JP2880987B1 - Antenna device - Google Patents

Abstract

An antenna device capable of sufficiently suppressing an interference signal in a side lobe direction including the vicinity of a main lobe without causing interference with a main lobe of a main antenna. A pre-circuit (14) is provided. The pre-circuit (14) adjusts the gain of an antenna pattern (15) of an antenna (1) and an antenna pattern (16) of an auxiliary antenna (2) so that their peaks coincide with each other. A pre-circuit output pattern 19 corresponding to the difference between the antenna pattern 17 of the first antenna pattern and the antenna pattern 18 of the auxiliary antenna 2 is formed. Then, the pre-circuit output pattern 19 is used as a pattern of a partner for performing a correlation process with the antenna pattern 15 of the main antenna 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an adaptive antenna used as, for example, a side lobe canceller.

[0002]

2. Description of the Related Art Adaptive antennas are used for various purposes, but are often used as side lobe cancellers. FIG. 3 shows a configuration of a conventional adaptive antenna in such an application.

[0003] The adaptive antenna shown in FIG. 3 includes a main antenna 1 and an auxiliary antenna 2 such as a horn antenna.
And a receiver 3 and a receiver 4 connected to the main antenna 1 and the auxiliary antenna 2, respectively. The outputs of the respective receivers 3 and 4 are guided to an adaptive circuit 11 and subjected to a correlation process to obtain an output 10 as an antenna reception signal.

The adaptive circuit 11 includes a subtractor 5, multipliers 6 and 9, a low-pass filter (LPF) 7, and a gain adjuster 8. Then, the output of the subtracter 5 is taken out as the output 10, and a feedback loop is formed to guide a part of the output to the subtracter 5 again in the order of the multiplier 9, the gain adjuster 8, the low-pass filter 7, and the multiplier 6. .

[0005] The output of the subtracter 5 is compared in phase with the output of the receiver 4 in a multiplier 9, a signal corresponding to the phase difference is adjusted in level by a gain adjuster 8, and then guided to a low-pass filter 7. Thus, a DC signal having a level corresponding to the phase difference is generated. This DC signal is multiplied as a coefficient by a multiplier 6 to the output of the receiver 4, and the output of the multiplier 6 is
Is subtracted from the output of.

That is, in the adaptive circuit 11,
The antenna pattern of the main antenna 1 matches the antenna pattern of the auxiliary antenna 2 in the direction of arrival of the jamming radio wave. That is, in the direction of arrival of jamming radio waves,
A signal from the main antenna 1, a signal from the auxiliary antenna 2,
Nulls are formed in the direction by subtracting the gain and the phase while making the gain and the phase coincide with each other, thereby eliminating an adverse effect due to jamming radio waves.

However, in the above configuration, when the interfering signal arriving from the side lobe direction is suppressed, a considerable amount of interference with the main lobe occurs. For this reason, in the antenna pattern 17 seen in the output 10, performance degradation such as a decrease in the reception level of the main lobe and a change in the beam shape occurs.

Therefore, an antenna device disclosed in Japanese Unexamined Patent Publication No. 6-138205 has been proposed. In the antenna device disclosed in the above publication, the directivity of the auxiliary antenna has a null (zero point) in the main lobe direction in order to reduce interference of the main antenna with the main lobe.

[0009]

However, in such a system, although interference with the main lobe can be certainly reduced, it is not possible to suppress even interference with a side lobe near the main lobe. This is because it is possible to realize a directivity (a directivity from the vicinity of the main lobe to a steep null) from having a null in the main lobe direction and not reducing the gain in other directions (especially near the main lobe). Due to difficulties.

For this reason, the reception level in the side lobe direction near the main lobe is reduced, and it is still difficult to sufficiently suppress the interference signal.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide an antenna device capable of sufficiently suppressing an interference signal in a side lobe direction including the vicinity of a main lobe without causing interference with a main lobe of a main antenna.

[0012]

In order to achieve the above object, the present invention provides a main antenna forming a first antenna pattern and an auxiliary antenna forming a second antenna pattern different from the first antenna pattern. In the antenna device comprising: the main antenna and the auxiliary antenna in the main lobe direction of the main antenna after matching the reception gain, after subtracting the first antenna pattern from the second antenna pattern, Third with sensitivity zero in main lobe direction of main antenna
Pattern forming means for forming the antenna pattern of the antenna device, and performing a correlation process between the first antenna pattern and the third antenna pattern when a disturbance signal to the main antenna arrives, thereby obtaining an output pattern of the antenna device. And a disturbance signal suppressing means for forming a null in the direction of arrival of the disturbance signal.

In this case, the third antenna pattern formed by the pattern forming means is used as a partner pattern for performing correlation processing with the antenna pattern (first antenna pattern) of the main antenna. This third
Is formed by matching the reception gains of the main antenna and the auxiliary antenna in the main lobe direction of the main antenna, and then subtracting the first antenna pattern from the second antenna pattern. . As a result, an antenna pattern having a null in the main lobe direction and exhibiting directivity in which the gain does not decrease in other directions (especially in the vicinity of the main lobe) can be realized as the third antenna pattern.

By performing the correlation processing on the first and third antenna patterns, it is possible to form a reception pattern having a null in the arrival direction of the interfering signal without reducing the reception level in the side lobe direction near the main lobe. . As a result, it is possible to sufficiently suppress the interfering signal without lowering the reception level of the main lobe of the main antenna.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration of an antenna device according to an embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals, and only different parts will be described here.

The antenna device shown in FIG. 1 includes, in addition to the antenna device having the configuration shown in FIG.
1, a pre-circuit 14 is provided.
The pre-circuit 14 adjusts the amplitude and phase of the branch output from the receiver 3, and subtracts the output of the amplitude-phase adjuster 12 from the output of the receiver 4 to the adaptive circuit 11. And a subtractor 13 for leading to.

The amplitude and phase adjuster 12 is, for example, as shown in FIG.
As shown in the figure, the variable attenuator 121 and the variable phase shifter 122 are connected in series.

Here, the gains of the receivers 3 and 4 and the variable attenuator 121 are the reception gain in the main lobe direction in the antenna pattern 15 of the main antenna 1 and the reception gain in the direction in the antenna pattern 16 of the auxiliary antenna. Are fixedly set in advance so that Similarly, the amount of phase shift in the variable phase shifter 122 is also determined by the receiver 3,
4 are fixedly set so that the outputs of the four coincide with each other.

In the above configuration, the difference between the antenna pattern 17 of the main antenna 1 after the gain adjustment and the antenna pattern 18 of the auxiliary antenna 2 after the gain adjustment in the output of the subtractor 13 is obtained. Circuit output pattern 1
9 is formed.

The pre-circuit output pattern 19 is supplied to the adaptive circuit 11 together with the antenna pattern 15 of the main antenna 1 whose gain is not adjusted by the pre-circuit 14.

The adaptive circuit 11 performs a correlation process between the pre-circuit output pattern 19 and the antenna pattern 15 of the main antenna 1. That is, the subtractor 5 is provided with the antenna pattern 20 of the main antenna 1 and the antenna pattern of the auxiliary antenna 2 having the same gain and phase in the direction of arrival of the interfering signal by the correlation processing in the adaptive circuit 11. Therefore, as the antenna pattern 23 at the output 10 as the difference between the two patterns, a pattern in which nulls are formed in the arrival direction of the interference signal can be obtained.

At this time, the pre-circuit output pattern 19 is
It has a shape having a sharp recess toward the main lobe direction of the main antenna. Thereby, it is possible to eliminate the interference of the main antenna 1 in the side lobe direction at the output of the subtracter 5.

Thus, in the present embodiment, the pre-circuit 14
The antenna circuit 15 of the antenna 1 and the antenna pattern 1 of the auxiliary antenna 2 are
6 and the gain is adjusted so that their peaks coincide with each other.
It corresponds to the difference between the antenna pattern 17 of the antenna 1 and the antenna pattern 18 of the auxiliary antenna 2 after the gain adjustment.
A pre-circuit output pattern 19 is formed. Then, the pre-circuit output pattern 19 is used as a pattern of a partner for performing a correlation process with the antenna pattern 15 of the main antenna 1.

In this way, it is possible to realize the pre-circuit output pattern 19 having a null in the main lobe direction of the main antenna 1 and having a sharp decrease in gain in this direction. In the adaptive circuit 11, by performing a correlation process between the pre-circuit output pattern 19 and the antenna pattern 15 of the main antenna 1, the antenna pattern 23 at the output 10 has a null in the arrival direction of the interference signal and In the main lobe direction, a pattern in which the gain does not decrease can be obtained.

Therefore, it is possible to sufficiently suppress the interfering signal coming from the side lobe direction near the main lobe without causing interference with the main lobe of the main antenna 1.

The present invention is not limited to the above embodiment. For example, although not shown, the receivers 3 and 4
A so-called DBF (Digital Beam Form) that provides an analog / digital converter at each output stage, converts received signals into digital signals, and performs beam forming by arithmetic processing.
ing) The present invention can be applied to a radar. In the case of such a configuration, as shown in FIG. 2B, the amplitude / phase adjuster 12 is realized as an arithmetic unit that multiplies a digital conversion signal output from the receiver 3 by a complex coefficient.

The main antenna 1 can be realized as an active phased array antenna.
In this case, the main lobe direction of the main antenna 1 moves for beam scanning.
And the phase shift amount of the variable phase shifter 122 are changed so that the reception gain in the main lobe direction in the antenna pattern 15 of the main antenna 1 and the reception gain in the direction in the antenna pattern 16 of the auxiliary antenna are matched. What should I do?

Further, in order to apply the present invention to a DBF radar that performs beam scanning, as shown in FIG. It is realized as an arithmetic unit that multiplies an optimum complex coefficient for each scanning angle. This complex coefficient is output from the memory 100 or the like which outputs the optimum complex coefficient by giving the beam scanning angle as its address, for example.
2 should be given. Also, there are various circuit types for the adaptive circuit 11, and the same applies to other circuit types.

In addition, various modifications can be made without departing from the spirit of the present invention, such as the form of the main antenna 1.

[0030]

As described above in detail, according to the present invention, the pattern forming means is provided so that the reception gains of the main antenna and the auxiliary antenna in the main lobe direction of the main antenna are matched. By subtracting the first antenna pattern from the second antenna pattern, a third antenna pattern having a zero point of sensitivity in the main lobe direction of the main antenna is formed, and the third antenna pattern is Since the first antenna pattern is used as a pattern of a partner that performs correlation processing, the interference signal from the side lobe direction including the vicinity of the main lobe is sufficiently suppressed without causing interference with the main lobe of the main antenna. It is possible to provide a suitable antenna device.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of an antenna device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of an amplitude / phase adjuster used in the embodiment.

FIG. 3 is a functional block diagram showing a configuration of a conventional antenna device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main antenna 2 ... Auxiliary antennas 3, 4 ... Receiver 5 ... Subtractor 6, 9 ... Multiplier 7 ... Low-pass filter 8 ... Gain adjuster 10 ... Output 11 ... Adaptive circuit 12 ... Amplitude phase adjuster 13 ... Subtraction Device 14: Pre-circuit 15: Antenna pattern of main antenna 1 16: Antenna pattern of auxiliary antenna 2 17: Antenna pattern of main antenna 1 after gain adjustment 18: Antenna pattern of auxiliary antenna 2 after gain adjustment 19: Prefix Circuit output pattern 20: Antenna pattern of main antenna 1 21: Antenna pattern of auxiliary antenna 2 corresponding to output of front circuit 14 after gain adjustment 22: Antenna pattern of main antenna 1 after gain adjustment 23: Antenna at output 10 Pattern 100 ... memory

Claims (6)

(57) [Claims] 1. A main antenna forming a first antenna pattern and a second antenna different from the first antenna pattern.
An antenna device comprising: an auxiliary antenna that forms an antenna pattern according to claim 1; wherein the reception gains of the main antenna and the auxiliary antenna in the main lobe direction of the main antenna are made to match each other, and Pattern forming means for forming a third antenna pattern having a zero point of sensitivity in the main lobe direction of the main antenna by subtracting the antenna pattern of the main antenna; An antenna characterized by comprising interference signal suppressing means for performing a correlation process between an antenna pattern and the third antenna pattern to form a null in an arrival direction of the interference signal in an output pattern of the antenna device. apparatus. 2. The interfering signal suppressing means sets the receiving characteristic indicated by the first antenna pattern and the receiving characteristic indicated by the third antenna pattern to coincide in the arrival direction of the interfering signal. 2. The method according to claim 1, wherein a difference between the first antenna pattern and the third antenna pattern is taken to form a null in an arrival direction of the interference signal in an output pattern of the antenna device. Antenna device. 3. A main receiver and an auxiliary receiver connected to the main antenna and the auxiliary antenna, respectively, wherein the pattern forming means comprises: a gain relating to a signal received from the main receiver; And a gain related to the received signal of the main antenna in the main lobe direction of the main antenna, and a variable gain adjustment unit, the gain of which is adjusted by the variable gain adjustment unit, the reception signal from the main receiver and the auxiliary receiver The antenna device according to claim 1, further comprising: a variable phase shift unit that matches a phase of the received signal with the phase of the received signal. 4. The apparatus further comprises two analog / digital converters respectively connected to the main receiver and the auxiliary receiver, wherein the pattern forming means includes a digital signal output from the two analog / digital converters. The antenna device according to claim 1, wherein the third antenna pattern is formed by performing an arithmetic process of multiplying a complex coefficient based on the third antenna pattern. 5. When an active phased array antenna that performs beam scanning in an observation direction is used as the main antenna, the pattern forming unit includes: a main antenna in a main beam direction of the main antenna that moves by the beam scanning. And by matching the reception gain of the auxiliary antenna and subtracting the first antenna pattern from the second antenna pattern, a third antenna pattern having a zero point of sensitivity in the main beam direction of the main antenna 2. The antenna device according to claim 1, wherein the antenna device is formed. 6. A digital signal output from the two analog / digital converters, further comprising two analog / digital converters connected to the main receiver and the auxiliary receiver, respectively. The antenna device according to claim 5, wherein the third antenna pattern is formed by performing an arithmetic process for setting an optimum complex coefficient for each beam scanning angle when multiplying the complex coefficient based on the above. .