SU1810842A1 - Antenna beam measurement - Google Patents

Description

UNION OF SOVIET SOCIALIST REPUBLICS.

... SU „„ 1810842 A1 (51) Y G 01 R 29/10

STATE PATENT OFFICE OF THE USSR (GOSPATENT of the USSR)

DESCRIPTION OF THE INVENTION t g /

TO COPYRIGHT CERTIFICATE (21) 4920403/09 (22) 03/19/91 (46) 04/23/93. Bull. No. 15 (71) Kazan Aviation Institute A.N. Tupolev (72) A.G. Bashirova. EM Golovin, S.E. Kolin and D.V. Lavrov (56) Mitsmakher M.Yu., Torgovanov V. Anechoic chambers of the microwave. - M .: Radio and communications, 1982, p. 12.

C. L. Bennet, Electromagnetic, scattering. - N.Y. Academic Precc, 1978.

(54) DEVICE FOR MEASURING ANTENNA DIAGRAM (57) Use: measuring the antenna pattern in anechoic chambers (BEC). The inventive measuring device consists of

. 2 of the burning antenna 2, connected to the generator 1, of the rotary stand 4 for installing the antenna 3. of the receiver 7, to which the integrator 8, the sampling and storage unit 9, the level shifting unit 10 and the indicator 11 are connected, is placed in the BEC 13, the inner surface is covered with radar absorbing material 14 and has a complex variable profile with a depth of at least Λ / 4. The BEC 13 is mounted on the rotation unit 15. When the BEC is rotated relative to the measuring unit, the output of the receiver 7 due to the arbitrarily structured inner surface of the BEC will have a random signal, averaging of which gives the desired result. 2 ill.

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The invention: relates to the field of measuring equipment and can be used to measure the radiation pattern (NAM),

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

Figure 1 presents the structural diagram of the measuring installation for removing the radiation pattern; figure 2 potentiogram explaining the principle of operation.

The device consists of a generator 1 connected to an auxiliary antenna 2, a test antenna 3 mounted on a rotary stand 4, a control antenna 4 connected to the first input of the adder 6. to the other input of which an antenna 3 is connected.

To the adder 6, a receiver 7, an integrator with a reset 8, BVX-9 are connected in series. The level 10 shift unit and indicator 11 are connected in series.

The clock generator 12 is connected to the control inputs of the integrator with a reset of 8 and BVX 9. The entire device is placed in the BEC 13, the inner surface of which is made of radar absorbing material 14 of an arbitrarily complex variable profile. BEC 13. is installed on the rotation block 15.

The device operates as follows. The signal generated by the generator 1, enters the auxiliary antenna 2 and is emitted, creating in the ideal case a beam of plane electromagnetic waves, in the field of which measurements are made of the investigated antenna 3, mounted on a rotary stand 4, necessary for its rotation and obtaining the desired angular dependence.

The signal from the antenna under study 3 through the adder 6 enters the receiver 7, and then through the integrator with reset 8, BVX 9 and the level shift block 10 to the indicator 11, where it is registered. From the generator of clock pulses 12 receive reset pulses to the integrator with reset 8, and the write pulses to BVH 9.

Obviously, with a constant signal from the output of the receiver 7 corresponding to a certain level of DN, averaging in the integrator with a reset of 8 and storing this value in BVX 9 will not make any changes to the value of the DN.

Since the adder 6 receives a signal from the control antenna 5. the sum of two signals is formed at its output. The signal from the control antenna is auxiliary (to save the concept of the phase of the signal in the adder), and after passing through all the blocks it is necessary to subtract it from the total total signal. This takes place in a level 10 shift unit, which is designed as a summing amplifier, where a constant negative voltage is added to the common signal. Its specific value is set depending on the control unit 5 of the antenna 5 and other blocks. In Fig.2, the signal level from the control antenna 5 is presented as Us. and the level of corresponds to the signal from the studied antenna 3, due to the direct passage of the signal from the auxiliary antenna 2.

However, in fact, the antenna 3 under investigation will also receive signals reflected from the walls of the BEC 13, which, after appropriate addition, taking into account the amplitudes and phases, will lead to a certain level shift from (in Fig. 2, from (0) the value of the level of the beam. Measured without rotation of BEC 13), which is perceived in known devices as a measurement error introduced by spurious reflections.

When rotating BEC 13, this displacement will change in time, because the phase and amplitude of the reflected signal from a certain direction depends on the length of the path traveled and the slope of the elementary section of the RPM 14, and when the texturing depth of the latter is at least L / 4, it can be both positive and negative relative to the nominal value of the useful signal (U6 in FIG. 2). .

At the output of the integrator with a reset of 8, a monotonically increasing voltage will be present for a time T, after which it will be reset to zero, and the process will be repeated again. Information is the value of the voltage at the end of the segment T. It is this voltage that brings the BVX9 at time T according to the signal from the GTI 12.

It will be maintained unchanged until the next 2T time. At the output of the BVX 9 there will be a step voltage, the constant component of which is proportional to the measured signal. It is displayed as a measured value.

The longer the averaging time T (angle of rotation of the BEC walls). the more accurate the measurement.

Minor fluctuations will also occur at the output of the control antenna 5. To minimize them, antenna 5 is made highly directional. The level of the control signal is selected from the condition: Us> U interference;

We give approximate calculations for estimating the anechoic coefficient. The entire inner surface of BEC 13 can be broken

181084’2 to independent sites emitting reflected energy.

This radiation creates a certain error signal in the studied antenna 3. When the walls of the BEC 13 rotate, this signal will change. We can assume that at time intervals ΔΤ the samples of this signal will be independent. It is known that the linear displacement of the walls of BEC 13 in this case should lie within L / 4 <ΔΧ <L.

During the time T, BEC 13 will rotate by an angle Δ ^ »= ωΤ. The length of the corresponding arc is Δ L - R ωΤ (R is the BEC radius, ω is the rotation frequency of the BEC walls).

The number of independent samples N at ΔΧ = -y:

_m ΔΙ_ 2 R®T>

^Ν -ΔΧ = ~ ΊΓ

From statistical radio engineering it is known that when summing N independent samples, the variance decreases by K = VN times, i.e. ^uh

So. at values of R 1 m, ω 20 p / sec. T - 0.01 s. λ8 mm.

the gain is about 20 dB.

Claims (1)

Claim 5 A device for measuring the antenna radiation pattern, including a generator, the output of which is connected to the input of the auxiliary antenna, a receiver and an indicator placed in an anechoic chamber, 10 different in that? that, in order to improve accuracy, an adder is introduced, the first input of which is an input for connecting the output of the antenna under study, and the second input is connected to the output of the input 15 control antenna, the adder output is connected to the receiver input, the integrator is connected in series with a reset, the input of which is connected to the output receiver, sampling and storage unit, level shifting unit 20, the output of which is connected to the indicator input, a clock pulse generator, the output of which is connected to the second input of the integrator with a reset and sampling unit Storage, block rotation bezeho25 howling camera around its axis, wherein the radio-absorbing coating the inner surface of an anechoic chamber arranged varying profile depth of not less than a quarter wavelength. Editor T. Ivanova Compiled by A. Bashirova Tehred M. Morgenthal Corrector S, Patrusheva Order 1444 Circulation Subscription VNIIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology 113035. Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhgorod. Gagarin St. 101