JPH07104408B2 - Antenna pattern processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna pattern processing apparatus capable of two-dimensionally compressing the beam width of an antenna pattern in a monopulse power feeding type antenna apparatus and reducing side lobes.

[0002]

2. Description of the Related Art Generally, not only a receiving antenna, but also one of the indexes showing the goodness of an antenna pattern is a beam width and a side lobe. The smaller the beam width or the smaller the side lobe, the more the antenna pattern becomes. The performance as is improved.

However, the beam width and the side lobe are in a contradictory relationship, and the beam width and the size (length) of the antenna are in an inversely proportional relationship. That is, when the size of the antenna is constant, the side lobe increases when the beam width is reduced, and the beam width increases when the side lobe is reduced. Further, when it is acceptable to change the size of the antenna, if the beam width is made small, the antenna becomes large, and if the antenna is made small, the beam width becomes large.

Therefore, for example, in the case of a radar antenna, first, regarding the relationship between the beam width and the side lobe,
When the side lobe is lowered, the beam width is widened, so that the resolution is deteriorated and the ability to discriminate the object is lowered, and there is a possibility that many objects are mistakenly recognized as one object. Conversely, if the beam width is reduced, the side lobe becomes large. Therefore, even if there is no object in the observation direction, if there is an object in the side lobe direction, it may be determined that there is an object in the observation direction. Regarding the relationship between the beam width and the size of the antenna, if the beam width is halved and the degree of identification of the object is doubled, the size of the antenna is doubled. If the size is doubled, not only the occupied area of the antenna becomes large, but also various problems such as an increase in weight of the antenna and an increase in size of the antenna support structure occur. On the contrary, if the size of the antenna is halved, the beam width will be doubled, and the discrimination will be halved.

As described above, since the beam width and the side lobe have the opposite properties, it is impossible to make both of them into an optimum state, and the beam width is minimized under a certain side lobe condition like Chebyshev distribution. , Or considering the distribution that minimizes the side lobes under certain beam width conditions, the beam width and side lobes are compromised to some extent. Further, the beam width and the size of the antenna also have the contradictory properties as described above, and in most practical antennas, the area occupied by the antenna and the like are limited. By the way, the current situation is to make a compromise.

In order to partially improve such a problem, conventionally, a beam compression for reducing the beam width by subtracting the difference signal pattern from the sum signal pattern of the reception signals of the same two antennas of the monopulse power feeding system. The method is known. FIG. 6 is a diagram showing an antenna device that performs such beam compression. Reference numerals 101 and 101 denote monopulse power feeding type antennas having a length a and a center-to-center distance d, and 102 denotes reception signals of the two antennas 101 and 101. Is a hybrid circuit that forms a sum signal Σ and a difference signal Δ, 103 is a detection circuit that detects the sum signal Σ and the difference signal Δ, and 104 is a subtraction circuit that subtracts the difference signal Δ from the sum signal Σ and outputs an antenna output signal. is there.

FIGS. 7 and 8 show a case where a horn antenna is used in which the antenna length a is about 25.7 times the received radio wave wavelength and the center-to-center distance d is the same value as a in the antenna device shown in FIG. It is a figure showing a simulation result of
The aperture plane distribution of the antenna is assumed to be a uniform distribution, and an electric field pattern (FIG. 7) and a power pattern (FIG. 8) normalized by the values when the angle is zero are shown. In these pattern diagrams, the broken line shows the sum signal Σ and the solid line shows the output pattern, and it can be seen that beam compression is performed.

[0008]

According to the above conventional beam compression method, the sum signal pattern which is the original antenna pattern is beam-compressed, but as can be seen from FIGS. 7 and 8, the output pattern has a large side lobe. Occurs.
That is, since the value of the difference signal Δ shows the maximum value in the vicinity of the value of the sum signal Σ becoming zero first, the value obtained by subtracting the value of the difference signal Δ from the value of the sum signal Σ is as shown in FIG. However, its magnitude b is considerably larger than the side lobe magnitude c of the sum signal pattern. Therefore, depending on the conventional beam compression method, the sum signal Σ
The side lobe becomes larger when the value of the difference signal Δ becomes larger than the value of, and beam compression is possible, but the side lobe becomes very large.

Further, the above-mentioned conventional method of performing beam compression uses only one antenna system consisting of two identical mono-pulse feeding type antennas, and can compress the beam width only one-dimensionally. , The discrimination ability is insufficient. That is, for example, if the main beam pattern when no beam compression is performed is a pattern 201 as shown in FIG. 9A, in this case, the five objects a, b, c, d, and e are identified. It is impossible. When this is one-dimensionally beam-compressed in the X direction, the compressed main beam pattern 202 becomes as shown in FIG. 9B, and the discrimination ability is improved as compared with the case where the beam compression is not performed, but it is still. There is a problem that the three objects a, c, and e cannot be discriminated, and the discrimination ability is insufficient.

The present invention has been made to solve the above-mentioned problems in the conventional beam compression method, and it is possible to improve the discrimination ability by performing beam compression in a two-dimensional manner and reduce side lobes in a two-dimensional manner. It is an object to provide a processing device for a possible antenna pattern.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has the same two features of the monopulse power feeding system.
One of Ri Do from the antenna, a first antenna system arranged to match the first direction is the beam width to be compressed,
Ri Do the same two antennas of a monopulse power feed system,
An antenna means composed of a second antenna system arranged such that its central axis coincides with the central axis of the first antenna system and coincides with a second direction orthogonal to the first direction ;
A means for scanning the antenna beam of the antenna means in a direction other than the first and second directions , a first antenna system and a second antenna system.
The received signal of each antenna of the antenna system is input, and the received signal of each antenna of the second antenna system is added to the signal obtained by subtracting the difference signal from the sum signal of the received signals of each antenna of the first antenna system. adding the signal obtained by subtracting those of the difference signal from the sum signal, the processing unit of the antenna pattern and a signal processing unit for outputting the sum signal as an output signal of the antenna means, the signal processing unit
Includes a comparing means , and outputs zero when the value of the sum signal of the first antenna system is less than or equal to the value of the difference signal or when the value of the sum signal of the second antenna system is less than or equal to the value of the difference signal.
2D beam compression and 2D low size
This makes it possible to make drobe.

In the antenna pattern processing method configured as described above, in the signal processing unit, the first and second
By subtracting the difference signal from the sum signal of the reception signals of the respective antennas of the first antenna system obtained by scanning in a direction other than the above, an output signal in which the beam width in the first direction is compressed is obtained. To be Similarly, the first and second ones
An output signal in which the beam width in the second direction is compressed is obtained by subtracting the difference signal from the sum signal of the reception signals of the respective antennas of the second antenna system obtained by scanning in a direction other than the direction. . Then, by adding these output signals, a two-dimensional beam-compressed antenna output signal in the first direction and the second direction can be obtained. Further, when the value of each sum signal of the first and second antenna systems is equal to or less than the value of each difference signal, zero is output to reduce the side lobes in the first and second directions. That is, since the side lobe becomes larger in a portion where the value of the difference signal is larger than that of the sum signal, the side lobe becomes smaller if the output in that portion is zero. Therefore, it is possible to compress the beam two-dimensionally and reduce the side lobes two-dimensionally. In the present invention, the antenna of the antenna means
Means for scanning the beam in a direction other than the first and second directions
I used it to scan the antenna beam.
Antenna beam of the antenna means in the first or second direction
Scan the beam in the second or first direction
No compression, only one-dimensional beam compression
Because the significance of using two sets of antenna systems is lost.
The means for scanning in a direction other than the first and second directions is 2
It is an essential requirement for dimensional beam compression.

[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 an antenna pattern processing method according to the present invention. In the figure, 1a and 1a are two receiving antennas of the same configuration of the monopulse power feeding system, and a horn antenna, an array antenna or the like is used, and they are arranged in the first direction (X direction) to form the first antenna system. I am configuring. Reference numerals 1b and 1b are also two receiving antennas of the same configuration of the monopulse power feeding system, which are horn antennas, array antennas, etc., and are arranged in the second direction (Y direction) orthogonal to the first direction and are arranged in the second direction. It constitutes the antenna system of. And this
The first and second two-antenna systems described above form antenna means.
The antenna means is in a direction other than the first and second directions.
Is configured to be scanned. 2a and 2b are hybrid circuits, the hybrid circuit 2a forms the sum signal Σ1 and the difference signal Δ1 of the reception signals from the two antennas 1a and 1a of the first antenna system, and the hybrid circuit 2b is the second circuit. Two antennas 1b of the antenna system,
The sum signal Σ2 and the difference signal Δ2 of the received signals from 1b are formed. Reference numerals 3a, 3a, 3b and 3b are detection circuits, and 4 is a signal processing unit, which is a sum signal Σ demodulated by the detection circuit.
A signal obtained by subtracting the difference signal Δ1 from 1 and a signal obtained by subtracting the difference signal Δ2 from the sum signal Σ2 are subjected to an addition process and output. At that time, the value of the sum signal Σ1 is equal to or less than the value of the difference signal Δ1. At this time, or when the value of the sum signal Σ2 is less than or equal to the value of the difference signal Δ2, the processing for making the output zero is performed.

When a radio wave arrives at the antenna device configured as described above, the hybrid circuit 2a which receives the received signal from the first antenna system receives the sum signal Σ1 corresponding to the sum signal pattern and the difference signal corresponding to the difference signal pattern. The signal Δ1 is output. Further, the hybrid circuit 2b to which the received signal from the second antenna system is input, the sum signal Σ2 corresponding to the sum signal pattern and the difference signal Δ2 corresponding to the difference signal pattern.
Is output. These outputs are detected by the detection circuits 3a, 3a, 3
After demodulation by b and 3b respectively, the signal processing unit 4 performs signal processing of adding a signal obtained by subtracting the difference signal Δ1 from the sum signal Σ1 and a signal obtained by subtracting the difference signal Δ2 from the sum signal Σ2. When the value of the sum signal Σ1 is less than or equal to the value of the difference signal Δ1, or when the value of the sum signal Σ2 is less than or equal to the value of the difference signal Δ2, the process of making the output zero is performed. As a result, an output corresponding to a pattern in which the beam width is two-dimensionally compressed and the side lobes are two-dimensionally reduced is obtained.

In FIG. 2, a square horn antenna having one side having a size six times the wavelength of the received radio wave is used as an antenna constituting the first antenna system and the second antenna system, and the first and second antenna systems are used. FIG. 8 is a diagram showing a simulation result when an antenna system in which the center distance between two antennas respectively configuring the above is set to about 8.48 times the received radio wave wavelength is used. At this time, it is assumed that the aperture plane distributions of all the antennas are uniform, and FIG. 2A shows a pattern obtained by adding the reception signals of the four square horn antennas forming each antenna system. (B) shows the two-dimensional beam-compressed and two-dimensional sidelobe-reduced patterns as contour plots, respectively, in dB display based on the origin value.
The values of 3, -6, -9, -12, -15, -18 and -21 are shown. From these patterns, it can be seen that the beam widths in the X and Y directions can be two-dimensionally compressed to about half, and the side lobes are two-dimensionally reduced.

Next, FIG. 3 shows a concrete configuration example of each antenna system of the antenna device. In this configuration example, the rectangular horn antenna 11 is used for both the first antenna system and the second antenna system.
a, 11a, 11b, 11b, the antennas 11a, 11a of the first antenna system are arranged in the first direction (X direction), and the antenna 1 of the second antenna system is
1b and 11b are arranged in the second direction (Y direction) with their antenna central axes aligned with the central axis of the first antenna system. The 12 Ri Oh Te support of the antenna system, the first
And the antenna device is scanned in a direction other than the second direction.
That it has been in.

As the signal processing unit, a general comparator, a differential amplifier or an adder circuit can be used for analog processing, and a detector output for digital processing. Known techniques can be used, such as a means for performing comparison, subtraction, and addition processing by a computer after the signal is converted into a digital signal by an A / D converter. An example thereof is shown in FIG. In the figure, 21, 22, 23, and 24 are A / D converters that convert the analog sum signal Σ1, difference signal Δ1, sum signal Σ2, and difference signal Δ2 demodulated by the detection circuit into digital signals, respectively. Reference numeral 25 is a computer, and when the sum signal Σ1 converted into a digital signal is larger than the difference signal Δ1 and the sum signal Σ2 is larger than the difference signal Δ2, a signal obtained by subtracting the difference signal Δ1 from the sum signal Σ1 is added to the sum signal. A value obtained by adding a signal obtained by subtracting the difference signal Δ2 from Σ2 is output, and zero is output in other cases.

In the above-described embodiment, the beam is formed by performing the same processing using the corrected difference signal obtained by multiplying the values of the difference signal Δ1 and the difference signal Δ2 by a coefficient larger than 1 as new difference signal Δ1 and difference signal Δ2. Further compression and side lobes can be further reduced. That is, in principle, the beam width can be made as small as possible and the side lobes can be made as small as possible by increasing the coefficient by which the difference signal Δ1 and the difference signal Δ2 are multiplied. As an example thereof, FIG. 5 shows a simulation result when the corrected difference signal obtained by doubling the values of the difference signal Δ1 and the difference signal Δ2 is processed as a new difference signal Δ1 and difference signal Δ2. The configuration of the antenna system at this time was the same as that of the simulation shown in FIG. FIG. 5 is a contour map display similar to that of FIG. 2B, and shows a two-dimensional beam compression and low sidelobe pattern.

[0019]

As described above with reference to the embodiments, according to the present invention, the beam width can be two-dimensionally compressed and the side lobes can be two-dimensionally reduced. Further, the corrected difference signal obtained by multiplying the values of the difference signal Δ1 and the difference signal Δ2 by a coefficient larger than 1 is used as the new difference signal Δ1 and the difference signal Δ2, whereby the beam can be further compressed and the side lobe can be reduced. .

[Brief description of drawings]

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

FIG. 2 is a diagram showing a combined pattern obtained by the antenna device shown in FIG.

FIG. 3 is a diagram showing a specific configuration example of an antenna system of an antenna device used for implementing the present invention.

FIG. 4 is a circuit configuration diagram showing a specific configuration example of a signal processing unit.

FIG. 5 is a diagram showing an output signal pattern when difference signals Δ1 and Δ2 multiplied by a coefficient are used.

FIG. 6 is a schematic diagram showing a conventional monopulse power feeding type antenna device for performing one-dimensional beam compression.

7 is a diagram showing an electric field pattern of an output signal of the antenna device shown in FIG.

8 is a diagram showing a power pattern of an output signal of the antenna device shown in FIG.

FIG. 9 is an explanatory diagram for explaining a discrimination ability by a main beam.

[Explanation of symbols]

 1a 1st antenna system antenna 1b 2nd antenna system antenna 2a, 2b Hybrid circuit 3a, 3b Detection circuit 4 Signal processing part

Claims (2)

[Claims] 1. A Ri Do the same two antennas of a monopulse power feed system, a first antenna system arranged to match the first direction is the beam width to be compressed, the same monopulse feeding system Ri Do from the two antennas, the central axis is coincident with the center axis of the first antenna system, formed by arranging to match the second direction and orthogonal to the first direction the
An antenna means arranged at a second antenna system, and means for scanning antenna beams of said antenna means in addition to the first and second directions, the first antenna system and the second antenna
The received signal of each antenna of the system is input, and the signal obtained by subtracting the difference signal from the sum signal of the received signals of the respective antennas of the first antenna system is added to the signal of the received signals of the respective antennas of the second antenna system. adding the signal obtained by subtracting those of the difference signal from the sum signal, the processing unit of the antenna pattern and a signal processing unit for outputting the sum signal as an output signal of the antenna means, said signal processing unit compares the hand
A stage, and outputs zero when the value of the sum signal of the first antenna system is less than or equal to the value of the difference signal or when the value of the sum signal of the second antenna system is less than or equal to the value of the difference signal.
Configured, processing device antenna pattern characterized in that to obtain the line 2D beam compression and two-dimensional low sidelobe to. Wherein Ri Do the same two antennas of a monopulse power feed system, a first antenna system arranged to match the first direction is the beam width to be compressed, the same monopulse feeding system Ri Do from the two antennas, the central axis is coincident with the center axis of the first antenna system, formed by arranging to match the second direction and orthogonal to the first direction the
An antenna means arranged at a second antenna system, and means for scanning antenna beams of said antenna means in addition to the first and second directions, the first antenna system and the second antenna
The received signal of each antenna of the system is input, and the signal obtained by subtracting the difference signal from the sum signal of the received signals of the respective antennas of the first antenna system is added to the signal of the received signals of the respective antennas of the second antenna system. adding the signal obtained by subtracting those of the difference signal from the sum signal, the processing unit of the antenna pattern and a signal processing unit for outputting the sum signal as an output signal of the antenna means, the signal processing section is a coefficient multiplication
Compensation difference signals are formed by multiplying the difference signals of the first antenna system and the second antenna system by a coefficient greater than 1 , and calculating the correction difference signals from the sum signals. When the value of the sum signal of the first antenna system is less than or equal to the value of the correction difference signal, or when the value of the sum signal of the second antenna system is less than or equal to the value of the correction difference signal. sometimes, and configured to output a zero, so obtain row two-dimensional beam compression and two-dimensional low-sidelobe
Processing apparatus antenna pattern characterized in that the.