SU1666981A1 - Method of direction diagram determination of stationary aerial - Google Patents

Abstract

This invention relates to antenna measurement techniques. The purpose of the invention is to improve the measurement accuracy and reduce the time when measuring the radiation pattern of a stationary antenna in specified directions in azimuth along the surface of the Earth. For this, auxiliary antennas (VA) are placed near the stationary antenna (ISA) under investigation and are oriented on a terrain along a compass. At each moment of time, ISA and VA are simultaneously received by electromagnetic signals at the studied frequency. The intensity of the electromagnetic field at each moment in time is determined for each direction from the system of equations and the MDI is determined by normalization to the maximum value of the solution of the system of equations. VA are made with non-uniform DNs in the horizontal plane, and their maxima are deflected from one another by an angle of 2ϕ / N, where N is the number of VA. 1 il.

Description

This invention relates to antenna measurement techniques.

The purpose of the invention is to improve the accuracy of measurements and reduce the time when measuring the radiation pattern of a stationary antenna in specified directions in azimuth along the surface of the earth.

The drawing shows a structural electrical circuit of a device that implements a method for determining the radiation pattern of a stationary antenna.

The device contains a stationary antenna under study (ISA) 1, N auxiliary antennas (BA) 2i. 2g2m

placed at a distance I D, from each other, N selective measuring units 3i, 32Zm, control block 4 and block 5

registration.

A method for measuring the radiation pattern of a fixed antenna is implemented as follows.

Auxiliary antennas 2i2m, which can be constructively made as a single unit, are located close to ISA 1 and are oriented using locally known methods (for example, by compass). The control unit 4 commands the 3tЗм + i blocks to measure the power of the received signal P (tj). ISA 1 and PBK (tj) of each of N ВА2 (К-1,2N) simultaneously. The measurement results are recorded in the memory of block 4. Block 4 determines eg Qs

(

ABOUT

about

00

the field at each time instant TjE (tj, pi) for each direction p (–1.2M) by solving M systems of equations of the form

LBK p () E2 (ti.) PBK (t)), (1)

I - 1

fj

where LF (/}) is the value of the unnormalized radiation pattern of the DOG in the direction fl;

LBK Ff3K (/}) - the value of unnormalized DN of the K-th auxiliary antenna in the direction of /

P (tj) PBK (TJ) are, respectively, the electromagnetic signal powers received, respectively, by the ISA and each VA.

Next, block 4 solves the system of equations

L X Г2Ыг (1,) Р (1,)

i - 1

and determines the days of ISA 1 by normalizing to the maximum results of its solution. Results of the determination of the DNs by the command of block 4 are recorded by block 5 of the registration.

The studied antenna is a stationary antenna of the low-frequency range (for example, CB, DV ...), the DN of which must be measured. Auxiliary antennas 2i2 are small-sized antennas of the considered range with a priori known irregular in the horizontal plane DN (for example, with DN approaching the cardioid), and their maxima are deflected one from the other. 2n angle, multiple

go on

-N -.- where

N

number

/ 24

auxiliary antennas.

Selective measuring units 3i 3w + i are designed to measure the instantaneous value of emf. induced in ISA 1 and BA 2, have selective inputs tuned in accordance with the commands of the control unit 4, and are standard radio measuring devices.

At any given time, at a particular frequency, antenna 1 is affected by the actual electromagnetic environment, i.e. the elementary strengths of the field E (O, p) coming to its location simultaneously from all directions.

The expression for the input power of the measuring instrument for a specific frequency, provided that the antenna is matched to the feeder and without considering the noise of the antenna, feeder and measuring instrument, can be written as

K 7

P (M l v- EV iF M / r / rit /)

p.o.

g 7

 vnndi / jq i.I j f l B ir fe b .- (hi je

 9-a

L1CH.7.171MGPF

ieo "4T

where f, 0-, respectively, azimuthal and meridional angular coordinates;

D (Ob, PO) is the directivity factor of the antenna in the maximum direction;

F (E, (p) is the value of the normalized DN antenna in the 0 direction, knots;

| Ј | 2-normalized polarization power transfer coefficient;

G is the reflection coefficient from the antenna input;

/ - Antenna efficiency. Since the antennas considered

25

thirty

The class n is located directly at the surface of the earth (the height of the antenna rising above the ground is much less than the wavelength), the propagation of radio waves in the low-frequency range is carried out mainly by the earth wave, i.e. the angle of the direction of the wave arrival can be considered equal to zero.

By presenting expression (3) as the sum of a number of terms, the total solid angle is divided into three areas: A is the lower hemisphere area encompassing all directions on the surface of the earth; B - the area of the horizontal plane above the ground; С - area of the upper hemisphere. The proportion of power due to area A (thermal noise of the earth), as well as the thermal noise of the antenna, its feeder path and measuring device are taken into account by a separate term using the well-known Nyquist ratio in R and RVc. The share of power due to area C in the daytime is small enough and can also be taken into account, and with a certain degree of accuracy for the daytime it can be neglected.

Thus, the transition from integration over a full solid angle to integration in the plane can be made, and the latter is represented as a sum of N integrals and transformed to the form of equations included in system (2). Accordingly, for each time instant tj, its own equation can be written and a system of equations of the form (2) is obtained, which is solvable (in the classical sense) under the condition of linear independence of N vectors E (tj.yi). The electromagnetic environment (EMO) in the low-frequency range is quite complex and saturated. It is formed by the following sources of EM radiation: radio transmitters

40

45

50

55

facilities; atmospheric electricity; alternating electric currents flowing in the circuits of electrical machines and devices.

In a real situation, at each specific frequency of the considered range, simultaneously there are many sources that are uncorrelated with each other, whose electromagnetic field in general is characterized by large, fast fluctuations. consequently, the sectors characterizing the instantaneous value of the EM field strength coming to the measurement point from different directions are generally linear, i.e. There are objective conditions for determining the ISA DN by solving the system of equations of the form (2),

The vectors E (tj,), which characterize the instantaneous EMO values at the location of the ISA, can be determined using auxiliary antennas with known characteristics, for each of which an equation in the form of (1) can be written at any particular time tj, and for all In the aggregate, the corresponding system of equations was obtained.

Claims (1)

Invention Formula A method for measuring the directional pattern of a stationary antenna, including measuring the power of an electromagnetic signal at a frequency under study, received by a stationary antenna and auxiliary antennas placed at a distance I from one to another, where I is the wavelength corresponding to the measurement frequency, characterized by in order to increase the accuracy of the measurement and reducing time when measuring the stationary antenna pattern in given directions in azimuth along the earth's surface, measuring the power received by the stationary and auxiliary antennas simultaneously at each time point, determine the intensity of the electromagnetic field E (tj yi) each time moment for each direction fi 1 1,2, ... Miz systems of equations LRK Ј FЈK () Е2 (t |, у}) Рвк (tj) i - 1 and determine the radiation pattern of the stationary antenna under study by normalizing to the maximum value of solving the system of equations L I F2fa) E2 (tj) P (t,). i 1 where L F (y}) is the value of the unnormal radiation pattern of the stationary antenna under investigation in the direction (Ј; LBK FBK (/ h) the value of the unnormalized radiation pattern of the Kth auxiliary antenna in the fl direction; P (tj) and PRK (tj), respectively, of the electromagnetic signal power, received respectively by the stationary antenna under study and each auxiliary antenna, the auxiliary antennas being made with non-uniform radiation patterns in the horizontal plane, and their maxima are deflected from one another by an angle that is multiple 2 / N where N is the number of auxiliary antennas.