JPS6319903A - Antenna system - Google Patents

Abstract

PURPOSE:To ensure the accurate tracking of a monopulse by using a memory storing the electric field level of a difference pattern of the main beam direction and setting this pattern at zero even when the zero point of sensitivity is set in the undesired radio wave arriving direction. CONSTITUTION:The N pieces of element antennas Ea1-EaN are divided into two groups and the signals of both groups are synthesized by a synthesizers 1 and 1. The sum signal SIGMA and the difference signal of both groups are produced by a hybrid circuit 6 and supplied to a receiver 2. When an angle instructing circuit 5 instructs the undesired wave arriving direction, a difference pattern auxiliary memory 7 set the sensitivity of the signal SIGMA at zero in said wave arriving direction end at the same time outputs the level square Ed obtained in the desired direction theta0 of the signal when a main beam is turned to the direction theta0 to a control processor 4. The processor 4 calculates the phase setting value of each of phase shifters Ps1-PsN by the nonlinear optimization method so that the sum of the square of the level in the undesired direction of the signal SIGMA, the difference square between the main beam direction level and the maximum level, and the square Ed is minimized. Then the phase setting value is delivered to a phase shifter controller 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an antenna device that forms a zero point at a desired angle other than the main beam of a radiation pattern by controlling a phase shifter connected to each element antenna. It is related to.

[Conventional technology]

FIG. 4 is a block diagram showing a conventional antenna device disclosed in, for example, Japanese Unexamined Patent Publication No. 57-38003. In FIG. 1, Eal, Ea2, . . . , EaN are element antennas, Psl, 'Ps2, . ...,
PslJ is a phase shifter.

il+ is a synthesizer, (2) is a receiver, and (3) is a phase shifter control device.

(4) is a control processor, and (5) is an angle instruction circuit.

Next, the operation will be explained. Here, the case where this antenna is used as a receiving device will be explained as an example. Radio waves received by the element antennas Ea1, Ea2, . . . , RaN are passed through phase shifters Ps1. Ps2,..., Pa
The phase can be changed by N. Next, the output signals of each phase shifter are combined by a combiner (1). This combined signal is transmitted to the receiver (2). When performing normal beam scanning, the control processor (4) calculates the setting amount of each phase shifter necessary for beam scanning, and according to the calculation result of the control processor, the phase shifter control device (3) Set the phase shifter and perform beam scanning. The operation described above is that of a normal phased array antenna.

If interference waves or clutter are present, in addition to the above operations, it is necessary to form a zero point of the radiation pattern in the direction in which the unwanted waves arrive. At this time, a secondary operation is performed. First, the angle instruction circuit (5) instructs the control processor (4) about the arrival direction of unwanted waves such as jamming waves and clutter. The control processor (4) calculates the phase setting amount of the phase shifters Ps1゜Ps2, ..., PsN for maintaining the level in the main beam direction and forming the zero point of the radiation pattern in the arrival direction of the unnecessary waves. do. For this calculation method, use the steepest descent method, 5
6quentialUnconstrained M
Inimization Tschnique (SU
Nonlinear optimization methods such as MT) and conjugate gradient method were used.

All of the above-mentioned nonlinear optimization methods are methods in which the phase setting amount is changed and calculations are performed repeatedly in order to realize a desired radiation pattern.

Next, according to the calculation result of the phase setting amount, the phase shifter control device (3) controls the phase shifter Pa1. Pg2 ,..., Ps
N was set, and a zero point was formed in the direction of arrival of unnecessary waves.

[Problem that the invention seeks to solve]

The conventional antenna device was configured as described above. When using this antenna device for radar, etc. to perform monopulse tracking, in addition to the sum pattern formed by combining all element antennas in the same phase, it is necessary to form a difference pattern by dividing the aperture into two and combining them in opposite phase. There is. FIG. 5 is a diagram showing an antenna device for forming a sum pattern and a difference pattern.

In the figure, (6) is an Fi hybrid circuit. The hybrid circuit has input terminals A and B and output terminals C and D. The signal input from terminal A is Sa.

When the signal input from terminal B is sb, terminal C outputs a sum signal X-8a+Bb, and terminals 1 to 8 output difference signals 1-8a-8b.

When the phased array performs normal operation without forming a zero point, the signals received by each element antenna are combined in the same phase, so Sa # Sb.

The difference signal Δ becomes zero. Monopulse tracking tracks a target by detecting the amplitude ratio of the sum signal and difference signal.

In conventional antenna devices, when performing this monopulse tracking by forming the zero point of the radiation pattern, the signals received by each element antenna are not combined in phase, so Sa
+Sb. The radiation pattern at this time is shown in FIG. In the figure, solid lines indicate a sum pattern, and dotted lines indicate a difference pattern. As shown in FIG. 6, the angle at which the difference pattern takes the minimum value and the angle at which the sum pattern takes the maximum value deviate from each other. This has caused a problem in that the direction of the target cannot be accurately tracked.

This invention was made to solve the above-mentioned problems, and it is possible to form a zero point in the direction of arrival of unnecessary waves, and also to minimize the level of the difference pattern to enable accurate monopulse tracking. The purpose is to obtain an antenna device.

[Means for solving the problem] The antenna device according to the present invention enables accurate monopulse tracking by providing a difference pattern compensation memory into which the electric field level of the difference pattern in the main beam direction is input. .

[Effect]

The antenna device according to the present invention reads the electric field level of the difference pattern in the tracking direction from the difference pattern compensation memory, maximizes the electric field level of the sum pattern in the tracking direction, and minimizes the electric field level of the difference pattern to perform accurate monopulse tracking. However, the zero point of the sum pattern is formed in the direction of arrival of unnecessary waves, improving the signal-to-noise ratio.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing one embodiment of the present invention. In the figure, (7) is a difference pattern compensation memory.

Other parts are similar to the conventional device described above.

Next, the operation of this invention will be explained. First, the direction θ0 of the target to be tracked and the arrival direction θ1 of the unwanted wave are determined by the angle indicating circuit (5). θ2. ..., θ, are specified.

Here, the number of elements is N and θ. The amplitude of the element electric field in the direction a. 1
(1-1~N) 1 phase po i (1-' ”-N)
*θ,.

θ ..., the amplitude of the element electric field in the θ direction is -1 (1-2
'1~N, -1~M), θ1. θ2. ..., θ, the phase of the element electric field in the direction pk (1-1 to N, -1 to M)
, and element numbers 1 to N/2. It is assumed that the aperture is divided into two by two element groups (N/2+1)-N. The difference pattern compensation memory stores the calculated value of the next electric field.

After reading the value of Ea in the control processor (4).

The excitation phase qi (i g-1 to N) satisfying the following conditions is determined using a nonlinear optimization method.

However, here E is θ of the sum pattern before zero point formation. is the electric field in the direction. The first term in Equation (2) is a term indicating the calculation for forming a zero point in the direction of arrival of unnecessary waves.

The second term is the target direction θ of the sum pattern. The third term is a term that indicates the calculation to minimize the electric field level in the target direction of the difference pattern.

according to the excitation phase obtained as a result of this calculation.

If the phase shifters Pa1, Pa2, ..., PaN are set by the phase shifter control device (3), the difference pattern θ
. A zero point is obtained in the direction. FIG. 2 is a diagram showing a radiation pattern by the antenna device of the present invention. In the figure, a solid line indicates a sum pattern, and a dotted line indicates a difference pattern. From Figure 2, θ of the sum pattern. The main beam is directed in the direction θ1. θ29. ..., a zero point is formed in the θ7 direction. Also, the difference pattern θ.

A zero point is also formed in the direction. By using an antenna device having the above radiation nozzle.

At the same time as eliminating the influence of unnecessary waves, accurate mononuclear tracking becomes possible.

A flowchart of the control operation of the present invention is shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, since the difference-turn compensation circuit is provided to deepen the zero point of the electric field in the tracking direction of the difference pattern, it is possible to eliminate the influence of unnecessary waves and to perform accurate monopulse tracking. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
3 is a flowchart showing the control operation of the invention, FIG. 4 is a block diagram showing the configuration of a conventional antenna device, and FIG. 5 is a diagram showing a radiation pattern obtained by implementing the present invention. FIG. 6 is a block diagram showing a configuration when monopulse tracking is performed using an antenna device, and FIG. 6 is a diagram showing a radiation pattern obtained by a conventional antenna device. In Figure 1, Ka1, Ea2, -, RaN are element antennas, Psl, Pa2j..., Ps
N is a phase shifter, (11 is a combiner, (2) is a receiver, (3)
is a phase shifter control device, (4) is a control processor, (5) is an angle indicating circuit, (6) is a no-brid circuit, and (7) is a differential pattern compensation memory. In addition, in FIG. 1, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] a plurality of element antennas, a phase shifter connected to each of the element antennas, and a phase shifter control device that controls the phase shifter;
and a combiner that divides the element antenna into two groups, an A group and a B group, and combines the received signals of the element antennas belonging to the A group, and a combiner that combines the received signals of the element antennas belonging to the B group, The combined signals of the above two combiners are S_A, S_
When B, terminal C outputs the S_A+S_B signal.
a hybrid circuit having a terminal D that outputs the signals S_A-S_B, an instruction circuit that indicates the direction of arrival of the desired signal wave and a plurality of unnecessary signal waves, and a sum radiation pattern related to the output of the terminal C of the hybrid circuit. , the main beam of the sum radiation pattern is directed in the arrival direction of the desired signal wave, and the zero point of the sum radiation pattern is formed in the arrival direction of the unnecessary signal wave, and the terminal of the hybrid circuit is and a control processor that calculates a set phase to be applied to the phase shifter so that the level of the main beam in the differential radiation pattern related to the output signal of D is below a certain value.