JP2573321B2 - Beam scanning reflector antenna - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam scanning type reflector antenna used for transmitting and receiving radio waves in a microwave band and a millimeter wave band.

[Conventional technology]

FIG. 4 shows, for example, JDKraus, Antennas ″, Mc GRAW-Hill
1 is a view showing a configuration of a cylindrical parabolic antenna which is a conventional beam scanning type reflector antenna shown in FIG.
(2a, 2b, 2c, 2d) are a plurality of primary radiators. When a rectangular coordinate system X, Y, Z having a reference direction as the positive direction of the Z-axis is set on the cylindrical parabolic antenna, the reflecting mirror 1 has a cross-sectional shape of the reflecting mirror 1 in a plane parallel to the ZX plane. It always has the same shape, with a point on the Y axis as the focal point, and a straight line connecting the focal point and the vertex given by a parabola parallel to the Z axis.

The conventional cylindrical parabolic antenna is configured as described above, and has one primary radiator 2 provided on the Y axis.
Is reflected by the above-mentioned reflecting mirror 1 so that the wavefront in a plane parallel to the YZ axis is an arc, and ZX
A wavefront in a plane parallel to the plane is converted into a radio wave given by a straight line parallel to the X axis. Therefore, the radiation pattern of the radio wave by the reflecting mirror 1 has a broad beam in the YZ plane,
It has a sharp beam in the ZX plane.

Next, when a plurality of the primary radiators 2 are provided on the Y axis and the primary radiators 2 are excited in the same phase, the radio waves radiated from the plurality of the primary radiators 2 are in a plane parallel to the YZ plane. The wavefront is given by a straight line parallel to the Y-axis, and the wavefront after being reflected by the reflecting mirror 1 is a plane wave traveling in the positive direction of the Z-axis. Therefore, the radiation pattern by the reflecting mirror 1 has a sharp beam in both the YZ plane and the ZX plane, with the beam direction being the positive direction of the Z axis.

Further, as shown in FIG. 5, the excitation phase of the plurality of primary radiators 2 is changed so that the wavefront 3a of a radio wave radiated from the plurality of primary radiators 2 in a plane parallel to the YZ plane becomes an XY plane. When a straight line having a constant angle β is formed, the wavefront reflected by the reflecting mirror 1 becomes a plane plate 3b that forms the angle β with the positive direction of the Z axis in the YZ plane. Therefore, the radiation pattern by the reflecting mirror 1 is such that the beam direction 4 is the plane wave 3b
Has a sharp beam in both the YZ plane and the ZX plane.

Thus, in the conventional cylindrical parabolic antenna, the excitation phases of the plurality of primary radiators 2 are controlled,
By scanning the main beam of the radio wave radiated from the primary radiator 2, the beam radiated from the cylindrical parabolic antenna can be scanned in a certain plane.

[Problems to be solved by the invention]

In the conventional beam-scanning reflector antenna as shown in FIG. 4, the radiation beam of radio waves can be scanned one-dimensionally in a certain plane, but it must be scanned in a certain curved surface or two-dimensionally. However, there is a problem that the directivity is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is configured to be able to scan a radiation beam of a radio wave within a certain curved surface, thereby improving a directivity. The purpose is to obtain.

[Means for solving the problem]

The beam scanning type reflector antenna according to the present invention is a reflector.
11 and a plurality of primary radiators 2, and the reflector 11 is a reflector antenna having a reference direction of a radiation beam as a Z-axis and a direction of arrangement of the plurality of primary radiators orthogonal to the Z-axis as a Y-axis. Each cross-sectional shape in a plane parallel to the ZX plane of the orthogonal coordinate system X, Y, Z set to is given by a parabola having the same focal length,
Further, a straight line connecting the focal point and the vertex of the parabola is orthogonal to the Y axis of the orthogonal coordinate system, and the angle formed by the straight line and the YZ plane changes in shape corresponding to the value of the Y coordinate. It is assumed that.

[Action]

In the present invention, the traveling direction of the plane wave after being reflected by the reflecting mirror 11 changes according to the value of the Y coordinate of the reflecting mirror 11.
Thus, a plurality of primary radiators 2 set in parallel with the Y axis
When the excitation phase of the reflector 11 changes and the area of the reflector 11 to which the radio wave radiated from the primary radiator 2 is mainly irradiated is changed, the reflector 11
The direction of the radio wave radiated from is changed. Therefore, the beam direction of the radio wave radiated from the plurality of primary radiators 2 is YZ
By scanning on a plane, the beam of the radio wave radiated from the reflecting mirror 11 can be scanned on a curved surface other than the YZ plane.

(Example of the invention)

FIG. 1 is a perspective view of a beam scanning type reflector antenna according to one embodiment of the present invention. In the figure, 11 is a reflecting mirror for reflecting a radio wave, and 2 (2a, 2b, 2c, 2d, 2e) are a plurality of primary radiators. When the reflecting mirror 11 sets an orthogonal coordinate system X, Y, Z with the reference direction as the positive direction of the Z axis, each cross-sectional shape of the reflecting mirror 11 in a plane parallel to the ZX plane has the same focal length. Given as a parabola, a straight line connecting the focal point and the vertex of the parabola is orthogonal to the Y axis of the orthogonal coordinate system, and the angle between the straight line and the YX plane changes in accordance with the value of the Y coordinate. I have.

That is, the reflecting mirror 11 is a parabolic curve in which the mirror surface curve in the ZX plane of the orthogonal coordinate system X, Y, Z set to the reflecting mirror antenna is focused on the origin of the orthogonal coordinate system and has a vertex on the negative axis of the Z axis. The mirror surface curve in a plane parallel to the ZX plane is given by a parabola having a focus on the Y axis, and the angle between the straight line connecting the focus and the vertex of the parabola and the YZ plane is the Y coordinate. The shape changes according to the value.

Specifically, an X 'axis and a Z' (see FIG. 2) respectively parallel to the X axis and the Z axis are set in a plane parallel to the ZX plane shown in FIG. The sectional shape of the reflecting mirror 11 in the Z'X 'plane is given by a parabola whose focal length is R, and a straight line Zo connecting the focal point and the vertex of the parabola is orthogonal to the Y axis at the focal point, and The reflecting mirror 11 is represented by a shape in which the angle α between the Zo and YZ planes is given by a function of the Y coordinate.

Next, as shown in FIG. 1, a plurality of primary radiators 2 are set in parallel with the Y axis, and the excitation phase of the primary radiators 2 is controlled in the same manner as in a conventional beam-scanning reflector antenna to control the primary radiators 2. The traveling direction of the radio wave radiated from the radiator 2 can be changed in the YZ plane, and the area of the reflecting mirror 11 mainly irradiated can be changed. In the reflecting mirror 11, since the traveling directions of the radio waves after being reflected by the reflecting mirror 11 are different in the respective regions having different Y coordinates, the radiation beam can be scanned in a curved surface other than the YZ plane. Therefore, by setting the function of the angle α and the Y coordinate according to the purpose, the X component and the Y component of the unit vector indicating the beam direction can be variously changed as shown by the curve 5a or 5b in FIG. .

〔The invention's effect〕

As described above, according to the beam scanning reflector antenna of the present invention, the reference direction of the radiation beam is set to the Z axis, and the arrangement direction of the plurality of primary radiators orthogonal to the Z axis is set to the Y axis. Each cross-sectional shape in a plane parallel to the ZX plane of the set orthogonal coordinate system X, Y, Z is given by a parabola having the same focal length, and a straight line connecting the focus and the vertex of the parabola is a Y axis of the orthogonal coordinate system. And a reflecting mirror having a shape in which the angle between the straight line and the YZ plane changes in accordance with the value of the Y coordinate, the radiation beam emitted from the plurality of primary radiators is provided. When the direction is scanned in the YZ plane, the beam radiated from the reflecting mirror is scanned in a certain curved surface other than the YZ plane, so that the effect of improving the directivity is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a beam scanning type reflector antenna according to one embodiment of the present invention, FIG. 2 is a diagram showing a cross-sectional shape of the reflector of this embodiment, and FIG. FIG. 4 is a perspective view of a conventional beam scanning reflector antenna, and FIG. 6 is a diagram showing the principle of the beam scanning reflector antenna. 2,2a ~ 2e: Primary radiator, 11: Reflector.

Claims (1)

(57) [Claims] 1. A radio wave radiation beam is scanned by changing an excitation phase of a plurality of primary radiators, comprising a reflecting mirror for reflecting a radio wave and a plurality of primary radiators for feeding the reflecting mirror. In the above-described beam scanning type reflector antenna, the reflector is provided on the reflector antenna with the reference direction of the radiation beam as the Z axis and the arrangement direction of the plurality of primary radiators orthogonal to the Z axis as the Y axis. Each cross-sectional shape in the plane parallel to the ZX plane of the set orthogonal coordinate system X, Y, Z is given by a parabola having the same focal length, and a straight line connecting the focal point and the vertex of the parabola is further defined by the orthogonal coordinate system. A beam scanning reflector antenna having a shape orthogonal to the Y axis and having an angle between the straight line and the YZ plane that changes in accordance with the value of the Y coordinate.