JPH04108202A - Multi-beam antenna - Google Patents

Abstract

PURPOSE:To send and receive two radio waves in a largely different direction through the common use of a large part of a reflecting mirror by adopting a curved face decided by the weighted mean of coordinates of two different paraboloids of revolution for a curved face of the reflecting mirror and making the coordinate and a normal at the coordinate of the two paraboloids of revolution coincident with each other at a point around a center of the reflecting mirror. CONSTITUTION:A reflecting mirror 1 has a curved face obtained by weighted mean of two different paraboloids of revolution A, B, the coordinate of the paraboloids of revolution A, B is coincident at a point P around the center of the reflecting mirror 1 and a normal vector of the paraboloid of revolution A and a normal vector of the paraboloid of revolution B are coincident at the point P. Thus, the paraboloids of revolution A, B are almost coincident around the point P and also almost coincident over the entire face of the reflecting mirror 1. Then primary radiators 11-14 of a 1st group are placed near a focus FA of the paraboloid of revolution A and a primary radiator 21 of a 2nd group are placed near a focus FB of the paraboloid of revolution B. Thus, two radio waves in a different direction are sent and received by using most part of the reflecting mirror 1 in common.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a multi-beam antenna that transmits and receives a plurality of radio waves in different directions, particularly when the directions are significantly different when divided into two direction groups. Regarding antenna configuration technology.

(Conventional technology) In recent years, with the advancement of satellite utilization technology, a large number of satellites for transmission and reception have been launched into geostationary orbit, but it is difficult to install an antenna for each satellite due to space, cost, etc. Although this is not a good idea, research and development is underway into multi-beam antennas that can transmit and receive data from multiple satellites using a single antenna.

Conventionally, this type of multi-beam antenna uses a torus reflector R8 as shown in FIG. 3 (Japanese Patent Publication No. 5'1-6281). This is a reflecting mirror with a curved surface formed by rotating the torus around a straight line (torus rotation axis) 7 that is substantially perpendicular to its central axis. and two primary radiators 18,
19, but these are arranged at a position rotated by a beam separation angle δ around the torus rotation axis 7. In a multi-beam antenna, each beam has a use area 81.
, 82 are different, but the feature is that the area of the reflector 8 does not need to be increased by sharing a part of the area used.For example, four satellites are in geostationary orbit at 150° east longitude and 154° east longitude.
When the beam separation angle δ is around 10°, as in the case where the beam separation angle δ is arranged at 158°, 158°, and 162°, the reflector 8 is not so large.

(Problem to be Solved by the Invention) However, in addition to the four satellites (referred to as the first directional group), there is also a satellite located at, for example, 110° on the geostationary orbit (referred to as the second directional group). If you try to target it, the satellites in both directions will appear about 55 degrees apart when viewed from the ground.

In this case, in the conventional multi-beam antenna described above, the beam separation angle δ becomes around 55 degrees, and there is no part that can be shared by the usage area for the beam direction of the first direction group and the usage area for the beam direction of the second direction group. As a result, the area of the reflecting mirror 8 becomes large, and there is a problem that the original purpose of the multi-beam antenna is lost.

The present invention was made in view of these problems, and its purpose is to provide a multi-beam antenna that does not impair the original purpose even when a plurality of radio wave directions are divided into two direction groups and the directions are significantly different. Our goal is to provide the following.

(Means for Solving the Problems) In order to achieve the above object, the multi-beam antenna of the present invention has the following configuration.

That is, the multi-beam antenna of the present invention is a reflection system in which a curved surface having one point as its center is determined by a weighted average of the coordinate values of two mutually different paraboloids of revolution whose coordinate values and normal line coincide at one point. a mirror; one first primary radiator or a group of two or more first primary radiators disposed near one focal point of the two paraboloids of revolution; One second primary radiator or a group of two or more second primary radiators arranged near the other focal point.

(Function) Next, the function of the multi-beam antenna of the present invention configured as described above will be explained.

In the multi-beam antenna of the present invention, the curved surface of the reflecting mirror is a curved surface determined by the weighted average of the coordinate values of two different paraboloids of revolution, and these two paraboloids of revolution are located at a point near the center of the reflecting mirror. At a point, match its coordinate value and normal line. One or more primary radiators are arranged near the focal point of each of these two paraboloids of revolution.

As a result, the central axes of rotation of the two paraboloids of revolution intersect at a relatively large angle, so that radio waves in two groups of widely different directions can be transmitted and received by sharing most of the reflecting mirror.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a multi-beam antenna according to an embodiment of the present invention. This multi-beam antenna consists of a reflecting mirror 1, a first group of primary radiators (11° 12, 13, 14), and a second group of primary radiators 21 (one in this example). . In the following description, a case will be described in which the antenna of the present invention is used as a transmitting antenna, but due to the reversibility of the antenna, similar effects can be obtained when used as a receiving antenna.

In the configuration shown in FIG. 1, the electromagnetic waves radiated from the first group of primary radiators are reflected by the reflector 1, and then 31
, 32, 33, and 34 directions. On the other hand, the electromagnetic waves radiated from the primary radiators 21 of the second group are reflected by the reflecting mirror 1 and then radiated in a direction 41, which is significantly different from that of the first group.

Next, the principle of operation of the antenna of the present invention will be explained with reference to FIG.

The reflecting mirror 1 is a curved surface obtained as a weighted average of two different paraboloids of revolution A and B. That is, paraboloid of revolution A
When the formula of is ZA = f A (X, Y) and the formula of paraboloid of revolution B is Za = fs (X, Y), the reflecting mirror 1 is Z = ZAm + Zi (1m) -・"-- (1) Here, m is the weight of the weighted average.

This is 0≦m≦1 and is determined by the method described later.

The x, y, and z coordinates are determined as shown in Figure 2.

Further, as shown in FIG. 2, the paraboloids of revolution A and B have the same coordinate values at one point P near the center of the reflecting mirror 1, and Z^=2. ) Furthermore, the normal vector of the paraboloid of revolution A and the normal vector of the paraboloid of revolution B at point P are set to match. By doing so, the paraboloid of revolution A and the paraboloid of revolution B almost coincide with each other in the vicinity of the point P, and can also be made to substantially coincide with each other over the entire surface of the reflecting mirror 1.

Then, the first group of primary radiators (11, 12, 13, 14
> is located near the focal point FA of the paraboloid of revolution A, and the primary radiator 21 of the second group is located at the focal point F3 of the paraboloid of revolution B.

Now, consider the case where the weight m is 1 in equation (1), that is, the case where the reflecting mirror 1 coincides with the paraboloid of revolution A (Z"ZA). At this time, some light emitted from the point FA If we consider the rays of In other words, the beam can be emitted in the direction of the rotation center axis 51 without deterioration in efficiency due to phase errors.If we consider several light rays emitted from point F, these rays are reflected. After being reflected by mirror 1, it does not become a parallel ray, and an optical path length error occurs. However, since reflecting mirror 1 (equal to paraboloid of revolution A in this case) is approximately equal to paraboloid of revolution B,
The beam becomes approximately parallel to the rotation center axis 52 of the paraboloid of revolution B, and the beam can be emitted in the direction of the rotation center axis 52, although the efficiency is lowered due to a phase error.

Next, when the weight m is O in equation (1), that is, when the reflection Ml coincides with the paraboloid of rotation B (Z = Z
Consider B). In this case, the situation is opposite to the above case, and there is no decrease in efficiency due to phase error in the direction of the rotation center axis 52.
Further, the beam can be emitted in the direction of the rotation center axis 51 with a slight decrease in efficiency.

Furthermore, when m=05, the reflecting mirror 1 becomes a curved surface intermediate between the paraboloid of revolution A and the paraboloid of revolution B, and can radiate the beam in the direction of the central axis of rotation 51 and 52 with almost the same efficiency.

Here, since the rotation center axes 51 and 52 intersect at a relatively large angle, the re-radiated beams share most of the reflecting mirror 1 and are emitted in two largely different directions.

Furthermore, as is clear from the above explanation, the weight m is changed from O to 1.
By changing within the range of , it is possible to change the magnitude relationship of the efficiency of beam radiation in the directions of the rotation center axis 51 and the rotation center axis 52. Therefore, m may be determined depending on the magnitude of gain requirements in two different directions.

(Effects of the Invention) As explained above, according to the multi-beam antenna of the present invention, the curved surfaces of the two reflecting mirrors are defined by the weighted average of the coordinate values of two different paraboloids of revolution. The two paraboloids of revolution are located at 1 near the center of the reflecting mirror.
At a point, match its coordinate value and normal line. Since one or more primary radiators are placed near the focal point of each of these two paraboloids of revolution, the central axes of rotation of the two paraboloids of revolution intersect at a relatively large angle. This has the effect of allowing radio waves in two largely different directions to be transmitted and received by sharing most of the reflecting mirror.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a multi-beam antenna according to an embodiment of the present invention, Fig. 2 is a sectional view for explaining the principle of operation,
FIG. 3 is a conceptual diagram of a conventional multi-beam antenna. 1...Reflector, 2...Normal vector, 11
12.13.14 ...First group primary radiator, 2
1... Second group primary radiator, 31.32.3
334...Beam radiation direction of the first group, 41.
...Beam radiation direction of the second group, 51.52...
...Rotation center axis of paraboloids of revolution A and B. Agent Patent Attorney Yoshihiro Yahata Malform Antenna of the Invention/l $l I Publication Dedication 1#a Tax Advancement

Claims (1)

[Claims] a reflecting mirror in which a curved surface centered around the one point is determined by a weighted average of coordinate values of two mutually different paraboloids of revolution whose coordinate values and normal lines coincide at one point; and the two paraboloids of rotation; one first located near one focal point of
a primary radiator or a group of two or more first primary radiators; one second primary radiator or two or more second primary radiators disposed near the other focal point of the two paraboloids of revolution; A multi-beam antenna comprising: a group of primary radiators;