SU1218347A1 - Method of determining coeficient of aerial converter non-linearity - Google Patents

Abstract

This invention relates to a measuring technique. The purpose of the invention is to improve the measurement accuracy. The device implementing the method contains a signal generator 1, a two-position attenuator 2, an electromagnetic field source 3 (TEM camera), an antenna converter (AL) 4, a coaxial load 5, an output signal meter 6, a control unit 7, a calculator 8. On AP 4 input serves a sequence of fixed levels of an electromagnetic field (EMR), the values of which are K times the values of the EMF levels of the first sequence. The signals at the AP output are measured 4. The nonlinearity coefficient is determined by the solution of the system of equations and (КХ- -Xi) (Xi) -Kf, (xi)}: j: 1 where Xj (i 1, 2, ..., and) - Sequences of fixed levels of EPM; f; (x) are functions of a simple form (J 1,2, ..., h); Cj is the nonlinearity coefficient of the AP. 1 W1. i (Л С в ю 00 оо 4 -х |

Description

one

The invention relates to a measurement technique and can be used to determine the inefficiency of antenna converters used to measure the strength of the electric and magnetic components of an electromagnetic field. The aim of the invention is to improve the accuracy

The drawing shows an electrical block diagram of a device that implements a method for determining the nonlinearity coefficient of an antenna converter.

The device contains a signal generator 1, a two-position attenuator 2, an electromagnetic field source 3 (TEM camera), an antenna converter 4, a coaxial load 5, an output signal meter 6, a control unit 7, a calculator 8.

At the command of block 7, the generator 1 of the signals supplies the input of a two-position attenuator 2 with a high-frequency voltage of frequency i) and amplitude and, the two-position attenuator 2 is set to one of the positions, and the attenuation introduced by them is equal to A. From the output of the two-position attenuator 2 high-frequency voltage is fed to the input of the source 3 of the electromagnetic field (TEM - camera), the Source 3 is a shielded strip line. The intensity value of the electric component of the electromagnetic field in the center of the TEM camera is determined by

V 1f

s - -

(one)

where RPR is the passing power inside the TEM - camera; Z - characteristic resistance of the TEM - camera; d is the distance between the planes of the inner and outer conductors of the TEM camera.

The density of the energy flow inside the TEM camera is defined as

2d Zb

(2)

where Zfa is the wave impedance of free spaces.

The intensity of the electric and magnetic components of the electromagnetic field inside the TEM chamber is related to the known ratio

1218347

X - -15- .-.

(3)

Certified antenna converter 4 is placed in the source 3 of the electromagnetic field. The dependence of the electric, magnetic, or power flux density (depending on the type of antenna converter 4 being certified) on the value of the output signal x is determined by the expression

y ah + f (x)

(four)

where y is the measured parameter of the electromagnetic field; a - coefficient of proportionality; F (the desired nonlinearity of the dependence of the measured parameter of the electromagnetic field on the output signal X.

The meter reading 6 is equal to X, which corresponds to the level of the electromagnetic field inside the TEM - camera y. The connection between y. and x according to the relation (4) has the following form

at F (k,).

(five)

At the command of block 7, the value of x is entered into the memory of the calculator 8. Then, the positioning attenuator 2 is moved to another position. In this position, the attenuation introduced by the two-position attenuator 2 is equal to Aj. The value of the power passing into the chamber changes by a factor of K. According to expressions (1) and (3), the intensity of the electric and magnetic components of the electromagnetic field varies by a factor of two, and the energy flux density of the electromagnetic field changes by K times, while the measured parameter of the electromagnetic field changes by K times and is equal to. The reading of the meter 6 will be equal to x and, at the command of block 7, will be entered into the memory of the calculator 8. The connection between and X is

.y, i

TO

qx; + F (x J

(6)

50

In equations (5) and (6), the value of y is unknown. Eliminating from (5) and (6) we get

ax-j + F

(XO

ah; + f (x;)

(7)

Unit 7 translates the on-off attenuator 2 to the first position.

changes the level of the output voltage of the generator 1. At the same time, the reading of the meter 6 is equal to X. This reading is stored in the memory of the calculator 8. Then the two-position attenuator 2 is transferred to another position. The measured parameter of the electromagnetic field decreases by a factor of K, which corresponds to the reading of the 6 Xj meter, which is stored in the memory of the calculator 7. The measurement results X 4 and X are interconnected by the relation (7).

Similar operations are repeated n times, choosing different values of the output voltage of the generator 1, which are monitored by the meter 6, at the same time, the memory, the calculator 8 records the value pairs); - X- ,. The number of pairs X j -X; is selected depending on the required accuracy of determining the nonlinearity of the antenna converter 4 under investigation.

Based on n equations of the form (7), the nonlinearity parameters F (x) of the antenna converter 4 are determined, as the sum of simple linearly independent functions of the simple form

.. P (X) s, S-iCx) (8)

i-1

Substituting (8) and (7) and taking into account everything: reduced measurements, we obtain a system of equations for n

coefficients;

and.-1

Q (KX; -xJ (X,) (X,) J i 1

about (kx; -Xj) (Xj) -K4 i (xi)

and a {KxU-x) - 52ci 4 i (x) (x;,) J

-one

Editor N.Gorvat

Compiled by V. Rabinovich

Tehred O. Netsecorrector S.Cherni

Order 1129/54 Circulation 730 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch ShSh Patent, Uzhgorod, st. Project, 4

218347

Solving system (9), transmitter 8 determines the coefficients C, which are used to determine the non-linearity of antenna converter 54.

Claims (1)

Invention Formula The method of determining the coefficient 10 non-linearity of the antenna converter unit by applying at its input a first sequence of fixed levels of an electromagnetic field and then measuring signals 15 at the output of the antenna converter, which is based on the fact that, in order to increase accuracy, a sequence of fixed levels of the electromagnetic field is fed to the input of the antenna converter, the values of which are K times the first sequence of the electromagnetic field, and the signals at the output of the 25 dA converter, and the nonlinearity coefficient of the antenna converter is determined by solving the system of equations thirty (Kxl-xJ- y gj fjCXil-KvpjCx-;)} J -1 9) where x j and - - respectively, the first and second sequences of fixed 35 levels of the electromagnetic field (i 1,2, ..., i); fj (x) are functions of a simple form, for example, Vj (x) with x-bbAj 1, 2,.,.,   . Cj is the nonlinearity coefficient of the antenna converter.