Method of Automatic Target Angle Tracking by Monopulse Radar under Conditions of Interference Distorting Location Characteristic

• US 20120013500A1
• Filed: 07/15/2010
• Published: 01/19/2012
• Est. Priority Date: 07/15/2010
• Status: Active Grant

• Current Assignee: Evgeny Markin
• Original Assignee: Evgeny Markin
• Inventors: Markin, Evgeny
• Granted Patent: US 8,896,483 B2
• Time in Patent Office: Days
• US Class Current: 342/149
• CPC Class Codes: G01S 3/08 Means for reducing polarisation errors, e.g. by use of Adcock or spaced loop antenna systems
• CPC Class Codes: G01S 3/325 Automatic tracking systems
• CPC Class Codes: H01Q 25/02 providing sum and difference patterns H01Q25/04 takes precedence

Abstract

Method of automatic target angle tracking by sum-and-difference monopulse radar covers radiolocation sphere and specifically monopulse direction finding systems. It can be used in order to increase guidance accuracy, for example, for anti aircraft missiles and of unmanned aerial vehicles to radar targets such as: radio beacons; aerial vehicles reflecting the radio signal that illuminates them; aerial vehicles and ground-based devices radiating radio signals and jamming signals. The aim of the method consists in the assurance of reliability and stability and in the enhancement of guidance accuracy of automatic target angle tracking due to elimination of automatic tracking losses and great errors arising during the influence of the signals of orthogonal polarization or polarization close to it.

The proposed method provides full protection from polarization jamming for all types of monopulse radars.

Claims

1. A method of automatic target angle tracking by the sum-and-difference monopulse radio direction-finder, said method comprising at least the following steps:

the receiving signals from the target by the monopulse antenna on the fixed polarization angle;

the difference signal amplitude is measured;

the phase difference value between the sum signal and difference signal is calculated;

the monopulse antenna is orientated in the direction of the target, said direction is calculated using said calculated values of the amplitude as the angular error value and the phase difference sign as and the angular error sign;

receiving additional signal component from the target on the different polarization direction, said different polarization direction being different in direction from that of working polarization of said monopulse antenna;

a difference value is calculated by subtracting amplitude value of said signal component from the amplitude value of the sum channel;

during the time interval when said difference value is less than a zero the orientation of the monopulse antenna is performed relying on the value of angular error, the sign of said angular error corresponds to the said phase difference value between said sum and said difference signals, and the value of said angular error is the formed by reverse conversion of the said signal amplitude values.

2. A radio direction-finder comprises

monopulse antenna, preferably a paraboloid of revolution with two-mode feed, with the vertical working polarization;

polarization filter mounted in the mouth of said monopulse antenna;

the outputs of said monopulse antenna are connected to the sum-and-difference device in the form of stripline ring or hybrid T-joint;

the sum output of said sum-and-difference device is connected to the first mixer and the difference output is connected to the second mixer;

first and second mixers are also connected to heterodyne;

said heterodyne is also connected to third mixer;

the signal input of said third mixer is connected to horn antenna having the horizontal working polarization, orthogonal relatively to the working polarization of said monopulse antenna and aperture (mouth) area 0.5 . . . 1.2λ

²;

said horn antenna is mounted on any convenient place of said monopulse antenna;

the outputs of said first and second mixers are connected to the inputs of the first and second intermediate-frequency amplifiers respectively;

the outputs of said first and second intermediate-frequency amplifiers are connected to the appropriate inputs of phase detector;

the output of said phase detector through error-signal amplifier is connected to drive mechanism of said monopulse antenna with polarization filter;

said polarization filter is located under radome;

first and third intermediate-frequency amplifiers are connected through first and second detectors to the appropriate inputs of a compare means (comparator);

the output of said g device;

the outputs of said first and second intermediate-frequency amplifiers are also connected to the appropriate inputs of said compare means the output of said automatic gain control system with said first and second intermediate-frequency amplifiers.

3. The A radio direction-finder as recited in claim 2, where said polarization filter has an ogival form.

4. The device as recited in claim 2, where said horn antenna is mounted on the edge of said monopulse antenna

5. The radio direction-finder comprises

monopulse antenna, preferably a paraboloid of revolution with two-mode feed, with polarization filter mounted in the mouth thereof, said monopulse antenna working polarization is vertical;

sum-and-difference device in the form of stripline ring or hybrid T-joint connected to outputs of said monopulse antenna;

the sum output of said sum-and-difference device (means) is connected to first mixer and the difference output of said sum-and-difference device (means) is connected to second mixer;

said first and second mixers are connected to heterodyne which is connected to third mixer;

the signal input of third mixer is connected to horn antenna having the horizontal working polarization orthogonal relatively to the working polarization of said monopulse antenna and aperture (mouth) area 0.5 . . . 1.2λ

²;

the outputs of said first and second mixers are connected to the inputs of first and second intermediate-frequency amplifiers, respectively;

the output of the first intermediate-frequency amplifier is connected to the input of automatic gain control system;

the output of said automatic gain control system is connected to said first and second intermediate-frequency amplifiers;

the outputs of said first and second intermediate-frequency amplifiers are connected to a phase detector, and the outputs of first and third intermediate-frequency amplifiers are connected through first and second detectors to the corresponding inputs of comparator;

the output of said comparator is connected to the control input of switching device;

the output of phase detector is connected to the signal input of said switching device;

the first output of said switching device is connected to drive mechanism of said monopulse antenna through error-signal amplifier;

the second output of said switching device through analog-to-digital converter, arithmetic unit, digital-to-analog converter and said error-signal amplifier is connected to said drive mechanism of said monopulse antenna.

6. The device as recited in claim 5, where said monopulse antenna is located under radome.

7. The device as recited in claim 5, where said monopulse antenna and having an ogival form.

8. The device as recited in claim 5, where said horn antenna is mounted on the any convenient place of monopulse antenna.

9. The device as recited in claim 5, where said horn antenna is mounted on the edge of said monopulse antenna.