JP3181405B2 - Radar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar antenna used in, for example, a long distance airborne radar apparatus, and more particularly to a radar antenna having a side lobe canceller for removing an interference signal.

[0002]

2. Description of the Related Art Generally, a radar apparatus for long-distance anti-aircraft includes an auxiliary antenna 2 in addition to a main antenna 1 as shown in FIG. Multiplied by weight w and sent to subtractor 4, main antenna 1
And a side lobe canceller that suppresses side lobes by subtracting from the received output of the receiver.

Specifically, as shown in FIG. 4, the gain of the main antenna 1 shows the maximum gain in the direction of θ = 0 with respect to the angle θ from the directional direction of the antenna beam, and the gain in the other directions. Low side lobes. On the other hand, the auxiliary antenna 2 is designed to have a gain that is uniform at almost all angles and has a level exceeding the side lobe level of the main antenna 1.

[0004] Expressed in the gain of the main antenna 1 _{G M} (θ), the gain of auxiliary antenna 2 _{G S} (θ), the complex weight _{w w = {G M (θ} ) / G S (θ)} e ^{By appropriately adjusting j} in accordance with the positional relationship between the main antenna 1 and the auxiliary antenna 2 and the direction of arrival of the interfering wave, it is possible to eliminate the interfering wave in the θ direction (of course, | w | By setting a limit, it works effectively only on the interfering wave incident from the side lobe direction).

Usually, there is a feedback loop for appropriately adjusting the value of the complex weight w.
The description is omitted here because it is not directly related to the present invention.

By the way, the gain of the auxiliary antenna 2 is made higher than the side lobe level of the main antenna 1, that is, |
The setting of G _M (θ) | <| G _S (θ) | comes from the demand of the system to make | w | a sufficiently small value.

Because, when | w |> 1, the noise input from the auxiliary antenna 2 side is amplified and the main antenna 1 is amplified.
This is because the sensitivity of the radar antenna is impaired. Further, since the value of w is determined by the side lobe of the main antenna 1 and the gain ratio of the auxiliary antenna 2 and fluctuates according to the side lobe pattern, the noise level fluctuates and the sensitivity of the system cannot be kept constant. It is.

Therefore, it is necessary to increase the gain of the auxiliary antenna 2 so as to satisfy | w | << 1, but it is necessary to have a wide beam width over the entire area where the side lobes of the main antenna 1 exist. Therefore, it is not always easy to realize, and the extent to which the side lobe of the main antenna 1 can be reduced and the extent to which the side lobe canceller operates (ie, the beam of the auxiliary antenna 2) Width) was usually a trade-off.

For these reasons, it has been very difficult to apply the side lobe canceller having the above configuration to a radar antenna which requires a high gain especially for the main antenna 1. Further, when flexible control such as controlling the antenna directivity according to the target distance is performed, there is a disadvantage that the side lobe canceller cannot cope with a change in the side lobe level.

[0010]

As described above, in the conventional radar antenna, when a high gain is required for the main antenna, the use of a low gain auxiliary antenna effectively reduces the side lobe of the main antenna. Could not be erased. In addition, when the radar beam is changed according to the target distance, the side lobe canceller cannot cope with the change in the side lobe level.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a side lobe canceller for a main antenna having a high gain can be formed by using a simple auxiliary antenna having a low gain. It is an object of the present invention to provide a radar antenna that can cope with disturbance in the lobe direction and that can cope with a change in side lobe level of a side lobe canceller even when a radar beam is changed according to a target distance.

[0012]

In order to achieve the above object, a radar antenna according to the present invention has a plurality of antenna elements arranged, and a plurality of reception signals for each antenna element or a plurality of reception signals divided and synthesized. Using a main antenna having an array antenna configuration for synthesizing a reception signal for each sub-array and a part or another antenna of the plurality of antenna elements, receiving an incoming wave from at least a direction different from the directional direction of the main antenna. An auxiliary antenna, and a side lobe canceller that cancels an incoming wave component from a side lobe direction for each of the received signals for each antenna element of the main antenna or the received signals for each of a plurality of subarrays, using the received signal of the auxiliary antenna. It comprises.

[0013]

In the radar antenna having the above configuration, the main antenna is configured as an array antenna, and the reception signal for each antenna element or the reception signals for each of a plurality of sub-arrays for dividing and synthesizing these reception signals are synthesized. A part of the plurality of antenna elements or another antenna is used, and the reception signal of the auxiliary antenna is received from each antenna element of the main antenna or the reception signal of each of the plurality of subarrays from the side lobe direction. Wave components are eliminated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the configuration of a radar antenna according to the present invention. In FIG. 1, the main antenna 1 has an antenna element 1a having n columns in an azimuth (AZ) direction and an elevation (E).
An array antenna is configured by arranging m rows in the L) direction. Then, the reception outputs of the antenna elements in the azimuth direction are combined and combined by m AZ combining units 111 to 11m, and the outputs of the AZ combining units 11 to 1m are converted into digital signals by A / D converters 121 to 12m. I do. Further, each A / D converter 121
１２12 m of digital output to subtracters 331 to 33 m to be described later.
And DBF (Digital Beamforming) using an array antenna is realized by sending the data to the EL synthesis unit 13 through the multiplexing unit. The main antenna 1 is configured to scan in all directions by a rotary drive mechanism (not shown).

On the other hand, the auxiliary antenna 2 is a simple one having a relatively low gain and covering all directions. The reception output of the auxiliary antenna 2 is converted into a digital signal by the A / D converter 21 and supplied to the side lobe canceller 3.

The side lobe canceller 3 distributes the digital reception signal from the auxiliary antenna 2 to m systems and supplies the signals to multipliers 311 to 31m provided in each system. The coefficients w1 to wm set by the coefficient generator 32 for each system are sent to multipliers 311 to 31m, multiplied by the coefficients corresponding to the digital reception signals, and the A / D of the main antenna 1 is multiplied.
It is configured to send to the subtracters 331 to 33m provided on the transmission lines of the converters 121 to 12m.

The subtraction results of the subtracters 331 to 33m are as follows:
As described above, the signals are sent to the EL synthesis unit 13 and fed back to the coefficient generator 32. The coefficient generator 32 determines the side lobe of the main antenna 1 from the subtraction result of each system, and generates coefficient strings w1 to wm for suppressing the side lobe.

That is, in the radar antenna having the above configuration, the main antenna 1 has an array antenna configuration, and although the gain of each antenna element is low, the reception output of each element is A.
A high antenna gain can be obtained by combining the signals in the Z combining units 111 to 11m and the EL combining unit 13. Therefore, the AZ-combined output is substantially the same as the pattern of the main antenna shown in FIG. 4 in the AZ direction, and the gain is approximately 1 / m of the final antenna gain.

In this state, in the side lobe canceller 3, the coefficient generator 32 receives the received signal for each system supplied to the EL combining section 13 of the main antenna 1, and
Is determined. Then, coefficients w1 to wm for suppressing the side lobe are generated. And
The digital reception signals of the auxiliary antenna 2 distributed to the m systems are multiplied by the corresponding coefficients, and subtracters 331 to 33m
The side lobe canceller 3 is operated for each system by subtracting from the corresponding AZ synthesis output (sub-array output). As a result, the gain required for the auxiliary antenna 2 is 1
/ M, it is possible to cover a wide range (in some cases, all directions) by using a simple auxiliary antenna 2. Thereafter, by performing EL combination, the gain as the main antenna 1 can be secured.

Further, there is an advantage that the characteristics of the side lobe canceller 3 are not deteriorated even when the beam directing direction is changed in accordance with the distance by changing the setting in the EL combining section 13. Thus, it is possible to cope with a wide range of interference in the side lobe direction, and to achieve the object of making the side lobe canceller cope with a change in the side lobe level even when the radar beam is changed according to the target distance.

The present invention is not limited to the above-described embodiment. As shown in FIG. 2, the main antenna 1 does not use the above-described AZ synthesizing unit, but uses the reflector 14 to provide n × m
(Only EL direction is shown in the figure) Antenna elements 11 to 1
Even when the received output of m is directly sent to the EL combining unit 13, the side lobe canceller 3 can be realized similarly. In this case, a multiplier and a subtracter are inserted for each antenna element to set the coefficient. In FIG. 2, FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted.

In the embodiment shown in FIG. 1, the AZ synthesizing unit 11
Although the side lobe canceller 3 is inserted between the EL synthesis unit 13 and the AZ synthesis units 111 to 11m.
Insert a multiplier and subtractor for each antenna element before input
A coefficient may be set. Alternatively, the side lobe canceller 3 may be inserted after the partial synthesis as a sub-array, and the sub-array may be further synthesized.

Further, it is possible to extend the auxiliary antenna 2 to a plurality, and it is also possible to realize the side lobe canceller 3 by analog processing. Further, the auxiliary antenna 2 does not always need to be provided independently.
May be used.

It goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0026]

As described above, according to the present invention, a side lobe canceller for a main antenna having a high gain can be formed using a simple auxiliary antenna having a low gain.
To provide a radar antenna which can cope with a wide range of interference in a side lobe direction, and which can make a side lobe canceller cope with a change in a side lobe level even when a radar beam is changed according to a target distance. Can be.

[Brief description of the drawings]

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

FIG. 2 is a block circuit diagram showing a configuration of another embodiment according to the present invention.

FIG. 3 is a block circuit diagram illustrating a configuration of a radar antenna including a conventional side lobe canceller.

FIG. 4 is a pattern waveform diagram showing a relationship between gains of a main antenna and an auxiliary antenna of a radar antenna.

[Explanation of symbols]

1 ... main antenna, 1a ... antenna element, 111 to 11 m
... AZ synthesis unit, 121 to 12 m ... A / D converter, 13 ...
EL combiner, 2 ... Auxiliary antenna, 21 ... A / D converter,
3: Sidelobe canceller, 311 to 31m: Multiplier, 32: Coefficient generator, 331 to 33m: Subtractor, w1
~ Wm ... coefficient.

Continuation of the front page (56) References JP-A-63-166305 (JP, A) JP-A-63-166304 (JP, A) JP-A-62-263482 (JP, A) JP-A-4-116485 (JP) JP-A-4-297883 (JP, A) JP-A-2-39704 (JP, A) JP-A-60-150304 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G01S 7/00-7/42 G01S 13/00-13/95

Claims (8)

(57) [Claims] 1. A main antenna having an array antenna configuration in which a plurality of antenna elements are arranged and a received signal for each antenna element is combined; and a direction different from at least a directional direction of the main antenna provided separately from the main antenna. An auxiliary antenna that receives an incoming wave from the antenna, and a side signal that eliminates an incoming wave component from a side lobe direction for each of the received signals before combining for each antenna element that constitutes the main antenna using the received signal of the auxiliary antenna. A radar antenna comprising: a lobe canceller; wherein the main antenna synthesizes and outputs an antenna element reception signal from which an incoming wave component from a side lobe direction has been eliminated by the side lobe canceller in accordance with a beam directing direction. . 2. The apparatus according to claim 1, wherein the main antenna includes a first analog / digital converter that converts a received signal for each antenna element into a digital signal, and the auxiliary antenna converts a received signal into a digital signal. An analog / digital converter, wherein the side lobe canceller includes the second analog / digital converter.
A signal distribution unit that distributes the digital reception signal on the auxiliary antenna side output from the digital conversion unit to a system corresponding to the number of digital reception signals on the main antenna side, and is independent of each digital reception signal distributed by this signal distribution unit A multiplication unit that multiplies the obtained coefficient, a subtraction unit that subtracts a calculation output of the corresponding multiplication unit from a plurality of digital reception signals on the main antenna side output from the first analog / digital conversion unit,
2. The radar antenna according to claim 1, further comprising: a coefficient generator that generates the coefficient in accordance with a side lobe level, wherein the main antenna combines and outputs an output of the subtractor in accordance with a beam directing direction. 3. . 3. A radar antenna having an array antenna configuration in which a plurality of antenna elements are arranged, wherein a part of the plurality of antenna elements is shared with a main antenna for an auxiliary antenna, and the auxiliary antenna and the main antenna are mutually separated. It shall form a reception beam independently, and using an antenna element reception signal for the auxiliary antenna,
The main antenna includes a side lobe canceller for eliminating an incoming wave component from a side lobe direction for each of the antenna element reception signals for the main antenna.The main antenna has an incoming wave component from the side lobe direction eliminated by the side lobe canceller. A radar antenna for combining and outputting antenna element reception signals according to a beam directing direction. 4. An analog / digital converter for converting received signals of a plurality of antenna elements constituting the main antenna and the auxiliary antenna into digital signals, respectively, wherein the side lobe canceller includes the analog / digital converter. A signal distribution unit that distributes the digital reception signal on the auxiliary antenna side output from the system to a system corresponding to the number of digital reception signals on the main antenna side, and an independent coefficient for each digital reception signal distributed by the signal distribution unit. A multiplying unit for multiplying, a subtracting unit for subtracting an arithmetic output of the corresponding multiplying unit from a plurality of digital reception signals on the main antenna side output from the analog / digital converting unit, and generating the coefficient according to a side lobe level. A mains antenna that outputs the output of the subtraction unit in accordance with the beam directing direction. The radar antenna according to claim 3, wherein the output. 5. A plurality of antenna elements are arranged, respectively.
A plurality of sub-arrays for dividing and synthesizing the received signal for each antenna element, a main antenna having an array antenna configuration for synthesizing the received signal for each sub-array, and provided separately from the main antenna, at least the directional direction of the main antenna An auxiliary antenna that receives an incoming wave from a different direction, and a side lobe canceller that cancels an incoming wave component from a side lobe direction for each of the sub-array received signals constituting the main antenna using the received signal of the auxiliary antenna. A radar antenna, comprising: a main antenna that combines and outputs a sub-array received signal from which an incoming wave component from a side lobe direction has been eliminated by the side lobe canceller in accordance with a beam directing direction. 6. The main antenna includes a first analog / digital conversion unit that converts a received signal for each of a plurality of sub-arrays into a digital signal, and the auxiliary antenna converts a received signal into a digital signal. Wherein the side lobe canceller includes the second analog / digital converter.
A signal distribution unit that distributes the digital reception signal on the auxiliary antenna side output from the digital conversion unit to a system corresponding to the number of digital reception signals on the main antenna side, and is independent of each digital reception signal distributed by this signal distribution unit A multiplication unit that multiplies the obtained coefficient, a subtraction unit that subtracts a calculation output of the corresponding multiplication unit from a plurality of digital reception signals on the main antenna side output from the first analog / digital conversion unit,
The radar antenna according to claim 5, further comprising: a coefficient generation unit that generates the coefficient in accordance with a side lobe level, wherein the main antenna synthesizes and outputs an output of the subtraction unit in accordance with a beam directing direction. . 7. A radar antenna having an array antenna configuration comprising a plurality of sub-arrays for arranging a plurality of antenna elements and dividing and synthesizing a received signal for each antenna element, and synthesizing a received signal for each sub-array, A part of the subarray is shared for an auxiliary antenna, and the auxiliary antenna and the main antenna form a reception beam independently of each other. The main antenna is configured by using a subarray reception signal for the auxiliary antenna. A side lobe canceller that cancels an incoming wave component from a side lobe direction for each of the sub array received signals, wherein the main antenna has a sub array received signal from which an incoming wave component from a side lobe direction has been eliminated by the side lobe canceller. Characterized in that they are combined and output according to the beam direction. Radar antenna. 8. An analog / digital converter for converting a plurality of sub-array received signals constituting the main antenna and the auxiliary antenna into digital signals, wherein the side lobe canceller outputs from the analog / digital converter. Signal distribution unit for distributing the digital reception signal on the auxiliary antenna side to a system corresponding to the number of digital reception signals on the main antenna side, and multiplication by multiplying each digital reception signal distributed by the signal distribution unit by an independent coefficient. And a subtraction unit for subtracting the operation output of the corresponding multiplication unit from a plurality of digital reception signals on the main antenna side output from the analog / digital conversion unit, and a coefficient for generating the coefficient according to a sidelobe level A generating unit, wherein the main antenna combines and outputs the output of the subtracting unit in accordance with the beam directing direction. The radar antenna according to claim 7, wherein that.