diff --git "a/txt-clean-pdf-without-outline-all2-onefile/cst.txt" "b/txt-clean-pdf-without-outline-all2-onefile/cst.txt" new file mode 100644--- /dev/null +++ "b/txt-clean-pdf-without-outline-all2-onefile/cst.txt" @@ -0,0 +1,32028 @@ +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 +Fest3D User Manual +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® +Fest3D User Manual +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 +Fest3D User Manual +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, +Fest3D User Manual +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: +Fest3D User Manual +10 +Fest3D User Manual +11 +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. +Fest3D User Manual +12 +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 +Fest3D User Manual +13 +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 +Fest3D User Manual +14 +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: +Fest3D User Manual +15 +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 +Fest3D User Manual +16 +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 +Fest3D User Manual +17 +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 +Fest3D User Manual +18 +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: +Fest3D User Manual +19 +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 +Fest3D User Manual +20 +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. +Fest3D User Manual +21 +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 +Fest3D User Manual +22 +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 +Fest3D User Manual +23 +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. +Fest3D User Manual +24 +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: +Fest3D User Manual +25 +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 +Fest3D User Manual +26 +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. +Fest3D User Manual +27 +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 +Fest3D User Manual +28 +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: +Fest3D User Manual +29 +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 +Fest3D User Manual +30 +–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 +Fest3D User Manual +31 +Create the following constraints in the Constraints page with the Add Constraint button: +Fest3D User Manual +32 +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 +Fest3D User Manual +33 +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: +Fest3D User Manual +34 +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: +Fest3D User Manual +35 +Next, click on the Linearize button. All the intermediate values will be created automatically, as shown in the +next figure: +Fest3D User Manual +36 +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: +Fest3D User Manual +37 +and +Fest3D User Manual +38 +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: +Fest3D User Manual +39 +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. +Fest3D User Manual +40 +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 +Fest3D User Manual +41 +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 +Fest3D User Manual +42 +.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. +Fest3D User Manual +43 +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. +Fest3D User Manual +44 +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. +Fest3D User Manual +45 +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. +Fest3D User Manual +46 +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: +Fest3D User Manual +47 +3. The Template Based Post-Processing window will pop up. Go to the Add new post-processing step combo +Fest3D User Manual +48 + and select Load data (1D or 0D) +Fest3D User Manual +49 +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. +Fest3D User Manual +50 +5. Now click on Ok in the Load 1D Data file window. The first Template Based Post-Processing result will be +shown: +Fest3D User Manual +51 +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 : +Fest3D User Manual +52 +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: +Fest3D User Manual +53 +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: +Fest3D User Manual +54 +10. Finally click on OK and the goal will be included in the Goals tab of the Optimization task: +Fest3D User Manual +55 +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. +Fest3D User Manual +56 +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: +Fest3D User Manual +57 +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. +Fest3D User Manual +58 +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 +Fest3D User Manual +59 +Launching an EM field Analysis +Click on the EM button ( +) to open the Configure Field Monitors window: +Fest3D User Manual +60 +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: +Fest3D User Manual +61 +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 +Fest3D User Manual +62 +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. +Fest3D User Manual +63 +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. +Fest3D User Manual +64 +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. +Fest3D User Manual +65 + 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. +Fest3D User Manual +66 +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 +Fest3D User Manual +67 +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. +Fest3D User Manual +68 +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. +Fest3D User Manual +69 +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. +Fest3D User Manual +70 +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. +Fest3D User Manual +71 +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: +/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. +Fest3D User Manual +72 +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 +Fest3D User Manual +73 +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 +Fest3D User Manual +74 +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. +Fest3D User Manual +75 +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: +Fest3D User Manual +76 +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 +Fest3D User Manual +77 +Frequency Specifications window +A typical window for the configuration of the frequency specifications is shown in this figure: +Fest3D User Manual +78 +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: +Fest3D User Manual +79 +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: +Fest3D User Manual +80 +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. +Fest3D User Manual +81 +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). +Fest3D User Manual +82 +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: +Fest3D User Manual +83 +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. +Fest3D User Manual +84 +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 +Fest3D User Manual +85 +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. +Fest3D User Manual +86 +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 +Fest3D User Manual +87 +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. +Fest3D User Manual +88 +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: +Fest3D User Manual +89 +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 +Fest3D User Manual +90 +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: +Fest3D User Manual +91 +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) +Fest3D User Manual +92 +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. +Fest3D User Manual +93 +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): +Fest3D User Manual +94 +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. +Fest3D User Manual +95 +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 +Fest3D User Manual +96 +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). +Fest3D User Manual +97 +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). +Fest3D User Manual +98 +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 +Fest3D User Manual +99 +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 +Fest3D User Manual +100 +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 +Fest3D User Manual +101 +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. +Fest3D User Manual +102 +Fig. 6. GUI for Resonances in Rectangular Resonator Enginnering Tool +Fest3D User Manual +103 +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. +Fest3D User Manual +104 +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. +Fest3D User Manual +105 +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 +Fest3D User Manual +106 +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 +Fest3D User Manual +107 +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] +Fest3D User Manual +108 +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: +Fest3D User Manual +109 +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). +Fest3D User Manual +110 +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] +Fest3D User Manual +111 +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. +Fest3D User Manual +112 +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. +Fest3D User Manual +113 +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. +Fest3D User Manual +114 +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: +Fest3D User Manual +115 +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. +Fest3D User Manual +116 +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: + --action=computFields --input= --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 +Fest3D User Manual +117 +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. +Fest3D User Manual +118 +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 +Fest3D User Manual +119 +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. +Fest3D User Manual +120 +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 +Fest3D User Manual +121 +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 +Fest3D User Manual +122 +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). +Fest3D User Manual +123 +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). +Fest3D User Manual +124 +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: +Fest3D User Manual +125 +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 +Fest3D User Manual +126 +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: +Fest3D User Manual +127 +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 +Fest3D User Manual +128 +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 +Fest3D User Manual +129 +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: + --input=/mycircuit.optx -- +engine_in=mycircuit.fest3x --out-curr==/mycircuit.out - +-out-prev==/mycircuit.out.prev --engine=/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" +Fest3D User Manual +130 +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 +Fest3D User Manual +131 +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 ( +) +Fest3D User Manual +132 +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. +Fest3D User Manual +133 +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= --engine-in=mycircuit.fest3 -- +Fest3D User Manual +134 +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. +Fest3D User Manual +135 +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. +Fest3D User Manual +136 +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. +Fest3D User Manual +137 +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. +Fest3D User Manual +138 +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. +Fest3D User Manual +139 +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) +Fest3D User Manual +140 +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 +Fest3D User Manual +141 +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 +Fest3D User Manual +142 +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 +Fest3D User Manual +143 +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. +Fest3D User Manual +144 +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. +Fest3D User Manual +145 +Fig. 3.a Inductive Iris. +Fig. 3.b Metal Inserts. +Fest3D User Manual +146 +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. +Fest3D User Manual +147 +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. +Fest3D User Manual +148 +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. +Fest3D User Manual +149 +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. +Fest3D User Manual +150 +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. +Fest3D User Manual +151 +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. +Fest3D User Manual +152 +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" -- +Fest3D User Manual +153 +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 +Fest3D User Manual +154 +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. +Fest3D User Manual +155 +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. +Fest3D User Manual +156 +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 +Fest3D User Manual +157 +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". +Fest3D User Manual +158 +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. +Fest3D User Manual +159 +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. +Fest3D User Manual +160 +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. +Fest3D User Manual +Cavities 1-2 +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. +- +- +- +- +- +- +- +- +- +Fest3D User Manual +162 +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. +Fest3D User Manual +163 + 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. +Fest3D User Manual +164 +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. +Fest3D User Manual +165 +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). +Fest3D User Manual +166 +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. +Fest3D User Manual +167 +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. +Fest3D User Manual +168 +Fig.3: Topology selection. +3. Electrical and Geometrical parameters +Now the wizard requests the information regarding some configurable dimensions. +Fig.4: Geometrical parameters. +Fest3D User Manual +169 +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: +Fest3D User Manual +170 +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. +). +Fest3D User Manual +171 +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 +Fest3D User Manual +172 +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. +Fest3D User Manual +173 + 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 +Fest3D User Manual +174 +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. +Fest3D User Manual +175 +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= +--output= +[--licenseServer=] +[--nthreads=n] +Copyright 2009-2022 Dassault Systemes Deutschland GmbH. +To show the usage and all comand-line options +Fest3D User Manual +176 +[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 = +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= +define type of action performed by FEST3D application. 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= +[--nthreads=] +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= +--eunits= +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= +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 +Fest3D User Manual +177 +OTHER MODIFIERS +-verbose= +set mildest severity that is reported (default: info) +Launching mode examples +S-PARAMETER LAUNCH +FORMAL +LAUNCH + +--action=runConfig +--config=Project:1/Model:1/ConfigGroup:1/SparamConfig:1// +--input="\.fest3x" +--output="\.out +--licenseServer=27000@localhost +--nthreads= +EXAMPLE "C:\Program Files (x86)\CST Studio \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 + +--action=computeFields +--input="\.fest3x" +--licenseServer=27000@localhost +--nthreads= +EXAMPLE "C:\Program Files (x86)\CST Studio \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 + +--action=exportfile +--input="\<\name>.fest3x" +--licenseServer=27000@localhost +--esatversion= +--efile=.sat +--eunits= +EXAMPLE "C:\Program Files (x86)\CST Studio \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 +Fest3D User Manual +178 +LAUNCH +--action=exportcst +--input="\<\name>.fest3x" +--licenseServer=27000@localhost +--efile=.cst +--eunits= +EXAMPLE "C:\Program Files (x86)\CST Studio \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 + +--input="\.optx" +--engine_in=.fest3x +--out-curr= +--out-prev= +--engine= +-- +--licenseServer=27000@localhost +--nthreads= +EXAMPLE "C:\Program Files (x86)\CST Studio \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. +Fest3D User Manual +179 +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 +Fest3D User Manual +180 +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 +Fest3D User Manual +181 +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: +Fest3D User Manual +182 +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: +Fest3D User Manual +183 +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: +Fest3D User Manual +184 +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. +Fest3D User Manual +185 +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. +Fest3D User Manual +186 +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: +Fest3D User Manual +187 +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. +Fest3D User Manual +188 +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. +Fest3D User Manual +189 +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 +Fest3D User Manual +190 +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 +Fest3D User Manual +191 +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 +Fest3D User Manual +192 +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. +Fest3D User Manual +193 +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. +Fest3D User Manual +194 +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. +Fest3D User Manual +195 +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. +Fest3D User Manual +196 +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. +Fest3D User Manual +197 +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: +Fest3D User Manual +198 +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. +Fest3D User Manual +199 +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. +Fest3D User Manual +200 +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: +Fest3D User Manual +201 +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. +Fest3D User Manual +202 +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. +Fest3D User Manual +203 +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. +Fest3D User Manual +204 +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. +Fest3D User Manual +205 +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 +Fest3D User Manual +206 +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: +Fest3D User Manual +207 +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. +Fest3D User Manual +208 +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. +Fest3D User Manual +209 +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: +Fest3D User Manual +210 +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. +Fest3D User Manual +211 +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). +Fest3D User Manual +212 +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: +Fest3D User Manual +213 +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. +Fest3D User Manual +214 +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: +Fest3D User Manual +215 +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. +Fest3D User Manual +216 +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. +Fest3D User Manual +217 +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. +Fest3D User Manual +218 +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: +Fest3D User Manual +219 +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. +Fest3D User Manual +220 +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. +Fest3D User Manual +221 +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: +Fest3D User Manual +222 +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. +Fest3D User Manual +223 +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. +Fest3D User Manual +224 +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: +Fest3D User Manual +225 +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. +Fest3D User Manual +226 +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. +Fest3D User Manual +227 +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 +Fest3D User Manual +228 +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 +Fest3D User Manual +229 +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 +Fest3D User Manual +230 +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 +Fest3D User Manual +231 +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. +Fest3D User Manual +232 +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. +Fest3D User Manual +233 +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: +Fest3D User Manual +234 +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: +Fest3D User Manual +235 +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 +Fest3D User Manual +236 +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: +Fest3D User Manual +237 +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: +Fest3D User Manual +238 +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. +Fest3D User Manual +239 +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: +Fest3D User Manual +240 +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: +Fest3D User Manual +241 +Fest3D User Manual +242 +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 +Fest3D User Manual +243 +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: +Fest3D User Manual +244 +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. +Fest3D User Manual +245 +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. +Fest3D User Manual +246 +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) +Fest3D User Manual +247 +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. +Fest3D User Manual +248 +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. +Fest3D User Manual +249 +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: +Fest3D User Manual +250 +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°. +Fest3D User Manual +251 +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. +Fest3D User Manual +252 +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. +Fest3D User Manual +253 +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. +Fest3D User Manual +254 +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 +Fest3D User Manual +255 +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. +Fest3D User Manual +256 +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): +Fest3D User Manual +257 +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: +Fest3D User Manual +258 +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: +Fest3D User Manual +259 +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: +Fest3D User Manual +260 +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: +Fest3D User Manual +261 + 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. +Fest3D User Manual +262 +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: +Fest3D User Manual +263 +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: +Fest3D User Manual +264 +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: +Fest3D User Manual +265 +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: +Fest3D User Manual +266 +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). +Fest3D User Manual +267 +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: +Fest3D User Manual +268 +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. +Fest3D User Manual +269 +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: +Fest3D User Manual +270 +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 +Fest3D User Manual +271 +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 +Fest3D User Manual +272 +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 +Fest3D User Manual +273 +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: +Fest3D User Manual +274 +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 +Fest3D User Manual +275 +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: +Fest3D User Manual +276 +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: # R . +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. +Fest3D User Manual +277 +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 +Fest3D User Manual +278 +Basic geometrical scheme of side view for H-plane +Fest3D User Manual +279 +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, +Fest3D User Manual +280 +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. +Fest3D User Manual +281 +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 +Fest3D User Manual +282 +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). +Fest3D User Manual +283 +Port 1 properties of the Rounded corner iris 3D +Fest3D User Manual +284 +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 +Fest3D User Manual +285 +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. +Fest3D User Manual +286 +Specific properties of the Rounded corner iris 3D EM Field +2.4.2.2 Junctions library +The Junctions library contains the following discontinuities: +Fest3D User Manual +287 +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. +Fest3D User Manual +288 +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: +Fest3D User Manual +289 +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: +Fest3D User Manual +290 +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: +Fest3D User Manual +291 +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. +Fest3D User Manual +292 +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 +Fest3D User Manual +293 +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. +Fest3D User Manual +294 +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 +Fest3D User Manual +295 +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 +Fest3D User Manual +296 +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. +Fest3D User Manual +297 +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. +Fest3D User Manual +298 +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: +Fest3D User Manual +299 +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: +Fest3D User Manual +300 +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 +Fest3D User Manual +301 +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. +Fest3D User Manual +302 +Fest3D User Manual +303 +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. +Fest3D User Manual +304 +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. +Fest3D User Manual +305 +The electromagnetic fields of this discontinuity can be computed and visualized. For this purpose, The EM Field tab +Fest3D User Manual +306 +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 +Fest3D User Manual +307 +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: +Fest3D User Manual +308 +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. +Fest3D User Manual +309 +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. +Fest3D User Manual +310 +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. +Fest3D User Manual +311 +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. +Fest3D User Manual +312 +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. +Fest3D User Manual +313 +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 +Fest3D User Manual +314 +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. +Fest3D User Manual +315 +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. +Fest3D User Manual +316 +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. +Fest3D User Manual +317 +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 +Fest3D User Manual +318 +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. +Fest3D User Manual +319 +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. +Fest3D User Manual +320 +Fest3D User Manual +321 +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. +Fest3D User Manual +322 +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. +Fest3D User Manual +323 +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 +Fest3D User Manual +324 +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 +Fest3D User Manual +325 +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: +Fest3D User Manual +326 +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. +Fest3D User Manual +327 +The Enable/Disable button allows enabling and disabling this element, as described in the Main Window Edit menu. +The following parameters can be edited: +Fest3D User Manual +328 +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. +Fest3D User Manual +329 +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. +Fest3D User Manual +330 +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: +Fest3D User Manual +331 +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. +Fest3D User Manual +332 +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 . +Fest3D User Manual +333 +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- +Fest3D User Manual +334 +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. +Fest3D User Manual +335 +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): +Fest3D User Manual +336 +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. +Fest3D User Manual +337 +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. +Fest3D User Manual +338 +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 +Fest3D User Manual +339 +to manually set a tradeoff value taking into account the dimensions of the cavity under consideration. +Fest3D User Manual +340 +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. +Fest3D User Manual +341 +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. +Fest3D User Manual +342 +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 +Fest3D User Manual +343 +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. +Fest3D User Manual +344 +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 +Fest3D User Manual +345 +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. +Fest3D User Manual +346 +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. +Fest3D User Manual +347 +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. +Fest3D User Manual +348 +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. +Fest3D User Manual +349 +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 +Fest3D User Manual +350 +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. +Fest3D User Manual +351 +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 +Fest3D User Manual +352 +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 +Fest3D User Manual +353 +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 +Fest3D User Manual +354 +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. +Fest3D User Manual +355 +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. +Fest3D User Manual +356 +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. +Fest3D User Manual +357 +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. +Fest3D User Manual +358 +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. +Fest3D User Manual +359 +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. +Fest3D User Manual +360 +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. +Fest3D User Manual +361 +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. +Fest3D User Manual +362 +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. +Fest3D User Manual +363 +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. +Fest3D User Manual +364 +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 +Fest3D User Manual +365 +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. +Fest3D User Manual +366 +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. +Fest3D User Manual +367 +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 +Fest3D User Manual +368 +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. +Fest3D User Manual +369 +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 . +Fest3D User Manual +370 +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 +Fest3D User Manual +371 +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 +Fest3D User Manual +372 +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) +Fest3D User Manual +373 +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: +Fest3D User Manual +374 +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 +Fest3D User Manual +375 +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. +Fest3D User Manual +376 +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) +Fest3D User Manual +377 +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. +Fest3D User Manual +378 +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. +Fest3D User Manual +379 +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 +Fest3D User Manual +380 +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 +Fest3D User Manual +381 +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. +Fest3D User Manual +382 +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 +Fest3D User Manual +383 +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 +Fest3D User Manual +384 +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 +Fest3D User Manual +385 +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 +Fest3D User Manual +386 +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: +Fest3D User Manual +387 +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). +Fest3D User Manual +388 +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. +Fest3D User Manual +389 +Figure E: Port properties of the Straight feed cavity, case of a coaxial port +Fest3D User Manual +390 +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) +Fest3D User Manual +391 +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. +Fest3D User Manual +392 +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 +Fest3D User Manual +393 +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 +Fest3D User Manual +394 +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 +Fest3D User Manual +395 +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 +Fest3D User Manual +396 +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. +Fest3D User Manual +397 +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 +Fest3D User Manual +398 +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: +Fest3D User Manual +399 +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). +Fest3D User Manual +400 +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 +Fest3D User Manual +401 +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. +Fest3D User Manual +402 +Figure E: Port properties of the Mushroom feed cavity, case of a coaxial port +Fest3D User Manual +403 +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) +Fest3D User Manual +404 +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. +Fest3D User Manual +405 +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 +Fest3D User Manual +406 +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. +Fest3D User Manual +407 +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 +Fest3D User Manual +408 +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 +Fest3D User Manual +409 +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 +Fest3D User Manual +410 +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: +Fest3D User Manual +411 +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). +Fest3D User Manual +412 +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 +. +Fest3D User Manual +413 +Figure E: Port properties of the Straight contact feed cavity, case of a coaxial port +Fest3D User Manual +414 +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) +Fest3D User Manual +415 +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. +Fest3D User Manual +416 +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 +Fest3D User Manual +417 +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 +Fest3D User Manual +418 +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 +Fest3D User Manual +419 +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 +Fest3D User Manual +420 +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 +Fest3D User Manual +421 +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: +Fest3D User Manual +422 +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). +Fest3D User Manual +423 +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 +Fest3D User Manual +424 +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 +Fest3D User Manual +425 +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) +Fest3D User Manual +426 +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. +Fest3D User Manual +427 +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 +Fest3D User Manual +428 +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 +Fest3D User Manual +429 +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. +Fest3D User Manual +430 +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 +Fest3D User Manual +431 +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. +Fest3D User Manual +432 +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. +Fest3D User Manual +433 +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 +Fest3D User Manual +434 +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 +Fest3D User Manual +435 +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 +Fest3D User Manual +436 +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: +Fest3D User Manual +437 +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. +Fest3D User Manual +438 +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 +Fest3D User Manual +439 +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 +Fest3D User Manual +440 +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 +Fest3D User Manual +441 +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 +Fest3D User Manual +442 +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. +Fest3D User Manual +443 +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: +Fest3D User Manual +444 +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). +Fest3D User Manual +445 +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. +Fest3D User Manual +446 +Figure E: Port properties of the Magnetic feed cavity, case of a coaxial port +Fest3D User Manual +447 +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) +Fest3D User Manual +448 +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. +Fest3D User Manual +449 +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 +Fest3D User Manual +450 +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 +Fest3D User Manual +451 +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. +Fest3D User Manual +452 +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 +Fest3D User Manual +453 +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 +Fest3D User Manual +454 +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: +Fest3D User Manual +455 +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 . +Fest3D User Manual +456 +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 +. +Fest3D User Manual +457 +Figure E: Port properties of the Top contact feed cavity, case of a coaxial port +Fest3D User Manual +458 +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) +Fest3D User Manual +459 +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. +Fest3D User Manual +460 +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 +Fest3D User Manual +461 +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 +Fest3D User Manual +462 +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. +Fest3D User Manual +463 +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 +Fest3D User Manual +464 +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 +Fest3D User Manual +465 +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. +Fest3D User Manual +466 +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: +Fest3D User Manual +467 +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). +Fest3D User Manual +468 +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. +Fest3D User Manual +469 +Figure E: Port properties of the General cavity, case of a coaxial port +Fest3D User Manual +470 +Figure F: Port properties of the General cavity, case of a second coaxial port with a Mushroom probe +Fest3D User Manual +471 +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) +Fest3D User Manual +472 +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 +Fest3D User Manual +473 +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. +Fest3D User Manual +474 +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 +Fest3D User Manual +475 +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. +Fest3D User Manual +476 +Figure B: Definition of the parameters that describe the helical resonator +Fest3D User Manual +477 +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 +Fest3D User Manual +478 +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 +Fest3D User Manual +479 +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: +Fest3D User Manual +480 +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 . +Fest3D User Manual +481 +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. +Fest3D User Manual +482 +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) +Fest3D User Manual +483 +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. +Fest3D User Manual +484 +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 +Fest3D User Manual +485 +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. +Fest3D User Manual +486 +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 +Fest3D User Manual +487 +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 +Fest3D User Manual +488 +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. +Fest3D User Manual +489 +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 +Fest3D User Manual +490 +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: +Fest3D User Manual +491 +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: +Fest3D User Manual +492 +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 +Fest3D User Manual +493 +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. +Fest3D User Manual +494 +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 +Fest3D User Manual +495 +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. +Fest3D User Manual +496 +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. +Fest3D User Manual +497 +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 +Fest3D User Manual +498 +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. +Fest3D User Manual +499 +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. +Fest3D User Manual +500 +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. +Fest3D User Manual +501 +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. +Fest3D User Manual +502 +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. +Fest3D User Manual +503 +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. +Fest3D User Manual +504 +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 +Fest3D User Manual +505 +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 +Fest3D User Manual +506 +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 +Fest3D User Manual +507 +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. +Fest3D User Manual +508 +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. +Fest3D User Manual +509 +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 +Fest3D User Manual +510 +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. +Fest3D User Manual +511 +Figure G: Port properties of the General rectangular cavity, case of a coaxial port +Fest3D User Manual +512 +Figure H: Port properties of the General rectangular cavity, case of a second coaxial port with a Mushroom probe +Fest3D User Manual +513 +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. +Fest3D User Manual +514 +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. +Fest3D User Manual +515 +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. +Fest3D User Manual +516 +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 +Fest3D User Manual +517 +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: +Fest3D User Manual +518 +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 +Fest3D User Manual +519 +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. +Fest3D User Manual +520 +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 +Fest3D User Manual +521 +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. +Fest3D User Manual +522 +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. +Fest3D User Manual +523 +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 +Fest3D User Manual +524 +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 +Fest3D User Manual +525 +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 +Fest3D User Manual +526 +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. +Fest3D User Manual +527 +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. +Fest3D User Manual +528 +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 +Fest3D User Manual +529 +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. +Fest3D User Manual +530 +Figure G: Port properties of the General cylindrical cavity, case of a coaxial port +Fest3D User Manual +531 +Figure H: Port properties of the General cylindrical cavity, case of a second coaxial port with a S probe +Fest3D User Manual +532 +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. +Fest3D User Manual +533 +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. +Fest3D User Manual +534 +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. +Fest3D User Manual +535 +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 +Fest3D User Manual +536 +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. +Fest3D User Manual +537 +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 +Fest3D User Manual +538 +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 +Fest3D User Manual +539 +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 +Fest3D User Manual +540 +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: +Fest3D User Manual +541 +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 +Fest3D User Manual +542 +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. +Fest3D User Manual +543 +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). +Fest3D User Manual +544 +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. +Fest3D User Manual +545 +Figure A: Cavity dimensions and local reference coordinate system employed +Fest3D User Manual +546 +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 +Fest3D User Manual +547 +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. +Fest3D User Manual +548 +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. +Fest3D User Manual +549 +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 +Fest3D User Manual +550 +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) +Fest3D User Manual +551 +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 +Fest3D User Manual +552 +, 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. +Fest3D User Manual +553 +Figure A: Cavity dimensions and local reference coordinate system employed +Fest3D User Manual +554 +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 +Fest3D User Manual +555 +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. +Fest3D User Manual +556 +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. +Fest3D User Manual +557 +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. +Fest3D User Manual +558 +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) +Fest3D User Manual +559 +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 +Fest3D User Manual +560 +, 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. +Fest3D User Manual +561 +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. +Fest3D User Manual +562 +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. +Fest3D User Manual +563 +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. +Fest3D User Manual +564 +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 +Fest3D User Manual +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: +Fest3D User Manual +566 +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 +Fest3D User Manual +567 +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. +Fest3D User Manual +568 +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. +Fest3D User Manual +569 +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 +Fest3D User Manual +570 +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). +Fest3D User Manual +571 +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 +Fest3D User Manual +572 +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. +Fest3D User Manual +573 +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. +Fest3D User Manual +574 +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: +Fest3D User Manual +575 +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 +Fest3D User Manual +576 +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. +Fest3D User Manual +577 +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. +Fest3D User Manual +578 +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 +Fest3D User Manual +579 +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. +Fest3D User Manual +580 +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. +Fest3D User Manual +581 +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: +Fest3D User Manual +582 +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. +Fest3D User Manual +583 +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. +Fest3D User Manual +584 +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 . +Fest3D User Manual +585 +Figure H: Port properties of the Coaxial T-junction, case of one of the fixed ports (1 and 2) +Fest3D User Manual +586 +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). +Fest3D User Manual +587 +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. +Fest3D User Manual +588 +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. +Fest3D User Manual +589 +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. +Fest3D User Manual +590 +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 +Fest3D User Manual +591 + 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. +Fest3D User Manual +592 +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. +Fest3D User Manual +593 +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 +Fest3D User Manual +594 +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: +Fest3D User Manual +595 +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 +Fest3D User Manual +596 +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. +Fest3D User Manual +597 +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. +Fest3D User Manual +598 +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 +Fest3D User Manual +599 +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). +Fest3D User Manual +600 +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 +Fest3D User Manual +601 +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. +Fest3D User Manual +602 +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. +Fest3D User Manual +603 +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: +Fest3D User Manual +604 +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. +Fest3D User Manual +605 +Figure B: Definition of the geometry of the General bend. Case without curvature radius. +Fest3D User Manual +606 +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 +Fest3D User Manual +607 +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: +Fest3D User Manual +608 +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 . +Fest3D User Manual +609 +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. +Fest3D User Manual +610 +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 +Fest3D User Manual +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 +Fest3D User Manual +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 \Licenses to find the Legal notices web page. Typically this is placed in C:\Program +files (x86)\CST Studio \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 +Fest3D User Manual +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 +Fest3D User Manual +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. +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 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  . 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  +. +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  . +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 + . +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. +Trademarks +icon, +the 3DS +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. +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. +Spark3D User Manual +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. +Spark3D User Manual +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. +Spark3D User Manual +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. +Spark3D User Manual +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: +Spark3D User Manual +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. +Spark3D User Manual +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 +Spark3D User Manual +10 +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. +Spark3D User Manual +11 +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. +Spark3D User Manual +12 +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. +Spark3D User Manual +13 +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 +Spark3D User Manual +14 +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. +Spark3D User Manual +16 +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. +Spark3D User Manual +17 +The simulation starts now and in the main window, the results window is opened so you can see the output in run- +time. +Spark3D User Manual +18 +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. +Spark3D User Manual +19 +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. +Spark3D User Manual +20 +Video Corona configuration window will be opened. +Spark3D User Manual +21 +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. +Spark3D User Manual +22 +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. +Spark3D User Manual +23 +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. +Spark3D User Manual +24 +Spark3D User Manual +25 +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 +Spark3D User Manual +26 +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. +Spark3D User Manual +27 +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 +Spark3D User Manual +28 +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. +Spark3D User Manual +29 +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. +Spark3D User Manual +30 +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: +Spark3D User Manual +31 +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. +Spark3D User Manual +32 +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. +Spark3D User Manual +33 +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. +Spark3D User Manual +34 +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 +Spark3D User Manual +35 +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. +Spark3D User Manual +36 +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. +Spark3D User Manual +37 +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. +Spark3D User Manual +38 +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. +Spark3D User Manual +39 +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. +Spark3D User Manual +40 +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 +Spark3D User Manual +41 +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. +Spark3D User Manual +42 +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". +Spark3D User Manual +43 + Multipactor configuration window will be opened. +Spark3D User Manual +44 +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. +Spark3D User Manual +45 +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. +Spark3D User Manual +46 +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. +Spark3D User Manual +47 +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. +Spark3D User Manual +48 + 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 +Spark3D User Manual +49 +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. +Spark3D User Manual +50 + Video can be exported using File -> Save Animation... The video size, duration and format can be chosen. +Spark3D User Manual +51 +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 +Spark3D User Manual +52 +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. +Spark3D User Manual +53 +Spark3D User Manual +54 +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: +Spark3D User Manual +55 +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. +Spark3D User Manual +56 +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. +Spark3D User Manual +57 +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, +Spark3D User Manual +58 +By doing so, the Import Window pops up asking for the mesh file with the EM field to be imported. +Spark3D User Manual +59 +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. +Spark3D User Manual +60 +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. +Spark3D User Manual +61 +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. +Spark3D User Manual +62 +This action will open the Analysis Regions Window, where the dimensions and position of the newly created region +can be defined. +Spark3D User Manual +63 +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, +Spark3D User Manual +64 +Once the region dimensions and position in the Analysis Regions Window have been set, you can visualize all regions +by clicking the Visualize button. +Spark3D User Manual +65 +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. +Spark3D User Manual +66 +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. +Spark3D User Manual +67 +Spark3D User Manual +68 +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. +Spark3D User Manual +69 +Spark3D User Manual +70 +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. +Spark3D User Manual +71 +Spark3D User Manual +72 +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. +Spark3D User Manual +73 +Spark3D User Manual +74 +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). +Spark3D User Manual +75 +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. +Spark3D User Manual +76 +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, +Spark3D User Manual +77 +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 +Spark3D User Manual +78 +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. +Spark3D User Manual +79 +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. +Spark3D User Manual +80 +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. +Spark3D User Manual +81 +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. +Spark3D User Manual +82 +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: +Spark3D User Manual +83 + 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. +Spark3D User Manual +84 +A Paraview window is opened, showing the materials of the imported mesh, with different colors assigned to each +one of them. +Spark3D User Manual +85 +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, +Spark3D User Manual +86 +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. +Spark3D User Manual +87 +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) +Spark3D User Manual +88 +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 +Spark3D User Manual +89 +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. +Spark3D User Manual +90 +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: +Spark3D User Manual +91 +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 +Spark3D User Manual +92 +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= (--config | --validate | -- +To work with *.spkx project as input file for Spark3D +list) [(--importDC= --fileTypeDC= -- +fieldTypeDC=)] [--output=] +spark3d.exe (--XMLfile= --importRF=) (-- +To work with *.xml and RF import files as input for Spark3D +validate | --list | (--config --projectName=) | (- +-generateProject --projectName=)) [(--importDC= + --fileTypeDC= --fieldTypeDC=)] [- +-output=] +To better understand the syntax of the usage patterns, next we analyze one of them: +spark3d.exe --input= (--config | --validate | --list) [(--importDC= --fileTypeDC= -- +fieldTypeDC=)] [--output=] +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 +Spark3D User Manual +93 +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 +Spark3D User Manual +94 +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 .spk file, Spark3D will automatically export it to the newest version as .spkx. The simulation results will be stored in the +new .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="\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\" +Spark3D User Manual +95 +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, 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, entity includes both a + entity and a property , whose tags are nested as shown below: + + <...> + {TUTORIAL_EXAMPLE.spkx} + + <...> + + +Elements that correspond to properties contain text between their tags which correspond to the value of the property they represent. For example, in +{TUTORIAL_EXAMPLE.spkx}, 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: +, , , , , , +, +Spark3D User Manual +96 +How to add or change a new region +Region entity is defined by the tags . As an entity belonging to , their tags should be nested. In the +same way, region properties are enclosed between region tags as shown below: + + <...> + + {RectangularRegion 2} + 2 + 0 + (0;0;0) + (0.01;0.01;0.01) + + <...> + +Values of highlighted properties may be modified by the user. In the following table a description of each property is given: +Property + +Type: user defined string of characters. +Description: User region name. It should not be repeated in other regions within the same Model. + +Type: integer. +Description: Region identification number. It should not be repeated in other regions within the same Model. + 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. + +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 section as the one shown above, changing at least both and +property values. +2. It is mandatory that for every new region added to a Model you create a new entity inside + 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. + + <...> + + <...> + + <...> + + {MeshConfigSpark 2} + 2 + {RectangularRegion 2} + + {FieldConfigCollection 1} + 1 + {MC 1} + + + {FieldConfigSingleSPARK 1} + 2 + {CW 6} + + + {FieldConfigSingleSPARK 2} + 3 + {CW 4} + + + <...> + + + +3. Values of and properties of should not be repeated in other which lie in the same scope. +4. The property should match value of the Region previously added. +5. For each existing signal in should have an entity associated to one signal. Depending on the type of signal, you should add: + related to continuous wave single carrier signals. + corresponding to multicarrier signals. +For both entities, values of and properties should not be repeated in the same scope. Property +must have the value of of the signal associated to it. +Spark3D User Manual +97 +How to add or change a multicarrier signal +Multicarrier signal is an entity of Model defined by the tags . As an entity belonging to , their tags +should be nested. Multicarrier element is defined by some properties and also its own entities, . Each 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. + + <...> + + {MC 1} + 1 + + {CW 4} + 0 + 1 + + + {CW 6} + 0 + 1 + + + <...> + +Values of highlighted properties may be modified by the user. In the following table a description of each property is given: +Property + +Type: user defined string of characters. +Description: User signal name. It should not be repeated in other signals within the same Model. + +Type: integer +Description: Signal identification number. It should not be repeated in other signals within the same Model. + 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. + Type: real number +Description: Corresponds to the phase in degrees associated by the user to the single carrier selected in . + Type: real number +Description: Corresponds to the power in wats associated by the user to the single carrier selected in . +In order to add a new multicarrier to Model: +1. You should include between Model tags a new whole section as the one shown above, changing at least both and +property values. +2. It is mandatory that for every new multicarrier signal added to a Model you create a new entity + associated to it within two different entities: + + and properties of should not be repeated in other +4. Property should match value of the multicarrier associated to it. + + <...> + + <...> + + <...> + + {MeshConfigImported 1} + 1 + {Circuit} + + {FieldConfigCollection 1} + 1 + {MC 1} + + <...> + + + {MeshConfigSpark 2} + 2 + {RectangularRegion 2} + + {FieldConfigCollection 1} + 1 +Spark3D User Manual +98 + {MC 1} + + <...> + + <...> + + + +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 . As a entity, their tags are nested as shown below. +Corona configuration is defined by some properties and the entity, , which determines pressure values where Corona analysis will +be done. + + <...> + + + <...> + + {CoronaConfig 1} + 1 + (({MeshConfigImported 1},({ImportRFField 1}))) + 100 + userdefined + 293 + 0.10000000000000001 + air + numeric_high_pressure + <...> + + {PressureSweep 1} + 1 + SWEEP_STEP + 1 + 6 + 1 + 6 + () + + + + + +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 + +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. + +Type: integer +Description: Corona configuration identification number. It should not be repeated in other Corona configurations within the same +Model. + +Type: vector(mesh configuration , vector(field configuration )) of strings of characters +Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the + of region and signal entities, you should include the 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 1} + 1 + {Circuit} + + {FieldConfigMulti 1} + 1 + {MC 1} + + + {ImportRFMesh 1} + 1 +Spark3D User Manual +99 + {ExportToSPARK3D(1).f3e} + CST + + {ImportRFField 1} + 1 + {CW 6} + + <...> + + +For a user defined region: + + {MeshConfigSingleSPARK 2} + 2 + {RectangularRegion 1} + + {FieldConfigMulti 2} + 1 + {MC 1} + + + {FieldConfigSingleSPARK 1} + 3 + {CW 6} + + <...> + + +Type: real number + 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 will be used as starting point +"automatic": the initial value is taken automatically from the high pressure analytical approach. + +Type: real number +Description: Corresponds to the ambient temperature (in Kelvin). + +Type: real number + +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" + +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. + + +Description: Represents the pressure value at which the sweep will start. + + +Description: Represents the pressure value at which the sweep will finish. + + +Description: Represents the step in pressure for the sweep. +Spark3D User Manual +100 +In order to add a new Corona configuration to Model you should include between Model tags a new whole section as the one shown above, +changing at least both and 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 . As an entity belonging to , their +tags are nested as shown below. Multipactor configuration is defined by some properties and the entity, , 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. + + <...> + + + <...> + + {MultipactorConfig 1} + 1 + (({MeshConfigImported 1},({ImportRFField 1}))) + () + () + () + () + 300 + 500 + 0.10000000000000001 + 1000000 + default + 10 + silver + Vaughan + 2.2200000000000002 + 30 + 0.5 + 165 + () + () + () + {} + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 1 + 0 + 1 + 0 + 10 + bisection + <...> + + {SweepUtil 1} + 1 + SWEEP_LIST + 9.9999999999999995e-07 + 9.9999999999999995e-07 + 0 + 1 + (500) + + + + + +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 + +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. + +Type: integer +Description: Multipactor configuration identification number. It should not be repeated in other Multipactor configurations within the +same Model. + +Type: vector(mesh configuration , vector(field configuration )) of strings of characters +Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the + of region and signal entities, you should include the of the mesh and field configurations associated to them (shown +Spark3D User Manual +101 +in red below). +This information is located in the following sections. +For Circuit region: + + {MeshConfigImported 1} + 1 + {Circuit} + + {FieldConfigMulti 1} + 1 + {MC 1} + + + {ImportRFMesh 1} + 1 + {ExportToSPARK3D(1).f3e} + CST + + {ImportRFField 1} + 1 + {CW 6} + + <...> + + +For a user defined region: + + {MeshConfigSingleSPARK 2} + 2 + {RectangularRegion 1} + + {FieldConfigMulti 2} + 1 + {MC 1} + + + {FieldConfigSingleSPARK 1} + 3 + {CW 6} + + <...> + + +Type: vector(DC_field) +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. + +Type: vector(DC_field) +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. + +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 . + +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 . + +Description: Number of electrons at the beginning of the simulation. + +Type: real number +Description: Starting power (W) used in the automatic multipactor breakdown search. +Spark3D User Manual +102 + +Type: real number +Description: Sets the desired precision in power level (in dB) for the automatic multipactor breakdown search. + +Type: real number +Description: Maximum simulation power allowed in the automatic multipactor breakdown search. + +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. + +Description: If the previous parameter is set to charge_min, this specifies the growth factor for considering multipactor. + +Type: user defined string of characters +Description: Arbitrary name that the user may set to the defined material. + +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 + +Description: If is set to Vaughan: +This parameter specifies the maximum value of the SEY curve. + +Description: If is set to Vaughan: +This parameter specifies the first cross-over energy of the SEY curve (lowest energy at which SEY = 1). + is set to Vaughan: +LowCrossover> +This parameter specifies the value of the SEY curve at low energies below the first cross-over energy. + +Description: If 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. + +Type: vector(real number) +Description: If is set to fromFile: +Vector of real numbers with the energy values of the SEY curve. +, and must have the same length + +Type: vector(real number) +Description: If is set to fromFile: +Vector of real numbers with the value of the SEY coming from ellastically reflected electrons. +, and must have the same length + +Type: vector(real number) +Description: If is set to fromFile: +Vector of real numbers with value of the SEY coming from true secondary electrons. +, and must have the same length + +Type: user defined string of characters +Description: Name of file from which the above curves where imported. It is only an informative field. + +Type: integer +Description: Can be 0 (false) or 1 (true). +If true, an external uniform DC magnetic field is added to the simulation. +Spark3D User Manual +103 + +Type: real number +Description: if is true, this parameter is the x-component of the external uniform DC magnetic field. + +Type: real number +Description: if is true, this parameter is the y-component of the external uniform DC magnetic field. + +Type: real number +Description: if is true, this parameter is the z-component of the external uniform DC magnetic field. + +Type: integer +Description: Can be 0 (false) or 1 (true). +If true, an external uniform DC electric field is added to the simulation. + +Type: real number +Description: if is true, this parameter is the x-component of the external uniform DC electric field. + +Type: real number +Description: if is true, this parameter is the y-component of the external uniform DC electric field + +Type: real number +Description: if is true, this parameter is the z-component of the external uniform DC electric field + +Description: It is the path integration error for the adaptive electron tracking step given in %. The lower the more precise (but slower) + 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. + +Type: integer +Description: Can be 0 (false) or 1 (true). +If true, extra 3D statistic files are stored in the simulation. + +Type: integer +Description: if is set to custom +Can be 0 (false) or 1 (true). +If true, multipactor simulation won't stop until is reached. +If false, the selected will be used. + +Type: real number +Description: if is set to custom and is set to true +This value specifies the maximum simulation time. + +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. + + + + +Type: nteger +Description: if is set to custom +This is the number of points in the custom power list. +Type: vector(real number) +Description: if is set to custom +This vector contains the values of the custom power loop. Its size must be equal to +How to add or change a video Corona configuration +Video Corona configuration is an entity of Corona Configuration defined by the tags . As a +configuration entity, their tags are nested as shown below. + + <...> + + {VideoCoronaConfig 1} + 1 + (({MeshConfigImported 1},({ImportRFField 1}))) +Spark3D User Manual +104 + 15 + 100 + 0 + densMax + 1000 + 1 + 1 + high + + <...> + +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 + +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. + +Type: integer +Description: Video Corona configuration identification number. It should not be repeated in other video Corona configurations within the +same Corona configuration. + +Type: vector(mesh configuration , vector(field configuration )) of strings of characters +Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the of +region and signal entities, you should include the 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 1} + 1 + {Circuit} + + {FieldConfigMulti 1} + 1 + {MC 1} + + + {ImportRFMesh 1} + 1 + {ExportToSPARK3D(1).f3e} + CST + + {ImportRFField 1} + 1 + {CW 6} + + <...> + + +For a user defined region: + + {MeshConfigSingleSPARK 2} + 2 + {RectangularRegion 1} + + {FieldConfigMulti 2} + 1 + {MC 1} + + + {FieldConfigSingleSPARK 1} + 3 + {CW 6} +Spark3D User Manual +105 + + <...> + +Just one pair of mesh and field configurations should be selected. + Type: integer +Description: Specifies the frame rate of the recording. The higher, the smoother the animation, but bigger video sizes will be generated. + +Type: real number +Description: Sets the input power (in W) for this specific video recording. + +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". + Type: real number +Description: Sets the maximum value of the computed electron density in the last frame of the video. + +Type: real number +Description: Sets the maximum time where the electron density time evolution will be calculated. + +Type: real number +Description: Sets the pressure value (in mbar) for this specific video recording. + +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 section as the one shown above, +changing at least both and 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 . As a + configuration entity, their tags are nested as shown below. + + <...> + + {VideoMultipactorConfig 1} + 1 + (({MeshConfigImported 1},({ImportRFField 1}))) + 15 + 100 + 0 + 10 + + <...> + +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 + +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. + +Type: integer +Description: Video Multipactor configuration identification number. It should not be repeated in other video Multipactor configurations +within the same Multipactor configuration. + +Type: vector(mesh configuration , vector(field configuration )) of strings of characters +Description: Corresponds to the selection of regions and signals where the simulation is performed. Instead of working with the of +region and signal entities, you should include the 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 1} + 1 + {Circuit} + + {FieldConfigMulti 1} +Spark3D User Manual +106 + 1 + {MC 1} + + + {ImportRFMesh 1} + 1 + {ExportToSPARK3D(1).f3e} + CST + + {ImportRFField 1} + 1 + {CW 6} + + <...> + + +For a user defined region: + + {MeshConfigSingleSPARK 2} + 2 + {RectangularRegion 1} + + {FieldConfigMulti 2} + 1 + {MC 1} + + + {FieldConfigSingleSPARK 1} + 3 + {CW 6} + + <...> + +Just one pair of mesh and field configurations should be selected. + Type: integer +Description: Specifies the frame rate of the recording. The higher the smoother the animation, but bigger video sizes will be generated. + +Type: real number +Description: Sets the input power (in W) for this specific video recording. + +Type: real number +Description: Sets the initial time (in ns) for video recording. + +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 section as the one +shown above, changing at least both and 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: +Spark3D User Manual +107 +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. +Spark3D User Manual +108 +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 +Spark3D User Manual +109 +A new Multipactor configuration item will appear in the tree in the framework of the Multipactor Configuration Group. +Spark3D User Manual +110 +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. +Spark3D User Manual +111 +Configuration window +The configuration window allows setting the multipactor simulation parameters. +Spark3D User Manual +112 +Fields +Spark3D User Manual +113 +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 +Spark3D User Manual +114 +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. +Spark3D User Manual +115 +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 +Spark3D User Manual +116 +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 +Spark3D User Manual +117 +(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 +Spark3D User Manual +118 +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 +Spark3D User Manual +119 +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. +Spark3D User Manual +120 +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 +Spark3D User Manual +121 +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 +Spark3D User Manual +122 +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: +Spark3D User Manual +123 +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. +Spark3D User Manual +124 +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. +Spark3D User Manual +125 +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 +Spark3D User Manual +126 +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 +Spark3D User Manual +127 +A new Multipactor video configuration item will appear in the tree in the framework of the Multipactor Configuration. +Spark3D User Manual +128 +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. +Spark3D User Manual +129 +Video Configuration +The video Configuration window is the following +Spark3D User Manual +130 +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. +Spark3D User Manual +131 +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. +Spark3D User Manual +132 +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 . +Spark3D User Manual +133 +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). +Spark3D User Manual +134 +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. +Spark3D User Manual +135 +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. +Spark3D User Manual +136 +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 +Spark3D User Manual +137 +A new Corona configuration item will appear in the tree in the framework of the Corona Configuration Group. +Spark3D User Manual +138 +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. +Spark3D User Manual +139 +Corona configuration window +It looks like this: +Spark3D User Manual +140 +Fields +Spark3D User Manual +141 +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 +Spark3D User Manual +142 +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 +Spark3D User Manual +143 +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 +Spark3D User Manual +144 +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 +Spark3D User Manual +145 +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); +Spark3D User Manual +146 +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 +Spark3D User Manual +147 +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. +Spark3D User Manual +148 +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: +Spark3D User Manual +149 +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 +Spark3D User Manual +150 +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 +Spark3D User Manual +151 +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 +Spark3D User Manual +152 +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 +Spark3D User Manual +153 +A new Corona video configuration item will appear in the tree in the framework of the Corona Configuration. +Spark3D User Manual +154 +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. +Spark3D User Manual +155 +Corona video configuration window +It looks like this +Spark3D User Manual +156 + 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 \Licenses to find the Legal notices web page. Typically this is placed in C:\Program +files (x86)\CST Studio \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. +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 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 ) 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. +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 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, +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 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 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 \ No newline at end of file