RU2584260C1 - Radio-measuring unit for measuring radar cross-section of objects - Google Patents

Abstract

FIELD: radio.

SUBSTANCE: radio-measuring unit for measuring radar cross-section of objects comprises: HF generator, a receiver, receiving-transmitting antenna, which is made in the form of a flat phased antenna array (PAA) with N channels, reference frequency generator, three mixers, high-frequency filter, a pulse generator, pulse modulator, power amplifier, a circulator, a system of √N +1 splitters, each splitter has √n outputs, N couplers, N attenuators, N phase changers, N radiators, adjusting unit of phased antenna array having N inputs of second output couplers, N first outputs control signals attenuators and N second outputs of phase changer control signals. Reference frequency generator output is connected with heterodyne inputs of mixers and input of heterodyne signal adjustment unit, signal input of first mixer is connected to HF generator output, and output of first mixer is connected to input of HF filter. HF generator output is connected with heterodyne inputs of second and third mixers, HF filter output is connected to signal input of power amplifier, and its output is connected to input of circulator, output-input is connected to input of first splitter system splitters, outputs of first splitter are connected to inputs of other splitters, outputs of which form N phased antenna array channels. Output of circulator is connected to signal input of second mixer output is connected to input of receiver. In each channel are connected in series: coupler, an attenuator, phase shifter and a radiator. Second outputs of couplers are connected to signal inputs of third mixers, whose outputs are connected to inputs of the adjustment unit, first N outputs connected to inputs of control signals attenuators, and the second N outputs are connected to inputs of control signals phase shifters.

EFFECT: technical result is increased area of homogeneous amplitude and phase front of electromagnetic field to area of aperture, possibility of measuring radar cross-section of large objects with high accuracy compared to prototype of invention and two-fold reduction of longitudinal dimensions of radio-measurement unit.

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Description

The invention relates to techniques for measuring the radar characteristics of objects in anechoic chambers and can be used to measure the effective scattering surface (EPR) of objects in the near zone of a transceiver antenna.

In accordance with the definition of EPR, the main condition for its unambiguous measurement is a uniform phase and amplitude distribution in the front of the electromagnetic field (EMF) incident on the object [1]. When measuring the EPR in the near zone of the antenna, collimator transceiver antennas are used that provide a uniform phase distribution in the front of the electromagnetic field at the antenna aperture [2] and near zone. The antenna collimator is irradiated by a radiator with a radiation pattern with a decreasing amplitude from its electric axis, a uniform amplitude distribution can be conditionally achieved only with some allowable amplitude heterogeneity in the front of the EMF, which leads to measurement errors.

Known collimator made in the form of a dielectric lens with an internal refracting surface [2]. The lens, aligning the phase distribution of the EMF front over the area of its aperture, increases the heterogeneity of the amplitude distribution, which is due to the radiation pattern of the irradiator, due to the expansion of elementary beam beams to its edges, due to different refraction angles of the beams. In this case, the area of the EMF front, conditionally uniform in amplitude, with an allowable error, turns out to be no more than a quarter of the lens aperture area.

The small area of a conditionally flat EMF and measurement errors are disadvantages of a dielectric lens with an internal refracting surface.

Known single-antenna meter polarization scattering matrix of its complex elements: EPR modules and phase arguments in the near zone of the transceiver antenna, adopted as a prototype of the invention [3]. The meter contains: a high-frequency (HF) transmitter, a polarizer, a directional polarization separator with orthogonal E and H side arms, two complex variable loads, two amplifometers and a collimator transceiver antenna. The output of the transmitter is connected to the inputs of the reference signals of the ampliometer and to the input of the polarizer, the output of which is connected to the input of the main arm of the directional polarization separator, in addition, the output of the polarization separator is connected to the input of the transceiver antenna. The non-directional outputs E and H of the lateral arms of the polarization separator are connected to variable loads, the directional outputs E and H of the lateral arms of the polarization separator are connected to the signal inputs of the corresponding amplifiers. The transceiver antenna is made lens, and the lens is made with an external refractive surface. In this case, the area of the EMF front, which is conditionally uniform in amplitude, with an allowable error, turns out to be no more than half the area of the lens aperture, and the amplitude heterogeneity leads to measurement errors of the EPR of objects, which is a disadvantage of the prototype.

Common features of the prototype of the invention are: a generator, a receiver and a transceiver antenna.

With the same antenna aperture areas of the prototype and the invention, the potential of the receivers and the sensitivity of the receivers, the technical result of the invention is to increase the area of the EMF front that is uniform in phase and amplitude at the aperture of the transceiver antenna to the area of its aperture, which is made in the form of a phased antenna array (PAR) and as a result, the possibility of measuring the EPR of large-sized objects with greater accuracy and halving the longitudinal dimensions of the radio measuring installation due to the absence of focus clear distance.

A PAR is called an antenna device consisting of N channels of emitters (N from several units to several thousand), each of which is able to radiate into space and receive radio signals from it [4].

According to the invention, the PAR is made in the form of a flat square or rectangular phased N-channel antenna array containing: √ N + 1 splitters, N couplers, N controlled attenuators, N controlled phase shifters, N emitters, a mixer and a tuner.

In accordance with the Huygens-Fresnel principle, in the near zone (Fresnel zone) of a flat headlamp an EMF front is formed that is uniform in amplitude and phase, with an area equal to its aperture area.

The invention is illustrated by drawings.

In FIG. 1 is a structural diagram of a radio meter according to the invention.

In FIG. 2 presents a view of the aperture of a flat nine-channel headlamp.

In FIG. 3 is a structural diagram of a headlight tuner.

The following notation is introduced in the figures: 1 — a signal generator of a reference frequency (GO); 2 - the first mixer (1 cm); 3 - high frequency signal generator (G); 4 - high-frequency signal filter (HPF); 5 - a generator of rectangular pulses (GI); 6 - pulse modulator (IM); 7 - amplifier RF power (PA); 8 - circulator (C); 9 - second mixer (2 cm); 10 - receiver (PC); 11 - splitter system splitters; 12 - coupler (From); 13 - attenuator (At); 14 - phase shifter (PV); 15 - channel emitter; 16 - third mixer (3 cm); 17 - tuner (BN); 18 - amplitude detector (HELL); 19 - the first analog-to-digital Converter (1ACP); 20 - phase detector (PD); 21 - the second analog-to-digital Converter (2 ADC); the first electronically controlled switch (1 KA) 22 signals from the outputs of 1 ADC; the second electronically controlled switch (2 KF) 23 signals from the outputs of 2AC; 24 - electronic computer (computer); 25 - the first digital-to-analog converter (1 DAC) of signals from the first computer signal output; 26 - the second digital-to-analog Converter (2 DAC) signals from the second signal output of the computer; 27 - the third electronically controlled switch (3 KF) signals from the output of the first 1 DAC 25; 28 - the fourth electronically controlled switch (4 KF) signals from the output of the second 2 DAC 26.

The technical result of the invention is achieved due to the fact that the radio installation for measuring the effective scattering surface of objects contains: a reference frequency generator (GO) 1; first 2, second 9 and third 16 mixers (1 cm, 2 cm, 3 cm); generator (G) 3; high-pass filter (HPF) 4; pulse generator (GI) 5; pulse modulator (IM) 6; power amplifier (PA) 7; circulator (C) 8; receiver (Pc) 10; √N + 1 splitters of 11 splitters system for 9 channels; N taps (From) 12; N attenuators (At) 13; N phase shifters (PV) 14; N channel emitters 15; tuner (BN) 17.

The signal generator of the reference frequency f (GO) 1 is made stabilized with a signal frequency (MHz) equal to the intermediate frequency of the radio measuring installation.

The first mixer (1 cm) 2 is designed to convert the signal of the generator (G) 3, with a frequency F (GHz), and the signal of the reference generator 1, with a frequency f (MHz), to the frequency F + f (GHz) of the probe signal.

The second (2 cm) 9 and third (3 cm) 16 mixers are designed to convert the frequency of the probe signal F + f to the intermediate frequency f, which is equal to the frequency of the signal GO 1.

Generator (G) 3 is configured to generate high-frequency electric monochromatic oscillations F (GHz).

The high-pass filter (HPF) 4 is designed to filter the frequency F + f formed at the output of the first mixer (1 cm) 2.

A pulse generator (GI) 5 is designed to generate short rectangular pulses, fractions of a microsecond, with a duty cycle longer than the time t required for the probing pulse to travel the distance from the PAR aperture to the measurement object and vice versa.

The pulse modulator (IM) 6 is designed to modulate the power amplifier (AM) 7 of a signal with a frequency of F + f by short rectangular pulses.

The power amplifier (UM) 7 of the high-frequency signal of the installation can be performed on a traveling wave lamp.

The circulator 8 is designed to separate the emitted probe pulses and pulses reflected from the measured object. Circulator (C) 8 - a device that provides the movement of the radio signal in one direction or another [4], consists of a branched waveguide joint and cylindrical ferrite, while the ferrite is under the influence of an external magnetic field.

The receiver (PC) 10 is used to receive and register a signal reflected from the measured object.

The splitter system contains four (√N + 1) splitters 11 with N equal to 9, each splitter has three (√N) branches - outputs.

The coupler of each channel (From) 12 has a signal input and two outputs and can be directional, designed to branch to the second output of the power part (for example, -10 dB). The second output From 12 is included in a closed circuit with feedback regulating the amplitude and phase of the probe signal in the emitter 15.

Channel attenuators (At) 13 are designed to align the amplitudes of the signals in the openings of the emitters 15.

Phase shifters (PV) 14 are designed to align the phases of the signals in the openings of the emitters 15.

The emitters 15 channels can be performed, for example, in the form of a waveguide horn with a wide radiation pattern.

The tuner (BN) 17 is designed to tune on the headlamp aperture a plane amplitude EMF uniform in amplitude and phase, by aligning the amplitudes and phases of the radiation in the openings of the emitters. BN 17 has an input of the signal generator GO 1, N inputs of signals from the outputs of the channel couplers From 12, N outputs of the control signals of the attenuators At 13 and N outputs of the control signals of the phase shifters FV 14. The BN 17 includes: N amplitude detectors (HELL) 18; N first analog-to-digital converters (1 ADC) 19 signals from the outputs of HELL 18; N phase detectors (PD) 20; N second analog-to-digital converters 2ACP 21 signals from the outputs of the PD 21; the first electronically controlled switch (1 KA) 22 signals from the outputs of the ADC 19; the second electronically controlled switch (2 KF) 23 signals from the outputs of the ADC 21; electronic computer (computer) 24; the first digital-to-analog converter (1 DAC) 25 signals from the first signal output of the computer; the second digital-to-analog converter (2 DACs) 26 signals from the second signal output of the computer; the third electronically controlled switch (3 KF) 27 signals from the output of the first 1 DAC 25; the fourth electronically controlled switch (4 KF) 28 signals from the output of the second 2 DAC 26.

The computer 24 can be made in the form of a personal computer and has two inputs (ports) for the signals from the outputs of the first 1 KA 22 and the second and 2 KF 23 switches and two outputs of these signals connected to the corresponding inputs of the first 1 DAC 25 and the second 2 DAC 26 The computer has two outputs of control signals synchronously controlling the operation of four switches 1 KA 22, 2 KF 23, 3 KA 27 and 4 KF 28.

The first switches 22 and 23 of the AD 18 signals and the PD 20 signals are intended for switching N signals at their inputs into a sequence of N signals at their outputs.

The second switches 27 and 28 of the signals from the first 1 DAC 25 and the second 2 DAC 26 are intended for switching a sequence of N signals at their inputs into parallel signals at N outputs of the switches 27 and 28.

The channel of each emitter 15, coupler 12, mixer 3 cm 16, amplitude detector 18 or phase detector 20, ADC 19 or ADC 21, switch 22 or switch 23, computer 24, DAC 25 or DAC 26, switch 27 or switch 28, attenuator 13 or phase shifter 14 form a closed circuit with feedback regulating the amplitudes or phases of the signals in all channels.

Headlamp tuning algorithm and installation operation

1. Turn on the power of all active units of the radio installation.

2. Signals appear in the channels of the HEADLIGHTER emitters, which are emitted into space in the form of sounding pulses of a radio signal.

3. The signals from the outputs of N mixers 3 cm 16 are fed to the BN 17 to N inputs of amplitude (HELL) 18 and N inputs of phase detectors (20), each of which is connected in series with its analog-to-digital converter (ADC) 19 and (ADC) 21. In addition, the signal from the output of GO 1 is fed to the heterodyne inputs of all PD 20.

4. From the outputs of the ADC 19 and ADC 21, the signals are fed to the corresponding inputs of the first (1 PKA) 22 and second (2 PCF) 23 switches.

5. In accordance with the program of work, the control signal of the computer sequentially connects the outputs of switches 1 KPA 22 and 2 KPF 23, through computers and (ADC) 19 and (ADC) 21, to the inputs of the third and fourth switches of amplitudes (3 PKA) 27 and phases (4 PKF) 28.

6. In accordance with the computer program of work, in the time intervals between the signals of each channel received by the computer, it measures the amplitudes and phases of the signals and remembers them.

7. In accordance with the program of work, the computer selects the channel with the smallest amplitude and middle phase, and, with the help of attenuators 13 and phase shifters 14, in a closed circuit with feedback, the signal amplitudes in the channels are aligned with the smallest amplitude and middle phase.

After that, all emitters emit in phase with the same amplitudes of the EMF, therefore, in accordance with the Huygens-Fresnel principle, a uniform in amplitude and phase EMF is formed in the near-side region of the PAR. Turn off the computer.

8. The support, with the measurement object placed on it, is placed in the near headlamp zone at a distance L from its aperture. The dimensions of the object should not exceed the dimensions of the PAR headlight.

The transmitter of the radio measuring installation generates sounding signals of frequency F + f in the form of short radio pulses of duration τ, a fraction of μs, with pauses - duty cycle (T), which depends on the distance L.

9. Irradiate the object with sounding signals.

To ensure the operation of the installation, the duration of the duty cycle and radio pulses must satisfy the inequalities:

where c is the speed of light.

During the duty cycle T, the receiver 10 receives radio pulses reflected from the object.

10. Using the receiver 10 measure and record the power of the signal reflected from the object, after which it is removed from the support. A reference reflector with a known EPR value is placed on a support, the power of the signal reflected from the reference is measured and recorded.

The ESR of the measured object σ _about determined by the formula (2):

where σ _about - EPR of the measured object;

σ _et - EPR standard;

Rob is the power of the signal reflected from the object;

Rat is the power of the signal reflected from the standard.

The technical result of the invention is achieved: the area of the EMF front, uniform in phase and amplitude, is increased to the area of the PAR aperture, which makes it possible to measure large objects in comparison with the antenna aperture of the prototype of the same area, and the accuracy of EPR measurements is increased due to the uniform EMF in the near area of the PAR.

Features of the invention

The transmit-receive antenna is made in the form of a flat phased antenna array with N channels.

Introduced: reference signal generator, first, second and third mixers, high-pass filter, pulse generator, pulse modulator, power amplifier, circulator, a system of √N + 1 splitters, each splitter has √n outputs, N splitters with two outputs, N attenuators, N phase shifters, N channel emitters, a phased array antenna tuner that has N signal inputs from the outputs of the third mixers, N first outputs of the attenuator control signals and N second outputs of the phase rotation control signals lyami.

The output of the reference frequency signal generator is connected to the heterodyne inputs of the first, second and third mixers and the heterodyne signal input of the tuner, the signal input of the first mixer is connected to the generator output, and the output of the first mixer is connected to the input of the high-pass filter.

The output of the generator is connected to the heterodyne inputs of the second and third mixers, the output of the high-pass filter is connected to the signal input of the power amplifier, the output of which is connected to the input of the circulator, the output-input of the circulator is connected to the input of the first splitter of the system from √ N + 1 splitters, the outputs of the first splitter are connected with inputs of other √N splitters, the outputs of which form N channels of a phased array antenna.

Each channel is connected in series: a coupler, an attenuator, a phase shifter and a radiator, and the second outputs of the couplers are connected to the signal inputs of the third mixers, the outputs of which are connected to the inputs of the tuner, the first N outputs of which are connected to the inputs of the control signals of the attenuators, and the second N outputs are connected to inputs of control signals of phase shifters.

The output of the circulator is connected to the signal input of the second mixer, the output of which is connected to the input of the receiver, and the pulse generator, pulse modulator and the input of the modulating signal of the power amplifier are connected in series.

Literature

1. J.R. Mentser. Diffraction and scattering of radio waves. m.: Sov. Radio, 1958.

2. E.N. Meisels, V.A. Merchants. Measuring the dispersion characteristics of radar targets. M .: Sov. radio, 1972, p. 59, fig. 3.1.a.

3. G.G. Valeev. “Single Antenna Meter for Polarization Matrix”. RF patent No. 2352952, IPC G01R 29/08, 2007.

4. Kartashkin A.S. "Radio surveillance of air objects." M .: RadioSoft, 2014.

Claims (1)

A radio measuring device for measuring an effective scattering surface of objects, comprising: a generator, a receiver and a transceiver antenna, characterized in that the transceiver antenna is made in the form of a flat phased antenna array with N channels, in addition, the following are introduced: a reference frequency signal generator, the first , the second and third mixers, a high-pass filter, a pulse generator, a pulse modulator, a power amplifier, a circulator, a system of √N + 1 splitters, each splitter has √N outputs, N taps with d knowing the outputs, N attenuators, N phase shifters, N channel emitters, a phased array antenna tuner that has N signal inputs from the outputs of the third mixers, N first outputs of the attenuator control signals and N second outputs of the phase shifter control signals, the output of the reference frequency generator being connected to the heterodyne inputs of the first, second and third mixers and the input of the local oscillator signal of the tuner, the signal input of the first mixer is connected to the output of the generator, and the output of the first mixer is connected inen with the input of the high-pass filter, in addition, the output of the generator is connected to the heterodyne inputs of the second and third mixers, the output of the high-pass filter is connected to the signal input of the power amplifier, the output of which is connected to the input of the circulator, the output-input of the circulator is connected to the input of the first splitter of the system √N + 1 splitters, the outputs of the first splitter are connected to the inputs of other √N splitters, the outputs of which form the N channels of the phased array antenna, are connected in series in each channel: b, an attenuator, a phase shifter and a radiator, the second outputs of the couplers being connected to the signal inputs of the third mixers, the outputs of which are connected to the inputs of the tuner, the first N outputs of which are connected to the inputs of the control signals of the attenuators, and the second N outputs are connected to the inputs of the control signals of the phase shifters, except Moreover, the output of the circulator is connected to the signal input of the second mixer, the output of which is connected to the input of the receiver, the pulse generator, pulse modulator and the input of the modulating signal ilitelya power are connected in series.

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