SU1385094A1 - Device for measuring dielectric permitivity - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the electrophysical characteristics of solid and liquid substances. The invention assumes the accuracy of the measurements. Test sample 1, intended to convert the force of electrical interaction with a non-uniform field into the axial force of elongation of the elastic sensing element 2, is made in the form of a cylinder of the test substance. Element 2 is designed to convert an axial tensile force into an electrical oscillation frequency and is a metal string, the upper end of which is fixed in support 3, and both ends are electrically connected to the inputs of an electronic auto-oscillator 7. A permanent magnet 4 creates a magnetic field, which contributes to the excitation of transverse vibrations of element 2. The drawing also shows: electrodes 5, voltage source 6, frequency meter 8. The dielectric permeability of the test sample is determined by the formula given in the specification. 1 il. . (L with

Description

00 00

SP

about with

four;

field in the axial force of extension of the elastic-2 k field. The force of interaction of the directionally sensitive element 2 and is made in the form of a cylinder of the test substance.

The elastic sensing element 3 is designed to convert the axial tensile force to the frequency of electrical oscillations and is a metallic string, the upper end of which is rigidly fixed in the support 3, and the ends are electrically connected to the inputs of the electronic autogenerator 7.

Support 3 provides rigid constructive fixation of the elastic sensing element.

The permanent magnet 4 is designed to create a constant magnetic field conducive to the excitation of transverse vibrations of the elastic sensitive element 2.

The device works as follows.

35

40

Lena in the region of the maximum intensity of the electric field and is equal to

o5 „E

(2)

where is the dielectric constant of the test substance from which sample 1 is made; Sj, - cross-sectional area

sample;

E is the intensity of the electric field in the space between the electrodes 5; e, - 8, f / m Formula (2) is valid when the intensity of the electric field at the upper end of sample 1 is zero, which is achieved in the device by the appropriate arrangement of electrodes 5. The force F leads to additional tension of the elastic sensitive element 2 and, consequently, to an increase in its resonant frequency transverse hesitation

The electronic oscillation oscillator 7 excites and maintains continuous transverse oscillations of the elastic sensing element 2 at its resonant frequency, which is recorded by frequency meter 8. When electrodes 5 are connected to the poles of voltage source 6, the additional elastic tension is applied to a non-uniform electric field element 2, resulting in a change in the frequency of its natural oscillations. This frequency change, which is a function of the dielectric constant, is detected by a frequency meter 8.

Lena in the region of the maximum intensity of the electric field and is equal to

o5 „E

(2)

where is the dielectric constant of the test substance from which sample 1 is made; Sj, - cross-sectional area

sample;

E is the intensity of the electric field in the space between the electrodes 5; e, - 8, f / m Formula (2) is valid when the intensity of the electric field at the upper end of sample 1 is zero, which is achieved in the device by the appropriate arrangement of electrodes 5. The force F leads to additional tension of the elastic sensitive element 2 and, consequently, to an increase in its resonant frequency transverse hesitation

45

f -

(3)

0

Relations (1) - (3) imply that it is necessary to determine the dielectric constant of the sample.

S

  1 +

41 r

p with p 2 Co Oj, C.

about o (f-f)

(four)

When measuring the dielectric constant of a liquid, sample 1 with a known permeability of 6 is immersed in the liquid under study with a permeability of 2 A similar calculation leads to the expression

f.e.41 p S foSoE,

(f f)

(five)

 2

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A device for measuring the dielectric constant, comprising an elastic sensing element reinforced with an upper end in a support, and a sample is attached to the lower end of the sensing element, characterized in that, in order to improve the accuracy of measurement and ten The measurement process includes a voltage source, electrodes, an auto-oscillator and a frequency meter, the electrodes are connected to a voltage source, and the elastic sensing element is designed as a vibrating metal string located in a magnetic field, the ends of which are connected to the corresponding inputs of an electronic auto-oscillator. , to the output of which the frequency meter is connected. + 0 О8