SU1242856A1 - Transducer of intensity of microwave radiation of object - Google Patents

Abstract

The invention relates to the technique of radar measurements and provides an increase in the accuracy of measurements in the study of inhomogeneous objects. The surface 3 of the dielectric plate (DP) 2 is in contact with the surface of the planar radiator 1, and the friend's V ///////// /////////////// Z its surface is working surface 4 of the sensor. The working surface 4 of the sensor is brought into contact with the surface of the object under study (EUT) 6, for example, with the surface of a biological tissue. The heat radiation of the EUT 6 is partially reflected, and the rest is received by the sensor and fed through terminals 5 to the receiver. The power of the receiver's own noise is fed to the input of the sensor and the radiation from 1. Some of this power is absorbed by the EUT 6, and the rest of the power is reflected and re-supplied to the receiver. Carrying out the DP 2 from a material whose dielectric constant is selected from condition 1 j5 - 12 (- max. Dielectric constant IO 6), and thickness d from condition d / L; 0.01–0.2 (wavelength in DP 2) reduces the fluctuations of the reactive component of the electromagnetic field of the planar radiator 1 and reduces the influence of a non-uniform medium on the emissivity of IO 6 at the sensor-object interface. 5 il. with and (L GS 4iai 1C CX) ate O5 in

Description

The invention relates to a technique of radio measurements and can be used for the contact measurement of the intensity of microwave heat radiation of objects.

The aim of the invention is to improve the accuracy of measurements in the study of inhomogeneous objects.

Fig. 1 shows the design of the microwave radiation intensity sensor of an object; Fig, 2-5 design planar emitters.

The intensity sensor of the microwave radiation of an object contains a plasma emitter 1, a dielectric plate 2, one surface 3 of which is in contact with the surface of a gyroscopic radiator 1, and the other is the working surface 4 of the sensor, and terminals 5 located on the surface of the planar radiator 1, anti-surface of the surface 3. The material of the dielectric plate 2 is chosen tav: it way that the condition

   - 12.

ll

Since the values for different objects are different, the specific materials of the dielectric plate 2 will also be different. For example, for the study of humans and animals (the maximum value of m of the real part of the dielectric constant of biotissues in the decimeter wavelength range is equal to 50), materials with a real part in the range of 80-600 values can be used. Some types of radio ceramics, as well as various types of metal ceramics and metal plastic, have such values of the real part of the dielectric constant. The thickness d of the dielectric plate 2 is chosen depending on the working wavelength o, in the material of a given dielectric,

d

 l

0.01-0.2.

A planar emitter 1, which is one or more flat metal conductors located on the surface 3 of the dielectric plate 2, can have any known construction. It can be executed, for example, in the form of a slit

ialuchatel (figure 2), loop virator (fig.Z), planar spiral radiator (figure 4), vibrator (figure 5), etc.

The microwave radiation intensity sensor of an object operates as follows.

The working surface 4 of the sensor is brought into contact with the surface of the test object 6, for example, with the surface of biological tissue, having a skin layer 7, a fat layer 8 and a layer of muscle tissue 9, and the keys 5 are connected to the inlet

receiver.

Microwave thermal injection of T., the object under study when passing through the interface of the sensor -. object partially reflects The intensity of the reflected radiation can be written as

,

()

where R is the reflection coefficient of

power. The remaining part of the radiation

(1 - R) T ETd, (2),

where E is the emissivity of the object at the sensor – object boundary

accepted by the sensor and then fed to the input of the receiver.

The power of the own input terminals: T, p of the receiver is fed to the input of the sensor and the radiator. Moreover, part of it is absorbed by the object:

AT „p (I - R),

(3)

where A is the absorption capacity of the object at the interface. sensor - an object

and the remaining part of the r r t

OL PR

(four)

It is reflected at the interface between the sensor and the object and is again fed to the input of the receiver.

Thus, the total power T of two microwaves of 55 microwave radiation will be recorded on the receiver's indicator

Т ЕТ, + КТ „, (I -R) Т, RT,

. T, R (1,)

or

t t.

AT,

(5) (6)

where -4 T R (T-p -T) is the measurement error of microwaves power

new radiation.

From the expression (6 it can be seen that for obtaining the minimum error of measuring the intensity of microwave radiation, it is necessary to have

either T „or R o,

(7) (8)

For noise signals of thermal radiation, equality () is equivalent to the equality of the noise temperature of the receiver input and the temperature of the object under study 6. However, it is impossible to fulfill condition (7) in general, since T is not known exactly, only approximate limits of variation of this value are known.

Condition (8) is also practically impossible to fulfill, but it can be limited to fulfilling the condition

R 1 - E const.

however, the measurement error of the intensity of the radiation can be reduced to zero during the calibration operations.

When measuring the depth temperature of biological objects, the propagation medium of microwave heat radiation is extremely heterogeneous. Biofabric with high water content (leather, mens, etc.) have ve

a substantial part of the dielectric constant for the decimeter wavelength range of about 50, while the adipose and bone tissues have a real part of the dielectric constant of about 5-10.

It was established experimentally that the random nature of the distribution of these

j

five

0

five

Q

five

0

five

tissues in the test object 6 has a significant impact on the structure of the electromagnetic field of the sensor, and on the distribution of currents in the plenary emitter of the first sensor. This leads to accidental changes in the emissivity E of the object at the interface between the sensor and the object and, accordingly, to a decrease in measurement accuracy.

In this sensor, the electric part of the reactive component of the electromagnetic field of the radiator is concentrated in the dielectric plate 2 with a large value of the real part of the dielectric constant, which allows reducing fluctuations of this part of the field and reducing the effect of a randomly inhomogeneous medium on the emissivity of the object under study 6 at the interface sensor is an object.

Claims (1)

Formula invented and The intensity sensor of the microwave radiation of an object, containing a planar emitter, placed on one surface of the dielectric plate, and terminals, that is, and that. In order to improve the accuracy of measurements in the study of inhomogeneous objects, in it the dielectric plate is made of a material, the dielectric constant a. which is chosen from the condition g   1.5 - 12, where bd is maximal A The value of the dielectric constant of the object, and has a thickness determined by the ratio 1 0.01 - 0.2, where is the wavelength in the dielectric plate, d is the width of the dielectric plate, the terminals are placed on the surface of the planar radiator, and The plate is the working surface of the sensor. FIG. 2 fig.Z fig L Editor N.Egorova Compiled by R. Kuznetsova Tehred O. Sopko Proofreader I. Muska Order 3699/43 Circulation 728 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 The Institute of Humanities and Culture, Uzhgorod, Proektna St., 4 FIG. five