 
The structure plot will change showing the new structure with the new box thickness:
You  can  generally  change  all  parameters  of  any  shape  by  selecting  the  shape  and 
editing its properties. This fully parametric structural modeling is one of CST EM Studio’s 
most outstanding features.  
The parametric structure definition also works if some objects have been constructed 
relative to each other using local coordinate systems. In this case, the program will try 
to  identify  all  the  picked  faces  according  to  their  topological  order  rather  than  their 
absolute position in space. 
The changes in parameters occasionally alter the topology of the structure too severely, 
so the structure update may fail. In this case, the History List function offers powerful 
options  to  circumvent  these  problems.  Please  refer  to  the  online  documentation,  or 
contact technical support. 
You may also assign variables to the structure parameters: Select the “Shell” operation 
from the history tree again (the dialog box should be still open) and click Edit. Now enter 
the string "thickness" as depicted below:Then  click  OK.  A  new  dialog  box  will  open  asking  you  to  define  the  new  parameter 
"thickness".  Here  enter  0.5  in  the  Value  field.  You  may  also  provide  a  text  in  the 
Description field so that you can later remember the meaning of the parameter: 
Closing this dialog box by clicking OK defines the parameter and updates the model. 
Now also close the History Tree window. Note that all defined parameters are listed in 
the parameter docking window:
The  Parameter  List  shares  the  same  space  with  the  Result  Navigator  and  it  may  be 
necessary to select the Parameter List tab in in the lower part of the CST Studio Suite. 
You can change the value of parameters by clicking on the corresponding entry in the 
Expression column of the parameter window and entering a new value. If you do this, 
the  message  “Some  variables  have  been  modified.  Press  ‘Home:  Edit   Parametric 
 (F7)’ ” will appear in the main view. Then, if you perform this update operation, 
Update 
the  structure  will  be  regenerated  according  to  the  current  parameter  value.  You  can 
verify  that  parameter  values  between  0.3  and  0.7  give  useful  results.  The  function 
Modeling: Edit  Parameters  Animate Parameter is also useful in this regard. It is 
also possible to define a new parameter by entering it in the parameter window. 
Since you now successfully parameterized your structure, it might be interesting to see 
how the apparent inductance values change when the thickness of the box is varied. 
The easiest way to obtain these variation results is to use the Parameter Sweep tool 
accessible from within the magnetostatic solver dialog box (Simulation: Solver  Setup 
Solver 
).  Note  that  the  Planar  Mesh  type  with  Adaptive  mesh  refinement  is  still 
selected. Click the Par. Sweep button to open the following dialog box:In  this  dialog  box,  you  can  specify  calculation  “sequences”,  which  consist  of  various 
parameter  combinations.  To  add  such  a  sequence,  click  the  New  Seq.  button.  Then, 
click the New Par button to add a parameter variation to the sequence:
In the dialog box that arises, you can select the name of the parameter to vary in the 
Name drop-down list. After selecting the item to sweep, you can specify the lower (From) 
and upper (To) bounds for the parameter variation. Finally, enter the number of steps in 
which the parameter should be varied in the Samples field. 
In this example, the thickness of the box should be swept From 0.3 To 0.7 in 5 Samples. 
After you click OK, the parameter sweep setting will appear in the  Sequences frame. 
Note that you can define an arbitrary number of sequences each containing an unlimited 
number of different parameter combinations. 
Now run the parameter sweep by clicking Start. A progress bar in the Progress window 
shows the current status of the parameter sweep. After the solver has finished its work, 
you  will  find  the  results  in  the  navigation  tree:  NT: 1D Results    Ms Solver   
Inductance Matrix, where the respective inductance values can be plotted against the 
parameter values covered by the sweep. Select the result for L coil 1, coil 1. If the X axis 
is  based  on  Run  IDs  (0..5),  switch to  the  parametric X  axis  by  selecting  “Parametric” 
from the dropdown list available at 1D Plot: 0D Result Axis  X Axis. You should get a 
graph similar to the following: 
Choosing NT: 1D Results  Ms Solver  Inductance Matrix  L coil 1, coil 2, you can 
inspect the mutual inductance in the same way:Assume that  you  now  want to  adjust the  self-inductance  of  coil  1 to  a value  of  3.2  H 
(which  can  be  achieved  within  a  parameter  range  of  0.3  to  0.7  according  to  the 
parameter sweep). However, figuring out the proper parameter may be a lengthy task 
that can be performed equally well automatically. 
Before you continue to optimize this structure, ensure that the thickness parameter is 
within the valid parameter range (e.g. 0.5). If you have to modify the value, do not forget
to update (Home: Edit  Parametric Update 
 (F7)) the structure afterwards. Note that 
you  must  enter  the  modeler  mode,  e.g.  by  clicking  on  the  “Components”  item  in  the 
navigation tree, before you can perform the update. 
CST  EM  Studio  offers  a  very  powerful  built-in  optimizer  feature  for  parametrical 
optimizations.  To  open  the  optimizer  control  dialog  box,  select  Simulation:  Solver  
Optimizer:First,  check  the  desired  parameter(s)  for  the  optimization  in  the  Settings  tab  of  the 
optimization  dialog  box  (here  the  “thickness”  parameter  should  be  checked).  Next, 
specify the minimum and maximum values for this parameter during the optimization. 
Here,  you  should  enter  a  parameter  range  between  0.3  and  0.7.  Refer  to  the  online 
documentation for more information on these settings.  
To store the parametric results calculated during the optimizer run, the Result storage 
settings should be changed in the General Properties dialog from the default “None” to 
“Automatic”: 
Next, specify the optimization goal. Hence, please click on the Goals tab:
Here,  you  can  specify  a  list  of  goals  to  be  achieved  during  the  optimization.  In  this 
example, the target is to find a parameter value for which the self-inductance of coil 1 is 
3.2 H.  
Therefore,  click  on  the  Add  New  Goal  button.  A  new  dialog  box  will  open:  Define 
Optimizer Goal. Since you want to find the thickness value for a self-inductance of 3.2 
H, select the corresponding result name (0D: .\Ms Solver\Inductance Matrix\L coil 1, coil 
1) and the equal operator in the Conditions frame and set the Target to 3.2:After you click OK, the optimizer dialog box should look as follows:
Since  you  now  specified  which  parameters  to  optimize  and  set  the  goal  for  the 
optimization, the next step is to start the optimization procedure by clicking Start. The 
optimizer will show the progress of the optimization in an output window in the Info tab, 
which is activated automatically. 
When the optimization is done, the optimizer output window shows the best parameter
Note that due to the sophisticated optimization technology, only a few solver runs were 
necessary to find the optimal solution with high accuracy. It even reuses your previously 
computed results for a more efficient use of resources. 
Now check the inductance value for the optimal parameter setting (thickness = 0.5456) 
by  clicking  NT:  1D  Results   Ms  Solver   Inductance  Matrix   L coil  1,  coil 1.  The 
computed inductance is very close to the target value:This ends the first application example. 
Summary 
This example should have given you an overview of the key concepts of CST EM Studio. 
You should now have a basic idea of how to do the following: 
1.  Model the structures by using the solid modeler 
2.  Specify the solver parameters, check the mesh and start the simulation using the 
tetrahedral solver with the adaptive mesh refinement feature  
3.  Specify the solver parameters, check the mesh and start the simulation using the 
hexahedral solver with the adaptive mesh refinement feature 
4.  Visualize the magnetic field distributions 
5.  Specify the solver parameters,  check the mesh and start the simulation using the 
planar solver with the adaptive mesh refinement feature 
6.  Define the structure using structure parameters 
7.  Use the parameter sweep tool and visualize parametric results 
8.  Perform automatic optimizations 
If you are familiar with all these topics, you have a very good starting point for an even 
more productive use of CST EM Studio. 
For more information on a particular topic, we recommend that you browse through the 
online help system which can be opened by selecting File: Help  Help Contents – Get 
help using CST Studio Suite 
. If you have any further questions or remarks, please do 
not hesitate to contact your technical support team. We also strongly recommend that 
you  participate  in  one  of  our  special  training  classes  held  regularly  at  a  location  near 
you. Please ask your support center for details.
Chapter 3 – Solver Overview 
Solvers and Sources 
The  example  in the  previous  chapter  demonstrates  how  to  define  a  coil  source  for  a 
magnetostatic  simulation.  The  general  workflow  of  electrostatic,  stationary  current  or 
low-frequency problems is quite similar to a magnetostatic application.  
The different simulation types differ in the definition of materials, boundary conditions 
and excitation sources. The way to define materials and boundary conditions in CST EM 
Studio is quite similar for all solvers, whereas there are larger differences in the definition 
of sources. For this reason, an overview of the sources that are supported by each solver 
is given below. 
Magnetostatic Solver: 
  Permanent magnet:  
Simulation: Sources and Loads  Permanent Magnet 
  Current or voltage coil:  
Simulation: Sources and Loads  Coil  
  Coil segment:  
Simulation: Sources and Loads  Coil  Coil Segment 
  Coil segment from solid:  
Simulation: Sources and Loads  Coil Segment from Solid 
  Coil group: 
Simulation: Sources and Loads  Coil  Coil Group 
  Current path:  
Simulation: Sources and Loads  Current Path 
  External magnetic field:  
Simulation: Sources and Loads  Magnetic Source Field 
  Stationary current field (via Solver checkbox) – the most important stationary 
) are available from 
 and Current Port 
current sources (Electric Potential 
the Simulation: Sources and Loads toolbar as wellTypical applications are: magnets, magnetic valves, actuators, motors, generators and 
sensors. 
Electrostatic Solver: 
  Potential definition on a PEC (perfect electric conductor) solid:  
Simulation: Sources and Loads  Electric Potential 
  Capacitive field grading on a PEC:  
Simulation: Sources and Loads  Electric Potential   Field Grading 
  Potential definition on a normal/electric boundary:  
Simulation: Settings  Boundaries 
(select the Boundary Potentials tab from within the Boundary dialog box) 
  Charge definition on a PEC:  
Simulation: Sources and Loads  Electric Charge on PEC 
  Uniform volume- or surface-charge distribution:  
Simulation: Sources and Loads  Electric Charge Distribution 
Typical applications are: high voltage devices, capacitors, MEMS and sensors.
Stationary Current Solver: 
  Potential definition on a PEC solid:  
Simulation: Sources and Loads  Electric Potential 
  Current port:  
Simulation: Sources and Loads  Current Port 
  Field import:  
Simulation: Sources and Loads  Field Import 
  Current path:  
Simulation: Sources and Loads  Current Path 
  Coil segment:  
Simulation: Sources and Loads  Coil segment 
  Coil segment from solid:  
Simulation: Sources and Loads  Coil Segment from Solid 
  Coil group: 
Simulation: Sources and Loads  Coil  Coil Group 
Typical applications are: sensors, coils, circuit breakers, IR drop simulations and 
grounding problems. 
LF Frequency Domain Solver (Full Wave and Magnetoquasistatics ): 
  Current or voltage coil:  
Simulation: Sources and Loads  Coil 
  Coil segment:  
Simulation: Sources and Loads  Coil  Coil Segment 
  Coil segment from solid:  
Simulation: Sources and Loads  Coil Segment from Solid 
  Coil group: 
Simulation: Sources and Loads  Coil  Coil Group 
  Current port:  
Simulation: Sources and Loads  Current Port 
  Current path:  
Simulation: Sources and Loads  Path Sources Current Path From Curve 
  Voltage path:  
Simulation: Sources and Loads  Path Sources  Voltage Path from Curve 
  External magnetic field:  
Simulation: Sources and Loads  Magnetic Source Field 
  Field import:  
Simulation: Sources and Loads  Field Import 
LF Frequency Domain Solver (Electroquasistatics): 
  Potential definition on a PEC solid:  
Simulation: Sources and Loads  Electric Potential 
Typical applications are: NDT, proximity sensors, inductively coupled power transfer, 
induction heating, magnetic and electric design of transformers. 
LF Time Domain Solver (Magnetoquasistatics): 
  Permanent magnet:  
Simulation: Sources and Loads  Permanent Magnet 
  Current or voltage coil:  
Simulation: Sources and Loads  Coil 
  Coil segment:
  Coil segment from solid:  
Simulation: Sources and Loads  Coil Segment from Solid 
  Coil group: 
Simulation: Sources and Loads  Coil   Coil Group 
  Current port:  
Simulation: Sources and Loads  Current Port 
  Current path:  
Simulation: Sources and Loads  Path Sources Current Path From Curve 
  Voltage path:  
Simulation: Sources and Loads  Path Sources Voltage Path from Curve 
  External magnetic field:  
Simulation: Sources and Loads  Magnetic Source Field 
  Rotational motion:  
Simulation: Motion  Motion 
  New Rotation 
  Translational motion: 
Simulation: Motion  Motion 
  New Translation 
LF Time Domain Solver (Electroquasistatics): 
  Potential definition on a PEC solid:  
Simulation: Sources and Loads  Electric Potential 
Typical applications are: transient device switching, nonlinear time-dependent 
problems such as electrical machines, sensors and high-voltage transformers. 
Partial RLC Solver: 
  Node definition on non-PEC solid face:  
Simulation: Sources and Loads  RLC Node 
Typical applications are: Printed circuit boards, Chip Packages, Network parameter 
(SPICE) extractionMagnetostatic Solver 
The magnetostatic solver can be used for static magnetic problems. Available sources 
are current paths, current or voltage coils, coil segments including those created from 
solids,  coil groups,  permanent  magnets  and  homogeneous magnetic  source fields  as 
well as the current density field previously calculated by the stationary current solver. To 
use  the  J-static  current  density  field  as  magnetostatic  source,  activate  the  checkbox 
Precompute  stationary  current  field  in  the  Magnetostatic  Solver  dialog  box.  The 
stationary current field will then be precomputed automatically. 
The main task of the solver is to calculate the magnetic field strength and the flux density. 
These results appear automatically in the navigation tree after the solver run.  
Nonlinear ferromagnetic Materials 
The magnetostatic solver also features nonlinear ferromagnetic materials. These can be 
defined  by  creating  a  BH-curve  describing  a  soft-magnetic  material  behavior  or  by 
creating a  JH-curve describing  a  hard-magnetic material  behavior.  A  nonlinear  solver 
will  use  a  smoothed  version  of  this  curve  in  order  to  improve  the  convergence.  The
resulting permeability distribution is also stored and can be accessed in the navigation 
tree. Below an example of a soft-magnetic BH-curve is shown. 
Inductance Calculation 
The magnetostatic solver can extract the inductance matrices of coils and coil segments. 
For  nonlinear  material  properties,  the  nonlinear  characteristic  of  the  material  is  taken 
into  account.  The  user  may  choose  the  extraction  of  the  apparent  inductance  matrix 
and/or the incremental inductance matrix. For n coils and coil segments, the computation 
of  the  inductance  matrix  requires  the  solution  of  n  equation  systems.  If  all  material 
properties  are  constant  (i.e.  type  is  Normal  and  no  nonlinear  properties  have  been 
defined), the apparent and the incremental inductances are identical. 
Current or Voltage Coils 
In the section Define Coils of the previous chapter, the main ideas of the simulation of 
coils  in  CST  EM  Studio  are  already  outlined.  Moreover,  you  can  find  a  step-by-step 
description of a coil creation there. 
Remember  that  a  current  and  voltage  coil  is  defined  as  an  a-priori  known  current 
distribution (also for voltage driven coils) which is constant over the cross-section of the 
coil body. The supporting material has no influence on the source current distribution. 
A coil in CST EM Studio can be constructed from two curves – the profile curve and the 
path curve. To create a current coil, you must define these two curves and then select 
Simulation: Sources and Loads  Coil 
. You will be prompted to select the coil profile 
curve and then the coil path curve. When the profile curve can be swept along the path 
curve successfully, the Define Coil dialog box will open automatically:In  this  dialog  box,  you  can  specify  the  Name,  the  Group  and  the  Conductor  Type 
(Stranded or Solid) as well as the current or voltage value, the Number of turns and the 
ohmic Resistance of a coil. The Phase value is relevant only for LF Frequency Domain 
simulations. The current direction can be reverted by checking Invert Current Direction.
Depending on the physical connections, coil sources can be gathered into so-called coil 
groups. A current or voltage coil group is represented by a series connection of coils 
characterized by a common current flowing through them. For the voltage coil groups, 
the  total  voltage  is  defined  by  the  individual  coil  group  voltages.  A  coil  group  can  be 
understood as a single conductor, only a single flux linkage embraces the coil group, 
and the coil group will only contribute to an inductance matrix as a single entity. 
When the Project profile to path checkbox is activated, the profile curve is aligned with 
the plane which is normal to the path curve. In the following example you can see the 
profile curve, which includes an angle of 10 degrees with the path curve. The coil on the 
left hand side will be obtained if the alignment is activated. To generate the coil displayed 
on  the  right  hand  side,  the  alignment  is  switched  off  so  that  the  profile  is  swept 
unchanged along the path curve.Coil Segments 
There are multiple ways to construct a coil segment in CST EM Studio. One is - similar 
to coils as described above - via profile and path curves, or via a previously picked planar 
face,  and  the  other  is from  a  previously  defined  solid.  Both  ways  will  be  described in 
more detail. 
Please note that coil segment sources are available for the tetrahedral-based solvers 
only – if a hexahedral solver is used, a thin path is created at the position of the path 
curve instead. 
To define the profile of the source, one can either pick a planar face before activating 
this mode or select a planar profile curve in the main plot window. If the tool is activated 
with a picked planar face, the interactive mode will start with the definition of the path or 
extrusion. The second step of the construction is to select a path curve. Alternatively, a 
numerical value could be used for the extrusion of the profile. To skip this step one can 
press ESC. If the profile is to be extruded to a picked point, it is necessary to pick this 
point before activating the construction mode. After the path selection was completed 
(either by selection or pressing ESC) a dialog box opens where all other settings can be 
defined. In total, there are six different ways to define a coil segment via predefined path 
and profile, which are summarized in the table below.
Path: 
selected curve 
Profile: selected curve 
1. Activate the creation tool 
2. Select the closed profile curve 
3. Select the open path curve 
Profile: picked face 
(needs to be picked beforehand) 
1. Pick a planar profile face 
2. Activate the creation tool 
3. Select the closed profile curve 
Coil segment created from a profile curve 
(red) and a path curve (blue) 
Coil segment created from a picked face 
(red dots) and a path curve (blue) 
Path: 
extruded to picked point 
(needs to be picked 
beforehand) 
1. Pick a point 
2. Activate the creation tool 
3. Select the closed profile curve 
4. Press ESC to open the dialog 
box 
1. or 2. Pick a planar profile face 
1. or 2. Pick a point 
3. Activate the creation tool 
4. Press ESC to open the dialog 
box 
Path: 
extrude with given 
numerical height value 
Coil segment created from a profile curve 
and a picked point 
1. Activate the creation tool 
2. Select the closed profile curve 
3. Press ESC to open the dialog 
box 
Coil segment created from a picked face 
(red dots) and a picked point (red) 
1. Pick a planar profile face 
2. Activate the creation tool 
3. Press ESC to open the dialog 
box 
Coil segment created from a selected profile 
curve and a numerical value for the 
extrusion height 
Coil segment created from a picked face 
(red dots) and a numerical value for the 
extrusion height 
Coil segments created this way always have the conductor-type ‘stranded’, which means 
they  have  a  homogeneous  current  distribution  in  its  cross  section.  This  source  type
Coil Segments from Solids 
Another way to create a coil segment is to create it from a previously defined solid. After 
creation  of  a  solid,  a  definition  of  a  coil  can  be  initiated  via  Simulation:  Sources  and 
Loads   Coil     Coil  Segment  from  Solid 
.  You  will  be  asked  to  specify  a  planar 
current entry and exit face. Finally, the coil segment characteristics are defined in the 
dialog box which opens as soon as both required current faces are specified:For these coil segments you can choose a conductor type, either solid or eddy current 
free. Depending on the conductor type, a coil segment can be characterized either by a 
lumped value for the electrical resistance (in Ohm) or an electrical conductivity (in S/m). 
Within  the  magnetostatic  solver    as  well  as  within  the  stationary  current  solver,  both 
definitions are equivalent and can be converted into each other. However, this statement 
does not hold within the magnetoquasistatic regimes of the frequency domain and time 
domain solvers. We will elaborate on this in the respective subsection(s).  
Note that the use of a coil segment from solid within any solver will require a stationary 
current solver run to precompute the source current density. 
The advantage of coil segment definition through a resistance is that this value can be 
chosen  independently  from  the  coil  segment  geometry,  which  may  vary  in  case  of 
intersections of associated solids or depending on mesh settings. On the other hand, a 
coil of conductor model solid with associated conductivity allows for skin-effect and eddy 
current analysis (in magnetoquasistatic simulations). 
Permanent Magnets 
To  define  a  permanent  magnet,  you  must  activate  the  permanent  magnet  tool  by 
selecting Simulation: Sources and Loads  Permanent Magnet 
. You will be prompted
to select a face of a solid in order to select the magnet’s geometry. Pick any solid with 
“Normal”  material  properties,  possibly  associated  with  a  nonlinear,  temperature 
dependent, hard magnetic J-H curve. 
You  can  define  constant,  radial  or  azimuthal  magnetizations.  For  details  refer  to  the 
online help. 
Constant 
magnetization 
Radial magnetization 
Azimuthal 
magnetization 
Current Paths 
The definition of a current path is very similar to a coil definition. A single curve must be 
defined before the current path tool can be activated by selecting Simulation: Sources 
and Loads  Current Path 
. You will be prompted to select a curve. Then a dialog box 
arises in order to define the total current through the loop:The phase value is only relevant for the LF Frequency Domain solver. 
It is important that the current path is closed or that it terminates on a union of perfect 
electric  conductors  (PEC)  and  electric  boundary  conditions  or  conductive  domains 
(generating a stationary current field) such that this union forms a closed loop with the 
current  path.  Otherwise  the  problem  is  not  solvable  since  such  a  source  violates  the 
continuity equation in a magnetostatic context. 
Left: A circular current path leaves the calculation domain through two electric boundaries – a solvable situation. 
Due to symmetries, only 1/4 of the structure has to be calculated. 
Right: A circular current path leaves the calculation domain through two magnetic boundaries  – not a solvable 
situation in magnetostatics.
Homogeneous Magnetic Field 
To simulate structures in a homogeneous magnetic field, it is possible to define such a 
source by selecting Simulation: Sources and Loads  Magnetic Source Field 
. The 
following dialog box allows you to define the magnetic field vector: 
Boundaries  along  the  direction  of  the  source  field  (i.e.  boundary  faces  for  which  the 
source field has non-zero flux) have to be set to type “magnetic”. Moreover, to set a valid 
problem using the tetrahedral solver, one of the remaining faces may also be set to type 
“magnetic”. 
The Field phase value is relevant only for LF Frequency Domain simulations. 
1D Solver Results 
After a magnetostatic solver run, all computed 1D Results are located in the navigation 
tree under NT: 1D Results  Ms Solver.  Here, you will find the simulation values for 
energy, co-energy, flux linkages and source parameters. In a case of setups with coil 
segments  and  current  ports  connected  to  the  conductors  and  simulated  using  the 
tetrahedral mesh, source parameters for voltages will include not only the voltages on a 
whole  conductive  rings,  but  also  the  separate  values  of  voltage  drops  on  attached 
conductors.  These  values  in  the  navigation  tree  are  provided  with  the  subscript 
“_conductor”. 
Electrostatic Solver 
The  electrostatic  solver  can  be  used  for  the  simulation  of  static  electric  problems. 
Available sources comprise fixed and floating potentials, boundary potentials, charges 
on PEC solids and homogeneous volume and surface charges. The main task for the 
solver is to calculate the potential, the electric field strength and the electric flux density. 
These results appear automatically in the navigation tree after the solver run.  
Open Boundaries 
The electrostatic solver features open boundary conditions. These help to reduce the 
number of mesh nodes when problems in free space are simulated. 
Potential Sources 
The  most  important  electrostatic  source  type  is  a  potential  definition.  To  define  a 
potential on a perfect electric conductor (the solid has to be assigned to PEC material) 
you must activate the potential tool first via Simulation: Sources and Loads  Electric 
Potential 
. The first step is to select the surface of a perfect electric conductor carrying
After a PEC surface has been selected, the potential dialog appears to assign a Name, 
a Potential value and a Type for the new source:The Phase value is relevant only for LF Frequency Domain simulations and thus will be 
ignored by the described solver. 
Note  that  for  a  potential  of  Type  "Floating",  the  value  itself  is  not  prescribed,  but  the 
resulting constant potential at the solid will obtain a value such that the resulting total 
charge of the conductor is zero. Consequently, defining a floating potential is equivalent 
to assigning a zero charge. The charge definition will be discussed later.  
Field Grading 
Capacitive field grading is an electrostatic source characterized by a linear distribution 
of  potential  on  the  PEC  solid  surface.  This  source  can  be  created  by  selecting 
Simulation: Sources and Loads  Electric Potential  Field Grading 
. Afterwards, a 
surface of a PEC solid can be picked, on which the field grading source is to be created. 
Then the field grading definition dialog box appears, where all the settings for the source 
can be defined.
The Grading direction is the vector along which the potential value must change linearly. 
In any plane perpendicular to this vector the potential value on the surface of the PEC 
object is constant. Upper and lower potential values define the range within which the 
electrical potential is changing on the surface of the PEC solid. 
After the necessary values are set, press the OK button. A new field grading source is 
created.Charge Sources  
Two different charge types exist in CST EM Studio: total charges on perfect conductors 
(resulting generally in a non-uniform surface-charge distribution along the PEC surfaces) 
and uniform charge distributions on normal material solids. 
For the charge definition based on PEC, the first step is very similar to the one carried 
out with the potential definition. After activating the charge tool via Simulation: Sources 
and Loads  Electric Charge on PEC 
, you can pick a surface to which the charge 
will be applied. Then the charge dialog appears to determine the name and the charge 
value: 
For the definition of a uniform charge-distribution definition, the first step is similar again 
- the only difference is that the source must be assigned to a normal material solid. You 
cannot  define  an  uniform  charge  distribution  on  a  PEC  material.  Use  Simulation: 
Sources and Loads  Electric Charge Distribution 
 and select a normal material solid. 
Then the following dialog will appear:
Here you can specify a name, a type and a value for the charge distribution. You can 
define a volume as well as a surface charge distribution. Remember that the latter will 
generate a jump in the normal component of the electric flux density. Furthermore, you 
can define the total charge or the charge density value. 
Boundary Potentials  
Finally, you can also assign an electrostatic potential to an electric boundary condition 
from within the boundary dialog. Open the boundary dialog box via Simulation: Settings 
 Boundaries 
 and select the Boundary Potentials tab: In order to specify a boundary 
potential, select the "Floating" type from the drop-down list or select the "Fixed" type and 
enter a value in the edit field.  
A  boundary  potential  can  be  defined  on  normal  or  electric  boundary  conditions  only. 
Boundaries with different potential values must not be adjacent. Again, you can define 
a fixed or floating potential. 
Stationary Current Solver 
The stationary current solver can be used to simulate DC current distributions. Available 
sources  are  potentials,  boundary  potentials,  current  paths,  current  ports  and  coil 
segments.  Additionally,  to  the  modeled  structure  with  defined  material  properties, 
lumped network elements, i.e. resistors, may be added into the computational domain. 
The main task for the solver is to calculate the electric field strength, current density and 
ohmic losses. These results appear automatically in the navigation tree after the solver 
run.  
Since  the  process  of  defining  potential,  coil  segments,  and  current  path  sources  is 
discussed in the two previous sections, we will focus on the definition of current ports 
and contact properties. For a more detailed description of the lumped network element, 
we  refer  to  the  subsection  Lumped  Network  Elements  in  the  section  LF  Frequency 
Domain Solver. 
Parameterized Electrical Conductivity 
The  stationary  current  solver  supports  not  only  fixed  electrical  conductivity  values 
(isotropic or anisotropic) but also temperature-dependent and nonlinear characteristics: 
  Temperature-dependent  electrical  conductivity  can  be  defined  by  setting  the 
material Type in the General tab of the Material Parameters dialog box to Temp. 
dependent.  Then  press  the  Properties  button  in  this  tab  to  open  the 
Temperature-Dependent  Materials  dialog  box,  where  you  can  define  the 
temperature  dependency  slope  of  electrical  conductivity.  A  temperature  field 
must be imported from a thermal project via Simulation: Sources and Loads  
Field Import
  Nonlinear  electrical  conductivity  is  defined  by  creating  an  E(J)  curve  in  the 
Electrical  Conductivity  Properties  dialog  box.  This  dialog  is  accessible  via  the 
Conductivity  tab  of  the  Material  Properties  dialog  box.  Here,  in  the  group  for 
Electrical conductivity check Advanced and press the button Parameters. 
Before setting either parameterization, a default non-zero value of electrical conductivity 
must be set. 
Current Ports 
A current port is a face on a conductive material surface, characterized by its normal 
direction and the total electric current flowing through it. The usage of current ports is 
somewhat  different  depending  on  the  mesh  type  utilized  by  the  stationary  current 
solvers: 
  When  using  hexahedral  meshes,  the  current  port  must  be  located  on  the 
computational domain’s boundary. 
  For tetrahedral meshes, this limitation does not apply. Besides, for such meshes 
the current port can be placed onto a surface between two conductive domains. 
In this case the solution guarantees the continuity of the normal component of 
current density on both sides of the current port surface. 
Note  that  if  no  sources  with  fixed  potentials  are  defined,  the  sum  of  the  prescribed 
currents  entering  and  leaving  the  computational domain must  be  zero. Otherwise the 
problem does not have a stationary solution. 
If the stationary current solution is intended to be used as a pre-computation step for a 
magnetostatic solution, all the current ports must be located either on the computation 
domain’s  boundary  or  between  two  conductive  domains,  in  order  to  ensure  the 
divergence-free current density distribution. 
The following picture shows a simple conductive bend inside the computational domain. 
The two conducting faces are highlighted.In order to define a current port on one of these faces, select the current port tool via 
Simulation: Sources and Loads  Current Port 
. Next pick an appropriate face on a 
conductive material. A dialog box opens where you can define the port’s name, a folder 
where the port is located and the magnitude of the current:
Contact Properties 
A contact resistance is defined via Simulation: Sources and Loads  Contact Properties 
. It is equivalent to a thin layer of conductive material at the interface between two (or 
several) solids. The definition is performed by selecting the solids associated with the 
“first” and then with the “second” side of the contact surface.A  contact  resistance  can  be  characterized  either  by  a  lumped  parameter  (integral 
electrical  resistance  in  Ohm)  or  by  its  thickness  and  conductivity  of  the  material 
assigned. Both definitions are equivalent and can be converted into each other: 
Here R is the lumped parameter representing integral resistance. In the material-based 
representation, electrical conductivity σ and layer thickness l are used. Contact area A 
is calculated by the solver.
The  advantage  of  contact  resistance  definition  through  integral  resistance  is  that  it  is 
independent on the contact area A which may vary in case of intersections of associated 
solids  or  depending  on  the  mesher  settings.  On  the  other  hand,  the  material-based 
definition offers much more flexibility, for example, it supports nonlinear or temperature-
dependent electrical conductivity via the material definition. 
Electrical losses which take place within the contact region are calculated and saved by 
the stationary current solver as surface losses, so they can be utilized afterwards for a 
thermal analysis. 
Contact  resistances  are  only  supported  by  the  tetrahedral-based  stationary  current 
solver. 
1D Solver Results 
After a solver run, all computed 1D Results are located in the navigation tree under 
NT: 1D Results  Js Solver.  Here, you will find the simulation values for loss power 
and  source  parameters.  In  a  case  of  setups  with  coil  segment  and  current  ports 
connected  to  the  conductors  and  simulated  using  the  tetrahedral  mesh,  source 
parameters for voltage will include not only the voltages on whole conductive rings, but 
also the separate values of voltage drop on the attached conductors. These values in 
the navigation tree are provided with the subscript “_conductor”. 
LF Frequency Domain Solver  
The LF Frequency Domain solver can be used to solve electromagnetic field problems 
with  time-harmonic  sources  and  linear  materials.  In  this  case,  all  quantities  are  time-
harmonic and it is possible to solve a complex-valued problem in the frequency domain. 
The  main  task  for  the  solver  is  to  calculate  electromagnetic  fields  and  the  resulting 
currents, losses, energies and source parameters. These results appear automatically 
in the navigation tree after the solver run has been finished. 
The LF Frequency Domain solver includes the following simulators: 
  Full Wave simulator 
  Magnetoquasistatic simulator  
  Electroquasistatic simulator 
The  Full Wave  simulator  solves the full  Maxwell’s  equations. The magnetoquasistatic
magnetic  (e.g.  eddy  current  problems)  or  electric  energy,  respectively.  A  typical 
application is the computation of AC current and loss distributions. 
In contrast to the static solvers, one or more calculation frequencies must be defined 
before the LF frequency domain solver can start. In order to do that, open the frequency 
dialog box Simulation: Settings  Frequency 
 for the modelled task: 
To add a new frequency to the list, double-click on the empty edit field, enter the value 
and confirm with the Enter key. The list becomes operative when you leave the dialog 
box by clicking OK. 
Full Wave and Magnetoquasistatic Simulator 
Available sources are current and voltage paths, current ports, coils and coil segments 
including those created from solids. Coils and coil segments can be collected into coil 
groups.  
Coil  and  current  path  definitions  are  discussed  in  the  magnetostatic  solver  section. 
Current ports have been introduced in the stationary current solver section. One minor 
difference exists: in addition to the current (or voltage) value, it is possible to assign a 
phase  value  to  a  current  path  or  a  coil  (for  magnetostatic  calculations,  this  setting  is 
ignored).  Coil  segments  created  from  solids  have  been  also  presented  in  the 
magnetostatic solver section. Within the magnetoquasistatic simulations however, the 
two  conductor  models  exhibit  significantly  different  behavior:  solid  coil  segments  are 
massive conductors carrying eddy currents and stipulating losses, whereas eddy current 
free coil segment sources are not affected by eddy current effects.  
Voltage Paths 
Voltage paths are similar to the previously described current paths. They are created 
from  a  curve  path.  A  typical  application  is  a  voltage  path  connecting  two  conducting 
regions, defining a voltage between the conductors:To define a voltage source, activate the appropriate tool via  Simulation: Sources and 
Loads    Path  Sources  Voltage  Path  from  Curve 
.  The  curve  selection  modus 
enables the selection of the curve that is to be transformed into a voltage path. After the
appropriate curve has been selected, the voltage path dialog box appears. Here you can 
determine the element’s name, its voltage and phase values. 
After the definition is complete, the voltage source is listed in the navigation tree folder 
Voltage Paths.  
Lumped Network Elements 
The  full  wave  and  the  magnetoquasistatic  formulations  of  the  LF  Frequency  Domain 
solver  account  for  the  inclusion  of  the  lumped  network  elements  in  the  simulation 
domain. In this context, one can make use of any parallel or serial circuits consisting of 
one resistor, one capacitor and one inductor. To add a new network, open the lumped 
element dialog box, Simulation: Sources and Loads  Lumped Element 
:In the lumped network element dialog box, the element values as well as the connection 
type for a lumped element – serial or parallel – are defined. Furthermore, the geometrical
location of the lumped element is set in the dialog box, i.e. the starting point and ending 
point of the network in the computational domain. 
Nonlinear equivalent permeability 
The  magnentoquasistatic  frequency  domain  solver  supports  nonlinear  material 
properties (B(H)) via a linear equivalent permeability computation. Note that this is an 
approximation; for fully nonlinear time-dependent calculations the LF time domain solver 
should be employed. Additionally, the LF frequency domain magnetoquasistatic solver 
supports time dependent nonlinear (B(H)) and linear material properties with coupling to 
CST MPhysics Studio. More information on these topics can be found in the online help. 
1D Solver Results 
After a solver run, all computed 1D Results are located in the navigation tree under 
NT:  1D  Results  LF  Solver.  Here,  you  will  find  the  simulation  values  for  losses, 
energies  and  source  parameters.  Sources  parameters  for  the  tetrahedral  full  3D 
frequency solver as well as for the broadband simulation regime described below are 
currents, voltages, induced voltages and flux linkages.  For the setups consisting of 
conductors attached to the coil segments and/or current ports, the computed source 
parameters are always the results for the whole current loops.  
Broadband simulation regime 
For  the  magnentoquasistatic  simulator  when  using  a  tetrahedral  mesh,  a  broadband 
calculation  regime  is  available,  which  allows  the  lf-stable  broadband  calculation  of 
impedance  matrices  as  well  as  broadband  source  parameters,  lumped  parameters, 
energies and losses from zero frequency to a specified maximum frequency. Broadband 
lumped  parameters  include  inductance,  resistance,  DC-resistance  and  conductance 
matrices.  For the setups consisting of conductors attached to the coil segments and/or 
current ports, the computed broadband source and lumped parameters are always the 
results  for  the  whole  current  loops.    Additionally,  in  contrast  to  the  standard  full  3D 
frequency  sweep  where  the  solution  of  a  large  linear  system  is  required  for  each 
calculation frequency, a faster frequency sweep is available where only a much smaller 
system has to be solved for each frequency value. Thus, this calculation mode should 
be the method of choice if solutions for multiple frequencies and/or broadband 1D results 
are required.  
Furthermore,  the  broadband  formulation  allows  for  a  deduction  of  a  macro-model 
representation of a field model, which finally results in the authoring of a reduced order 
models as a Functional Mockup Units according to the FMI standard. The created .fmu 
archive is issued automatically as soon as a broadband simulation is chosen and can 
be  imported  into  any  simulation  tool  capable  to  interpret  the  FMI  standard  for  Model 
Exchange.  
Electroquasistatic Simulator 
In  the  electroquasistatic  approximation  of  the  full  Maxwell’s  equations,  the  time 
derivative  of  the  magnetic  field  is  ignored  in  the  Faraday-law.  Hence,  the  computed 
electric field is curl-free in the whole space. Consequently, electroquasistatic problems 
can be described by a complex scalar potential, which reduces the number of unknowns 
in the equation system to be solved. 
Thus, running the electroquasistatic simulator is usually much faster and more robust 
than running the full wave simulator on the same mesh. Whenever the time derivative 
of the magnetic field is negligible in Faraday’s law, you should use the electroquasistatic 
solver to solve your low frequency problem. Typical applications are insulator problems,
Potentials  are  available  as  excitation  sources.  These  are  already  discussed  in  the 
electrostatic solver section. Again, a minor difference exists: In addition to the potential 
value, it is possible to assign a phase value (for electrostatic calculations this setting is 
ignored). Please refer to the online help for further details. 
LF Time Domain Solver 
The LF Time Domain solver can be used to solve electromagnetic field problems with 
the time-dependent sources driven at low frequencies. This solver includes the following 
simulators: 
  Magnetoquasistatic simulator 
  Electroquasistatic simulator 
The solver features both  a  constant  and an  adaptive  implicit  time-stepping  algorithm. 
The adaptive time-stepping scheme requires solving four linear or nonlinear systems of 
equations in each time step. 
Furthermore, if the solution of the investigated problem is known to be periodic in time, 
the LF time domain solver provides a dedicated steady state time-stepping algorithm, 
which  may  accelerate  the  calculation  of  the  steady  state  solution.  The  online  help 
provides further information on the steady state solver. 
Magnetoquasistatic Simulator 
In the magnetoquasistatic approximation of the Maxwell’s equations, the time derivative 
of  the  displacement  current  can  be  omitted  with  respect  to  the  conduction  currents. 
Typical use cases are the nonlinear eddy current problems or transient simulations (e.g. 
switching devices, actuators, sensors). 
Within the simulator, supported excitation sources are permanent magnets, current- and 
voltage-driven coils and wires, coil segments including those created from solids, coil 
groups, current ports, transient external magnetic source fields and rigid body motions. 
The main task for the simulator is to calculate the time evolution of the magnetic and 
current  fields  as  well  as  the  resulting  losses,  energies,  source  parameters  and  other 
derived quantities like e.g., forces. Sources parameters are currents, voltages, induced 
voltages and flux linkages.  For the setups consisting of conductors attached to the coil 
segments and/or current ports, the computed source parameters are always the results 
for the whole current loops.  
For 2D models where the period of the fundamental frequency is known a priory, the 
steady state detection mode can be activated. In this case, the solver stops as soon as 
a steady state solution based on the ohmic loss computations has been reached. For 
more  information  on  the  steady  state  detection  solver  mode  please  refer  to  the 
corresponding pages in the online help. 
Electroquasistatic Simulator 
The electroquasistatic approximation of the Maxwell’s equations is employed when the 
influence  of  the  magnetic  induction  can  be  neglected.  Thus,  a  description  of  an 
electroquasistatic  field  is  completed  by  a  scalar  potential  function  which  reduces  the 
number of unknowns in the equation system to be solved. Typical use case includes, 
e.g., a high-voltage bushing.  
Electrical potentials are available as excitation sources. These are already discussed in
defined  together  with  the  potential  value,  is  relevant  only  for  LF  Frequency  Domain 
simulations and thus will be ignored by the described simulator. 
Workflow 
The workflow for a time domain simulation is very similar to the workflow of static and 
time harmonic simulations. However, some additional steps must be performed before 
the solver is started: 
1.  One or more excitation signals must be defined. 
2.  Excitation signals must be associated with the sources. 
3.  Monitors must be defined. 
4.  A simulation duration must be set. 
These differences result from the fact that additional information is necessary about the 
time evolution of the excitations and the size of the time interval of interest. Furthermore, 
storing the  whole evolution  of all  computationally  available results  needs a  lot  of disk 
space. For this reason, the concept of time monitors is introduced, which allows a more 
specific definition of the results of interest. 
Note: The excitation definition as well as the usage of monitors in CST EM Studio is 
very similar to those available in CST Microwave Studio. 
The following subsections will describe these additional steps in short. For more detailed 
information, please refer to the online help. 
Signal Definition 
In a new project, only a constant "default" signal is defined. For a meaningful simulation 
with the LF Time Domain Solver, at least one non-constant signal should be defined.  
A  new  signal  can  be  defined  via  Simulation:  Sources  and  Loads   Signals     New 
. A dialog box opens where a signal type, its parameters and a name 
Excitation Signal 
can be set:The parameters of the signal depend on the individual signal type and are described in 
the online help. The parameter Ttotal must be set for almost all signal types and defines
the  size  of  the  definition  interval.  For  time  values  larger  than  Ttotal,  the  signal  is,  in 
general, continued by a constant value. It is also possible to import a signal or to create 
a user defined signal or to select a pre-defined signal from the signal database. 
All defined signals are visible in the Excitation Signal folder in the navigation tree.  
A signal can be displayed by selecting it in the navigation tree: 
Excitations: Assigning Signals to Sources 
As for the static solvers, the source value defines the strength of a source field. The time 
evolution of a source is defined by assigning a signal to it. 
This can be done by opening the solver dialog box via Home: Simulation  Setup Solver
A sub-dialog opens showing each defined source that can be interpreted by the solver. 
Also the  source values are  displayed.  Each  source can  be  switched  on or  off for  the 
simulation. By default, all sources are switched on.  
For each source, a signal can be assigned via a drop-down list. The same signal can be 
assigned to several sources. Optionally, an individual time delay 
can be defined for 
each source. 
The resulting time dependent excitation
coil current) and the (possibly shifted) assigned signal
: 
is the product of the source value 
 (e.g. the 
Example 
 . 
Two sources are defined, one current path with source current 1 A and one coil, also 
carrying  1  A  in  each turn.  A  previously  defined signal  "signal1"    is 
assigned to both sources. The signal of the coil is shifted by 0.5 s by clicking in the field in column Time shift. With 
these settings, the Excitation Selection dialog will look like this: 
For this example, the resulting excitations used by the solver look like this:
Reference Signal 
There is always one signal tagged as the 'reference signal'. This signal is highlighted in 
the navigation tree by a yellow background. The reference signal can be changed by 
marking  another  signal  in  the  navigation  tree  and  selecting  Simulation:  Sources  and 
Loads  Signal  Use as Reference. 
By default, all sources are set to use the currently defined reference signal. Hence, it is 
not necessary to visit the Excitations sub-dialog of the solver dialog if only one source 
or  only  one  signal  shall  be  used  for  the  simulation.  Then,  it  is  sufficient  to  select  the 
desired signal being the reference signal and by default all sources are automatically 
assigned to this signal. 
Rigid Body Motion Definition  
The  2D  and  3D  magnetoquasistatic  time  domain  solver  allows  for  the  definition  of 
periodic  rotational  or  translational  rigid  body  motions,  which  can  be  used  for  the 
simulation  of  electrical  machines  and  actuators.  The  movement  is  described  by  the 
mechanical  motion  definition  and  the  motion  Gap.  The  mechanical  motion  definition 
defines the absolute movement in time of the moving objects and the moving direction 
for translations or rotation axis and its center for rotations. The absolute movement in 
time can be defined by a constant motion, by a time signal or by an equation of motion. 
The motion Gap is a closed surface that surrounds the moving objects and is located in 
the air gap between moving and static objects. Multiple motions including nested gaps 
can be defined if the gap surfaces do not intersect and the following limitations do apply. 
Limitations for nested gaps definition 
If nested gaps are defined, the absolute value of the speed defined in the dialog applies 
for the gap parts which are not part of any other gap nested inside the gap. It is possible 
to have one of the following combinations of nested gaps: 
  Rotation gaps inside rotation gaps with possibly nested gaps 
  Translation gaps inside translation gaps with possibly nested gaps 
  Rotation gaps inside translation gaps with possibly nested rotation gaps 
It is not possible to define the following (intersecting) combination of gaps: 
  Translation gap inside a rotation gap, because the translation gap is required to
Rotation definition 
A new rotational motion is defined by opening the Define a Rotational Motion dialog via 
Simulation: Motion  Motion 
  New Rotation 
 :The rotation axis is defined in the active working coordinate system and must be aligned 
with one of the global axes, and in case of 2D simulations, with the normal of the 2D 
planar mesh. The center of the rotation axis is defined by the coordinates U center, V 
center and W center.  
The movement can be specified as one of the following: 
  Constant defined by the Angular velocity (revolutions per minute, rpm) and the 
Initial angle (degrees) 
  Signal based, which allows the selection of a previously defined excitation 
signal (with the y-component in radians and the time axis in user units) 
  Equation of motion defined by the solid parameters Moment of inertia (kg·m2), 
Damping constant (kg·m2/(s·rad)), Torsion spring (N·m/rad), External torque 
(N·m), Initial position (degree) and Initial speed (rpm). At least the Moment of 
inertia must be non-zero in order to allow the calculation of motion.  
The rotational motion gap is defined by clicking on one of the options on the Active gap 
drop-down menu ([New gap from polygon] or [New gap from radius]). If you already have 
closed the dialog box, you can define a new gap by selecting the corresponding entry 
from the context menu, when selecting the newly defined rotation item in the navigation 
tree. 
While the Radius gap definition mode is active, the specified rotation axis is shown and 
you can define an outer and an inner radius in the plane normal to the rotation axis. All 
values can be reviewed and edited in the Create Rotation Gap from Radius dialog box 
after closing the gap definition mode.
While the polygon gap definition mode is active, a working coordinate system is shown 
with the Z axis pointing in the direction of the specified rotation axis. Now you can define 
a (closed) polygon in the plane normal to Z, which then will be rotated around the Z axis. 
The polygon is automatically closed if you select the option project to rotation axis for 
the Start / End point. The coordinates of the polygon points can be reviewed and edited 
in the Points table of the Define Rotation Gap Profile dialog box:It is possible to create more than one gap for a motion, but only one of them can be 
active  before  starting  the  simulation.  To  activate  a  gap  please  use  the  context  menu 
option Select as Active Gap in NT  Motion  Motion name  Gap name. 
Translation definition 
A new translational motion is defined by opening the Define a Translational Motion via 
Simulation: Motion  Motion 
  New Translation 
.
The translation Direction is defined as one of the axes (U, V or W) in the active working 
coordinate system with the translation direction being aligned with one of the axes of the 
global coordinate system. Furthermore, the translation direction should be found in the 
planar mesh plane for a translational planar mesh and parallel to the axis for a rotational 
planar mesh. The Periodicity of the boundaries normal to the translation direction can 
be Periodic or Antiperiodic.  
The Movement can be defined as one of the following: 
  Constant defined by the Velocity (m/s) and the Offset (m) 
  Signal based, which allows the selection of a previously defined signal (with the 
y-component in m and the time axis in user units) 
  Equation of motion defined by the solid parameters Mass (kg), Damping 
constant (N·s/m), Spring constant (N/m), External force (N), Initial position (m) 
and Initial velocity (m/s). At least the Mass must be non-zero in order to allow 
the calculation of motion. 
The translational motion gap is defined by clicking on one of the options on the Active 
gap drop-down menu ([New gap from polygon] or [New gap from circle]). If you already 
have  closed the  define motion dialog  boxes  without  defining a gap,  you  can  define  a 
new gap by selecting the corresponding entry from the context menu NT  Motion  
Motion name  Gap name. 
The Polygon translational gap tool allows the definition of a closed polygon in a plane 
normal  to the  movement  direction.  The  translation  gap  is  defined  by  extrusion  of  the 
polygon between the two outer boundaries of the model. While the gap definition mode 
is  active,  a  working  coordinate  system  is  shown  with  the  W’  axis  aligned  with  the 
translation  direction.  Now  you  can  define  a  (closed)  polygon  in  the  U’-V’  plane.  The 
coordinates of the polygon points can be reviewed and edited in the Points table of the
The Circle translational gap tool allows definition of the circular profile gap. This is useful 
if a rotational planar calculation is done, which allows motion only in the rotational axis 
direction. While the gap definition mode is active, a helper coordinate system is shown 
with the W’ axis pointing toward the translation direction. Now you can define a center 
point and an inner and outer radius of the cylindrical extrusion gap in the U’-V’ plane. All 
values can be reviewed and edited in the Create Cylindrical Extrusion Gap dialog box 
after closing the gap definition mode.It is possible to create more than one gap for a motion but only one of them can be active 
before starting the simulation. To activate a gap, please use the context menu option 
Select as Activate Gap in NT  Motion  Motion name  Gap name. 
Monitor Definition  
In  contrast  to  the  static  and  time-harmonic  solvers,  where  all  simulation  results  will 
appear automatically in the navigation tree, only so-called automatic 1D results will be 
produced  by  the  transient  solver  and  located  in  the  navigation  tree  under  NT:  1D 
Results LT Solver. Here, you will find the simulated over the time  values for losses 
and  energy.  For  magnetoquasistatic  simulations  also  a  co-energy  and  source 
parameters  are  automatically  computed.  For  coils  and/or  current  ports  additionally 
induced  voltages  and  flux  linkages  will  be  shown.  For  the  setups  consisting  of 
conductors  attached  to  the  coil  segments  and/or  current  ports,  the  computed  source 
parameters are always the results for the whole closed current loops.  
It is not possible to store all the fields and secondary results at every computed time 
step as this would require a tremendous amount of disk and memory space. That is why 
the idea of Monitor definition has been introduced into the solver. In this definition, you 
can specify which certain results and at which time intervals the solver will record the 
desired data.
Several different kinds of monitors are available in CST EM Studio: 3D Field Monitors, 
Monitors at Points, Monitors on Edges or Curves, Monitors on Faces and Monitors on 
Solids or Volumes. The 3D Field Monitors yield field plots, which can be animated over 
the simulated time. The other monitors are classified by the objects on which appropriate 
integral  functionals  are  defined.  They  yield  1D  curves  of  scalar  values  versus  the 
simulated time. 
All  defined  monitors  are  listed  in  appropriate  subfolders  of  the  Monitors  folder  in  the 
navigation  tree.  Within  this  folder,  you  may  select  a  particular  monitor  to  reveal  its 
parameters in the main view. 
3D Field Monitors 
Several kinds of monitors record 3D vector or scalar fields (e.g. B-field, H-field, E-field, 
conductive  current  density,  etc.).  A  3D  Field  Monitor  can  be  defined  via  Simulation: 
Monitors  Field Monitor 
. A dialog box opens where the type of the field, the start 
time and the sample step width can be defined:Available field types for the magnetoquasistatic simulator are B-Field, H-Field, E-Field, 
Cond.  Current  Densities,  Potential  (only  for  2D  models  showing  the  magnetic  vector 
potential), Material (showing the relative permeability), Ohmic Losses, Averaged Ohmic 
Losses, and Magnetic Energy Density.  
Within the electroquasistatic simulator, the time evolution of the E-field, D-field, Cond. 
and Displ. Current Densities as well as Potential (showing the scalar electric potential) 
can be monitored. 
After  the  solver  run,  the  recorded  result  can  be  accessed  via  the  NT:  2D/3D  Results 
folder in the navigation tree. The scalar or vector field can be animated over the defined 
time period. 
Monitors at Points 
These  kinds  of  monitors  record  scalar  values  that  are  defined  at  a  point  (previously 
picked or entered numerically), e.g. the x-component of the magnetic flux density at a 
fixed  position.  Such  a  monitor  can  be  created  via  Simulation:  Monitors   Monitor  on 
Entity  Monitor at Point 
.
The  magnetoquasistatic  solver  supports  following  monitor  types:  B-Field,  H-Field, 
E-Field,  Cond.  Current  Density,  Material,  Potential  (magnetic  vector  potential,  only 
available for 2D simulations), and Ohmic Losses.  
For the electroquasistatic solver, available monitor types are E-field, D-field, Cond. and 
Displ. Current Densities and Potential (the scalar electric potential). 
The monitor generates a 1D-plot over time during the solver run. The result plot can be 
accessed in the NT: 1D Results  LT Solver folder. 
Please note that this kind of monitor is similar, although not identical, to Probes available 
within CST Microwave Studio. 
Monitors on Edges or Curves 
These kinds of monitors record scalar values that are defined for (previously picked via 
(Simulation: Picks  Picks 
) model edges or on curve items. Currently available are 
the  voltage  and  the  source  current  along  a  path.  You  can  create  it  via  Simulation: 
Monitors   Monitor on Entity  Monitor on EdgeAgain, the monitor generates a 1D-plot over time during the solver run and the result 
plot can be accessed in the NT: 1D Results  LT Solver folder. 
Monitors on Faces 
These  kinds  of  monitors  record  scalar  values  that  are  defined  for  (connected  set  of) 
model faces, which have to be picked (Simulation: Picks  Picks 
) before the monitor
definition.  For  the  3D  magnetoquasistatic  simulations,  magnetic  flux  and  conduction 
current  monitors  are  supported.  You  can  create  them  via  Simulation:  Monitors    
Monitor on Entity  Monitor on Face 
. 
Again, the monitor generates a 1D-plot over time during the solver run and the result 
plot can be accessed in the NT: 1D Results  LT Solver  folder. 
For the electroquasistatic simulator, this monitor type is not supported. 
Monitors on Solids or Volumes 
Within the magnetoquasistatic simulator, these kinds of monitors record values that are 
defined for a solid, volume or a group of solids (the force on a solid etc.). You can create 
it via Simulation: Monitors   Monitor on Entity  Monitors on Volume 
.Available monitor types for the magnetoquasistatic simulator are: Ohmic Losses, Force 
and  Torque,  Iron  Losses,  Apparent  and  Incremental  Inductance  Matrices  as  well  as 
Demagnetization.  
Again, the monitor generates a 1D-plot over the time during the solver run (or in case of 
Force monitors one 1D-plot per component) and the result plot can be accessed in the 
NT: 1D Results  LT Solver folder. The demagnetization monitor does not generate a 
1D-plot but only gives a warning if the maximum demagnetizing field strength is higher 
than the set value and generates a 3D Field monitor similar plot with the distribution of 
the  maximum  demagnetization  field  strength  in  solids.  The  iron  loss  monitor  also 
generates a plot with the distribution of the iron losses in solids along with the calculated 
loss in the NT: 1D Results  LT Solver folder. 
The monitors can be defined everywhere, on a certain solid or on groups of solids. The 
groups of solids are defined in NT: Groups as Normal Groups and are populated with 
solids via Drag&Drop. 
This monitor type is not supported for the electroquasistatic simulator.
Starting the Simulation 
As  already  mentioned,  the  solver  dialog  box  can  be  opened  via  Home: Simulation  
Setup Solver 
. Firstly, define the Equation type you are going to employ. Secondly, 
before  starting  the  simulation,  the  Simulation  duration  must  be  entered.  This  value 
defines the length of the simulated time interval in the currently active time unit. Note 
that every simulation starts at time zero.If at least one non-constant signal is in use, the maximum over all assigned time signal 
is displayed below the duration entry field (taking possible time shifts into account). This 
information gives some hint for a reasonable simulation duration and can be used for 
cross-checking,  e.g.  to  ensure  that  signals  and  simulation  duration  are  defined  for  a 
similar time period and scale. 
Two  different  time-stepping  strategies  are  available  for  the  solver:  Constant  and 
adaptive time-stepping. By default, the constant time-stepping is enabled, which should 
always  be  used  for  simulations  that  contain  rigid  body  motion.  The  adaptive  time-
stepping  may  be  used  for  simulation  without  motion,  especially  for  calculation  with  a 
fading  transient  component  since  the  adaptive  strategy  may  be  more  efficient  in  this 
case. 
The default settings for the constant time-step algorithm are accessible in the Time step 
settings  dialog  after  selecting  Properties  and  are  set  to  40  steps  for  the  simulation 
duration. This default setting should be changed to allow a sufficient discretization of the 
time axis considering the expected signals variation in the simulation time.
If adaptive time-stepping is preferred, you need to switch the Method to High Order and 
then select the Adaptive time step radio button. It is a good idea to have a look at the 
parameters  of  the  adaptive  time-stepping  scheme  before  starting  the  simulation.  The 
parameters can be displayed and modified in the Time step settings sub-dialog, which 
can be activated by pressing the Properties button:The most important value is the Relative error tolerance. The smaller this value the more 
rigorous  is  the  behavior  of  the  adaptive  scheme,  leading  to  smaller  time  steps  and 
smaller time-discretization errors.  On the  other  hand, smaller  time steps will  increase 
the simulation time. Furthermore, you can define upper and lower bounds for the size of 
a time step and set the size of the initial time step. If you have some knowledge about 
typical time scales of your model, it might be meaningful to modify the default settings. 
Note that for some problems it may be also necessary to increase the accuracy for the 
solution of the linear (or respectively nonlinear) systems of equations that are solved for 
each time step. This can be done by choosing the necessary Accuracy in the solver start 
up dialog box. However, in most cases, the default-settings can be left unchanged. 
Finally, the LF Time Domain solver can be started by pressing the Start button and the 
results can be analyzed. 
Coupled Simulations with CST MPhysics Studio 
Ohmic  and  iron  losses  from  the  solvers  of  CST  EM  Studio  can  be  imported  by  the 
thermal solvers of CST MPhysics Studio to conduct a thermal analysis. The temperature 
fields  calculated  by  the  thermal  solvers  can  then  be  used  to  update  temperature 
dependent  material  properties  in  the  stationary  current  solver  or  the  LF  frequency 
domain  solver.  In  addition,  the  Mechanical  Solver  of  CST  MPhysics  Studio  can  be 
employed to perform continuative stress simulation for a given temperature distribution.
Moreover, force density distributions from magnetostatic or electrostatic simulations can 
be fed into the mechanical solver as well. 
Please  refer  to  the  CST  MPhysics  Studio  Workflow  document  for  more  detailed 
information about these multi-physics workflows. 
Equivalent Circuit EMS/DS Co-Simulation 
Equivalent circuit parameters describing the physical behavior of the field part of a CST 
EM  Studio  model  can  be  used  for  co-simulations  within  CST  Design  Studio.  The 
extraction of the lumped parameters from the field model is supported by the following 
tetrahedral mesh based solvers: 
  Electrostatic Solver 
  Magnetostatic Solver (linear and nonlinear problems) 
  Stationary Current Solver 
Please note: For nonlinear problems, the equivalent circuit parameters are calculated in 
the working point determined by the excitation sources defined within CST EM Studio. 
To cover the full parameter space of a nonlinear model, a parameter sweep can be used 
to retrieve the required data in a convenient way. 
For  further  information,  please  refer  to  the  examples  within  the  Equivalent  Circuit 
EMS/DS Co-Simulation section contained in the CST EMS Examples of the online help 
system. 
State Space Model 
The 2D/3D magnetostatic simulators offer a possibility to compress the equivalent circuit 
parameters describing the physical behavior of the field part of the model into a so-called 
state space model. This feature is useful for exporting accurate reduced order models 
of e.g. actuators to system simulators. For models composed of nonlinear materials, the 
lumped  parameters  are  calculated  in  the  working  point  determined  by  the  excitation 
sources.  
The  extraction  of  a  state  space  model  is  realized  through  the  embedded  mechanism 
called  “Export  State  Space  Model”  available  via  Simulation:  Solver    State  Space
In this dialog box, the user can define the name of the state-space model and specify 
which sources have to be involved. Within the magnetostatic solver, the export to CST 
Design Studio simulators is possible. 
Since the export is realized on the basis of the lumped parameters, a sufficient amount 
of  data  has  to  be  prepared  in  advance.  This  ensures  the  availability  of  the  required 
values  to  interpolate  the  state  space  model  during  a  system  simulator  run.  For  this 
purpose, the Parameter Sweep option is available directly from the State Space Model 
dialog  box.  The  lumped  parameters  employed  in  the  presence  electromagnetic 
excitation  sources  are  incremental  inductances.  For  the  magnetostatic  solver,  the 
calculation  of  the  incremental  inductance  has  to be  activated  within  the  solver  dialog 
Parameters dialog box before the collection of data for the state-space model starts. 
The preparation of the numerical data for the state-space model is launched with the 
Start  button  of  the  embedded  Parameter  Sweep  dialog.  During  this  process,  a  large 
number  of  working  points  is  calculated  and  stored  parametrically  within  the 
corresponding CST EM Studio project.    
After the calculation of all working points is finished, the state space model of a system 
is extracted into the binary file specified by the Export State Space Model dialog box. 
This file contains the serialization of the calculated working points, which is used as a 
basis for the calculation of the lumped parameters during the system simulation. The 
serialized data can then be imported by CST Design Studio.   
For  more  information  on  the  coupled  simulation  based  on  the  state  space  model 
concept, please refer to the online help. 
Electrical Machine Task 
For  fast  and  convenient  configuration  of  electrical  machine  models,  the  electrical 
machine task is available in the system assembly modeler (SAM). The task allows the 
simulation of predefined typical drive scenarios for usual electrical machine types. For 
further details on the electrical machine task workflow, the component library includes 
preconfigured drive scenarios and electrical machines elaborating the workflow. 
Partial RLC Solver 
The  Partial  RLC  Solver  can  be  used  for  calculation  of  equivalent  circuit  parameters 
(partial  inductances,  resistances,  and  capacitances)  and  features  optional  SPICE 
export.  It  is  of  use  in  the  following  fields  of  application,  e.g.,  printed  circuit  boards, 
packaging problems, and network parameter extraction. 
The excitation for this solver uses RLC nodes. Please refer to the online documentation 
for information on how to set up models for this solver.  
Drift-Diffusion Solver 
The  Drift-Diffusion  Solver  can  be  used  to  simulate  semiconductor  devices  with 
dimensions in the micrometer range, which can be modelled by a classical description. 
The  solver  computes  the  stationary  electron  and  hole  distributions,  which  arise  from
The  solver  uses  a  standard  approach  to  solve  the  coupled  equation  system  of  the 
density distributions and the electrostatic potential. This scheme is typically referred to 
as Gummel iteration in literature. One iteration carries out the following steps: calculation 
of the electrostatic field and a subsequent sequentially calculation of the electron and 
hole densities. These steps are repeated until the specified convergence criterion has 
been reached. Please refer to the online documentation for additional information.  
Boundary Conditions 
The drift-diffusion solver supports two types of boundary conditions: electric (flux normal 
to boundary is zero) and magnetic (flux tangential to boundary is zero). Electric boundary 
conditions allow specifying potentials and carrier boundary conditions without defining 
PEC  contacts  for  the  model.  Magnetic  boundary  conditions  truncate  the  simulation 
domain.  
Potential Sources and Boundary Potentials 
The  most  important  electrostatic  source  type  is  a  potential  definition.  A  potential  is 
defined  on  a  perfect  electric  conductor.  Please  refer  to  the  electrostatic  solver  for  a 
detailed description of Potential Sources and Boundary Potentials. 
Doping Density 
The most important carrier source type is the doping density. An impurity is attributed to 
a body which material is not a perfect electric conductor (the solid has to be assigned to 
PEC material). The definition of a new doping density is similar to defining a Potential 
Sources. A new doping density is activated via Navigation Tree  Doping Density 
. 
The first step is to select the surface of a body carrying the new impurity. After a surface 
has been selected, the doping density dialog appears to assign a Name, Folder Name,  
Acceptor density and Donator density.
Semiconductor Material Models 
Different  material  models  are  applicable  for  a  semiconductor  material.  The  mobility 
offers the functionality to define a Lattice Scattering model. Following models for adding 
volumetric  carrier  recombination  and  generation  terms  to  the  simulation  exist:  Auger 
recombination, band-to-band recombination, impact ionization, optically induced carrier 
generation and Shockley-Read-Hall recombination. These settings can be changed by 
opening the material dialog through the Navigation Tree  Materials  Material Name
Chapter 4 – Finding Further Information 
After having read this manual carefully, you should already have some idea of how to 
use CST EM Studio efficiently for your own problems. However, when you are creating 
your own first models, some questions will arise. In this chapter, we give you a short 
overview of the available documentation. 
The QuickStart Guide 
The main task of the QuickStart Guide is to remind you to complete all necessary steps 
in order  to  perform  a  simulation successfully.  Especially  for  new  users  –  or for  those 
rarely using the software – it may be helpful to have some assistance. 
The QuickStart Guide is opened automatically on each project start, when the checkbox 
File:  Options     Preferences     Open QuickStart  Guide  on  project  load  is  checked. 
Alternatively, you may start this assistant at any time by selecting QuickStart Guide from 
the Help button 
 in the upper right corner. 
When  the  QuickStart  Guide  is  launched,  a  dialog  box  opens  showing  a  list  of  tasks, 
where  each  item  represents  a  step  in  the  model  definition  and  simulation  process. 
Usually, a project template will already set the problem type and initialize some basic 
settings like units and background properties. Otherwise, the QuickStart Guide will first 
open a dialog box in which you can specify the type of calculation you wish to analyze 
and proceed with the Next button:As  soon  as  you  have  successfully  completed  a  step,  the  corresponding  item  will  be 
checked and the next necessary step will be highlighted. You may, however, change 
any of your previous settings throughout the procedure. 
In order to access information about the QuickStart Guide itself, click the Help button. 
To obtain more information about a particular operation, click on the appropriate item in 
the QuickStart Guide. 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by choosing File: Help  Help 
. The online help 
system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  directly  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties.
When  no  specific  information  is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system. 
Please refer to the CST Studio Suite - Getting Started manual to find some more detailed 
explanations about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  Some documented macro examples. 
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

Copyright 
© 1998–2022 Dassault Systemes Deutschland GmbH 
CST Studio Suite is a Dassault Systèmes product. 
All rights reserved. 
Information in this document is subject to change without notice. The 
software described in this document is furnished under a license 
agreement or non-disclosure agreement. The software may be used 
only in accordance with the terms of those agreements. 
No part of this documentation may be reproduced, stored in a 
retrieval system, or transmitted in any form or any means electronic 
or mechanical, including photocopying and recording, for any 
purpose other than the purchaser’s personal use without the written 
permission of Dassault Systèmes. 
Trademarks 
icon, 
IdEM,  Spark3D,  Fest3D,  3DEXPERIENCE, 
CST,  the  CST  logo,  Cable  Studio,  CST  BOARDCHECK,  CST  EM 
STUDIO,  CST  EMC  STUDIO,  CST  MICROWAVE  STUDIO,  CST 
PARTICLE  STUDIO,  CST  Studio  Suite,  EM  Studio,  EMC  Studio, 
Microstripes,  Microwave  Studio,  MPHYSICS,  MWS,  Particle  Studio, 
PCB  Studio,  PERFECT  BOUNDARY  APPROXIMATION  (PBA), 
Studio  Suite, 
the 
Compass 
logo,  CATIA,  BIOVIA,  GEOVIA, 
SOLIDWORKS, 3DVIA, ENOVIA, NETVIBES, MEDIDATA, CENTRIC 
PLM,  3DEXCITE,  SIMULIA,  DELMIA  and  IFWE  are  commercial 
trademarks or registered trademarks of Dassault Systèmes, a French 
"société  européenne"  (Versailles  Commercial  Register  #  B  322  306 
440), or its subsidiaries in the United States and/or other countries. All 
other  trademarks  are  owned by  their respective owners.  Use  of  any 
Dassault  Systèmes  or  its  subsidiaries  trademarks  is  subject  to  their 
express written approval. 
the  3DSDS Offerings and services names may be trademarks or service marks 
of Dassault Systèmes or its subsidiaries. 
3DS.com/SIMULIA
Chapter 1 – Introduction 
Welcome 
Welcome to CST PCB Studio, the powerful and easy-to-use program for the analysis of 
electromagnetic characteristics of complex PCBs.  
CST PCB Studio is embedded into the CST Studio Suite, which is referred to in the CST 
Studio Suite Getting Started manual. The following explanations assume that you have 
already installed the software and familiarized yourself with the basic concepts of the 
user interface. 
How to Get Started Quickly 
We recommend that you proceed as follows: 
  Read the CST Studio Suite Getting Started manual. 
  Work  through  this  document  carefully.  It  should  provide  you  with  the  information 
necessary to understand the advanced documentation found in the online help. 
  Take look at the Component Library in the startup window. There are all kinds of 
already prepared examples that will give you a good idea of the types of workflows 
that  can  be  addressed.  These  short  examples  are  designed  to  give  you  a  basic 
insight into a particular application domain. You can filter by e.g. PCB & Packages 
to reduce the number of listed examples. 
  After working through this booklet, you can start with your own examples. Choose 
a reasonably simple example that will allow you to quickly become familiar with the 
software. 
What is CST PCB Studio? 
CST  PCB  Studio is  an  electromagnetic  simulation  tool  specially  designed for the fast 
and  accurate simulation  of  real-world  PCBs  and can  be  used for  pre-layout  and post 
layout analysis. It allows the simulation of effects like resonances, reflections or crosstalk 
on any kind of PCBs from single-layer up to multilayered high-speed PCBs. 
CST PCB Studio can be easily integrated into any existing design flow by importing PCB 
designs directly from many popular EDA layout tools and provides a powerful tool for 
the automated layout checking and correction of geometric errors. 
CST PCB Studio has an intuitive user interface that makes it easy to define a design 
from scratch for pre-layout analyses. There are advanced functions to navigate through 
a design and to select, hide or visualize any objects like traces or areas. 
CST PCB Studio incorporates three different solver techniques to account for all kinds 
of  PCBs.  Single-  or two layer  PCBs  are  usually  designed  without  any  special  ground 
reference layers and are therefore dedicated to the lower- or medium frequency range. 
The  method  best  suited  to  this  kind  of  application  is  the  quasi-static  Partial  Element 
Equivalent Circuit method (PEEC). The program generates equivalent circuits out of any 
selected combination of conductors. Skin effect and dielectric loss are modeled in both 
the frequency and the time domain.  
CST PCB Studio uses CST Design Studio to define passive and active devices on the 
modeled  PCB  layout  with  the  help  of  an  easy-to-use  schematic  editor.  The  powerful 
built-in  network  simulator  in  CST  Design  Studio  enables  the  simulation  of  the  whole 
system  consisting  of  the  equivalent  circuit  of  the  PCB  and  its  termination  in  both 
frequency and time domain. Broadband equivalent circuits can be exported in several
CST  PCB  Studio  offers  a  modeling  technique  dedicated  to  the  analysis  of  power 
distribution  networks  (PDN)  in  multi-layer  PCBs.  Given  a  set  of  PDN  nets  to  be 
characterized,  the  full-wave  three-dimensional  Finite  Element  Frequency  Domain 
solver, hereafter referred to as 3D (FE FD), is able to compute PDN impedances directly. 
The  results  can  be  used  to  check  whether  the  design  margins  imposed  by  the  IC 
component are met. Using the CST PCB Studio component library, this modeling option 
enables the assessment of different decoupling capacitor strategies, taking into account 
the full-wave electromagnetic effects in the PDN.  
Applications 
  SI analysis on single/multilayer PCBs and packages 
  PI analysis on single/ multilayer PCBs and packages 
 
  DDR4 analysis on PCBs that use DDR4 technology 
IR-Drop analysis on single/ multilayer PCBs and packages 
CST PCB Studio Key Features 
An overview of the main features of CST PCB Studio is provided in the following list. 
Please  note  that  not  all  options  may  be  available  to  you  due  to  license  restrictions. 
Please contact your local sales office for details. 
For the circuit simulator only some selected key features are listed below. A full list can 
be found in the CST Design Studio Workflow manual. 
General  
  Native graphical user interface based on Windows and Linux operating systems. 
  Tight interface to CST Design Studio.  
  PEEC method specializing in the simulation of single- and two-layer boards. 
  Transmission  line  modeling  method  for  SI  analysis  of  high-speed  multi-layer 
PCBs and packages. 
  Specialized  FEM  method  for  PI  analysis  of  high-speed  multi-layer  PCBs  and 
packages.  
  IR-Drop analysis to simulate DC power/ground behavior of a PCB and package. 
  SITD  and  SIFD  analysis  to  simulate  signal  behavior  in  time  and  frequency 
domain. 
  DDR4 wizard to quickly set up memory analysis.PCB Structure Modeling 
  Import of PCB designs from Cadence Allegro/APD/SiP. 
  Import of PCB designs from Zuken CR-5000/8000 ASCII. 
  Import of PCB designs from Mentor Graphics Hyperlynx.  
  Import of PCB designs from ODB++. 
  Import of PCB designs from IPC-2581. 
  PCB layout checker with automatic correction. 
  Interactive PCB editing tools. 
  Advanced navigation through the PCB. 
  Hiding/visualizing selections. 
PCB Electric Modeling 
  Automatic meshing and extraction of 3D PEEC models. 
  Automatic meshing and extraction of 2D transmission line models. 
  Automatic meshing and extraction of 3D (FE FD) models and PDN impedances. 
  Consideration of skin effect and dielectric loss in time and frequency domain. 
  Export of equivalent SPICE circuits. 
  Export of current distribution and near fields for radiation analysis. 
  Advanced export of PCB sub structures to CST Microwave Suite.
Circuit Simulator  
  Schematic editor enables the easy definition of passive and active devices. 
  Fast circuit simulation in time and frequency domain. 
  Support of IBIS models and eye-diagram analysis. 
  Import and Export of S-Parameter data via TOUCHSTONE file format. 
  Parameterization of termination circuitry and parameter sweep. 
About This Manual 
This manual is primarily designed to enable a quick start to the modeling capabilities of 
CST PCB Studio. It is not intended as a reference guide of all available features, but 
rather as an overview of the key concepts. Understanding these concepts will allow you 
to  learn  working  with  the  software  efficiently  with  additional  help  from  the  online 
documentation. 
To learn more about the circuit simulator please refer to the CST Design Studio Workflow 
manual. 
The next chapter Overview is dedicated to explaining the underlying concepts of CST 
PCB Studio and to showing the most important objects and related dialog boxes. The 
chapter Examples will guide you through the three important analysis types. We strongly 
recommend studying both chapters carefully. 
Document Conventions 
  Buttons that should be pressed within dialog boxes are always written in italics, 
e.g. OK. 
  Key combinations are always joined with a plus (+) sign. Ctrl+S means that you 
should hold down the Ctrl key while pressing the S key. 
  The program’s features can be accessed through a Ribbon command bar at the 
top of the main window. The commands are organized in a series of tabs within 
the Ribbon. In this document a command is printed as follows: Tab name: Group 
name  Button name  Command name. This means that you should activate 
the proper tab first and then press the button Command name, which belongs to 
the group Group name. If a keyboard shortcut exists, it is shown in brackets after 
the command. 
Example: View: Change View  Reset View (Space) 
  The project data is accessible through the navigation tree on the left side of the 
application’s  main  window.  An  item  of  the  navigation  tree  is  referenced  in  the 
following way: NT: Tree folder  Sub folder  Tree item. 
  Example: NT: Components  IC100  IC100-A1 
Your Feedback 
We are constantly striving to improve the quality of our software documentation. If you 
have  any  comments  regarding  the  documentation,  please send  them to your  support
Chapter 2 – Overview  
CST PCB Studio is designed to be easy to use. However, to get started quickly you will 
need to know your way around the interface and have knowledge of the basic features 
and concepts. The main purpose of this chapter is to provide an overview of the general 
interface. 
User Interface 
Launch CST Studio Suite from the Start menu or by clicking on the desktop icon. In the 
Modules and Tools list click on PCBs & Packages.  
A new CST PCB Studio project is opened with an empty Main View.  
Main 
View 
Navigation 
Tree 
Ribbons 
View 
Attributes 
Messages 
Window 
Progress 
Window 
The user interface consists of several areas: 
1.  The Main View shows the 2D/3D visualization of the PCB design. 
2.  The Ribbons allow quick access to the most important dialog boxes and options. 
3.  The  View  Attributes  window  allows  the  setting  of  specific  visualization  and  selection 
properties for many objects. 
4.  The Navigation Tree allows access to all objects of the project. It is organized into folders 
and subfolders with specific contents. When selecting an item it will be highlighted in the 
Main  View.  It  also  includes  a  powerful  tool  for  a  more  convenient  selection  of  different 
objects. It makes it possible to track logical net list relations in a physical geometry due to 
its hierarchical tree structure and due to the connection with the Main View. 
5.  The Messages window shows general information, solver progress, warnings and errors 
during project set-up or simulation. 
6.  The Progress Window lists all open projects and any solver progress. The user has the
Importing a PCB 
In order to import an existing PCB layout from the Component Library in the main window 
of  CST  Studio  Suite,  we  search  for  the  ‘PCB  Workflow  Example’  and  select  the 
corresponding item. 
You can use the predefined filter ‘PCBs & Packages‘. 
We do not import the predefined project itself, but press the button with the three dots 
and select View to see more details. A  new  frame  will  appear  where  we  select  the  folder  icon  ‘workflow.dar’  in  the 
Attachments frame.
In a last step, we press the Download button in the upper right corner: 
This  will  download  the  file  into  a  temporary  folder  and  makes  it  available  in  the 
Attachments frame: 
To import the file, we double click on the folder next to the workflow.dar icon.  
A file browser will open where we can either drag & drop the file directly into the CST 
PCB Studio main window or we store the file in a separate folder, go back the CST PCB 
Studio and import the file by choosing Home Exchange Import/Export EDA Import.
Before pressing the Import button, we can switch off the Show simulation wizard in the 
left bottom side of the dialog box for this example.  
We  recommend  performing  the  steps  in  the  Simulation  Wizard  though  for  regular 
boards. 
The  import  will  only  take  a  few  seconds  and  the  PCB  design  like  the  one  below  will 
appear in the Main View. The layer visibility may be different due to individual settings 
or use of a remote desktop.
Exploring the PCB 
This section will explain the most important tools for exploring a PCB. The  Main View 
window includes a powerful 2D layout viewer that allows a fast investigation even for 
complex  PCBs.  The  three  main  modes  to  manipulate  the  view  on  the  layout  are 
Selection, Zoom and Pan. They control the behavior of the mouse for the viewer and 
can be switched using View: Mouse Control as shown in the figure below: 
An important characteristic of the board is its overall size.  
When importing an existing board, the corresponding units will be set automatically and 
can be found in Home: Units  View Units: 
The view unit can be changed by selecting any unit, which is available in the drop down 
menu. Changing the view unit will not change the physical size of any structure on the 
PCB. The PCB dimensions are just shown in the new unit. We will change the view unit 
to mil as shown in the figure below and continue our exploration.  
Note: switching the unit is possible with many other dialog boxes in CST PCB Studio.  
The  best  way  to  get  an  overview  of  the  available  objects  and  functions  is  using  the
We start by inspecting the objects within the Technology section.  
When selecting the object Board, the PCB representation in the Main View will change. 
Board defines the outline of the PCB and this outline can be edited using Edit Outline 
with the right mouse button or double clicking with the left mouse. 
The following dialog box will appear where we see the polygon defining the outline of 
the PCB:  
We  can  change  its  shape  either  by  changing  the  coordinates  from  the  table  or  by 
dragging the point interactively using the mouse in the Main View. New points can be 
added or imported as well. We will close the dialog box without changing anything.  
Three  predefined material  types  are  already  available  when  we  expand  the  Materials 
tree item:After double clicking Materials, picking Edit Layout > Materials in the ribbon or choosing 
Edit by using the right mouse button the following dialog box will appear: 
We are  able to edit  the existing  materials  or to create  new  materials  by  pressing  the 
indicated buttons. We close the dialog box without applying any changes.
After expanding the Layers tree item, a list appears defining the layer stack-up: 
We see four metallic layers (LR1, LR2, LR3 and LR4) and the corresponding dielectric 
layers  in  between.  We  will  see  the  editing  of  such  a  layer  stack-up  later  in  the  sub-
chapter Stackup Manager.  
Expanding the Pad Stacks tree item shows a list of objects, which represent the different 
pad stacks available in this layout. If you select e.g. VIA_01 and expand the object, you 
will see a list of four items defining a stack of connected pads in all four metallic layers: 
Choosing Edit by using the right mouse or a double click on this pad stack will open up 
the following dialog box:The list of pads corresponds with the items in the expanded Navigation Tree. Each pad 
can be edited by selecting the corresponding item and pressing Edit.  
A conductive tube connects the pads in the different layers.
A Drill shape and its sleeve thickness define the outer diameter of this tube. The Pad 
Stacks are not designed for a direct manipulation. They serve as auxiliary objects and 
are referenced by the objects Vias as well as by Footprint Pins. 
Expanding the Footprints tree item, a list of available footprints will appear as shown in 
the figure below: 
These footprint items can be edited as well as created from scratch. They are usually 
generated automatically during the EDA-import of an existing PCB design as part of the 
component definition. The user can also manually create footprints. 
They  define  the  geometrical  layout  of  a  component  including  its  pins  and  are  placed 
either on the top or the bottom layer of a PCB through the placement of the component 
that uses the footprint. 
In a next step we open the Nets navigation tree node.  
A Net is a group of conductive shapes that are electrically connected. If you scroll down 
the Navigation Tree and select the MAGNFIN item, the corresponding net is highlighted
We select the Net Classes object and expand it. A list with the four different net classes 
can be seen: 
Net  class  differential  and  net  class  single-ended  are  both  nets  meant  to  transport 
signals.  Net  class  differential  is  a  special  class  type  necessary  to  identify  a  pair  of 
different nets that are usually symmetrically aligned along their path through the PCB 
and in that way establish a complete transmission line.  
A net of type single-ended needs another net serving as path for the return current. In 
most cases a net from the ground net class is used to complete the transmission line.  
The power net class is used to identify all nets that do not transport signals but supply 
power for connected active devices. Nets of the ground net class typically serve as return 
current path for all other nets.  
The import process tries to assign the different nets to their corresponding net classes 
by means of the net’s names (e.g. net GND gets assigned to net class ground).  
In  case  the  import  format  does  not  provide  this  functionality,  please  use  the  Auto-
Tagging  functionality  available  in  Home:  Layout  ->  Net  Editor  ->  Edit  Nets  ->  Auto-
Tagging or perform the steps in the Import Wizard during import. 
We strongly recommend performing this step.The column Signal Specifications provides additional information on signal nets, which 
can be also used in workflows like CST BOARDCHECK or PI analysis.  
CST PCB Studio contains many predefined signal specifications, but it is also possible 
to  define  own  specifications  when  needed.  Signal  type  nets  can  be  auto-tagged  to 
contain this additional information. 
The column DDR4 Signal Type is quite similar to Signal Specifications. The DDR4 signal 
type gets used in the DDR4 Analysis simulation workflow to set up specific analyses for 
nets that have a certain DDR4 signal type assigned.
As  for  Signal  Specifications,  the  DDR4  Signal  Type  cannot  be  assigned  to  power  or 
ground nets. 
Next, we expand the Components object. While selecting different items in the list we 
see the corresponding components highlighted in the Main View.  
Scrolling down the Navigation Tree and selecting MN1 will highlight the rectangle with a 
solid colored frame as shown in the figure below:Another tree item is called Terminals. A terminal is a geometric test point that the user 
can place on conductors. In the modeling phase, terminals are used as dedicated spots 
to measure voltages or drawing currents at this specific location. The creation and use 
of terminals will be explained in more detail in the chapter Examples. 
The next three folders Traces, Areas and Vias all contain geometric objects related to a 
net.  
First, we expand the Select frame at the bottom of the Navigation Tree and select Traces 
instead of Entire nets. This allows the selection of exactly one single trace instead of all 
traces that belong to a certain net: 
You  will  recognize  the  change  of  the  Main  View.  The  outlines  of  the  traces  are  now 
visible.
In order to remove all previous selections we press Home: Select  Unselect All: 
Next, we expand the Traces folder, scroll down the Navigation Tree and select trace_41. 
You  will  see  the  corresponding  trace  highlighted  in  the  Main  View.  Choosing  Edit  by 
clicking the  right  mouse button  or  double clicking the following  dialog  box  will  appear 
showing the definition of the trace:The trace is part of the MAGNFIN net and its width is 10 mil. The path of the trace is 
defined by the list of x/y-points on layer LR1. The x/y coordinates can be edited. 
In addition, the buttons on the right hand side allow the user to edit the list of points and 
even to import/export points from/to a text file. 
Next,  we  remove  the  selection  by  pressing  Unselect  All  again,  change  to  the  Select 
frame and check Areas as shown in the figure below:
We expand the folder Areas and select the first item Area. The corresponding area is 
highlighted in the Main View as can be seen in the figure below: 
We right mouse (or double) click and choose Edit. The following dialog box will appear 
showing the definition of this area:The area is part of the GND net and is located on Layer LR2. An area consists of exactly 
one outline shape and it optionally also contains an additional number of cutout shapes.  
All sub-shapes are listed in the frame Available shapes on the left of the dialog box. If 
you select an item in this list, the highlighted lines of all shapes change in the Main View 
and the definition of the selected shape will appear in the table on the right side of the 
dialog box. The points can also be shifted in the main view using the mouse.
Apart  from  the  general  Arc  Polygon  (which  supports  a  special  description  for  round 
corners) Polygon, Rectangle and Circle shape type are also available after import or can 
be used for a quick manual creation of an area. 
In order to investigate the area object more deeply, we look into Cutouts to see the list 
of all cutouts: 
After selecting the item Cutout 145, we see a crosshair in the Main View showing the 
location of the cutout:We activate the axis by selecting Home: Visibility  Axis.  
For closer inspection, we zoom into the location of the cutout.  
To perform zooming select View: Mouse Control  Zoom. The mouse cursor changes 
to  a  magnifying  glass  and  allows  zooming  into  the  location  of  the  selected  cutout.
Alternatively,  a  mouse  wheel  can  be  used  to  zoom  in  and  out  of  the  current  cursor 
location.  
The magnified location looks like in the figure below: 
Now we switch back into the selection mode in order to return to the default behavior of 
the mouse cursor (by selecting View: Mouse Control  Selection).  
After that we change back to the dialog box, we select the first point in the arc polygon 
definition, and start clicking through all other points by using either the left mouse button 
or the up and down arrows on your keyboard. We will see the synchronized movement 
of the crosshair in the Main View.  
Every shape can be edited by changing the values in the table or dragging the selected 
node in the main view. We will now close the dialog box without changing any values and reset the Main View 
by selecting View: Change View  Reset View.  
There  will  be  a  more-in-depth  explanation  on  the  editing  possibilities  in  sub-chapter 
Editing and Checking the PCB.
As the last object of the Navigation Tree, we select and expand the object Vias: 
We unselect all selected objects by using Home: Select  Unselect All and check Vias 
in the Select frame as shown in the figure below: 
Now we move down the list of vias, select via_7 and see it highlighted by a cross hair in
We choose Edit by clicking the right mouse button (or double click) and see the following 
dialog box: 
This via is part of the VCC net and refers to (and thereby uses) the pad stack VIA_02. 
The position on the board is defined in two fields x and y. 
On layouts that support the feature, a Die Stacks tree item is visible. In case die elements 
were  imported,  this  navigation  tree  item  provides  information  about  the  inner  layers, 
traces, areas and nets in such a Die.  
Those elements behave in the same way as their counterparts in the main PCB layout 
and can be edited in the same way. 
We now have completed the overview of all major objects of CST PCB Studio and in the
View Attributes Window and Color Modes  
A central tool for manipulating the view on the PCB is the  View Attributes window as 
shown in the figure below: 
The  panel  consists  of  four  different  tabs  where  important  view  characteristics  of  the 
objects Layers, Nets, Net Classes, and Components can be edited. The default tab is 
Layers.  
All  tabs  are  organized  in  the  same  way:  The  columns  define  the  view  characteristics 
Color, Visible and Selectable. The rows contain the corresponding items of the objects 
Layers, Nets, Net Classes, and Components. 
Let  us  first  observe  the  behavior  by  selecting  the  Top  Components  item  in  the  first 
column  on  the  left  side.  After  doing  this,  only  the  top  side  of  the  board  with  its 
components is displayed. Stepping down with the cursor, you will notice that only the 
currently selected layer with its corresponding structures will be displayed. In the figure
We restore the visibility of all layers by selecting All Layers: 
In a next step, we investigate the different view characteristics. For this, we double-click 
on the red cell in column Color of layer Top Components. A dialog box appears in which 
we can choose another color for elements of this layer. We select for example a light blue-grey color, press Ok and see the new color for all 
components in the Main View.
If we uncheck the cell in column Visible, we will notice that all components are hidden in 
the Main View as shown in the figure below:In  order  to  demonstrate the  purpose  of  the  column  Selectable,  we  first  check  Visible 
again and then select layer LR1 as shown in the figure below:
In a next step, we select Entire nets in the Select frame as shown below: 
In the Main View, we now double-click at net UNLOAD_SWITCH as shown in the figure 
below: 
We uncheck the cells in column Selectable as shown in the figure below and try to select 
another net. With the selectable box inactive, it will not be possible to select this net by mouse click 
on the main view. This function is very useful e.g. when selecting an object in a layer 
which is obscured by objects in other layers. In this case, the other layers can be set to 
not selectable which allows us to select the object in a convenient way. You should try 
the  behavior  of  the  settings  for  tab  Nets,  tab  Net  Classes,  and  tab  Components  by 
yourself. 
The function Color Mode corresponds to the functions provided in the View Attributes 
window. With Color Mode, we can assign different colors to objects in order to distinguish 
between different layers, between different nets or between different net classes.
The default color mode is Layers and this means all objects on a layer have a certain 
color.  
In order to switch into the color mode Nets (or Net Classes), we select View: Color  
Color Mode  Nets as shown in the figure below: 
You  are  also encouraged  to  try  the  behavior  of  the  settings for color mode  Nets  and 
color mode Net Classes by yourself. 
Stackup Manager 
The  definition  of  the  layer  stack-up  is  very  important  to  the  overall  electromagnetic 
behavior  of  the  PCB.  Importing  a  layout  design  via  an  EDA-import  does  not  always 
automatically ensure that the layer stack-up is defined correctly.  
Many  designs  do  not  contain  correct  values  (or  no  values  at  all)  for  this  important 
parameterization and the user has to make sure the layer stack-up is defined correctly. 
The layer stack-up is accessible in the Stackup Manager dialog. We can open the 
dialog box by selecting Home: Layout  Stackup. The following dialog box will appear:We see the  number  of  layers  and the  thickness  of the  board. There  are four  metallic 
layers  LR1,  LR2,  LR3  and  LR4  in  the  table.  Dielectric  layers  separate these  metallic 
layers and there are usually two additional dielectric layers on the bottom and the top of 
the board.  
The columns in the table provide access to all the relevant settings. Most values can be 
edited. Material properties reflect the global values and cannot be changed here. 
There is also an option so define a specific material that is used for via connections.
To create a new layer, we press the Create New Layer button. The following dialog box 
will appear: 
To choose, whether the layer is metallic or dielectric, we select the marked cell in the 
dialog box above. A drop down list show us the selection as shown in the figure below: 
Signal and Reference Plane are both metallic. Apart from the Dielectric type, there are 
two additional types, namely Enclosure and Mirror Plane. Both are metallic layers but 
do  not  belong  to  the  board  itself  but  rather  they  provide  the  possibility  to  define  the 
environment around the board.  
We do not want to create a new layer right now so we press Cancel. 
The Material button allows the selection of a material type from the material library. The 
selection depends on the layer type: for metallic layers only metallic materials can be 
selected and for dielectric layers only dielectric materials can be selected.  
In  the  Fill  box,  we  are  able  to  define  the  position  of  the  conductive  structures  in  the 
metallic layer relative to the boundary line of the dielectric underneath. The meaning of 
the  two  parameters  Above  and  Below  is  best  explained  by  looking  at  the  conductive
Etch type and etch factor determine the way production technology affects the shape of 
the structure. 
Etch Factor: Y divided by X. Default value is  2.0 but it can be adapted to the current 
technology. 
Etch  Type:  This  field  determines  how  the  conductive  traces  shapes  are  interpreted. 
Possible values are: 
  None: Traces are regarded as rectangular. 
  Consistent with Fill: Trapezoid shape where the broad base is set on the edge 
between two dielectrics (for all typical layouts). 
  Contrary to Fill: Trapezoid shape where the small top is set on the edge between 
two dielectrics below the substrate (only for some rare layouts). 
 
The Stackup Manager allows saving or loading of a  previously saved layer definition. 
This can be done by simply pressing the Create LDF File button or the Read LDF File 
button as shown in the figure below: 
LDF  is  short  for  Layer  Definition  File.  This  storage  function  is  useful  when  importing 
different  designs  based on  the  same  layer  stack-up technology.  It  can  also be  useful 
when optimizing the electromagnetic behavior of a certain design by trying different layer
Pressing the View… button shows a 3D representation of the current layout stackup. 
The  effect  of  changes  for  e.g.  Thickness,  Fill  and  Etch  parameters  will  be  visualized 
there interactively. 
We close the dialog box and examine the Net Editor. 
Net Editor 
In order to assign the different nets to the corresponding net classes we open the Net 
Editor with Home: Layout  Net Editor: The dialog box consists of several columns, but we are interested in the first and second 
only.  The  first  column  lists  the  nets  by  name  and  the  second  the  corresponding  net 
classes. We scroll down and see that net GND is set to net class ground and the net 
VCC is set to the net class power.  
Some layouts do not contain the required net class information and all nets are of type 
single-ended.  This  can  be  fixed  by  auto-tagging  of  the  layout.  To  see  and  apply  the 
default expressions we press the Auto-Tagging button on the top menu bar of the dialog 
box.
A new dialog box appears including the two tabs Net Classes and Signal Specifications. 
In the Net Classes tab, the values in the column Net Name can be edited and adapted, 
if necessary. The Signal Specifications are used in CST BOARDCHECK to determine 
specific signal properties by name of a net. *USB1* e.g. tags a net with the specification 
for USB 1.1. 
We now close the Auto-Tagging dialog box again and try to assign a net class manually. 
To assign e.g. net Supply to net class power, we double-click on the corresponding value 
in the Net Class column and select “power” as shown in the figure below.To see the effect of the net class assignments we now select View: Color  Color Mode 
 Net Classes. Then we move to the View Attributes window and select the Net Classes 
tab. 
In case the View Attributes window is not visible, please activate it using View: Window 
 Windows  View Attributes.
Now we select the row single-ended. All single-ended nets will be highlighted as shown 
in the figure below: 
In  order  to toggle  the  black  background  color,  we  uncheck  the  button  View:  Color  
Invert View
Select Filter 
The Select filter supports many actions related to the selection of objects on the PCB 
and we have already seen in the last chapter how to control the selection mechanism 
by checking different buttons in the Select frame : 
We can either select the entire nets, even if we just select one single trace of the net (if 
it is checked as in the figure above), or you can select a single trace e.g. by checking 
Traces instead of Entire nets.  
If we check the button “& Nets connected” not only an entire net will be selected but also 
other nets that are separated from the original selected net by components like resistors 
or resistor arrays. We will see this powerful function in the example SI on Multilayer in 
chapter 3. 
In general, there are two possibilities to select an object. It is done either by selecting 
the object in the Navigation Tree or by simply clicking on it in the Main View. Navigating 
and selecting on the PCB can be a difficult task because of the large number of layers, 
conductors and components. 
To show some more select functions we first switch the Color Mode back to layer (View: 
Color  Color Mode  Layers) and activate the black background color again (View: 
Color  Black Background). 
Then we go into the View Attributes window, change to the Layers tab, select layer LR1 
and make sure that Visible and Selectable is selected for All Net Classes as shown in
The Main View should look like in the figure below: 
We zoom into the marked region of the figure above and see something like the figure
Before we select a net, we first make sure that Entire nets is marked in the Select 
frame. We check the button Only selected items at the top of the Navigation Tree: 
All  listed  items  in  the  Navigation  Tree  become  hidden  and  we  will  see  the  top  folder 
structure only. We now select a net in the Main View as shown in the figure below:Now we observe the following effect: The net is highlighted in the  Navigation Tree as 
shown in the figure below:
We can now expand the item and navigate to the available connected objects: 
Once you are familiar with this functionality, it will prove to be useful when navigating 
and searching for specific elements on the PCB.  
In order to fit the PCB view to the original size again, we can either use View: Change 
View  Reset View, or click with the right mouse button in the Main View and select 
Reset view to structure from the drop-down menu, or simply press the spacebar on the
Editing and Checking the PCB 
This section describes how to create and edit traces and areas and how to check and 
repair overlaps. First, we close the existing project and create a new, empty project. We 
will create a simple PCB from scratch in the next few steps. 
Drawing a new Trace and Area 
Before we start drawing a simple rectangular area, we first press View: Visibility  Axes 
to get the following display in the Main View:We press Edit: New Object  Rectangular Area. A message will appear asking the user 
either  to  define  the  area  directly  by  double-clicks  with  the  mouse  or  by  using  the 
corresponding dialog box.  
We press ESC in order to start the dialog box. In the dialog box, we assign the new area 
to the standard net GND, choose Rectangle as Shape Type and enter the coordinates 
and size as shown in the figure below:
After pressing the Ok button, the new area should look like the figure below: 
Next, we create a new trace by pressing Edit: New Object  Trace. Again, we press 
ESC  to  open  the  corresponding  dialog  box  where  we  enter the  data  as shown in  the
After pressing Ok, we have two distinct overlapping nets as shown in the figure below: 
Before we go to the next section, we will take notice of the Object Spy in the right bottom 
corner. The Object Spy can be turned off and on via  View: Visibility  Object Spy or 
using the right mouse context menu.  
While  we  move  the  mouse  cursor  over  the  Main  View,  the  Object  Spy  shows  the
Layout Checker 
The two overlapping nets from above represent a very simple layout. Nevertheless, this 
simple  layout  reproduces  an  issue  that  often  occurs  when  importing  a  complex  PCB 
layout. The input data of a complex layout may be incorrect and in order to generate a 
valid  mesh  for  the  modeling  phase  later  on  it  is  necessary  to  find  and  repair  these 
overlapping spots. 
To find potential geometry problems we press Edit: Check Layout  Layout Check. A 
dialog box will appear where we press the Start button. The tool immediately starts to 
analyze the geometry of the whole PCB in order to find overlapping or open-ended nets. 
When  using  this  feature  for  a  complex  PCB  you  will  see  progress  information  in  the 
Messages Window. In this simple case, the report dialog box appears quickly as shown 
in the figure below: 
All overlapping nets will be shown in the tree on the left side of the dialog box.  
In our  case  both nets  GND  and  Signal  are  listed,  because GND  overlaps  Signal  and 
Signal overlaps GND. Upon expanding of the nets, we will find all other nets that overlap 
with the root element. On the right side of the dialog box all positions, where an overlap 
occurs, as well as the affected structures  will be listed. In our case, there is only one 
location.  
We select Signal on the left side of the dialog and the cell TOP with the left mouse button 
and  see  the  crosshair  appear  in  the  Main  View  showing  the  zoomed  location  of  the
Repair Function 
It  is  important  to  find  critical  regions  with  overlapping  nets  and  to  repair  such 
configurations. In order to repair the overlap in a complex layout there is a powerful built-
in repair function available. Let us zoom into the existing layout to have a closer look at 
the overlap: 
Next, we go into the Navigation Tree, select the area and choose Edit by using the right 
mouse button or double click on it. In the dialog box, we press the Repair button: 
A new dialog box will prompt us to enter a Spacing value. The spacing distance defines 
the minimal  distance  (free  space)  between two conductive but  not  connected  objects 
after the repair procedure.  
The value is in the global unit that is specified by View: Units  View Units.We leave the default value and press OK. The repair algorithm now tries to cut free the 
overlapping conductors using the given spacing. A message will appear reporting the 
successful separation.
Now we have a layout without overlapping conductors:
Chapter 3 – Examples 
Chapter 1 and 2 are an introduction to the handling and interface of CST PCB Studio. 
This  chapter  will  present  five  simple  examples  offering  an  insight  into  the  numerical 
techniques (solvers) available in CST PCB Studio.  
The first example uses the 2DTL-solver directly.  
The second example demonstrates the use of the SITD-solver, which is based on the 
2DTL-solver but provides additional features for setting-up a complete simulation in a 
very convenient way.  
The third example explains how to use the impedance calculator.  
The forth example shows the usage of the PI-solver.  
The last example demonstrates the handling of the 3D(PEEC)-solver.  
Design and Simulation of a Differential Strip Line using 2DTL Modeling 
Task Definition  
Sometimes  it  can  be  necessary  to  build  up  a  small  example  from  scratch  in  order  to 
analyze the behavior of a certain structure on a PCB in a so-called “pre-layout-analysis”. 
In this example, we generate a pair of embedded strip lines and analyze the differential 
transmission characteristic of the pair.  
The PCB Design 
We  create  a  new  and  empty  PCBS-project  and  save  it  with  the  name  ‘Differential 
Striplines’.  (The  complete  example  of  the  same  name  can  also  be  fetched  from  the 
Component Library.) 
In  a  first  step,  we  go  into  the  Navigation  Tree  and  adapt  the  default  values  for  the 
material “fr4” as shown in the figure below:Next, we open the stackup editor by pressing Home: Layout  Stackup. In a first step, 
we  add  an  additional  insulator  (Dielectric)  and  signal  layer  (Signal).  Then  we  set  the 
materials accordingly and change the layer type of the TOP and BOT layer to “Reference 
Plane”.  
We check “Filled Up” for both reference planes, since this will automatically fill the whole 
layer with metal. All three metallic layers should have a thickness of 0.02mm, the two 
dielectric layers should get a thickness of 0.25mm. Make sure to arrange the layers in 
the order below. It may be necessary to update the main view by pressing F5.
After these steps, the stackup should look like in the figure below: 
In a next step we go into the Technology /Board node of the Navigation Tree and make 
sure the width of the board outline is as shown in the figure below: 
Now we open the net editor by pressing Edit: New Object  Net and generate two nets 
as shown in the figures below:The next step in the set-up is to press Home: Layout  Net Editor
Here we declare the two nets “sig-p” and “sig-n” as corresponding differential signal lines 
by changing the netclass of one to differential and pick the other as differential partner 
net: 
Now we are able to place two parallel traces. We begin with the upper trace using Edit: 
New Object  Trace, which will be part of net “sig-p” as shown in the figure below: 
The definition of the second trace should look like this:Now we have to place a terminal at each end of both traces.  
To  do  this,  we  open  the  Edit  Terminal  dialog  box  by  pressing  Edit:  New  Object  
Terminal. We add four terminals with the values shown below: 
T1: Layer Signal, Net sig-p, x=0mm,     y=100.45mm 
T2: Layer Signal, Net sig-p, x=600mm, y=100.45mm 
T3: Layer Signal, Net sig-n, x=0mm,     y=100mm 
T4: Layer Signal, Net sig-n, x=600mm, y=100mm
If you zoom into the layout, it should look like in the figure below:    47
2D TL Modeling  
Now we can generate the equivalent circuit of the differential stripline pair. To do that, 
we go into the Navigation Tree and select the two nets “sig-p” and “sig-n”. We open the 
2D (TL)-dialog box by pressing Home: Parasitic Extraction  2D (TL).  
We go to the Selection tab and add the two nets to the list of selected nets as shown in 
the  figure  below  by  either  pressing  Add  or  dragging  the  selected  items  from  the 
navigation tree to come to this setup: 
We switch to the Modeling tab and set the parameter “Model valid up to frequency” to 
10GHz as shown in the figure below. All other settings should be left at their default. We press the Update Schematic button and change to the Schematic tab where we see 
the generated schematic block of our stripline pair.  
If  the  pins  are  not  located  like  shown  in  the  figure  below,  correct  their  position  by 
selecting the block, clicking the right mouse button and selecting Change Pin Layout.
Next, we load the schematic block according to the schematic in the figure below: 
We use 100 Ω and 1000 Ω resistors to load the block. The probes P1 and P2 are differential 
ports and measure the voltage between T1-T3 and T2-T4.  
We now set up a Transient task: In the corresponding Task Parameter List, we select the Excitations tab and choose 
Define Excitation as shown in the figure below:
A new dialog box shows up where we insert settings of our excitation:  
Next, we change to the Transient-tab and change the maximum simulation time to 20 
ns: 
In the last step, we press  Update to start the simulation. The figure below shows the 
result of the simulation. You can select the relevant results out of the list of results.The delay time of about 4 ns through the differential pair is clearly visible and a slight 
increase of the voltage at one port due to some reflection of the signal can be observed.
Signal Integrity on a Multilayer using the SITD-solver  
The purpose of this example is to acquaint you with the  
  Usage of the SITD-solver. 
  Time domain analysis with focus on signal integrity. 
Task Definition  
In many high-speed PCB designs, it is important to check the integrity of the signal paths. 
This  means  the  whole  system  consisting  of  selected  high-speed  transmission  lines, 
signal sources and loads has to be analyzed with respect to delay, over- and undershoot 
and  crosstalk.  For  this  kind  of  analysis,  the  power  delivery  systems  are  typically 
considered as ideal and the simulation is performed in the time domain. In this example 
we perform such an analysis on the basis of a single transmission line on a PCB. 
The PCB Design 
First, we prepare a new project by importing an existing PCB design. The accompanying 
example is part of the Component Library as ‘Signal Integrity Analysis’ example data. 
We select the corresponding box in the Component Library and see two attachments: 
‘high speed.dar’ and ‘parts.ppt_lib’. We sequentially click on the folder icons next to both 
files and download them into a temporary folder. 
We keep the stored file ‘parts.ppt_lib’ in mind and start with importing ‘high speed.dar’ 
by double- clicking on the folder beside the high speed.dar icon. A file browser will open 
from where we drag & drop the file directly into the CST PCB Studio main window.  
The PCB should look like in the figure below: We save the project as e.g. ‘Signal Integrity Analysis’.  
Now we start to examine the design.  
We see an integrated circuit on the left side that connects to two other integrated circuits 
on the right side via some address lines.
We press Home: Layout  Stackup and see the different layers of the PCB. The board 
consists of seven metallic layers and has an overall thickness of about 1.12 mm.  
The material of the dielectric layers is fr4 with a relative permittivity of 4.2. 
Note the particular sequence of Above and Below values in the Fill column and refer to 
the CST PCB Studio online help for more details on the meaning of these parameters. 
By pressing the View button, the effect of changing those Fill values can be observed in
Now let us have a closer look at the components of the board.  
We go to the View Attributes window and select the first two layers Top Components 
and L1 by selecting the first column of the layer table (Top Components ) and then with 
mouse button still pressed go down to the next line (L1). Mouse click with shift/control 
key pressed is another option. 
We see the three integrated circuits. 
Next, we select the last two layers L7 and Bottom Components. We see another two 
ASICs on the bottom side. To improve the visibility of the nets switch the black 
background color to white by pressing View: Color  Invert View:The  address  bus  connects  each  signal  from  a  pin  of  the  IC  on  the  left  side  with  the 
corresponding pins of the four ICs on the right side. 
We are interested in what kind of and how many pins are connected to the net ADDR1. 
In order to select the net, we go into the Navigation Tree, expand the Select frame and 
check  the  three  buttons  (‘Entire  Nets’,  ‘&  Nets  Connected’  and  ‘&  Components 
Connected’) as shown in the figure below:  
Checking the box ‘&Nets Connected’ makes sure that all nets connected to a selected 
net  (e.g.  by  a  resistor)  will  be  automatically  selected,  too.  Checking  the  box  ‘& 
Components  Connected’  means  that  all  components  connected  to  any  selected  net
(including  the  automatically  selected  nets)  will  be  automatically  selected.  This  is  a 
powerful functionality, as we will see in the next steps. 
We go into the Navigation Tree, expand the Nets folder and see ADDR1 as shown in 
the figure below: 
We select ADDR1 and in addition, we press View: Visibility  Hide Unselected Nets to 
hide all other not selected nets.  
Next,  we switch the  black  background  color  on  again  and go  into  the  View  Attributes 
window. Here, we select All Layers in order to make all layers visible as shown in the 
figure below:Now we go into the Main View and if necessary adjust the view. We should now have a 
view similar to the one shown in the figure below:
We see the selected net is highlighted with an additional net on the left side, both just 
separated  by  a  resistor  array.  We  go  back  into  the  Navigation  Tree  and  check  Only 
selected items.  
The two selected nets and the six components will be listed: 
Next,  we  go  back  to  the  View  Attributes  window  and  select  the  two  top  layers  Top 
Components and L1 only. We zoom into the region of the resistor array and should have 
a view like this: We take a closer look at the signal path of the selected nets. In order to do this, it is 
convenient to expand the selected nets in the Navigation Tree as shown in the figure 
below: 
Now we can easily follow the signal path starting from pin IC1-A1 of the left IC to pin 
Rarr-1 of the resistor array.
The resistor array consists of 10 Ohm resistors and connects the signal to pin Rarr-8. 
From this pin, the net ADDR1 starts and connects the pins to the four other ICs.  
To show the location of these pins we first zoom out again (by pressing View: Change 
View  Reset View). Then we zoom in on the ICs on the right side and switch on the 
pin names (by pressing View: Visibility  Pin Names or right mouse menu Pin Names). 
The figure below shows the pins of IC3t.  
We change back to the View Attributes window and select the two bottom layers L7 and 
Bottom Components. We zoom into the corresponding regions and recognize pin IC5b-
1 and IC4b-1:Now  we  uncheck  View:  Visibility   Pin  Names  and  uncheck  the  tag  “Only  selected 
items” (at the top of the Navigation Tree) to start with the SITD-simulation.
SITD-Solver 
In  order  to  start  a  signal  integrity  analysis  on  net  ADDR1,  we  have  to  prepare  the 
involved components first. To do this, we check the components models by selecting 
Home: Components  Components. The following dialog box will appear presenting the 
Component Library: 
In the left column we see a table that shows all components placed on the PCB. The 
first five components are the ICs and the last is the resistor array.  
We select IC1 and see that it refers to a part with name ic1x. This part is stored in the 
Part  Library.  You  can  examine  the  part  by  either  pressing  “Edit”  straight  away  in  the 
dialog  box  above  or  by  going  in  the  Navigation  Tree  and  double-clicking  on  the 
corresponding part item ‘ic1x’: 
After doing so, a dialog box appears showing that the part is still undefined:The next four ICs in the list (IC2T, IC3T, IC4b and IC5b) reference the part ic2y, which 
has no electrical model. The resistor array Rarr references to an already defined part 
pn-rx4array_10R.
The  program  recognizes  the  corresponding  model  type  R-HF,  but  only  the  default 
parameters have been defined so far: 
We now update the parts by importing the correct models from the file ‘parts.ppt_lib’, 
which we have downloaded from the Component Library at the beginning of this chapter. 
To do this, we right-mouse-click Part Library in the Navigation Tree and select Import as 
shown in the figure below:A file browser appears and allow us to select the file ‘parts.ppt_lib’ from the folder where 
we have stored the file at the beginning of this chapter.
After pressing Open, a new dialog box appears showing the parts that can be imported 
from the file: 
We see ic1x and ic2y defined as I/O Device. All available pins are of pin type signal. The 
part pn-rx4array_10R consists of 10 Ohm resistors with parasitic capacitances of 30 pF 
and parasitic inductances of 5 nH.  
Since the parts are already available and only their parameters have to be updated, we 
check “Assign values to available parts” on the bottom left of the dialog box and press 
Ok. A message window tells us that the three parts have been updated successfully. 
To the SITD analysis, we press Home: Simulation  SITD Analysis.  
In the following dialog we choose the pin “IC1-A1” from the Available pins frame and 
shift it to the right side by pressing the add button or by dragging them with the mouse.The workflow automatically inserts IC1-A1, and in addition it also inserts all other pins 
which are connected to IC1-A1 via Used nets and Used components. In this case the 
two connecting nets are ADDR1 and net1 and the connecting component is the resistor 
array Rarr in between.  
Both  the  nets  and  the  component  connected  to  the  user  selection  are  listed  in  two 
separate fields in the Used nets/Used components frame. If necessary expand that field 
using the small + below the Excitations/ports:
The icon to the left of the resistor array indicates that this component is based on a part 
library electrical model. 
The green marker on the right side of the resistor indicates that the setup has found a 
valid electrical model for this kind of simulation and so a whole simulation set-up can be 
generated successfully. 
If  that  box  is  yellow,  it  means  the  corresponding  component  has  either  no  electrical 
model  assigned  to  it,  or  that  the  model  assigned  is  not  suitable.  The  results  of  the 
simulation may be inaccurate and not as expected in this case.  
Selecting the components in the left list and choosing Edit Component(s)… in the right 
mouse button menu allows inspection and changes to those component models. Note 
the warning message at the bottom - we will come to that in a few moments. 
We now close the component editor again; select the two nets ADDR1 and net1 in the 
Used nets/Used components frame and see how the nets and the resistor array will be 
highlighted in the Main view:In a next step, we assign suitable I/O-models to the listed pins.  
For this,  we select  the  corresponding  Model field for the  pin “IC1-A1”  and  select  Edit 
from the drop -down menu after a double click as it is shown in the figure below: 
In the following dialog box, we choose “Digital Pulse” for the Signal model type. The 
parameter “V-amplitude” means the digital pulse will swing from 0V to 5V. The 
paramter ”t-rise/fall” defines the rise- and fall time in seconds.
The parameter “R-inner” defines the dynamic inner resistance during the voltage swing 
happens. We change this value to 15 Ohm and press Ok. 
In a next step, we multi-select the rest of the pins and double click on the Model field in 
the top control row (responsible for multiple model editing) as shown in the figure 
below: 
In the following dialog box, we again choose “Digital Pulse” for the Signal model type 
and set the same parameters as before for all selected pins:For every digital pulse definition CST PCB Studio creates an equivalent IBIS model 
during the simulation setup which will later be used in the following circuit simulation.
Next, we assign a stimulus sequence as excitation to the pin IC1-A1 by double-clicking 
into the Stimulus field of the pin and selecting Select as shown in the figure below: 
The following dialog box shows the default stimulus sequences.  
We select the DDR_Write stimulus and close the dialog box by pressing the Ok button. 
Next, we multi-select the remaining four pins and set the stimulus Quiet by selecting 
Stimulus -> Select the top row of the table to pick a value for all selected pins. 
In a last step, we define an additional parallel termination resistance at pin IC2t-1.  
To do this, we double-click into the corresponding cell in the table and choose Edit as 
shown in the figure below:We choose the Termination type “parallel R”, assign 100 Ohm to the parameter R1 as 
shown in the figure below and press Ok.
The setup of the SITD analysis is now finished. We just check that the overall simulation 
time is 80ns and that a simple “local simulation run” will be used instead of generating 
simulation projects.  
Before we start the simulation we have a quick look at some control settings. We press 
the Specials button at the right side of the dialog box. A dialog box opens providing four
We  see  that  both  ohmic  and  dielectric  losses  are  taken  into  account  and  that  the 
generated equivalent circuit will be valid up to a maximum frequency of 1000 MHz. Feel 
free to experiment with the effects of other control parameters. 
Now we are ready to start the signal integrity analysis by pressing the Start button at the 
bottom of the SITD-dialog box. As a first step of the following automatized process, the 
equivalent circuit model of the selected nets is calculated. In a second step, a complete 
schematic gets generated and in a last step, the circuit simulation will be started. This 
will take a few seconds and you can observe the individual steps in the Message and 
Progress windows. 
After the process is finished, we change to the schematic tab and see the generated 
schematic.We see the schematic block in the center which holds the equivalent circuit of the nets 
“net1” and “ADDR1” and in also the included equivalent circuit of the connecting resistor 
array “Rarr”.  
We can also see the corresponing IBIS blocks for the driver pin “IC1-CA1” on the left 
side and the other four input buffer pins on the right. 
The results, i.e. the pins voltages, can be seen by selecting the values from the 
corresponding result folder for the SI-TD task in the Navigation tree: 
We finish the example by switching back to the SITD-dialog box and pressing the 
Show Mesh button as it is shown in the figure below:
An additional 2D(TL) Mesh View Manager dialog box will appear providing the list of all 
calculated 2D the cross-sections. In the Main view the corresponding segments to the 
cross-sections are marked in white colored frames.  
We  scroll  through  the  list  of  cross-sections  and  can  see  how  the  corresponding 
segments get highlighted in the Main View. 
In  order 
to  see 
the  cross-sections
A  separate  Cross  Section  View  window  will  appear  showing  the  cross-section  of  the 
element, which will look something like this: 
While we scroll through the list of cross-section elements keeping the cross section view 
open, we see that the corresponding cross-section will change as well. 
We now have finished the signal integrity analysis of a simple net. If you now added a 
second net, e.g. net ADDR2, you could also check the crosstalk effects from one net to 
the other. You are encouraged to trying this additional step by yourself. 
Note: For further explanations on how to use CST PCB Studio for more complex signal
Impedance Calculator 
The purpose of this example is to introduce of the PCB Studio Impedance Calculator. 
A very important task of signal integrity analysis is to decide for a good layer technology. 
The technology should provide desired single-ended and differential impedances on all 
the layers.  
This chapter demonstrates how the impedance calculator can be used to optimize the 
layer technology. 
We start by creating an empty PCB Studio project. First, we open the stackup dialog box 
and define a 10-layer technology like shown in the figure below:The conductor layers are equidistant from each other and all have the same thickness. 
Fill is set alternatingly to ‘Above’ and ‘Below’. The insulator layers between the conductor 
layers all have the same thickness. 
Next, we open the dialog box of the impedance calculator by pressing Home: Layout  
Impedance  Calculator.  We  can  see  a  table  of  layers  similar  to  the  stackup  manager. 
There are a few more columns. Some of the additional columns are necessary to define 
the distances between traces and the width of the traces. In addition, on the right-hand 
side there are columns that show the impedance results after an impedance calculation. 
At the bottom of the dialog box, the following message is shown: 
The  reason  for  this  is  that  the  impedance  calculator  needs  the  information  on  which 
layers are to be filled completely or partially with ground or power planes. These planes 
have a high impact on the impedance values.  
We  define  four  reference  plane  layers  like  shown  in  the  figure  below.  The  Type 
‘Reference Plane’ of a layer has no meaning for all other solvers in CST PCB Studio.   
In addition, we set a trace width of 0.2 mm for all the layers. We see a configuration as 
shown in the figure below:
The tool calculates impedances even for layers that are set as reference plane layers. 
In order to do this, the tool assumes that the signal tracks are guided by the ground or 
power planes and define a coplanar geometry. 
Now, we calculate the impedances for the first time by pressing the button Calculate. 
The four columns on the right hand side of the table are now showing some impedance 
values (they may vary slightly). 
You can find a more detailed description on the specifics of these impedances in the 
online documentation.We press the button Specials to check the settings used by the impedance calculator. 
We  change  the  value  Maximum  relative  error  from  0.01 to  0.001.  This  increases the 
solver accuracy concerning the optimization by reducing the relative error threshold that 
is used as the iteration stop criteria. 
The first impedance value we want to achieve is 50 Ω for ZSingle on the layer TOP.  
We unfold the frame Optimization at the top of the dialog box, there we select the button 
Optimization, and set the options like shown in the figure below: 
We now want to optimize the target impedance Zsingle depending on the variation of the 
thickness of the dielectric layer Insulator1.
After  pressing  Calculate,  we  get  as  the  result  a  value  for  thickness  that  provides  the 
intended impedance of 50 Ω. The value is 0.105928 mm.  
For some reason (e.g. limit of the available technology) this value is below a threshold 
that we do not want to go below.  
We  enter  this  imaginary  threshold  value,  e.g.  0.15  mm.  In  a  next  step,  we  want  to 
achieve the 50 Ω by optimizing the trace width of on layer TOP instead.  
After pressing Calculate again, we get this result: 
We press ‘To Stackup’ to apply the calculated value of 0.286549 mm for the trace width 
to the layer TOP. 
We  then  optimize  the  trace  width  of  layer  Layer3  to  get  ZSingle  of  50  Ω  on  this  layer 
(resulting in a trace width of 0.173062 mm). We do the same for layer Layer5 (result is 
0.233833 mm). We want to have a symmetric layer stackup. For this, we copy the values 
of the trace width from  layer TOP to layer Bottom, from  layer Layer3 to layer Layer8, 
and from layer Layer5 to layer Layer6. 
Now,  we  want  to  achieve  differential  impedances  of  90  Ω  on  the  signal  layers.  We 
optimize the trace gap on these layers. For this, we need again to choose the respective 
target and variate variables. If all is done correctly, the optimization gives the trace gap 
values of 0.220683 mm on TOP, 0.188951 mm on Layer3, and 0.257296 mm on Layer5.  
Again, we make the stackup symmetric by copying the values for the trace gap to the 
layers in the lower half of the stackup. 
Finally,  we  uncheck  the  button  Optimization  and  start  a  full  calculation  by  pressing 
Calculate. The results now should look like shown in the figure below:In  a  last  step,  we  check  the  cross-section  that  is  the  basis  to  calculate  one  of  the 
impedance  values.  To  do  that  we  double-click  in  the  table  on  the  impedance  value 
ZDifferential on layer Layer5.
We see the cross-section corresponding with this value. It looks like the figure below: 
If  you  want to  apply  all the  changes  of the  layer settings  in the  impedance calculator 
dialog  box  back  to  the  CST  PCB  Studio  layer  stackup,  you  need  to  press  the  button 
Apply at the bottom of the impedance calculator dialog box. 
The Reset button next to it replaces the setting in the Impedance Calculator with those
PI Analysis using the PI-Solver  
The purpose of this example is to acquaint you with the  
  Selection, and Modeling dialog for the 3DFEFD solver 
Impedance analysis with focus on power integrity 
 
Task Definition 
In this chapter, we want to investigate the impedance of a power delivery network (PDN). 
The stackup of our example consists of four metallic layers (two GND, two VCC). The 
GND layers are connected to each other through vias, and similarly, the VCC layers are 
connected to each other through other vias:  
The lower VCC- and GND-layers are loaded with two decoupling capacitors C1 and C2, 
which are placed at the bottom side of the board. In addition, the top side of the left via 
pair  is  loaded  at  X1,  drawing  power  from  both  the  VCC  and  GND  layers.  We  are 
interested in the impedance that is seen from X1. 
The PCB Structure 
First,  we  create  a  new  project  by  importing  the  existing  PCB  design  “Power  Integrity 
Analysis” from the Component Library. In a first step, we locate the attachment through 
“View…” and click on the folder icon next to the attached “power delivery system.dar” 
file. We download the file by pressing the Download button in the upper right corner and
We save the project as ‘Power Integrity Analysis’ and then start to examine the design.  
On the lower left of the PCB, we see the red image of component X1. It provides the 
port where we want to analyze the impedance. We go to the View Attributes window and 
select layer TOP.   
We now see the two drills connecting X1 to VCC (on this layer) and to GND (on the layer 
below): 
We  zoom  into  the  region  around  the  drills  to  see  there  is  a  connection  between  the 
conductor on the layer and the left drill, and no connection between the layer and the 
right drill because of a cutout in the area shape:Now we zoom out again and change to layer BOT to see the drills and the connections 
for  the  two  decoupling  capacitors    and  finally  select  layer  Bottom 
Components to see the capacitor components.
In  order  to  have  a  deeper  look  at  the  capacitors’  electric  models  we  first  go  to  the 
Navigation Tree and expand folder Components as shown in the figure below: 
We select C1 and choose Edit by using the right mouse button or a double click. The 
following dialog will appear: 
We see C1 refers to a model definition in the part named Cap. In order to edit this part, 
we press the highlighted Edit button . A dialog box offers us to assign 
a Touchstone file to this part.In order to assign just a simple capacitor model to this part, we click on the field Model 
type and select Standard Model from the drop-down menu.
The dialog box changes so that we can set the corresponding capacitor model for the 
part Cap:  
We change the capacitance value to 1.0 nF, leave the values for the parasitic resistance 
and parasitic inductance and finally press Ok.  For the second capacitor C2, we do not 
have to make any further settings, since C2 also refers to the same part Cap.  
Before starting with the simulation setup, we briefly explore the component X1:We see that the part reference X1 is a generic Vendor Device or Undefined Device type, 
which  has  no  internal  electrical  model  defined  in  the  Part  Library. We  do  not  need  a 
further examination of this component since X1 will only be used to define a port in the 
following impedance analysis.
PI-Solver 
We  set  up  the  simulation  task  by  pressing  Home:  Simulation    PI  Analysis.  The 
following dialog box will appear:  
We see that there are by default only power pins listed in the Available pins frame. This 
is  because  PI-analysis  is  a  power  analysis  tool  so  only  power  pins  and  their  related 
ground reference pins are of interest. 
We want to calculate the impedance between the VCC- and GND-pin of X1. We select 
the  pin  X1-1(VCC)’  and click  on the marked  arrow  in the  middle of the  dialog  as  it  is 
shown in the figure above. On the right side, we see a new port consisting of the selected 
power pin and its corresponding ground reference pin. 
We set the Simulation settings as follows:With  the  button  Consider  components,  we  can  control  whether  the  linear  two-pin 
components (resistors,  inductors, capacitors),  which  are  listed  in  the  Used  nets/Used 
components  frame  should  be  considered  during  the  simulation  or  not.  For  the  first 
simulation, we uncheck the button and press Start.
After a few seconds, a result like the one below will appear: 
If we expand the Used nets/Used components frame, we can see that the two capacitors 
C1 and C2, which both are connected to net VCC and net GND. This indicates that they 
were involved in the simulation. 
In order to store the curve for a comparison afterwards, we generate a folder with name 
comparison  below  the  Results folder  and copy  the  result curve from  the  Impedances 
folder into the comparison folder under the name without decaps as shown in the figure 
below:Now  we  change  back  to  the  Solver  Settings  tab  and  set  the  value  of  Consider 
components to true:
We accept the ‘Change value & Delete model’ prompt and press the Start button once 
again. After another few seconds the new curve will appear. The curve now includes the 
effect of the decoupling capacitors.  
We copy this curve under the name with decaps in the comparison folder and compare 
two plots as shown in the figure below: 
In order to get a logarithmic scaling of the curves, we change the setting in the 1D Plot 
ribbon accordingly:
We go back to the PI-solver dialog and press the Specials-button. In the dialog box, we 
select the Spatial Impedance Plots-tab as shown in the figure below:  
We activate the “Generate plots” flag and choose the bottom layer “BOT” as Reference 
layer. This causes the electric potential on this layer to be considered as zero. 
If we repeat the impedance calculation, the 2D results will appear in the PCB Main View 
somewhat like to the figure below:Please note the Plot Attribute selection at the bottom left of the main view. It is switched 
to Maximum. 
On the left, there is a list of calculated frequencies, where a local impedance maximum 
occurred.  You  can  select  any  of  them  and  watch  the  corresponding  impedance 
distribution. 
You can find more information about PI Analysis in the online documentation.  
Especially the EDA Decap Tool is an interesting add-on to analyze and improve PDN 
behavior.
Crosstalk on Split Power Planes using PEEC Modeling 
The purpose of this example is to acquaint you with the  
  Most important tools to edit and navigate through a PCB. 
  Selection, Meshing and Modeling dialog box for PEEC. 
  Usage of the PEEC model in the circuit simulator. 
  Frequency domain analysis. 
Task Definition  
For many PCBs, it is common practice to provide different power delivery systems for 
different applications. It is for example common for the analog and digital systems on 
the board to be separated like this.  
A standard measure to prevent noise coupling from one power system to the other is to 
separate the power planes by introducing slots. In order to check the effectiveness of 
the  slot  in  the  higher  frequency  range,  PEEC  modeling  can  be  used  and  this  is 
demonstrated in the example below.  
The PCB Design 
We create  a  new  project  by  importing the  existing  PCB design  ‘Power  Crosstalk  with 
Reference Ground Conductor’. We either load the project from the component library or 
download the corresponding ‘split plane.dar’ file and import it into CST PCB Studio:We  save  the  project  as  ‘Power  Crosstalk with  Reference  Ground  Conductor’  and 
start with having a look at the stack-up technology.  
To do this, we expand the folder Navigation Tree: Technology  Layers.  
We  can  find  four  metallic  layers  L_Power,  L_Signal1,  L_Signal2,  L_Gound  and  the 
corresponding dielectric layers in between.
In order to investigate the layers, we go to the View Attributes window, select the Layers 
tab and then select the first layer Top Components. All other layers are hidden now. 
Next, we switch on the object spy (View: Visibility  Object Spy) and move the mouse 
pointer  over  one  of  the  red  marked  frames  on  the  lower  side  as  shown  in  the  figure 
below: 
We select layer L_Power and see two different planes separated by a thin slot:In addition to the slot, we see the characteristic via pattern of the SMA sockets.
We switch off Object Spy and zoom into the region of the bottom left socket: 
It can be seen, that the via pad in the center is connected to the power plane whereas 
the pads of the four outer vias are connected to ground and are separated by a cutout 
(in black). 
We again zoom out (by using right mouse click or selecting Reset view to structure from 
the  drop  down  menu  /  Space  key)  and  select  the  next  layer  L_Signal1.  The  layer  is 
empty but for the small conductive pattern of the vias and their corresponding pads and 
the same applies to L_Signal2.  
We select L_Ground. We see a single plane with a cutout on the left as shown in the
If we again zoom into the region of one of the sockets, we now see the pads of the outer 
vias are connected to the surrounding plane and the pad of the center via is insulated: 
The layer Bottom Components is an empty layer.  
In order to investigate the layer stack-up technology we press Home: Layout  Stackup. 
We  look  at  the  Prepreg  parameter  and  see  its  value  is  Nominal,  which  indicates  the 
metallic layer is pressed into the surrounding layers and their thickness does not count 
for the total board thickness.  
We also see the  two upper  metallic  layers  are  of  type  Fill  =  Above,  whereas  the  two 
lower metallic layers are of Fill = Below. For details on the Prepreq- and Fill parameter 
we refer to the CST PCB Studio online help. The top and bottom dielectric layers have a thickness of 0.12 mm whereas the one in 
the center has a thickness of 0.14 mm.  
The material for all dielectric layers is fr4 and the overall thickness of the board is about 
0.4 mm. This will later determine the mesh size in the Meshing and Modeling section.  
We continue our investigation by having a look at the available nets.  
We first select layer L_Power in the Layers tab of the View Attributes window. Then we 
select View: Color  Color Mode Nets and once again change to the View Attributes 
window to select the Nets tab.  
We select VCC1 and VCC2 by using Shift + left mouse button. In order to see the pin 
names of the nets on these layers, we press  View: Visibility  Pin Names and make 
sure that the zoom level is big enough to visualize the pin names.
We should now see something similar to the following view: 
To see the GND net on the L_Ground layer first select net GND in the Nets tab (in the 
View Attributes window) and then change to tab Layers and select layer L_Ground.  
If you zoom into the lower region, you will see each socket connects to GND through 
four pins as shown in the figure below: 
If the text size of the pin names does not fit, we can change it in a dialog box that you 
can open with View: Options View Options 
The dialog box looks like shown in the figure below:We zoom out again and switch on the axes via View: Visibility  Axes. Displaying the 
axes scaling helps to estimate the real dimensions of the PCB and this can give a good 
orientation on the mesh size to choose in the next section.
After selecting the two layers Top Components and L_Ground the Main View now should 
look similar to the figure below: 
Before we open the meshing dialog box, we will finish the section by having a look at 
Home: Layout  Net Editor.  
We see that net GND is of net class ground and the two nets VCC1 and VCC2 are of 
net class power. This is an important fact because any net of net class ground or power 
can be treated as an ideal reference conductor during the PEEC modeling process. 
No separate inductive or capacitive elements will be generated for reference conductors. 
Their contribution is considered in the capacitive and inductive value of the remaining 
signal elements. 
Assigning the net class ground to a net and choosing net class ground as reference can 
speed up the modeling and simulation phase, but it is only effective if the assumption of 
an ideal reference conductor is sufficiently fulfilled. A conductor can be interpreted as 
an ideal reference conductor if it allows a sufficient current return path along the path 
near the corresponding signal conductor.  
This is, for instance, not true, if the conductor has considerable slots or constrictions. 
As  a first step,  we will  model  the  GND  net  as an  ideal  reference  conductor  and then
3D PEEC Meshing and Modeling  
Now we select the three nets in the Navigation Tree as shown in the figure below: 
We select Home: Parasitic Extraction  3D (PEEC) Model. In the dialog box, we choose 
the Selection tab. We add the three selected nets by either pressing the Add button or 
by dragging the nets in from the navigation tree:  
These three nets will be considered during the meshing and modeling phase. We now 
expand net GND in the list of Selected Nets:We see  the  list  of  all  available  pins on  net  GND.  Every  checked  pin will  appear  as  a 
terminal in the equivalent circuit, which will be generated later, provided that GND is not 
considered as a reference conductor. Although GND will be interpreted as a reference 
conductor  in the  first  simulation,  we  will  prepare  the  pin  selection for  later  simulation 
setup.  
The  two  pins  of  interest  are  SMA11_1-2  and  SMA11_2-2.  All  other  pins  should  be 
unselected by clicking on the corresponding check box. Expand net VCC1 and VCC2 
and see the available pins are selected by default.
We keep these settings and move to the Meshing tab: 
We now want to investigate the different available settings. The first frame,  Extraction 
settings  for  netclass  “power”  and  “ground”,  determines  whether  net  class  power  and 
ground should be modeled as a reference conductor (simplified null potential) or not. 
In addition, a Channel width can be assigned individually to both net class power and 
ground. The channel width can significantly reduce the size of the overall structure to be 
calculated.  This  is  a  powerful  feature  when  modeling  transmission  lines  along  or 
between  reference  conductors,  because  the  whole  reference  conductor  will  not  be 
considered  but  only  parts  within  the  specified  channel  width  around  the  transmission 
line.  
In our example, there is no transmission line, but instead there are power planes which 
are of similar size as the ground reference planes. Therefore, specifying a channel width 
does  not  make  sense.  We  turn  off  the  option  for  both  netclass  ground  and  netclass 
power . 
The next frame, Meshing settings, allows the specification of the mesh cell size for the 
PEEC mesh cell. We set the value to 1.2 mm and keep the other parameters with their 
default values. 
The next frame is Dielectric settings. If we drop down the menu Board Dielectric, we see 
four choices of how to treat the dielectric layers during the modeling phase:The  first  entry,  layer  stack  (original),  means  each  dielectric  layer  will  be  considered 
during  the  capacitance  calculation.  This  is  the  costliest,  but  also  most  precise
consideration of the dielectric layers. The second item average (between signal layers) 
performs an averaging of all dielectric layers between two adjacent metallic layers.  
The third item, average (total board), causes an averaging between all dielectric layers 
of the board. This approximation speeds up the capacitance calculation procedure but 
the  user  has  to  be  aware  of  this  simplification.  In  our  case,  there  are  three  dielectric 
layers  consisting  of  the  same  material  and  so  we  will  choose  this  option  for  our 
calculation without any loss of accuracy. 
The last item, none (uniform), ignores the presence of any dielectric and the user is able 
to define a background dielectric material. Choosing this function makes the capacitance 
calculation as fast as possible. It can be useful for a rough and quick estimation of the 
electromagnetic  effects  or  in  cases  where  the  capacitive  effects  of  the  board  are  not 
dominant.  
Checking  the  box  Shrink  board  outline  helps  to  shrink  the  overall  board  when  only 
conductors  in  a  small  bounded  region  are  selected.  In  this  case,  the  program  avoids 
meshing  the  entire  dielectric  layer  of  the  board  but  adapts  the  board  outline  to  an 
adequate size around the selected conductors. In our case, the selected conductors fill 
the whole board outline and so checking the box won’t have any effect. We leave the 
Shrink board outline parameter activated.  
The settings frame, Regions, allows the setting of a finer mesh for user defined regions 
on the board. We do not need this function right now and this also is true for the last 
settings frame, Geometry simplification. It allows the setting of parameters controlling 
the abstraction of the board during the layout import. These parameters should only be 
changed by expert users. 
In order to start the meshing, press Start Meshing in the lower left corner of the tab. The 
meshing  process  will  start  showing  some  information in the  Message Window. There 
will be a warning “No DC path from following terminals”. This means there is no further 
terminal for the corresponding nets VCC1 and VCC2 found and so there will be no DC 
connection. Since we are interested in a crosstalk analysis between VCC1 and VCC2, 
we can ignore this message.  
The meshing process will run for a few seconds and the result can be seen by pressing
In  the  View  Attributes  frame  on  the  right,  we  un-select  the  first  two  layers 
(Top_Components and L_Power). We change to the 3D View using View: Change View 
 3D View and rotate the meshed structure as shown in the figure below: 
We finally  reset  the  view  by  pressing  the  space  bar. We  now  switch  to  the  Modeling 
settings. In the Modeling settings frame we uncheck Dielectric losses in order to get a simpler 
model and leave all other parameters at their default values.
We have a look at the Parameter calculation frame: 
The settings apply for both inductance and capacitance calculations. In general, there 
are two calculation methods: complete or step by step. The expression ‘complete’ simply 
means that all mesh elements (careas and isegs) will be coupled with each other. This 
is the classical PEEC approach but it implies two problems: 
First,  the  coupled  capacitive  areas,  for  example,  are  modeled  by  using  a  static 
capacitance and the longest distance between these areas limits the maximum allowed 
frequency  range  of  the  model.  In  case  of  complete,  the  maximum  valid  frequency  is 
directly limited by the size of the board, ignoring all screening effects that can lead to a 
considerable de-coupling between different regions of the board. 
Secondly, the calculation method ‘complete’ in general leads to longer calculation times. 
The  method  is  started  by  the  program  only  if  the  Maximum  number  of  elements  for 
complete  calculation  is  not  exceeded.  The  method  often  leads  to  larger  equivalent 
circuits that can only be avoided by using the Tolerance limit for minor couplings.  
Calculation  method  complete  should  only  be  adapted  when  a  PCB  has  only  a  few 
metallic structures and so fewer screening effects for decoupling certain regions can be 
expected. This is sometimes true for single-layer or double-layer PCBs.  
In  all  other  cases,  the  calculation  method  step  by  step  is  recommended.  With  this 
method, the complete capacitance (or inductance) matrix is constructed using several 
calculations on different sub-regions. The size of these sub-regions is best chosen by 
setting the radius value in the Search by field.  
In  general,  the  Search  radius  should  be  about  ten  times  the  distance  between  the 
metallic  layers  or  at  least  three  times  the  mesh  size  to  make  sure  the  available 
conductors can lead to the expected screening effects. Screening only takes place within 
an environment with considerable conductive materials. 
In our  case,  there  is  a  high  presence  of conductive materials  on  both layers  allowing 
good  screening. The  mesh  element size  was chosen  to be  1.2 mm  and the  distance 
between the layers is about 0.4 mm, so we choose 4.0 mm as Search by radius. 
Choosing  value  factor  in  the  field  Search  by  makes  the  program  define  an  adequate
As a last step, we change the Tolerance limit for minor couplings to 0.2 % as shown in 
the figure  below.  The  solver  will  delete  all  off-diagonal  entries  of the  inductance-  and 
capacitance  matrix,  which are  lower than 0.2  % of their  corresponding main-diagonal 
values. This leads to a sparser PEEC model and to a faster simulation, especially if the 
Calculation method is set to complete.  
Now  we  press  the  button  Update  Schematic.  The  generation  of  the  corresponding 
schematic symbol will take only a few seconds and we change to the Schematic tab:  
We see the two pins of net VCC1 and VCC2. Because of the assumed ideal reference 
behavior of net GND, there is no need for further pins and we can connect the loads 
between the pins and the ground reference symbol.  
We load the schematic block at both sides with a 50-Ohm resistor and put an excitation 
port on at the left side. In addition, we put a probe at the right side of the block. The 
whole schematic should look like in the figure below:Note: the direction of the probe in your project can differ to the direction in the picture 
above.  This  is  due  to  the  fact  the  probe’s  direction  depends  on  the  direction  of  the 
connector where the probe is placed on. The connector’s direction is defined by how the 
connector was drawn, either from the left pin to the right pin or vice versa. Since we are 
interested  in  voltages  and  not  currents,  the  probe’s  direction  will  not  influence  our 
results.
Next, we define an AC-task by pressing Home: Simulation  New Task. A dialog box 
will appear where we select “AC, Combine results” as shown in the figure below: 
In  the  Task  Parameter  List,  we  select  the  AC  tab  and  choose  Fmin=0.005  GHz, 
Fmax=0.5GHz and the number of Samples=80 as shown in the figure below: 
Next,  we  change  to  the  Excitations  tab  of  the  Task  Parameter  List,  select  Load  and 
choose Define Excitation from the drop-down menu as shown in the figure below: 
In this dialog box, we keep the default parameters and close the box again by pressing 
the Ok button.Now we select Home: Simulation  Update and start the simulation. In a first step, the 
inductances and capacitances of the PEEC model will be calculated. In a second step, 
the actual circuit simulation starts. The Messages window informs about the progress 
and when the whole simulation task is finished.
To display the results in an appropriate way, we go into the Navigation Tree, select folder 
Results, choose Add Result Plot (by using the right mouse button) and name the new 
result folder GND as reference: 
We open the result folder, select AC1 FD Voltages P1 and copy it. 
We paste it into the newly created result folder and rename it. 
Now we generate another PEEC model using the calculation method complete instead 
of step-by-step to compare the two methods.  
To  do  this,  we  change  to  the  PCB  tab  and  press  Home:  Parasitic  Extraction   3D 
(PEEC): 
Once we switch to complete as Calculation Method, we will be prompted to accept the 
value change and the fact that the old model will be deleted. We agree with Yes. Then 
we  switch  back  to  the  Schematic  tab  and  restart  the  simulation  by  pressing  Home: 
Simulation  Update.  
The  simulation  may  take  a  few  seconds  longer  than  the  previous  one.  In  order  to 
compare the new result with the existing, we select the Result folder GND as reference
We see a second curve that is almost identical to the first: 
In order to see the effect of the cutout in the net GND, we must consider the net GND 
as a regular net and not as a reference conductor. To do this, we change to the PCB tab 
and press Home: Parasitic Extraction  3D (PEEC).  
In this dialog box, we select the Meshing tab and uncheck the Model netclass “ground” 
as reference button. We will be prompted to accept the value change and we press Yes. 
The settings in the Extraction settings for netclass “power” and “ground” frame should 
look like in the figure below:Next, we select to the Modeling tab and change the Calculation Method back to step-
by-step as shown in the figure below: 
Again, we press Update Schematic and see the information in the Messages window.
In order to prepare the PEEC model, we recommend removing the ground symbols, 
the electric connection lines and the probes from the schematic block by simply 
selecting them and pressing delete.  
We start with the following schematic, making sure the four terminals are selected: 
First,  we  transform  the  port  1  to  a  differential  port.  To  do  this,  we  select  the  Port  P1 
appearing in the Navigation Tree. Then we select the property Differential in the Block 
Parameter List as shown in the figure below: 
If we do so, we will see an additional terminal below the yellow port and we can complete 
the schematic like in the figure below: 
Finally, we place a differential probe between both terminals on the right hand side as 
shown above. To do this, we select the two corresponding connector lines and perform 
Home: Components  Probe. 
Now we can run the simulation again by pressing Home: Simulation  Update. The 
simulation will take considerably longer than for the previous ones since the GND
The differential voltage of interest is now called P1 Diff. Comparing the new result with 
the two curves from the last pages we see that the peak is a little bit smaller.  
In general, the result shows no significant influence from the cutout in the net GND:   
Low Frequency Extraction 
We will now slightly change the layout by introducing two terminals on either side of the 
slot as can be seen in the figure below:The two terminals are defined as follows: 
T1: Layer L_Power, Net VCC1, Position x=39.5, y=315.0 
T2: Layer L_Power, Net VCC2, Position x=40.5, y=315.0
Next, we change the global frequency unit in Schematic to MHz: 
In the Meshing tab, we model the netclass “ground” as reference and choose a suitable 
channel width, as shown in the figure below: 
We leave the existing settings in the Modeling tab and launch the PEEC modeling by 
immediately pressing the Update Schematic button.  
Now we change to the schematic tab and see the schematic block with two new pins for 
both terminals T1 and T2. Between T1 and T2 we connect a resistor with 0.1 Ohm, the
Next we set-up an AC-task in the frequency range from 1 𝑀𝐻𝑧 to 100 𝑀𝐻𝑧.  
As  excitation  we  again  choose  an  ideal  voltage  source  of  1𝑉.  This  means  that  the 
excitation needs not to be changed. 
After pressing the Update button the simulation will take a few seconds. The calculated 
voltage on probe P1 is shown in the figure below:It can be seen that the transmitted voltage decreases for frequencies higher than 3 MHz 
and this is due to the inductance and capacitance properties of the layout structure. 
It is sometimes useful and necessary to consider such parasitic layout effects in a more 
complex system simulation. The first way would be to export the complete equivalent 
circuit of the PEEC-model but this often would overwhelm the whole set-up. And often 
the user is only interested in the first order effects which can be accurately modeled by 
a reduced low frequency approximation of the PEEC-model.
We  now  generate  such a  low-frequency  approximation model  by  going  back  into  the 
Modeling tab.  
First, we check the button “LF reduction at” and set the corresponding frequency, where 
the approximation should take place, to 1.0 kHz: 
In the Export model frame, we choose Spice3 as simulator output type and specify the 
name and folder the SPICE subcircuit should be written to.  
The final step is to press the Export Model button and wait for the modeling process to 
finish.  
In  order  to see  the  similar  behaviour  of  this  SPICE  circuit  we  open  a  new  Circuits  & 
Systems  Schematic project and import the SPICE sub-circuit by going into the Block 
Selection Tree, selecting the folder Data Import and draging the SPICE block onto the 
empty schematic sheet:A file browser appears where we have to specify the Spice circuit that we have exported 
on the page before.
Next,  we  re-arange the pins  of the  Spice  block and  load  them  as  it  was  done for  the 
PEEC-block before: 
As a last step we set-up an identical AC-task as in the simulation before. After pressing 
the Update button the simulation provides a very similar result, but within a significantly 
shorter calculation time: 
Such equivalent circuits can be used to expand existing SPICE setups e.g. to consider
Chapter 4 – General Terminology  
CST PCB Studio is designed to be easy to use. However, to work with the tool in the 
most  efficient  way  the  user  should  know  the  principal  methods  behind  it.  The  main 
purpose of this chapter is to explain the theoretical concepts. 
3D (PEEC) Modeling 
The Partial Element Equivalent Circuit (PEEC) method divides a selected 3D structure 
(including  conductors  and  dielectrics)  into  a  mesh  of  short  conductive  segments  and 
small  conductive  and  dielectric  areas.  Constant  currents  within  the  segments  and 
constant charges on the areas are assumed. 
There are different types of PEEC methods that differ in the way they treat retardation 
effects and in the way they handle dielectrics. The common feature of all types of PEEC 
methods  is  the  transformation  of  the  electromagnetic  field  problem  into  an  electric 
network that can be simulated with a network simulator in time and frequency domain. 
Because of the electric connection of the conductive segments in the network simulator, 
the models work for low frequency and DC. 
CST PCB Studio uses a quasi-static PEEC approach. The magnetic coupling between 
the conductive segments is done by inductive coupling devices and the electric coupling 
between the conductive areas is done by capacitors, which takes into account the impact 
of the dielectric areas.  
The size of the circuit can be reduced by the amount of the dielectric areas and this is a 
big  advantage  of  this  approach  but  also  the  reason  for  limitations  on  the  maximum 
allowed frequency.  
The  longest  distance  between  two  coupled  elements  (segments  or  areas)  limits  the 
maximum frequency range of the whole circuit. The  program evaluates the maximum 
valid frequency automatically. 
There  are  many  applications  of  the  PEEC  method  and  CST  PCB  Studio  features 
additional approximation tools in order to enable the usage for complex PCBs. But the 
most appropriate applications for this method are boards with a small number of layers 
and no reference plane with clearly defined characteristic impedances present.  
This means the 3DPEEC method is most suitable in the case that the conductors cannot 
be modeled as microstrips or striplines due to the absence of a ground, from which the 
characteristic impedance could be determined. 
2D (TL) Modeling 
The Transmission Line Modeling method parses a single trace or a group of traces and 
divides them into a finite number of straight segments. For each segment the program 
checks for any conductive areas surrounding the traces which may serve as reference 
conductors.  All  traces  in  a  segment,  in  combination  with  additional  reference  areas, 
define its cross-section. A static 2D field solver will calculate the primary transmission 
line parameter per unit length (R, L, C, G’).  
In  a  following  step,  all  segments  will  be  transformed  into  an  equivalent  circuit.  The 
procedure even considers vias and creates related equivalent circuits as well.  
Finally, all circuits are connected together into one single electrical model representing 
the whole trace or group of traces. 
The procedure implies that only TEM propagation modes can be considered and this 
causes two limitations. First, the model is only valid in a frequency range from DC to a 
maximum  frequency.  This  is  due  to  the  fact,  that  the  primary  transmission  line
the calculation are significantly smaller than the shortest wavelength of the propagating 
wave. A second limitation is that additional effects on typical discontinuities like bends, 
deviations or open ends are not considered. 
The method is best used in the classical SI analysis where wave propagation effects on 
signal  lines  into  high-speed  multi-layer  boards  have  to  be  analyzed.  The  method 
assumes ideal power delivery systems and does not take into account any effects like 
ground bouncing. 
3D (FE/FD) Modeling 
The  3D  (FE  FD)  solver  is  based  on  the  frequency-domain  Finite-Element  method, 
combined with a domain-decomposition approach. Problem-adapted basis functions are 
used to  improve  simulation  performance  by  exploiting the structural  characteristics  of 
the PCB. 
In order to explain the underlying idea, we first note that multi-layer PCBs, despite their 
first-sight  high  complexity,  exhibit  strong  internal  structuring,  such  as  the  layer-based 
geometry,  solid  power/ground  planes,  highly  repetitive  local  via  domains,  and  signal 
traces which follow strong design constraints, like bounding to reference planes and 45-
degree routing, just to name a few.  
It  is  clear  that  exploiting  these  characteristics  within  a  numerical  method  leads  to 
tremendous  performance  improvements  when  compared  to  a  general  but  monolithic 
approach (like standard Finite Elements). 
Thus, as an essential first step, the present solver algorithm identifies the partial volumes 
(called specific domains) of the whole PCB volume that allows a specialized and efficient 
numerical description, due to the above-mentioned structural elements.  
In the current version, these are: (i) domains sandwiched between copper areas/planes, 
possibly containing intermediate signal layers, (ii) vias and their local surroundings, (iii) 
domains containing microstrip lines.  
Ideally, the specific domains cover all relevant aspects of the PDN. 
Method Approximations 
CST  PCB  Studio  specializes  in  the  fast  and  accurate  simulation  of  electromagnetic 
transmission  effects  of  PCBs.  This  specialization  brings  some  limitations  which  are 
summarized below: 
  The  PEEC  modeling  method  is  based  on  a  quasi-static  3D  approach  where  all 
selected conductors are divided into a number of elements and transferred into an 
equivalent circuit consisting of resistors, inductors and capacitors. The capacitor and 
inductor  representing  the  longest  distance  between  two  mesh  elements  limit  the 
maximum frequency range of the whole circuit. The program evaluates the maximum 
valid frequency automatically. 
  The 2D modeling method is based on classical transmission line theory where all 
selected transmission lines are divided in a finite number of straight segments with 
constant  cross-sections  and  is  used  for  signal-integrity  applications  (SITD 
Analysis  and  SIFD  Analysis).  For  each  segment  the  primary  transmission  line 
parameters  (R’,  L’,  C’,  G’)  will  be  calculated  via  a  2D  static  field  calculation.  
This means the maximum frequency range is limited by the largest dimension of the 
cross-section  within  a  segment.  The  program  evaluates  the  maximum  valid 
frequency automatically.  
  The  3D  (FE  FD)  method  has  been  developed  with  the  focus  on  power-integrity 
applications  (PI  Analysis).  As  described  above,  the  current  implementation 
accurately  models  the  full-wave  electromagnetic  effects  for  the  typical  building
domains  sandwiched  between  PDN  copper  areas/planes,  (ii)  vias  and  their  local 
surroundings, (iii) domains containing microstrip lines. The solver should therefore 
be used for analyzing PDNs with distributed capacitance (power/ground plane pairs). 
In turn, if this precondition is not met, other modeling techniques are recommended
Chapter 5 – Finding Further Information 
Online Documentation 
The online help system is your primary source of information. You can access the help 
system’s overview page at any time by choosing File: Help  Help Contents 
. The 
online help system includes a powerful full text search engine.  
In  each  of  the  dialog  boxes,  there  is  a  specific  Help  button,  which  opens  the 
corresponding manual page. Additionally, the F1 key gives some context sensitive help 
when a particular mode is active. For instance, by pressing the F1 key while a block is 
selected, you will obtain some information about the block’s properties. 
When  no  specific  information  is  available,  pressing the  F1 key  will  open  an  overview 
page from which you may navigate through the help system. 
Please refer to the CST Studio Suite - Getting Started manual to find some more detailed 
explanations about the usage of the CST Studio Suite Online Documentation. 
Tutorials and Examples 
The component library provides tutorials and examples, which are generally your first 
source of information when trying to solve a particular problem. See also the explanation 
given when following the Tutorials and Examples Overview link 
 on the online help 
system’s  start  page. We  recommend  that  you  browse  through  the  list  of  all  available 
tutorials and examples and choose the one closest to your application. 
Technical Support 
Before contacting Technical Support, you should check the online help system. If this 
does not help to solve your problem, you find additional information in the Knowledge 
Base and obtain general product support at 3DS.com/Support. 
Macro Language Documentation 
More information concerning the built-in macro language for a particular module can be 
accessed from within the online help system’s VBA book: Visual Basic (VBA) Language. 
The macro language’s documentation consists of four parts: 
  An overview and a general description of the macro language. 
  A description of all specific macro language extensions.  
  A syntax reference of the Visual Basic for Applications (VBA) compatible macro 
language.  
  Some documented macro examples.  
History of Changes 
An overview of important changes in the latest version of the software can be obtained 
by following the What’s New in this Version link 
 on the help system’s main page or 
from the File: Help backstage page. Since there are many new features in each new 
version, you should browse through these lists even if you are already familiar with one

o  Memory and performance improvements for 3d field monitors, especially for 
subvolume monitors (T) 
o  Mesh feedback is now available for unintentional electrical connections between 
different objects due to a coarse mesh (TLM) 
o  Added an option for a higher accuracy lossy metal model for electrically thin 
objects (TLM) 
o  Added support for field monitor frequency limits per sequential port excitation 
(TLM) 
  Frequency Domain Solver 
o  Option for log-linear sampling of 1D results, equally suited for both logarithmic 
and linear frequency axis 
o  Several improvements with respect to robustness, usability, and performance of 
o 
the domain decomposition solver 
Improved model preparation for the domain decomposition mesh generation, for 
those cases where domains are inserted into the base decomposition 
o  Thin panel improvements for the general purpose solver with tetrahedral mesh 
(improved technology preview, manual cuts may still be required at junctions) 
o  Enhancements for partially saturated ferrites including Generalized Debye 
material 
o  Non-parametric optimization (FD: Fast reduced order model) 
  S-parameter 
  Radiated power 
  Farfield 
  Combination of design responses  
  Asymptotic Solver 
o  New framework for Channel Computation in Post-Processing for different antennas 
without the need to rerun the solver 
o  New ray data export for arbitrary ray field quantities  
o 
o  Prefiltering of ray tubes which reach a target for simulation speedup   
Improved ray based F-Parameter calculation 
 
Integral Equation Solver 
Improved accuracy via automatic solver parameter setting 
o 
o  Enhanced solver abort functionality: Keep results after abort / Obtaining  I solver 
results with partial convergence 
o  New fast farfield and radiated power calculation for direct and ACA solver  
o  Support S-Parameter definition for thin panel material  
o  Calculation of Radiation/scattering per solid  
o  Pause the simulation and temporarily release the license  
  Eigenmode Solver 
o  More  Q  information  in  the  1D  results  for  the  General  (Lossy)  Eigenmode  solver               
o 
(external Q per port and mode, radiated Q, loss-Q for materials) 
“Automatic”  solver  mode,  which  chooses  the  appropriate  Eigenmode  method 
according to the physical problem 
o  Non-parametric optimization (E: General Lossy) 
  Eigenfrequency 
  Q-factor 
  Combination of design responses  
  Hybrid Solver Task (Uni-/Bi-directional) (SAM task) 
o  Added support for uni-directional (near field) coupling in the Hybrid Solver Task 
o  Added connection of uni-directional Hybrid Solver task S-parameter results to AC,
Platform  domain  must  be  Integral  or  Asymptotic  Solver  if  ports  are  present  in 
multiple domains 
o  Added support for logarithmic and arbitrary frequency sampling 
o  Reduced disk space for large field source data and on model archive 
o  Combine Results Task for Hybrid Solver Task: 
  Added  1D  /  far  field  combine  results  for  TLM,  Integral  and  Asymptotic 
platform domains (Transient already in v2022) 
  Added E and H near field combine results for source and platform domains 
Low Frequency Simulation 
  Drift-Diffusion 
o  Support for Adaptive mesh refinement  
o  Added computation of junction capacitance 
o  New Carrier generation & recombination models 
o 
o 
  LF TD Solver 
Import of 3D power loss fields from HF Time-Domain Solver 
Improved current density visualization  
o  Added steady state detection algorithm 
  Partial RLC 
o  GUI and Result Handling Improvements 
  SAM Machine Simulation Sequence 
o  Several enhancements  
  Non-parametric optimization (LT: Electrical machine) 
o  Torque 
o  Lumped radial force 
o  Fourier coefficient 
o  Combination of design responses  
Particle Simulation 
  Added support for ion-impact ionization in Electrostatic PIC Solver 
 
Improved performance for field solver in Electrostatic PIC Solver 
Spark3D 
  Corona Breakdown Analysis in Modulated Signals is now available 
  Design Studio Spark3D task: 
o  Enabled results visualization from Design Studio 
o  Enabled the use of Spark3D task in Parameter Sweep and Optimization task 
EDA Import 
  New Single-Layer Gerber Import (via EDA Import) 
  Support of parameters (via python scripting) 
  Add, move, remove layers in EDA Import Dialog box and Python API 
  Multiple Stack-ups 
  User layers and computed layers 
  Auto-create python user script from simulation settings 
  EDA and PCB-converter settings window 
  Area selection: added negative selection shapes and editing of exact coordinates 
  Option to import bond wires as thin wire geometry to better utilize the TLM solver 
PCB Simulation 
  PI-Solver control via Python automation (since v2022.4) 
  PI-Solver: List all considered components in PI "Used Components" window
  Automatic setup of IBIS_AMI simulation within SI-TD 
  Stimulus preview for SITD and DDR4 (since v2022.3) 
  DDR4 Analysis: Flexible choice between results at die and/or at package pin 
  DDR4 Analysis: Additional termination settings for digital pulse excitation 
  DDR4 Analysis: Simulation with three different 3D MWS solvers possible (since v2022.3) 
  DDR4 Analysis: Convenient assignment of IBIS buffer models per signal type 
  Temperature dependent bidirectional co-simulation in IR-Drop with three different thermal 
solvers 
  Decap Tool: Support for Multi-Pin Devices 
BoardCheck 
  Python API to control automated board checking from design import to solver run and result 
viewing 
Array Task 
  Added possibility to edit the excitation values in the task parameter list 
 
Improved the user interface of the array task 
  Added option to define the element excitation settings before the simulation project creation 
  New subarray option to define an array layout 
  Enhanced usage of multiple excitation lists for special TSV file based array tasks 
  Added option to define an element reference position for the array layout 
  Array simulation by zones yields F-Parameters/Active S-Parameters/Active Z-Parameters 
Antenna Magus 
Spec-Based Designs 
  Spec-based designs are static designs linked to specifications, exportable directly from the 
Specification Chooser and Editor. Designs have been optimized for certain scenarios & are 
therefore more practical than standard designs. 
Smaller Service Packs 
  Upgrades  to  Antenna  Magus  will  be  made  available  in  much  smaller  service  pack 
downloads compared to previous versions. These service  packs will allow a user to add 
the latest software and content upgrades onto a Golden installation 
New Devices 
  A  number  of  new  devices  (antennas  and/or  transitions  and/or  array  layouts)  have  been 
added to the database 
Cable | Circuit | Filter Design | Macro Models 
Cable Simulation 
  Allow bi-directional cable simulation in 3D modeler (T, TLM): 
o 
Introduction  of  new  cable  ports  in  3D  modeler  incl.  backward  compatibility  for 
legacy projects and result viewing in 3D 
o  Support of MPI (T only) and combine results 
  Accurate frequency dependent dielectric losses in 2D solver now also for 3D shapes 
  2DTL: Consider common mode also for modal models 
 
 
 
Improved impedance calculator workflow 
Improved cable solver infrastructure to be more flexible and allow caching of existing results
  Create  a  3D  cable  using  the  cable  bundle  definitions  within  a  SP  of  various  HF  and  LF 
types 
Interference Tool 
  N-to-1 task: New Analysis considers all possible channel combinations with N transmitters 
  1-to-1 task: improved CPU resources consumption 
  Enabled harmonics with arbitrary taper 
Schematic Editing | Circuit Simulation 
  Reworked UI for IBIS block settings. They are now accessible through the block parameter 
list as for all other blocks 
  More flexible file handling for SPICE file reference blocks 
  Circuit Simulation 
o 
o 
o 
Improved  Vector  Fitting  workflow:  More  intuitive  access  and  easy  switching 
between built-in and IdEM vector fitting methods 
Increased simulation accuracy for blocks described by pre-calculated or measured 
N-Port parameters 
Improved time gating defaults for periodic excitation signals 
  Signal Integrity / Eye diagram signal processing  
o  More robust identification of eye apertures and calculation of secondary quantities 
in eye diagrams 
o  Automatic eye mask alignment for 2D eyes (previously only available for 1D eyes) 
o 
IBIS AMI: Jitter and Noise in its various forms is supported 
o  Classical IBIS: Fine-tuned modeling for improved accuracy 
o  Classical  IBIS:  Passive  linear  pin-pin  transfer  models  (serial  elements)  are 
considered now 
Filter Design | Macro Models 
  FD3D 
o  Lowpass and highpass filter synthesis for classical and advanced filter responses. 
o  Lumped element filter synthesizer constructs schematics with R/L/C realization for 
given ideal filter response and topology 
o  Extended library for microstrip and stripline filter types 
o  Quickly  converging  Space  Mapping  optimization  methodology  for  automatic 
dimensioning 
  Fest3D 
o  Enhanced performance of elements based on CST High Frequency solver 
o 
o  Synthesis tools enhanced performance and enabled automatic post optimization 
Improved goal functions definition in optimizer 
when exporting to Design Studio 
o  Design Studio Fest3D Block: 
  Enhanced exporting from Fest3D to Design Studio projects (includes field 
monitors and optimization tasks) 
Improved messaging and block performance 
 
 
IdEM 
o  New IdEM Builder macro modeling tool to support SIMULIA Unified License Model 
with Tokens and Credits 
Multi-Physics Simulations 
Thermal Simulation 
  Added Ability to disable thermal features in the navigation tree
Improved robustness of non-watertight models and self-intersecting surfaces 
  Add support for Bi-directional EM-Thermal Coupling with PCB Studio (IR-Drop) 
  CHT Solver 
o 
o  Speed-up of simulation with radiation (view factor calculation) 
o  Performance improvements through parallelization of octree meshing 
o  Added support for importing models using ECXML standard 
o  Added support for JEDEC Delphi model 
o  Visualization of gravity vector 
o  Support for non-homogeneous materials touching TEC and two-resistor models