Standards related to:

GB/T 5597-1999**GB/T 5597-1999: PDF in English (GBT 5597-1999) **

GB/T 5597-1999

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

ICS 31.030

L 90

Replacing GB/T 5597-1985

Test Method for Complex Permittivity of Solid Dielectric

Materials at Microwave Frequencies

ISSUED ON: MAY 19, 1999

IMPLEMENTED ON: DECEMBER 01, 1999

Issued by: The Quality and Technology Supervision Bureau

Table of Contents

Foreword ... 3

1 Scope ... 4

2 Definition ... 4

3 Principle of Test ... 4

4 Test Environment Conditions ... 5

5 Instruments and devices ... 5

6 Specimen Sizes and Requirements ... 7

7 Test Procedure ... 8

8 Calculation of Results ... 9

9 Test Error ... 11

Appendix A (Prompted) Schematic Diagram of Dielectric Test Cavity Structure ... 12

Appendix B (Prompted) Test Errors and Selection of Sample Thickness ... 13

Appendix C (Prompted) Schedule ... 16

Test Method for Complex Permittivity of Solid Dielectric

Materials at Microwave Frequencies

1 Scope

This Standard specifies the test method for the microwave complex permittivity of

homogeneous and isotropic solid dielectric materials.

This Standard applies to the determination of the complex dielectric constant within the

frequency range of 2 GHz ~ 18 GHz. The recommended test frequency is 9.5 GHz. Its

measurement range: the real part of the relative permittivity ε' is 2 ~ 20, and the dielectric loss

tangent tanδε is 1×10-4 ~ 5×10-3.

2 Definition

The complex permittivity εሶ is as follows:

Where:

εr - complex relative permittivity;

ε0 - vacuum permittivity, its value is 8.854×10-12F/m.

The complex permittivity mentioned in this Standard actually refers to the relative permittivity,

and is characterized by the real part of the relative permittivity ε' and the dielectric loss tangent

tanδε=ε"/ε'.

3 Principle of Test

At a certain frequency, the resonant length of the cylindrical TE0 01n mode high-quality factor test

cavity is lo, and the inherent quality factor is Qoe, as shown in Figure 1(a). When a disk-shaped

sample with a thickness d is placed in the test cavity, as shown in Figure 1(b), two changes will

occur: (1) since the dielectric constant ε of the dielectric sample is greater than 1, the phase

constant of the section of the waveguide filled with the sample medium will increase; and the

length of the resonant cavity at the original frequency will be shortened to ls; (2) since the

dielectric sample will introduce additional dielectric loss, the inherent quality factor of the test

Voltage resolution is 1µV, 4 ଵଶ digits of reading.

5.6 Crystal detector

Non-modulated broadband crystal detector.

5.7 Isolator

The isolation ratio is superior than 20 dB; and the forward and reverse standing-wave-ratio

coefficients are less than 1.20.

6 Specimen Sizes and Requirements

6.1 Sample diameter Ds

Where:

R – radius of test cavity, in mm;

δ – The amount related to the size of the test cavity is recommended to be 1.5 mm in the test

cavity with the recommended test frequency.

6.2 Sample thickness d

The principle of selecting the sample thickness d is to take its electrical length at about 85° to

improve the test sensitivity and reduce the test error. When the dielectric constant ε of the

material to be tested is roughly known, the sample thickness can be calculated according to the

following Formula.

Where:

fo – test frequency, namely, the resonant frequency of the test cavity, in GHz;

R - radius of test cavity, in mm;

d – sample thickness, in mm.

Selection of sample thickness can refer to Appendix B (prompted).

6.3 Sample requirements

The non-parallelism of the two main planes of the disc-shaped sample is no more than 0.01 mm;

and the non-straightness of the two main planes is no more than 0.01 mm.

There shall be no abnormal spots and scratches on the surface of the sample, and no abnormal

impurities and pores inside; it shall be strictly cleaned and dried before testing.

7 Test Procedure

7.1 Measurement of empty test cavity

7.1.1 Turn on the machine and warm up for 15 minutes to make the system work normally.

7.1.2 Set the signal source to output the continuous wave frequency at the test frequency fo,

adjust the precision graduated attenuator within the range of 9.0 dB~9.8 dB; adjust the output

level of the signal source; and make the crystal detector output can read the indication number

α0 of about 10 mV on the digital voltmeter; and record the attenuation amount A1 of the precision

graduated attenuator at this time.

7.1.3 Adjust the medium test chamber. The test cavity has been adjusted to the resonance point

determined by the digital voltmeter indicating that has dropped to the lowest point. The

frequency of the resonance point is fo. Record the piston position scale lo and resonance

frequency fo of the dielectric test cavity. At this time, the reading on the digital voltmeter is αr.

7.1.4 Adjust the precision graduated attenuator (decrease the attenuation), so that the reading

on the digital voltmeter rises from αr to return and rise to α0; record the attenuation A2 of the

precision graduated attenuator at this time, then the attenuation introduced by the dielectric test

cavity introduced at the resonance point is Aoe=A1-A2 in decibels.

7.1.5 Calculate the attenuation Ahe at the "half power point" of the resonance curve according

to Formula (4); and set the precision graduated attenuator at Ahe+A2. At this time, the reading

on the digital voltmeter is α'r, α'r< α0.

7.1.6 Fine-tune the frequency of the signal source. On both sides of the resonant frequency fo,

adjust the reading of the digital voltmeter to return to α0, and record the two frequencies f1 and

f2. Calculate Δfe=f2 - f1.

7.2 Measurement of the test cavity after placing the sample

7.2.1 Use the same exact procedure as in 7.1 to measure the piston position scale ls at the original

frequency fo, the resonance point attenuation Aos, the half power point attenuation Ahs and the

Where:

Δfo - resonant frequency test error;

ΔR - machining accuracy of test cavity radius;

ΔS1 - the error introduced by the micrometer precision of the cavity when measuring S;

Δf'o - the deviation of the tuning of the test cavity between two tests before and after being

placed in the dielectric. It is determined by experimental statistics;

Δd - the measurement error of the thickness of the dielectric sample;

Δ(Δf)s - after the sample is loaded into the test cavity, measure the error of the bandwidth at the

“half power” point of the test cavity. Determined by experimental statistics;

Δ(Δf)e – measure the error in frequency width of the “half power” point of the test cavity without

a sample, determined by experimental statistics;

ΔA11 – measure the error of attenuation A1 introduced by the accuracy of the attenuator;

ΔA21s - after the sample is loaded into the test cavity, measure the error of the attenuation A2

introduced by the accuracy of the attenuator;

ΔA21e - when no sample is loaded in the test cavity, the error of the attenuation A2 introduced

by the accuracy of the attenuator;

In order to achieve:

The above accuracy, the following requirements shall be met in the test:

......

Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.