JP2544298B2 - Beam compression processing method of antenna pattern in radar - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an antenna pattern in a radar for improving the beam compression performance by removing the distortion of the combined reception pattern that occurs when the beam compression processing of the antenna pattern using the principle of the multiplication type array is performed. Beam compression method.

[0002]

2. Description of the Related Art In general, one of the indices indicating the goodness of an antenna pattern such as a receiving antenna is a beam width. The smaller the beam width, the better the performance as an antenna pattern. However, the beam width and the size (length) of the antenna are inversely proportional to each other. When the beam width is reduced, the antenna size increases, and when the antenna size is reduced, the beam width increases. Would.

For example, in a radar antenna, if the degree of discrimination of an object, that is, the resolution is to be doubled, the beam width must be halved, and the size of the antenna is doubled. When the size is doubled, not only the area occupied by the antenna becomes large, but also various adverse effects such as an increase in antenna weight and an increase in the size of the antenna support structure are caused. Conversely, if the size of the antenna is reduced to half, the beam width is doubled, and the discrimination degree is reduced to half.

As described above, it is well known that the beam width and the antenna size have contradictory properties. In most of the actual antennas, the area occupied by the antenna is limited, and therefore the beam width is compromised to some extent under such restrictions.

In order to improve such a problem, conventionally,
There is known a beam compression method for reducing the beam width by multiplying received signals of a plurality of antenna elements by using the principle of a multiplication type array. FIG. 7 is a diagram showing an antenna device that performs such beam compression. In the figure, 101 is a main antenna element composed of an array antenna in which a plurality of radiating elements are arranged in a straight line at equal intervals, and 102 is a sub-antenna element, which is a beam width direction to be compressed from the main antenna element 101. Are separated from each other in the X direction. Ten
Reference numeral 3 is a transmission circuit, and the transmission power obtained by the transmission circuit 103 is supplied to the main antenna element 101. Ten
4 is the received signal of the main antenna element 101 and the sub-antenna element 10
It is a multiplication circuit that multiplies the received signal of 2. In the drawing, the beam axis direction is a direction perpendicular to the XY plane, that is, the paper surface.

In the antenna device having such a structure,
The signals received by the respective antenna elements 101 1 and 102 are input to the multiplication circuit 104 with their phases aligned and subjected to multiplication processing,
For example, the directivity characteristics of the main antenna element 101 as shown in FIG. 8A and the sub-antenna element as shown in FIG. 8B.
The directivity characteristic of 102 is multiplied to obtain a combined directivity characteristic in which the beam width is compressed from θ _W to θ _WC as shown by the solid line in FIG.

[0007]

By the way, when the above-mentioned conventional antenna pattern beam compression method is applied to a radar, an effect equivalent to that of a beam being compressed can be obtained. However, even if scatterers of the same size in terms of radio waves exist at different positions due to the Grating's globe of the sub-antenna element 102, it is said that a pattern that will not be the same in the combined reception pattern after the multiplication processing is formed. There is a problem, that is, a problem of causing distortion in the combined reception pattern.

The present invention has been made in order to solve the above problems in the conventional antenna pattern beam compression processing method, and the antenna pattern beam in a radar that compresses the beam width and does not cause distortion of the combined reception pattern. An object is to provide a compression processing method.

[0009]

In order to solve the above problems, the present invention has a main antenna element for transmitting and receiving radio waves and a compression of the main antenna element with respect to the main antenna element. A step of preparing an antenna system composed of one or more reception-only sub-antenna elements arranged adjacent to each other in the beam width direction and with the beam axis aligned with the beam axis of the main antenna element; and the antenna beam of the antenna system Scanning in the direction of the beam width to be compressed, the radio wave transmitted from the main antenna element is reflected by the scatterer and returned, and is received by the main antenna element and the sub antenna element. A step of performing a multiplication process by matching the phases of the reception signals of the antenna element, and the reception signal of the main antenna element and the multiplication process. The step of performing the process of making the combined reception pattern output signal obtained in the step as an input signal to the radar display device, and the value of the combined reception pattern output signal for radar display processed as the radar display device input signal, the radar When the ratio to the maximum set value of the display device becomes a preset value or more, the ratio of the value of the radar display combined reception pattern output signal to the maximum set value of the radar display device is a preset value or more. The received signal for radar display of the main antenna element corresponding to the angular range of the beam width of the part is output as the final antenna pattern output signal instead of the combined received pattern output signal for radar display. And an output signal processing step for making the output signal of 0 to 0.

In general, when the beam compression method by the multiplication process is applied to the radar, as described above, the spread of the combined reception pattern near the position where the scatterer is present becomes small and the beam is compressed. Although an effect equivalent to is obtained, even if scatterers of the same size in terms of radio waves exist at different positions, the sizes may appear significantly different in the combined reception pattern. On the other hand, in the reception pattern of the main antenna element, the spread near the position where the scatterer is present is large, but when the scatterer of the same size in terms of radio waves is present, The size is almost the same and the distortion is small. In general, when displaying the received signal of the radar, the maximum set value of the radar display device is generally used in order to remove the influence of the side lobe because the dynamic range of the CRT used as the radar display device is only 10 dB. The method is to display only the received signals of 0.1 or more. Further, depending on the observation target, there is a case where a received signal having a value different from the maximum set value of 0.1 is displayed.

Therefore, as in the present invention, the magnitude of the product of the combined reception pattern output signal, which has been subjected to the multiplication processing to reduce the spread of the reception pattern, as the input signal for the radar display device is the maximum set value of the radar display device. When the ratio to the above is greater than or equal to a preset value, the main range corresponding to the angular range of the beam width of the portion where the ratio of the radar display combined reception pattern output signal to the maximum set value is greater than or equal to the preset value. When the radar display reception signal of the antenna element is output instead of the radar display combined reception pattern output signal, and the value of the radar display combined reception pattern output signal is less than the preset value in the ratio to the maximum set value. When the output signal of the antenna pattern is cut, the output signal of the combined reception pattern for radar display that has been multiplied is displayed in the radar table. The angle range of the beam width, which is equal to or larger than the preset value of the maximum set value of the device, is narrowed by the beam compression, and therefore the received signal for radar display of the main antenna element corresponding to the narrow angle range is finally output. It is output as a signal. Since the received signal of the main antenna element has little distortion, the beam width is eventually compressed and it is possible to obtain a received pattern without distortion.

The preset value of the ratio of the radar display combined reception pattern output signal to the maximum set value of the radar display device is generally 0.1, but a specific observation target, for example, For port radar, air traffic control radar, etc., it may be better to use a value different from the above ratio (0.1). Therefore, the value of the above ratio is set to an optimum numerical value in advance by experiments or the like according to each observation target.

[0013]

EXAMPLES Next, examples will be described. FIG. 1 is a diagram showing a schematic configuration of an antenna device for explaining an embodiment of a beam compression processing method for an antenna pattern according to the present invention. In the figure, 1 is a main antenna element for transmitting and receiving radio waves, and an antenna such as a horn antenna or an array antenna is used. 2 is a sub-antenna element dedicated to reception, and any antenna such as a dipole antenna, a horn antenna or an array antenna can be used,
The main antenna element 1 is arranged adjacent to the main antenna element 1 in the beam width direction (X direction) of the reception pattern to be compressed and with the beam axis (direction perpendicular to the XY plane) aligned. Reference numeral 3 is a transmission circuit, and the transmission power output from the transmission circuit 3 is supplied to the main antenna element 1 and transmitted from the main antenna element 1. Reference numeral 4 denotes a reception signal multiplication circuit and a signal processing circuit, which performs a multiplication process of the reception signal of the main antenna element 1 and the reception signal of the sub antenna element 2, and also a combined reception pattern output signal obtained by the multiplication process and the main antenna element 1. When the value of the radar display combined reception pattern output signal is 0.1 or more, which is the maximum set value of the radar display device, The reception signal for radar display of the main antenna element 1 corresponding to the angular range of the beam width of the combined reception pattern output signal is output as the final output signal instead of the combined reception pattern output signal for radar display, and the combined reception pattern for radar display is output. Do not output the final output signal of the antenna pattern when the output signal value is less than 0.1 which is the maximum setting value of the radar display device. Things.

The process of using the combined reception pattern output signal obtained by the multiplication process and the reception signal of the main antenna element as the input signal to the radar display device is performed for the following reason. That is, depending on the radar, the range of the scattering cross section of the object of the radar may be close to 100 dB, which is very large in most cases compared with the dynamic range of the radar display device of 10 dB. Therefore, a method is used in which the logarithm of the combined reception pattern output signal or the reception signal of the main antenna element is obtained and then input to the radar display device. The processing for obtaining this logarithmic value is the processing content.

In the thus constructed antenna device, the antenna beam is scanned while transmitting the radio wave from the main antenna element 1, and when the transmitted radio wave is reflected by the scatterer and returns, the main antenna element 1 and the sub antenna Antenna element 2
Outputs a reception signal corresponding to each antenna pattern. These reception outputs are matched in phase, and the multiplication circuit and the signal processing circuit 4 perform multiplication processing and signal processing,
With that output as the final output, the beam is compressed and an undistorted output is obtained.

2 to 4, a rectangular antenna having a uniform distribution in which the antenna length in the scanning direction is 10 times the reception wavelength is used as the main antenna element, and the antenna length in the scanning direction is 1 time the radio wave wavelength as the sub antenna element. When an antenna system is constructed by using a square antenna with a uniform distribution of, and the antenna system is scanned, +20 degrees, +10 degrees, 0 degrees, −
It is a figure which shows the simulation result of a received power pattern, when the point scatterers which are the same in terms of radio waves exist equidistant from the said antenna system in the 10 degree and -20 degree directions. Figure 2
FIG. 3 is a diagram showing a reception power pattern for radar display of a main antenna element, FIG. 3 is a diagram showing a reception power pattern by a beam compression processing method according to the present invention, and FIG. 4 is a synthetic reception for radar display by a conventional beam compression processing method. It is a figure which shows a power pattern. Each of these patterns is displayed based on the maximum value, and the downward arrow at the upper end of each figure indicates the position where the point scatterer exists.
2 and 4, the received power pattern of each point scatterer or the combined received power pattern shows a case where the maximum set value of the radar display device is 0.1 or more, and in FIG. 4 shows a received power pattern in the present invention corresponding to the case where the combined received power pattern in FIG. Is indicated by a dotted line.

As can be seen from these figures, according to the beam compression processing method of the present invention, the distortion of the pattern that occurs in the conventional beam compression processing method, that is, as shown in FIG. The closer to the 0 ° direction of the antenna rotation axis, the distortion that the reception power is reduced is removed, and the beam has a reception power pattern compressed from the antenna pattern of the main antenna element. That is, when the reflected radio wave is received by the single antenna element without performing the compression process, the angular range in which it is determined that the scatterer is present is, for example, 0 degree of the received power pattern of the main antenna element in FIG. In the part, the angle range is b _{1 to} b ₂ . When beam compression by multiplication process, when indicated by the portion of the same 0 ° in FIG. 4, the angular range of the scattering body narrows the range of a ₁ ~a _2. Therefore,
In the received power pattern of the main antenna element, by outputting only the values in this narrow angular range a _{1 to} a ₂ ,
As shown by the solid line in FIG. 3, a distortion-removed and beam-compressed received power pattern is obtained.

Next, a concrete configuration example of the antenna device used for carrying out the method of compressing the antenna pattern according to the present invention will be described with reference to FIG. In this configuration example, as the main antenna element 11 and the sub-antenna element 12, a circular patch array antenna is used to configure the antenna system,
The sub antenna element 12 is arranged so as to be separated from the main antenna element in the beam width (X direction) to be compressed. And the transmitter circuit
Transmission power is supplied to the main antenna element 11 from 13 and received signals of the main antenna element 11 and the sub antenna element 12 are input to the multiplication circuit and signal processing circuit 14 for processing.

The transmitting circuit 13 may have a known structure. As the multiplication circuit and the signal processing circuit 14, a known technique such as a means for converting a received signal into a digital signal by an A / D converter and then performing a multiplication operation and a signal value comparison by a computer can be used. FIG. 6 shows a configuration example of the multiplication circuit and the signal processing circuit 14. In FIG.
21 is a main antenna element, 22 is a sub-antenna element, 23 and 24 are receivers for receiving the radio waves captured by the respective antenna elements 21 and 22,
25 is a local oscillator that gives the same local signal to the receivers 23 and 24, 26 and 27 are A / D converters that convert the outputs of the receivers 23 and 24 into digital signals, and 28 is A / D converters 26 and 27. 29 is a signal processing circuit for performing processing for using the combined reception pattern output signal output from the multiplier 28 as an input signal to the radar display device, and 30 is a signal processing circuit 29.
A comparator for comparing the combined reception pattern output signal for radar display with a predetermined value of 0.1 times the maximum set value of the radar display device,
Reference numeral 31 is a signal processing circuit for processing the reception signal of the main antenna element converted into a digital signal by the A / D converter 26 as an input signal to the radar display device, and 32 is a control signal output from the comparator 30. In response, it is a drive circuit for driving and outputting the radar display main antenna element reception signal from the signal processing circuit 31.

In the multiplication circuit and the signal processing circuit configured as described above, the main antenna element 21 and the sub antenna element 22
The received signal received at is input to the receivers 23 and 24, and each of the receivers 23 and 24 obtains the same local signal from the local oscillator 25 and outputs the amplitude and phase of the power of the received signal. The outputs of these receivers 23 and 24 are input to A / D converters 26 and 27,
After being converted into a digital value, it is multiplied by the multiplier 28. The output of the multiplier 28 is passed through the processing circuit 29 and the comparator.
It is input to 30 and compared with a predetermined value of 0.1 times the maximum set value of the radar display device, the drive circuit 32 is driven by the control signal which is the comparison output, and the radar display of the main antenna element from the processing circuit 31. Control the output of the reception signal for.

In the configuration example of the above antenna device, one sub-antenna element is used, but a plurality of sub-antenna elements can be used, and a dipole antenna, a horn antenna,
Any antenna such as an array antenna can be used. The multiplication process when a plurality of sub-antenna elements are used can be performed by the following two methods. The first method is a method of adding the outputs of a plurality of sub-antenna elements and then multiplying by the output of the main antenna element. In this case, since the reception power of the sub-antenna element increases, one The antenna gain and S / N are better than in the case. The second method is a method of multiplying the outputs of the plurality of sub-antenna elements with the outputs of the main antenna element, respectively. In this case, the side lobe can be reduced together with the compression of the beam width.

[0022]

As described above based on the embodiments, according to the present invention, when the reception signals of the main antenna element and the sub-antenna element are multiplied, the combined reception pattern output signal obtained by the multiplication processing is obtained. Is further processed as an input signal for the radar display device and the ratio of the value of the value to the maximum set value of the radar display device is equal to or more than a preset value, the radar display of the value of the combined reception pattern output signal for radar display The radar display reception signal of the main antenna element corresponding to the angular range of the beam width of the portion where the ratio to the maximum set value of the device is a preset value or more is output instead of the radar display combined reception pattern output signal, In other cases, since the antenna pattern output signal is not output, the distortion of the reception pattern caused by conventional beam compression is removed. Together, it is possible to compress the beam width of the main antenna.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an antenna device for explaining an embodiment of a beam compression processing method for an antenna pattern according to the present invention.

FIG. 2 is a diagram showing a simulation result of a reception power pattern of a main antenna element.

FIG. 3 is a diagram showing a simulation result of a reception power pattern obtained by the beam compression processing according to the present invention.

FIG. 4 is a diagram showing a simulation result of a combined reception power pattern by a conventional beam compression processing method.

5 is a perspective view showing a specific configuration example of the antenna device shown in FIG.

6 is a block configuration diagram showing a specific configuration example of a multiplication circuit and a signal processing circuit shown in FIG.

FIG. 7 is a schematic configuration diagram showing an antenna device that performs a conventional antenna pattern compression process.

8 is a diagram showing directivity characteristics and combined directivity characteristics of each antenna element in the antenna device shown in FIG.

[Explanation of symbols]

 1 main antenna element 2 sub-antenna element 3 transmission circuit 4 multiplication circuit and signal processing circuit

Claims (2)

(57) [Claims] 1. A main antenna element that transmits and receives radio waves, is adjacent to the main antenna element in the beam width direction of the main antenna element to be compressed, and has a beam axis as the beam axis of the main antenna element. A step of preparing an antenna system composed of one or more reception-only sub-antenna elements arranged so as to coincide with each other, scanning an antenna beam of the antenna system in the beam width direction to be compressed, and transmitting from the main antenna element. A step of receiving the radio wave reflected by the scatterer and returning by the main antenna element and the sub antenna element,
In the beam compression processing method, which comprises a step of performing a multiplication process by matching the phases of the reception signals of the main antenna element and the sub-antenna element, a reception signal of the main antenna element and a combined reception pattern output signal obtained in the multiplication processing step, The step of performing the processing as an input signal to the radar display device, and the ratio of the value of the radar display combined reception pattern output signal processed as the radar display device input signal to the maximum set value of the radar display device is preset. If the ratio is equal to or more than the value set, the ratio of the value of the radar display combined reception pattern output signal to the maximum setting value of the radar display device corresponds to the angular range of the beam width of the part where the ratio is equal to or more than a preset value. Replacing the radar display reception signal of the main antenna element with the radar display combined reception pattern output signal Is outputted as the antenna pattern output signal, the antenna pattern beam compression method in the radar, characterized in that an output signal processing step with zero output signal of the antenna pattern otherwise. 2. The preset value of the ratio of the value of the combined reception pattern output signal for radar display to the maximum set value of the radar display device is 0.1. Beam compression method for antenna pattern in radar.