SU1835506A1 - Method of surface-resistance metering - Google Patents

Description

The invention relates to a microwave measurement technique and can be used in the electronic and electrical industries, in scientific research, in particular, for measuring the surface resistance of high-temperature superconductors.

The aim of this invention is to increase the sensitivity and accuracy of measurements.

The advantages of the proposed method are to increase the accuracy and sensitivity of measurements due to the location of the DR on the test sample and taking into account the steepness of tuning the frequency of the DR by the test sample; in the possibility of measuring R _{s of} thin-sheet conductive materials due to direct pressing of the sample to the end surface of the DR and in high measurement performance, because no special technology for the manufacture of the sample is required.

This goal is achieved by the fact that in the known method for determining the surface resistance of conductive materials on a microwave. consisting in measuring the intrinsic Q-factor of the dielectric resonator Q _o . in placing the dielectric resonator on the surface of the test sample and measuring the intrinsic Q-factor of the dielectric resonator Qocr and the resonant frequency f a and determining the surface resistance R _s , additionally determine the slope of the tuning of the resonance frequency of the DR by the distance between the test sample and the dielectric resonator

1835506A1

and the surface resistance Rs of the test sample is determined by the formula _o π /// ζ _ο ί ² _σ 'Qo / ki /' where: Q (7 == (Q _{0 (} j-Кг Q _o

Kg - coefficient depending on the parameters of the DR;

μ is the relative magnetic permeability of the test sample.

The resonator is made of dielectrics with low dielectric losses, such as monocrystalline quartz, leucosapphire (tg d = 10 ' ⁵ 10' ⁶ ). In this case, the intrinsic Q factor of the DR is limited only by dielectric losses and significantly exceeds the Q factor of metal volume resonators (at 300 k by 5–10 times, and when cooled to cryogenic temperatures 100–1000 times).

The sample for the studied conductive material is pressed against the flat end surface of the DR. The measurement of R _{s is} carried out by changing the intrinsic Q factor of the DR with a pressed sample relative to the intrinsic Q factor of the DR, which is at least half the working wavelength from the conducting surface.

A comparative analysis of the proposed solution with the prototype shows that the claimed method differs from the known one in that the surface resistance R _s is calculated by measuring the intrinsic Q factor of Qq-DR located directly on the test sample, taking into account the steepness of the tuning of the resonance frequency of the DR by the studied sample.

Figure 1 shows the structural electrical circuit of the installation for measuring the surface resistance of conductors that implements the proposed method.

The device comprises a microwave generator 1, a directional coupler 2, a valve 3, a polarization attenuator 4, a dielectric waveguide 5, a measuring cell 6 with a dielectric resonator 7 and an investigated conductive sample 8, a microwave detector 9, an indicator 10, a frequency meter 11.

Figure 2 shows the measuring cell 6, in which the resonator 7 is placed, rigidly mounted on a metal movable rod 12 with a spring 13, providing a constant pressure of the resonator on the test sample 8, which is located on a metal base

14. The movement of the rod 12 is carried out by the adjusting screw 15, and its fixation by the screw 16.

Fig. 3 shows the experimental results of determining the surface resistance R _{s of} conductive materials.

In the absence of the studied metal sample 8 in cell 6, a dielectric resonator (DR) 7 with azimuthal oscillations is excited using a dielectric waveguide 5 by the signal of the microwave generator 1. The transmitted microwave signal is detected by the microwave detector 9 and detected by the indicator 10. At frequencies f _n coinciding with the resonant DR frequencies, resonances are observed in the transmitted signal. The half-width of the resonance curve and the depth of the resonance dip determine the values of the loaded Q factor Q _n . coupling coefficient β and intrinsic Q factor Qo = Qn (1 + β) for a sequence of resonant frequencies fn for oscillations ΗΕη, ι, ΐ.

Claims (1)

Claim A method for determining the surface resistance of conductive materials on microwave, which consists in measuring the intrinsic Q factor of the dielectric resonator Qo, in placing the dielectric resonator on the surface of the sample and measuring the Q factor of the actual dielectric resonator 0 ₀₀ resonant frequency f θ- and determining the surface resistance, In order to increase the sensitivity and accuracy of measurements, they additionally determine the steepness of tuning the resonant frequency of the dielectric resonator in the distance between the test sample and the dielectric resonator Κι ^K1 “ah” h = 0 and the surface resistance of the test sample is determined by the formula _η _ πμμα / σ ^{Rs =} Qa = (Q ^ -K2Q _o ' ¹ ) ^-1 ; where R ₂ is a coefficient depending on the parameters of the dielectric resonator; μ is the relative magnetic permeability of the test sample. Fig J (6 Ί