OPERATION MANUALFP Series Fabry-Perot resonator

EM LABS INC.
Aug 20, 2023

Contents
1.

Product Overview.............................................................................................................2
Appearance and structure of resonator ................................................................................2
Product Specifications .........................................................................................................3
Accessories ...........................................................................................................................32.

Measurement....................................................................................................................4Sample Preparation..............................................................................................................4
About sample size .............................................................................................................4
Measurement of sample thickness ....................................................................................5
Before starting measurement ...............................................................................................6
Instrument connection .....................................................................................................6
For accurate measurements ..............................................................................................7
Measurement Procedure ..................................................................................................73.

Maintenance and Repairs .................................................................................................8Health check with stable samples.........................................................................................8Daily cleaning ......................................................................................................................8If you think something is wrong...........................................................................................8Repair ...................................................................................................................................8Appendix 1. Chart: Relation between Sample Thickness and Dielectric Constant .....................9Appendix2. Sample Plates for the Broadband Model ..............................................................10Guided plates....................................................................................................................10Plates without guide .......................................................................................................10First edition: September 1, 2022
2nd edition: April 14, 2023
3rd edition: June 2, 2023
4th edition: August 20, 2023

1

1. Product Overview
This section provides an overview of the product.
FP Series Fabry-Perot resonators are designed to be connected to a network analyzer andmeasure complex relative permittivity of dielectric materials. To accurately measure low
permittivity and low loss materials, the loss of the resonator is designed and manufactured
extremely low. You can efficiently measure samples with the instructions of the permittivity
measurement software, which enables automatic measurement to obtain the frequency
characteristics within a band.
Appearance and structure of resonator(Refer to the FP-MA operation manual for the operation of each part.)

Cover: Set on the resonator body during measurement.
Sample Plates: Set the sample between two sample plates.
Sample holder: Insert the sample plates into the sample holder.
Waveguide connector: Connect to the network analyzer.
Adjustment micrometer: Use to adjust the position of the sample holder after sample
insertion.
Handle: hold the handle when lifting the resonator body.

2CAUTION

1. When lifting the resonator body, be sure to hold the handle.
Holding the waveguide connector may damage the resonator.
2. Treat the sample plates carefully. Bending due to external pressure
may cause measurement errors.

Product Specifications
model

Resonance characteristics
Frequency*Connector

ModeUn-loaded Q

TEM>100,000type

FP-BB

Broadband (25-110 GHz)

1mm(f)

FP-E

E-band (60-90 GHz)

WR12

FP-W

W-band (75-110 GHz)

WR10

FP-D

D-band (110-170 GHz)

WR 6.5

FP-G

G-band (140-220 GHz)

WR 5.1

FP-J

J-band (220-330 GHz)

WR 3.4*Permittivity is measured at approximately every 2.5 GHz.
Operating temperature : 10 to 40℃ (non-condensing)Accessories
FP-TB waveguide connection tables and clamps (2 each ): Accessories required for waveguide connection
Appropriate cables are required depending on the network analyzer. For the E/W band coaxial
cable connection, coaxial-waveguide adapters are required.

3

2. Measurement
This section describes what you need to know about how to proceed with the measurement,
focusing on precautions for handling the resonator and samples to ensure correct
measurements.
Sample PreparationThe sample must be processed into a plate shape to fit the resonator. Since the thicknessof the sample is used to calculate permittivity, it is important to know the accurate thickness.
Ideally, the sample should be flat and uniform in order to accurately determine the thickness.
Also, a wavy sample can cause significant errors in the permittivity measurement results.
Proper sample preparation is the first step for accurate measurements.
About sample size
It is important to prepare samples of the appropriate thickness for accurate measurements.
The appropriate thickness depends on the dielectric properties and the resonator used, but
100 μm is a good rule of thumb. The higher the frequency and the higher the dielectric
constant, the thinner the sample needs to be.
Refer to Appendix 1 for the relationship between thickness, dielectric constant andmeasurement frequency band. Note that thinner samples may be required for samples withhigh loss (tanδ>0.01).
The recommended sample size is shown in the table below. Larger sample will not fit into
the sample plates. Smaller sample will not adequately cover the measurement area, resulting
in measurement errors. (See "Sample Plate Shape" below.)

Recommended sample size

Broadband model: 65 mm square on each side
Other models: 50 mm square on each side

Note that it is possible to evaluate anisotropy by using a square sample. As a vertical electricfield in the resonator is used to measure the permittivity, anisotropy can be evaluated byrotating the sample by 90 degrees. It is recommended to mark the sample so that its
orientation can be identified.

4

Measurement of sample thickness
In the measurement procedure, you need to input the sample thickness according to themeasurement software instruction. It is recommended to measure the sample thickness inadvance. Since the error of the input value causes the error of the permittivity measurement,
accurate measurement is necessary.
Although it depends on the processing conditions of the sample, it is generally recommended
to measure about five locations with a micrometer, etc. and use the average value. It is
important to measure the thickness of the area used for the measurement. Refer to the sample
plate shape below for the specific location of the part to be used.
Sample plate shape

FP-BB(High/Low)

FP-BB(High only)

FP-E/W/D/G/J

r30 ㎜

22.5 ㎜21.5 mm

h39 ㎜

25.0 mmd107 ㎜63.0 mm

w94 ㎜

55.0 mm

Two types of sample plates for FP-BB are provided, one with a guide and the other without
a guide. When using the sample plates with guide, the sample should be processed 6 mm
smaller than the width (w) so that it fits into the sample plates.
NOTE
Refer to the Appendix for details on the use of sample plates for FP-BBwith/without guide.

5

Before starting measurement
Before starting the measurement software, make sure that the following preparation has beencompleted.
・ The temperature of the resonator should be stable. It is recommended to startmeasurement at least 60 minutes after setting the fixture in the actual measurement
environment.
・ The network analyzer should be sufficiently warmed up (in accordance with therecommended time for each network analyzer).
・ The size of the sample must be measured and recorded.
・ A torque wrench and spanner for connector connection must be prepared if coaxial cables
are used. Tweezers and gloves for handling samples are prepared, if necessary.
Instrument connection
Connect the resonator to the network analyzer with a waveguide/cable. The connector typevaries depending on the frequency band. The connector type is described in the productspecifications.
Connecting waveguide connectors

1. Align the height of the connector between the resonator and the waveguide. (Usethe waveguide connection tables for millimeter wave modules.)2. Connect the connectors.
3. Clamp them and tighten the knobs firmly by hand.
Connecting coaxial connectors
Connect the resonator to the network analyzer using appropriate cables.

NOTE

It is important to use a torque wrench to apply proper torque whentightening the connector. Excessive torque can damage the connector.
Torque shortage causes measurement errors and rotation of the center
6

conductor, which can damage the connector. Also, be careful to rotate
only the nut of the male connector. Rotating the center conductor
leads to wear and damage of the connector.

For accurate measurements
The Fabry-Perot resonator is designed and manufactured to measure permittivity with highaccuracy. There are some key points in order to make full use of its performance.

About the CoverKeep the dedicated cover on the fixture except when loading and unloading samples. This willstabilize the measured values.

Vibration
Be careful not to touch the resonator, millimeter-wave modules, or cables during
measurement sweep. Vibration or mechanical stress may affect the measured values. It is notnecessary to use a vibration isolator.

Measurement Procedure
Start the FP-MA software and follow the on-screen instructions to perform the measurement.
Refer to the FP-MA software manual for detailed instructions.

73. Maintenance and Repairs
This section explains daily maintenance and simple troubleshooting.
Health check with stable samples
It is recommended to periodically measure samples with stable characteristics and check thecondition of the measurement system.
Daily cleaning
The Fabry-Perot resonator is basically maintenance free. If the sample plates becomecontaminated due to transfer from the sample etc., wipe them clean with a non-woven clothwith a small amount of alcohol.

NOTE

Do not disassemble the fixture for cleaning as it may cause malfunction.
Especially, do not touch the inside of the resonator. Performance may
deteriorate greatly.
If you think something is wrong...
This section describes how to respond to abnormal measurement values. First, check that theconnectors are firmly connected. Clean the surface of the sample insertion spaceaccording to Daily cleaning. If the problem persists, repair is necessary.
RepairPlease contact us directly through our Web site for repair.
https://www.emlabs.jp

8Appendix 1. Chart: Relation between Sample Thickness and Dielectric Constant

The relationship between the sample thickness, dielectric constant, and frequency band isshown in the charts below. The maximum sample thickness that can be measured correctly
throughout the entire measurement frequency band of each device is shown in the chart.

9Appendix2. Sample Plates for the Broadband Model

Use accordingly based on the following characteristics.
NOTEBe very careful that the sample does not slide off the sample plates andinto the sample holder. If a sample falls into the sample holder, it may
not be removed. In this case, the repair will be required.

Guided plates
Basically, use this sample plates. Guides on the sample plates prevent the sample from slipping
off.
Plates without guide
The above guides may get in the way of placing thin film samples flat on the sample plates.
Use the plates without guide in such cases. The bottom edges of the sample plates may besecured together with thin tape.

10