SU1388817A1 - Microwave emission sensor - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve the measurement accuracy. The sensor contains a microwave radiation absorber 4 and a piezoelectric element 5 with plates 6, which are electrically connected with cable 7 to recorder 8. Three sound pipes 1-3, the lengths of which are L, L, L, are connected to the sensor with the duration of HS-RF radiation mi L ,, L, V o / 2, LJ Vf, where V is the speed of sound in the sound duct. As a result of the absorption of microwave energy, the p-absorber 4 heats up and tends to expand. The compressive voltage arising in the absorber 4 propagates along the conduits 1 and 2 in the form of sound pulses (PZ). The first ZI comes to the piezoelectric element 5 after the end of the microwave pulse and the electromagnetic pickups accompanying it, and the subsequent ZI (reflected from the free ends of the sound lines 1 and 3) after the registration of the first one ends. 1 il. a (/) C

Description

with

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113

The invention relates to a measurement technique and can be used, for example, to measure the intensity of microwave radiation in waveguide and quasi-optical transmission lines.

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

The drawing shows a structural electrical circuit of the microwave radiation sensor.

I The microwave radiation sensor contains the first I 1, second 2 and third 3 sound channels. Between the ends of the sound ducts 1 and 2, the absorber 4 of microwave radiation is rigidly fixed. Between the other end i of the sound duct 2 and the end of the sound duct: 3 the piezoelectric element 5 is rigidly fixed: plates 6. The latter are connected via cable 7 to an electrically connected with the recorder 8.

Dips L,, L, L. sound lines 1 - i3 are associated with speed. V sound in sound- and coprod and the duration of the microwave impulse

vr, „, vf

L 7 VT; I.

(one)

I To ensure uniform heating of the microwave absorber 4, the latter is made of a material whose absorption coefficient K is related to the transverse dimension d of the microwave radiation absorber 4 by the ratio K 1 / d. The transverse size d of the microwave absorber is limited from below (on the side of small quantities) by the need to ensure sufficient mechanical strength of the microwave sensor, and from above (on the side of large quantities) by the condition that it is small compared to the characteristic size of the microwave heterogeneity.

The absorption coefficient Kg of sound ducts 1-3 is advisable to choose from the condition of low elastic stresses LR, resulting from heating of sound ducts 1-3, as compared to the stresses & P ' resulting from heating the absorber 4 of microwave radiation.

& R os, E 3 Kz

lr "" "E" KP

one,

(2)

„„ Is the linear expansion coefficient of the absorber material; 55 cij - coefficient of linear expansion of the material of the sound pipes

1-3;

P

-

E - Young's module absorber 4

five

0

Zd d

d

50

55

Microwave radiation;

EJ - Young's module of sound ducts 1-3.

To ensure acoustic matching of all elements of the device, it is advisable to make them in the form of cylinders with the same cross section and from materials with similar wave impedances. I

The microwave sensor operates as follows.

Pulsed microwave radiation generated by a pulsed microwave generator (not shown), falls on the absorber 4 of microwave radiation and is partially absorbed in it. As a result of the absorption of microwave energy, the absorber 4 of microwave radiation heats. and strives to expand. The compression voltage arising in the 4.SHF-radiation absorber propagates along the conduits 1 and 2 in the form of sound pulses, the magnitude of the compression voltage in which is proportional to the intensity of the SEC radiation. Since the piezoelectric element 5 is rigidly fixed between the ends of the sound lines 2 and 3, the sound pulse compresses the piezoelectric element 5 ". At the same time, the plates 6 exhibit an electrical voltage proportional to the compression voltage in the sound pulse (and, consequently, the microwave radiation intensity), which is recorded by the recorder 8.

Since the length L of conduit 2 satisfies relation (2), the first sound pulse arrives at the piezoelectric element 5 after the end of the SBCh pulse, therefore, the detection of an electrical voltage pulse arising on the electrodes of the piezoelectric element 5 under the influence of a sound pulse occurs in the absence of accompanying generation of microwave radiation electromagnetic pickups on the electrodes of the piezoelectric element 5 and the registration circuit (cable 7 and recorder 8), which allows to increase the registration accuracy. A sound pulse excited by the absorber 4 of the microwave radiation in the sound duct 1 and then reflected from the free end of this sound duct, and the sound pulse passed through the piezoelectric element to the sound duct 3 and then reflected from the free edge of the sound duct 3, arrives at the piezoelement after the registration of the transceiver 313888174 ends

because of the measurement, the absorber of microwave radiation

the lengths of the sound ducts 1 and 2 are satisfactorily placed between the ends of the entered perrut relationships (1) and (2) of this and the second sound ducts, and this means that the reflected sound element is placed between the ends of the sound pulses that do not overlap the first and the third sound pulse produced. waters, and the length of the first, second

and the third sound ducts are selected

Claims (1)

The claims of the ratio ten A microwave radiation sensor comprising L V C- / 2; L V-T; L V c / 2, microwave absorber and piezo. an element connected to the registrar where V is the speed of sound in the sound prop, differing in water; that, in order to improve the accuracy of jc tT, is the duration of the microwave radiation.