JP2000031736A - Phase mono-pulse antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute optionally extension of an azimuth detection range in the phase mono-pulse antenna system, optimization of antenna directivity and revision of a characteristic. SOLUTION: The antenna system has two antennas 21, 22 where a plurality of antenna elements are configured with arrangement of a comb-line (or in one column), and the antennas 21, 22 are placed opposite to each other in a way that the lengthwise directions of comb teeth (or columnar directions) are inparallel with each other and the phase centers are deviated by a prescribed amount in the lengthwise directions of comb teeth. Then the lengthwise directions of comb teeth (or columnar directions) of the comb lines of the array antennas 21, 22 are placed in parallel with an azimuth angle detection plane of the antenna system. Thus the phase center interval L0 is set without being affected by the interval of the antenna elements 13, the size and number of the elements 13 or the like by shifting optionally the array antennas 21, 22 in the lengthwise directions of comb teeth to detect an azimuth angle. Furthermore, only a phase difference within an azimuth angle detection plane can be detected by eliminating a deviation of the phase center in other directions than the azimuth angle detection plane of the array antennas 21, 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase monopulse type antenna device which uses two array antennas composed of a plurality of antenna elements and detects a direction of arrival of a radio wave from a phase difference between received waves of the two array antennas. Related to the configuration.

[0002]

2. Description of the Related Art In a phase monopulse type antenna apparatus, as shown in FIG. 7, two antennas are arranged side by side, a phase difference Δφ of a received wave is detected, and an arrival direction of a radio wave is determined based on the phase difference Δφ. (Azimuth angle θ).

FIG. 8 shows a configuration of a conventional antenna device of such a phase monopulse system. As shown in FIG. 8, in the phase monopulse antenna device, two array antennas 1 and 2 configured by arranging a plurality of antenna elements 3 in a row are arranged on the same plane in each of y in FIG.
They are arranged side by side in the axial direction. When plane waves arriving from the same direction are received by the array antennas 1 and 2, respectively, the phase difference Δφ of the received waves appearing at the ports P1 and P2 is expressed by the following equation (1).

[0004]

Δφ = (2π / λ) · L · sin θ (1) where λ is the wavelength at the operating frequency of the radio wave, L is the interval between the phase centers 1PC and 2PC of the two array antennas, θ
Represents the azimuth at which the radio wave arrives. Normally, the range of the detected phase difference in the phase monopulse method is -π <Δφ <π. Therefore, if the phase center interval L is λ / 2, −π / 2 <
θ <π / 2, and all azimuth angles on the front surface of the antenna device can be detected (see FIG. 9).

The interval d between the plurality of antenna elements 3 constituting each of the array antennas 1 and 2 is usually set in the range of λ / 2 to λ. In order to improve the gain, the number of rows of array antennas, that is, the number of comb teeth of a comb antenna may be increased. However, as shown in FIG. 8, in a configuration in which two array antennas are simply arranged in parallel in the y-axis direction, , The phase center interval L becomes several λ or more. Then, the detection range of the azimuth angle θ becomes narrow, and detection at a wide angle becomes impossible.

On the other hand, for example, Japanese Patent Application Laid-Open No. 9-16262
In the planar array antenna included in the monopulse radar device disclosed in Japanese Unexamined Patent Application Publication No. 6-2006, the phase center interval L between the two array antennas can be set to λ or less. FIG. 10 shows the configuration of this planar array antenna. As shown in the drawing, the two array antennas 5 and 6 are configured such that a plurality of antenna elements (microstrip antenna elements) 3 are arranged so as to form a comb-shaped comb tooth, and the two comb-teeth are engaged with each other. Two array antennas 5 and 6 are arranged to face each other. In the two array antennas 5 and 6, the phase center interval L in the y-axis direction perpendicular to the longitudinal direction of the comb teeth is determined according to the distance d _y between the comb teeth of each array antenna 5 and 6, and the number of comb teeth It is possible to make L equal to or smaller than λ even if is increased.

[0007]

However, FIG.
In the planar array antenna, spacing d _y of the antenna elements 3 of the array antenna 5 and 6, by the approaching of the antenna element having a normal lambda / 2 about a length, in order to reduce the amount of coupling between the antenna elements, lambda Must be set above. Since the distance d _y between the antenna elements 3 affects the phase center distance L between the two array antennas 5 and 6, the phase center distance L is set to λ / 2 or less in the antenna device of FIG. It becomes impossible.

In the antenna device shown in FIG.
The distance s (= d _y / 2) between the antenna element 3 of another array antenna adjacent in the y-axis direction needs to be constant. Therefore, in order to change L to a desired value, in the comb-shaped array antennas 5 and 6, the intervals s of all the antenna elements 3 in the y-axis direction are made the same, and then s is increased or decreased. Will be. But s
Changes, the gain and directivity of the entire antenna device change, and it is practically impossible to adjust L by changing the value of s. Therefore, s is fixed to a value at which the gain and the directivity of the array antenna are optimized, and then the phase centers 5PC and 6PC of the array antennas 5 and 6 are shifted as shown in FIG. A method of changing the interval L has to be adopted. Therefore, the phase center interval L
Can take only discrete values such as s, 2s, 3s,..., And has a problem that the degree of freedom in changing antenna characteristics is low and it is not easy to obtain optimum characteristics. is there.

In order to solve the above problems, the present invention provides
It is an object of the present invention to provide a phase monopulse antenna device that enables wide-angle azimuth detection and that can easily optimize and adjust the antenna gain and directivity.

[0010]

To achieve the above object, the present invention has the following features.

First, a phase monopulse antenna device according to the present invention has two array antennas each having a plurality of antenna elements arranged in a row or in a comb shape. The longitudinal directions of the comb teeth are arranged parallel to each other, and the phase centers of the array antennas are opposed to each other such that the phase centers of the array antennas are shifted from each other by a predetermined amount in the row direction or the comb tooth longitudinal direction. Further, a column direction or a comb tooth longitudinal direction of the two array antennas is arranged parallel to an azimuth angle detection surface of the antenna device.

With such a configuration, the phase center interval between the two array antennas for azimuth angle detection is
It can be set by shifting the array antennas in the column direction or the comb-shaped longitudinal direction of the comb teeth. The value of the phase center interval is not affected by the interval and size of the antenna elements. Therefore, the phase center interval and the number and interval of the antenna elements can be set independently of each other as required.

Another feature of the present invention is that, in the phase monopulse antenna device, at least one of the two array antennas has two or more rows, and further, the length of the row direction or the comb-shaped comb teeth That is, the phase centers of the array antennas in the direction orthogonal to the direction are arranged so as to coincide with each other.

With such a configuration, it is possible to prevent a phase difference from occurring in the received wave with respect to an angle component other than the plane direction of the detected azimuth plane, and it is desired to detect the direction in which the radio wave arrives. Even in the case where the direction fluctuates other than the direction, it is possible to detect the direction with high accuracy.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

[First Embodiment] FIG. 1 shows a configuration of a phase monopulse antenna device according to a first embodiment. 2
One of the array antenna 11 and 12, respectively, in parallel y-axis direction in the azimuth angle detection surface, a plurality of antenna elements 13 arranged in a row at intervals d _y is configured by connecting to each other. The two array antennas 11 and 12 are
The phase centers 11PC and 12PC in the y-axis direction are L
They are displaced by ₀ , are spaced apart by an interval s _x in the x-axis direction orthogonal to the y-axis direction, and are arranged point-symmetrically about the origin 0.

FIG. 2 shows the array antennas 11 and 12 according to the embodiment shown in FIG. 1 in which five antenna elements are arranged at an interval of d _y = 0.93λ by shifting the array antennas 11 and 12 by a predetermined amount in the negative and positive directions of the y-axis, respectively. It is arranged. Here, FIG.
(A), (b), (c) relative to the phase center distance L ₀ is respectively 0.5d _y caused by the deviation (0.465
λ), 1.5 d _y (1.395λ), 2.5 d _y (2.3
25λ). FIG. 3 shows the relationship between the azimuth angle θ and the phase difference (phase monopulse signal) Δφ ₀ of the received waves obtained by the array antennas 11 and 12 using the phase center interval L ₀ shown in FIG. 2 as a parameter. ing.

In the phase monopulse antenna device according to the first embodiment, the azimuth angle detection plane is a yz plane formed by the z axis orthogonal to both the y axis and the x axis and the y axis. With respect to the azimuth angle θ in the yz plane, the array antenna 1
The phase difference Δφ ₀ of the received wave appearing at the port P 1 of the No. 1 and the port P 2 of the array antenna 12 is expressed by the following equation (2).

[0019]

Δφ ₀ = (2π / λ) · L ₀ · sin θ (2) As is apparent from the above equation (2), the shift amount (phase center interval) L ₀ in the y-axis direction is zero. Then port P1
Difference Δ between the received wave (incident wave) generated at the port and the port P2
φ ₀ is always zero even when the direction changes, and the phase center interval L ₀
Increases, the amount of change in the detected phase difference Δφ ₀ with respect to the azimuth angle θ of the received wave increases. This is clear from FIG. That is, the L ₀ as shown in FIG. 2 0.465
When λ and 1.395λ, the relationship between Δφ ₀ and the azimuth angle θ is such that the slope of the characteristic line becomes steeper as the phase center interval L ₀ increases, and the detected phase difference Δ
The variation of φ ₀ is large. As a result, FIG.
As can be seen from the above, normally, the range of the detected phase difference in the phase monopulse method is -π <Δφ <π, and therefore L ₀
In the case of <λ / 2, the detected azimuth θ is | θ |> π / 2, whereas when L ₀ is increased, the value of | θ | decreases.

As described above, in the first embodiment, each of the two array antennas is connected to a plurality of antennas along the direction (y-axis direction) parallel to the azimuth angle detection plane (yz plane) to be detected. The elements are arranged in a line. Therefore,
By shifting the phase centers 11PC and 12PC of the two array antennas from each other in the y-axis direction, the phase center interval L ₀ can be set arbitrarily, and L ₀ <λ / 2 can be satisfied. The corner can be detected. Further, the distance d _y between the antenna elements 13 can be set to an optimum value irrespective of the phase center distance L _0, and the distance between the antenna elements can be freely set in order to generate the objective of setting the width and the gain of the directional beam to the optimum values. It is easy to realize a phase monopulse antenna device that can be set and has high performance.

[Second Embodiment] FIG. 4 shows a configuration of a phase monopulse antenna device according to a second embodiment. In the second embodiment, the two array antennas 21 and 22 are each configured by a comb array antenna having the same number of comb teeth arranged in the x-axis direction. By using a comb-shaped array antenna as shown in FIG. 4 instead of the row-shaped array antenna of the first embodiment, in the antenna device of the second embodiment, the beam width in the xz plane is narrowed to increase the directivity. It is possible.

These comb-shaped array antennas 21 and 2
As shown in FIG. 4, the two comb-tooth portions are formed by arranging a plurality of antenna elements 13 in a line along the y-axis direction and at a distance d _{y from} each other. The two array antennas 21 and 22 are arranged to face each other so that their comb teeth mesh with each other.

In the second embodiment, with respect to the phase center interval L ₀ in the y-axis direction, as in the first embodiment, the amount of change of the detected phase difference Δφ ₀ with respect to the azimuth θ, in other words, the azimuth θ Each array antenna 21,
22 can be set by shifting the phase centers 21PC and 22PC in the y-axis direction. Therefore, the distance d between the antenna elements 13
L ₀ can be set to an arbitrary value regardless of _y .

[0024] With such a configuration, in the second embodiment, not only by adjusting the distance d _y and the number of antenna elements y-axis direction of the antenna element 13, the number of antenna elements is further arranged in the x-axis direction (the comb By adjusting the number of teeth)
The beam width in the xz plane and the yz plane can be set arbitrarily. On the other hand, as described above, the phase center interval L ₀ between the two array antennas 21 and 22 can be arbitrarily set independently of the beam width or the like.

[Third Embodiment] A feature of the third embodiment is that the phase centers in the x-axis direction of the two comb-shaped array antennas 31 and 32 described in the second embodiment are matched with each other.

In the configuration of the first and second embodiments,
The two array antennas detect the azimuth θ of the radio wave arrival direction in the yz plane by being shifted by an arbitrary L _{0 in the} y-axis direction. However, since the phase centers of the two array antennas are also shifted in the x-axis direction, the positions of the received waves are actually changed at the ports P1 and P2 due to the change in the azimuth angle in the xy plane. A phase difference occurs, and an error occurs in the phase difference Δφ ₀ in the yz plane to be detected.

Therefore, in the third embodiment, as shown in FIG. 5, the phase center in the x-axis direction is matched by the two array antennas 31 and 32 so that the change in the azimuth angle in the xz plane is received. It prevents the wave from being generated as a phase difference.

In the antenna device of FIG. 5, the number of comb teeth (the number of columns) of one of the two array antennas (the antenna 31 in FIG. 5) is increased by one from that of the other antenna. Then, in the x-axis direction, the incremental comb teeth are arranged outside the outermost comb teeth of the array antenna 32 having the smaller number of comb teeth, so that the antenna element 13 of the array antenna 31 and the antenna element 13 are arranged. The distance between the antenna 32 and the antenna element 13 in the x direction is set to be s _x (= d _x / 2), and the phase centers of the two array antennas in the x axis direction are matched.

In the above example, since the number of comb teeth is different between the two array antennas 31 and 32, there is a slight difference between the beam widths in the xz plane between the two antennas. It hardly affects the phase difference Δφ _{0 that} appears and the characteristics of the antenna device. By using the configuration shown in FIG. 5 for the array antenna, it is possible to prevent the occurrence of a phase difference on the xz plane and to improve the characteristics of the phase monopulse antenna device.

Further, in the third embodiment, both the two array antennas 31 and 32 are not limited to the configuration having a plurality of comb teeth as shown in FIG. 5, but, for example, the row-shaped array of the first embodiment (see FIG. 1). One of the antennas 11 and 12 may be arranged in a row by increasing the number of rows to form a comb shape, and two comb teeth may sandwich a row forming the other antenna element.

FIG. 6 shows another configuration example of the third embodiment. In the configuration shown in FIG. 6, for example, when each of the array antennas 41 and 42 has two comb teeth, the comb teeth of the two array antennas are not engaged with each other alternately, but one of the array antennas (here, the antenna 42). Outside of the two comb teeth, the other array antenna (here, antenna 41)
Are arranged one by one. And
In FIG. 6, the phase centers of the two array antennas 41 and 42 in the x-axis direction are set so as to be near the center of the comb teeth of the array antenna 42 in the x-axis direction.

In the configuration shown in FIG. 6, the outside of the antenna element 13 of the array antenna 41 and the array antenna 42
Interval during which the inner adjacent antenna elements 13, and both s _x (vertical direction in the figure) on both sides, is set to be equal.

In the third embodiment, the phase centers 31PC and 32PC or 41PC and 42PC in the y-axis direction are used.
PC, as in Embodiment 2, the comb teeth to be able to shift only arbitrarily L ₀ each other by shifting from each other in the longitudinal direction and the number of comb teeth, distance d _y of the antenna elements, s _x
By setting the number of antenna elements arranged in the x-axis direction and the optimum value, the characteristics of the antenna device can be adjusted to desired ones.

[0034]

As described above, in the present invention, the phase center interval between two array antennas for azimuth angle detection can be arbitrarily set without being affected by the interval and size of antenna elements. It is easy to optimize the antenna characteristics and change the antenna characteristics.

In addition, it is possible to prevent a phase difference from occurring in a received wave with respect to an angle component other than the azimuth plane to be detected, and to improve the performance of the phase monopulse antenna device with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a phase monopulse antenna device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration when a phase center interval L ₀ of each array antenna of the first embodiment is shifted.

FIG. 3 shows a phase difference Δφ obtained when the interval between the phase centers of the two array antennas of the first embodiment is changed according to FIG. 2;
FIG. 6 is a diagram illustrating a relationship between ₀ and an azimuth angle θ.

FIG. 4 is a diagram illustrating a configuration of a phase monopulse antenna device according to a second embodiment.

FIG. 5 is a diagram illustrating a configuration of a phase monopulse antenna device according to a third embodiment.

FIG. 6 is a diagram illustrating a configuration of a phase monopulse antenna device according to a third embodiment different from that of FIG. 5;

FIG. 7 is a conceptual diagram illustrating the principle of the phase monopulse method.

FIG. 8 is a diagram showing a configuration of a conventional phase monopulse antenna device.

FIG. 9 is a diagram showing a relationship between a phase difference Δφ and a detected azimuth angle θ in a phase monopulse signal obtained in a conventional phase monopulse antenna device.

FIG. 10 is a diagram showing a configuration of a conventional phase monopulse antenna device different from FIG. 7;

11 is a diagram illustrating a method of changing a phase center interval L in the phase monopulse antenna device of FIG. 9;

[Explanation of symbols]

11, 12, 21, 22, 31, 32, 41, 42 Array antenna, 11PC, 12PC, 21PC, 22P
C, 31PC, 32PC, 41PC, 42pcp Phase center, 13 antenna elements, P1, P2 ports.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kujio Sakakibara 41-1, Oku-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture F-term in Toyota Central Research Laboratory Co., Ltd. 5J021 AA05 AA07 AA11 DA01 HA11 JA00 JA10 JA10 5J070 AA02 AC11 AD07 AD08 AK22

Claims (2)

[Claims] 1. An array antenna comprising a plurality of antenna elements arranged in a row or in a comb shape, wherein the two array antennas have their respective row directions or comb-shaped comb tooth longitudinal directions parallel to each other. And the phase centers of the array antennas are arranged to face each other such that the phase centers thereof are shifted from each other by a predetermined amount in the row direction or the comb tooth longitudinal direction, and the row direction or the comb tooth longitudinal direction of the two array antennas is an antenna. A phase monopulse antenna device, which is arranged parallel to an azimuth detection plane of the device. 2. The phase monopulse antenna device according to claim 1, wherein at least one of the two array antennas has two or more rows, and is orthogonal to the row direction or the comb tooth longitudinal direction. A phase monopulse antenna device, wherein the phase centers of the array antennas in directions are arranged so as to coincide with each other.