SU1550436A1 - Method of determining dielectric permeability of materials - Google Patents

Abstract

The invention relates to the measurement of the electrical parameters of materials, in particular to the measurement of the dielectric constant. The aim of the invention is to improve the accuracy. The method consists in the fact that the flat surface of the dielectric material is irradiated with microwave radiation of variable frequency, polarized in the plane of incidence, with Gaus power distribution over the beam section, the reflected radiation is recorded at two angles, one of which is larger, the other is smaller than the angle of incidence, Brewster angle is determined by the presence of reflected radiation of equal intensity at two angles of registration and, based on the Brewster angle, the dielectric constant is calculated. 1 il.

Description

The invention relates to instrumentation technology and can be used for non-destructive testing of the dielectric constant of materials in chemical, radio, etc. industry.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows a block diagram of the device for implementing the proposed method.

The essence of the method is that the monitored material is irradiated with a variable frequency electromagnetic wave, sequentially changing the fillet angle, recording the reflected radiation, and determining the Brewster angle from which the dielectric constant is calculated. Moreover, the irradiation of the controlled material is produced by a Gaussian microwave beam, polarized parallel to the plane of incidence, the reflected radiation is simultaneously recorded at two angles, one of which is larger and the other is smaller than the angle of incidence, and the Brewster angle is eliminated by the presence of reflected radiation of equal intensity at two reception angles. The wave of the main type of the beam transmitter has a Gaussian distribution of the electric field intensity in the cross section of the beam guide. When such beams of a final aperture or similar to them at the interface of two materials fall, a number of effects are observed that are different from the case of a plane wave, namely longitudinal and side mixing of the microwave

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the beam, the propagation of the reflected beam at an angle not equal to the angle of incidence, the splitting of the reflected beam into two beams, etc. These effects are most pronounced in the case of internal reflection, and the exception in the measurement process leads to an additional error.

This method of measuring the dielectric constant permits reading parameters of the probe microwave beams and, moreover, is based on the effect of splitting the reflected beam into two beams, propagating along the / t angles of angles relative to the angle of incidence. This effect is physically explained by the fact that microwave beams (for example, with a Gaussian distribution) can be considered as a superposition of a set of plane waves of various amplitudes and directions. Since the amplitude and Laza of the reflected flat-wave component depend on the angle of incidence, i.e. for different components different, the reflected beam may propagate at an angle different from the angle of incidence. If the angle of incidence of the microwave beam, polarized parallel to the plane of incidence, is equal to the Brewster angle after reflection, two beams propagating pop are formed; angle j; koi; K corner of Brewster. Thus, it is shown that the value of D on is determined by the following relationship:

, - $ 2 JR (sintfp) / coso4 g,. 100 - K, W0 (K1W0) r / R (sinoie) / U

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where o (.v is the angle of Brewster;

K, is the wave number in the first medium;

2W0 - beam width;

siting) / - derived from the sinoi reflection coefficient modulus.

By analyzing the distribution of the electromagnetic field of the reflected microwave wave, the Brewster angle with a high degree of accuracy can be fixed by the appearance of two reflected beams.

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The device contains an automatic sweep generator 1, a generator power supply unit 2, a waveguide-beam transition 3, a polarizer 4 emitting 5 and receiving 6 and 7 antennas in the form of open ends of the light emitters, a waveguide-beam transitions 8 and 9, receivers 10 and And radiation , the comparator 12 and the dielectric prism 13. The controlled material 14 is installed on the base of the prism 13.

The method is carried out as follows.

A beam of electromagnetic linearly polarized parallel to the plane of incidence of variable frequency electromagnetic waves is directed at an angle to the controlled material through a dielectric prism. The angle of incidence is changed and the reflected radiation is recorded simultaneously at two angles, one of which is smaller, and the other is increased by 1 - 5 ° angle of incidence. Brewster angle is recorded by the presence of reflected radiation of equal intensity at two reception angles and the dielectric constant is calculated from the known ratios.

Claims (1)

Invention Formula The method for determining the dielectric constant of materials, which implies that the flat surface of the material under study is irradiated with a variable frequency electromagnetic microwave wave, the angle of incidence is subsequently changed, the reflected radiation is recorded and the Brewster angle is determined, based on the value of which the dielectric constant is calculated. l and h and u and -s with the fact that, in order to increase the accuracy of measurements, the material is irradiated by a microwave Gaussian beam, polarized parallel to the plane of incidence, reflected Radiation is simultaneously recorded at two angles, one of which is larger and the other is smaller than the angle of incidence, and the Brewster angle is determined by the presence of reflected radiation of equal intensity at two reception angles. w