This standard specifies the test method for the microwave complex dielectric constant of uniform, isotropic solid dielectric materials. This standard is applicable to the determination of the complex dielectric constant within the frequency range of 2GHz~18GHz. GB/T 5597-1999 Test method for microwave complex dielectric constant of solid dielectric materials GB/T5597-1999 Standard download decompression password: www.bzxz.net

1 Scope
National Standard of the People's Republic of China
Test method for complex permittivity of soliddielectric materials at microwave frequenciesGB/T5597-1999
Replaces GB/T5597--1985
This standard specifies the test method for the microwave complex permittivity of uniform and isotropic solid dielectric materials. This standard is applicable to the determination of complex permittivity within the frequency range of 2 GHz to 18 GHz. The recommended test frequency is 9.5 GHz. The measurement range is: the real part of the relative dielectric constant is 2 to 20, and the dielectric loss tangent tano. is 1×10-4 to 5×10-3. 2 Definition
The complex dielectric constant e is:
=·E,=('-je\)
Where: e—complex relative dielectric constant;
—vacuum dielectric constant, its value is 8.854×10-12F/m. (1)
The complex dielectric constants mentioned in this standard actually refer to the relative dielectric constant, and are characterized by the real part of the relative dielectric constant = and the dielectric loss tangent tand,=e\/e.
3 Test principle Www.bzxZ.net
The resonant length of the cylindrical TE% mode high quality factor test cavity at a certain frequency is l. , and the inherent quality factor is Q, as shown in Figure 1(a). When a disk-shaped sample with a thickness of 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 waveguide filled with the sample medium will increase, and the cavity length that resonates at the original frequency will be shortened to 1.; (2) Since the dielectric sample will introduce additional dielectric loss, the inherent quality factor of the test cavity will decrease to Qos.
According to the change in the resonant length S (S=l.-1.) and the change in the quality factor of the test cavity before and after the dielectric sample is placed, the dielectric constant = and the dielectric loss tangent tano of the dielectric material can be calculated respectively. Approved by the State Administration of Quality and Technical Supervision on May 19, 1999 and implemented on December 1, 1999
GB/T5597-1999
Therefore, the test of the complex dielectric constant can be attributed to the test of the resonant cavity length and inherent quality factor of the high-quality factor test cavity before and after the dielectric sample is placed.
Test environment conditions
20℃～30℃
5 Instruments and equipment
5.1 Test system
Relative humidity
45%~75%
Adopt a "reaction type" system, as shown in Figure 2. Signal source
Digital
Voltmeter
Atmospheric pressure
86kPa~106kPa
Precision scale
Attenuator
Detector
Isolator
Test cavity
The characteristic of this system is that the precision scale attenuator is used to adjust the test level, and the crystal detector is used for equal level indication. The attenuation of the dielectric test cavity when measuring the quality factor is measured by the "high-frequency substitution method". The crystal detector can completely avoid the error caused by the nonlinearity of the crystal detector by using the equal level indication.
5.2 Signal source
a) Output power greater than 10dB;
b) Amplitude stability better than 0.01dB/10min;c) Frequency stability better than 1×10-8/10min;d) Frequency fine-tuning resolution better than 1×10-7f. It is recommended to use a frequency synthesis signal source.
5.3 Precision scale attenuator
Use range: 0~10dB, accuracy: 0.02dB/10dB. It is recommended to use a gyroscopic attenuator.
5.4 Dielectric test cavity
Single-mode T E1. Working, the cavity unloaded quality factor Q≥40000, the tuning piston position reading accuracy is 0.01mm. See Appendix A (suggested appendix) for the test cavity diagram.
5.5 Digital voltmeter
Voltage resolution 1μV, 4% digit reading.
5.6 Crystal detector
Non-adjustable wideband crystal detector.
5.7 Isolator
Isolation ratio is better than 20dB, and the forward and reverse standing wave ratio coefficients are less than 1.20. 2
6 Sample size and requirements
6.1 Sample diameter D,
Where: R-test cavity radius, mm,
GB/T5597—1999
D,=(2R-)± 0.1mm
8——Quantity related to the test cavity size. In the test cavity with the recommended test frequency, it is recommended to be set to 1.5mm. 6.2 Sample thickness d
·(2)
The principle of selecting the sample thickness d is to take its electrical length at around 85° to improve the test sensitivity and reduce the test error. When the dielectric constant e of the material to be tested is roughly known, the sample thickness can be calculated according to the following formula. d=0.236
Where: f. Test frequency, that is, the resonant frequency of the test cavity, GHz; R——test cavity radius, mm;
d sample thickness, mm.
For the selection of sample thickness, see Appendix B (suggestive appendix). 6.3 Sample requirements
The two main planes of the disc-shaped sample The non-parallelism shall not exceed 0.01mm, and the non-straightness of the two main planes shall not exceed 0.01mm. ·(3)
The sample surface shall be free of abnormal spots and scratches, and the interior shall be free of abnormal impurities and pores; it shall be strictly cleaned and dried before testing.
7 Test procedure
7.1 Measurement of empty test chamber
7.1.1 Turn on the machine and preheat for 15 minutes to make the system work normally. 7.1.2 Set the signal source output continuous wave frequency to the test frequency f. Adjust the precision scale attenuator within the range of 9.0dB to 9.8dB, adjust the output level of the signal source, so that the crystal detector output reads an indication of about 10mV on the digital voltmeter, and record the attenuation A1 of the precision scale attenuator at this time.
7.1.3 Adjust the dielectric test chamber. When the digital voltmeter indicates the lowest point, it is determined that the test chamber has been adjusted to the resonance point. The resonance point frequency is f. , record the piston position scale l of the medium test chamber. And the resonant frequency. At this time, the reading on the digital voltmeter is ar. 7.1.4 Adjust the precision scale attenuator (reduce the attenuation) so that the reading on the digital voltmeter rises from ar to ao, and record the attenuation A2 of the precision scale attenuator at this time. The attenuation introduced by the medium test chamber at the resonance point is A=A,-A2, in decibels. Ahe=10lg(1+10%)-3. 01
·（4）
7.1.5 Calculate the attenuation Ahe of the "half-power point" of the resonance curve according to formula (4), and set the precision scale attenuator to A. + A2. At this time, the reading on the digital voltmeter is a'.,a,A>7dB
GB/T5597-1999
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