JPH0473881B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-beam antenna that enables simultaneous communication with a plurality of satellites in a geostationary orbit using one antenna.

(Prior Art) A conventional multi-beam antenna, as shown in FIG. It consists of a paraboloid of revolution reflector 5 that reflects the light in different directions, and a primary radiator 21,
2 and 23 are arranged in the vicinity of the focal point F of the paraboloid of revolution at an appropriate distance apart. In addition, each primary radiator includes, as illustrated for the primary radiator 21,
A power feeding section 6 and a low noise amplifier 7 are arranged so as to extend in the axial direction of the antenna shaft.

(Problems to be Solved by the Invention) However, in the conventional multi-beam antenna shown in FIG. It is necessary to widen the spacing between 21, 22, and 23, but in doing so, the arrangement positions will be moved away from the focal point F, and the optical path length from each primary radiator will be different, causing a phase error. Disturbance occurs in the wavefront at the aperture of the parabolic reflector 5, and the antenna gain decreases.

In addition, a power feeding section 6 directly connected to the primary radiator 21, etc.
Since the low noise amplifier 7 extends in the axial direction of the antenna shaft, there is a problem that the axial length of the antenna shaft becomes long.

The present invention was devised in view of these conventional problems, and its purpose is to increase the deviation of the radiation beam without increasing the disturbance of the wavefront at the aperture surface, that is, to improve the antenna efficiency. An object of the present invention is to provide a multi-beam antenna that can shorten the axial length of the antenna axis.

(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 includes a plurality of primary radiators; and irradiates the radio waves emitted from each of the plurality of primary radiators directly or through one plane reflector. It has a plurality of irradiation areas that receive the radiation indirectly, and there is an appropriate overlap between adjacent irradiation areas among the plurality of irradiation areas, and each of the plurality of irradiation areas receives its irradiated radio waves. A multi-beam antenna comprising: one main reflector that emits light in different directions from each other in a specific direction determined by the curved shape of the irradiation area; the plurality of irradiation areas of the main reflector are: A plurality of paraboloids of rotation having different curved surface shapes are set in advance corresponding to each of the plurality of irradiation areas, and curved surface coordinates giving the curved surface shape of each irradiation area are set in advance according to the curved surface coordinates corresponding to the irradiation area. It is set by a weighted average of the coordinate values of the relevant paraboloid of revolution and the coordinate values of the relevant paraboloid of revolution corresponding to the adjacent irradiation area, and the weighting of the weighted average is set based on the weighting of the plurality of primary radiators. This multi-beam antenna is characterized in that each radiated electromagnetic field is formed by setting the intensity of the radiated electromagnetic field in the aperture distribution formed on the main reflecting mirror surface.

(Function) Next, the function of the multi-beam antenna of the present invention having the above configuration will be explained.

The curved surface shape of each of the plurality of irradiation areas of one main reflecting mirror is a paraboloid of rotation that is approximately equal to the paraboloid of revolution which is the curved surface shape of the irradiation area when one main reflecting mirror has one irradiation area. Therefore, although there is an appropriate overlap between adjacent irradiation areas among the plurality of irradiation areas, each irradiation area can be regarded as a mutually independent paraboloid of revolution reflector.

Therefore, each of the plurality of irradiation areas directs its irradiated radio waves in a different direction to a specific direction determined by the curved shape of the irradiation area, that is, toward the central axis of a predetermined paraboloid of rotation that gives the curved shape of the irradiation area. Radio waves can be emitted in a direction parallel to .

At this time, since the deviation angle of the radiation beam is determined by the curved shape of the irradiation area, even if the deviation angle is increased, the disturbance of the wavefront at the aperture surface can be significantly reduced, and the antenna efficiency is therefore improved.

Also, when irradiating the main reflector from the primary radiators, each primary radiator will be placed facing the main reflector if it is directly irradiated.
The antenna axis length becomes longer as in the conventional case.

However, if we choose to irradiate indirectly through one plane reflector, the plane reflector will be placed so as to face the main reflector, and each primary radiator will reflect the plane in the direction around the antenna axis. Since the antenna is arranged so that the irradiated radio waves are obliquely incident on the plate, the axial length of the antenna can be shortened.

Note that each of the plurality of primary radiators is arranged at the focal position (mirror image point position if a plane reflector is involved) of a predetermined paraboloid of rotation that gives the curved shape of the corresponding irradiation area, Since multiple irradiation areas can each have different curved shapes,
The manner in which the plurality of primary radiators are arranged is not fixed and may be in any manner.

As explained above, according to the multi-beam antenna of the present invention, the plurality of irradiation areas of one main reflecting mirror have a curved surface of each irradiation area, although there is an appropriate overlap between adjacent irradiation areas. The shape can be made into a paraboloid of revolution which is approximately the same as the curved surface shape of the irradiation area when one main reflector and one irradiation area are formed by weighted average operation, so each irradiation area is different from each other. It can be considered as an independent paraboloid of revolution reflector. Therefore, according to the present invention, a highly efficient multi-beam antenna can be constructed.

Further, by indirectly transmitting the irradiated radio waves from the plurality of primary radiators to the main reflecting mirror via one plane reflecting plate, there is an effect that the antenna axial length can be shortened.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a multi-beam antenna according to a first embodiment of the present invention. The multi-beam antenna according to the first embodiment is a two-beam antenna consisting of a main reflecting mirror 1 and two primary radiators 21 and 22, as shown in FIG. 1a.

In FIG. 1a, the main reflecting mirror 1 has two irradiation areas A and B with an appropriate overlapping area A in the center. The curved surfaces of the irradiation areas A and B are approximately paraboloids of revolution formed by the weighted average method described later.

Here, axis Z is the central axis of the antenna.
The axes Z _a and Z _b are the central axes of paraboloids of rotation forming curved surfaces of the irradiation areas A and B, and points F _{a and F b on} these axes indicate focal points, respectively.

In the illustrated example, the focal lengths of both paraboloids of revolution are made equal. The central axes Z _a and Z _b are each inclined at an angle δ/2 with respect to the central axis Z, and the focal point
F _a and F _b are separated by a distance of 2d.

The primary radiator 21 is placed at a focal point F _a to mainly irradiate the irradiation area A, and the primary radiator 22 is placed at a focal point Fb to mainly irradiate the irradiation area B.

By the way, in this embodiment, the two-beam antenna is composed of one main reflector 1 and two primary radiators 21 and 22, but the irradiation areas A and B have a slight overlap part A. Therefore, as shown in Fig. 1b, the paraboloid of revolution A' that defines the irradiation area A and the paraboloid of revolution B' that defines the irradiation area B are set to be slightly shifted from each other. become.
However, if the main reflector 1 is aligned with the paraboloid of revolution A', the ray emitted from the focal point Fa becomes a ray parallel to the central axis Za after being reflected by the main reflector 1 (beam A radiation direction).

Furthermore, if the main reflecting mirror 1 is coincident with the paraboloid of rotation B', the light ray emitted from the focal point Fb becomes a ray parallel to the central axis Z _b after being reflected by the main reflecting mirror 1 (beam B radial direction).

Therefore, the curved shape of the main reflecting mirror 1 is a paraboloid of rotation within the irradiation area A excluding the overlapping part A.
It almost coincides with A', and in the irradiation area B excluding the overlap part A, it almost coincides with the paraboloid of revolution B', and in the overlap part A, it gradually changes from the paraboloid of revolution A' to the paraboloid of revolution B' If the shape is set like this, the efficiency of both beams A and B can be improved, and the central axes Z _a and Z _b
This makes it possible to realize a multi-beam antenna that emits radio waves in two different directions.

Specifically, since the irradiation intensity of beam A gradually weakens as it goes to the periphery, it gradually changes from the paraboloid of revolution A' to the paraboloid of revolution according to the degree of weakening.
The curved surface is made to change to B', and the method for this is to weight the irradiated electric field strength and take the weighted average of the two paraboloids of revolution A' and B'.

Therefore, the curved shape of the main reflecting mirror 1 is determined as follows.

That is, the X, Y, and Z axes are determined as shown in Figure 1a, and the paraboloid of revolution A' and the paraboloid of revolution B' are functions of (X, Y), respectively, and Z=f _a (X, Y) ...(1) Z=f _b (X, Y) ...(2) In addition, the radiated electric field at the point (X, Y) on the main reflecting mirror 1 of the aperture distribution of the main reflecting mirror surface, which is generated on a plane perpendicular to the Z-axis by the radio waves emitted from the primary radiators 21 and 22, is Each intensity is E _a
(X, Y), E _b (X, Y), the curved surface coordinates Z (X, Y) of the main reflecting mirror are f _a (X, Y) and f _b (X,
As a weighted average of E _a (X, Y) and E _b (X, Y) of Y), for example, Z (X, Y) = E _a (X, Y) f _a (X, Y) +
E _b (X, Y) f _b (X, Y)/E _a (X, Y) + E _b (X, Y
)...(3).

According to the above equation (3), the main reflector 1 is the primary radiator 2
1 is stronger than the radiation electric field from the primary radiator 22, that is, within the irradiation area A excluding the overlapping part A, it is close to the paraboloid of revolution A', and conversely, the radiation electric field from the primary radiator 22 is close to the paraboloid of revolution A'. Where the radiated electric field is stronger, that is, within the irradiation area B excluding the overlap part A, it is close to the paraboloid of revolution B', and where the two electric fields are equal, that is, within the overlap part A, it is a paraboloid of revolution. It becomes a curved surface between A' and B'. In other words, overall, the irradiation area A including the overlapping part A is approximately equal to the paraboloid of revolution A', and the irradiation area B including the overlapping part A is approximately equal to the paraboloid of revolution B',
Each can be regarded as an independent paraboloid of revolution reflector.

Therefore, according to the present invention, it is possible to improve the efficiency reduction caused by the phase error in the aperture plane as in the conventional art.

Next, FIG. 2 shows a multi-beam antenna according to a second embodiment of the present invention. In the first embodiment, the primary radiator and the corresponding irradiation area were on the same side with respect to the antenna center axis Z, whereas this second embodiment
In the embodiment, the primary radiators and their corresponding irradiation areas are set on opposite sides of the central axis Z. The rest is the same as the first embodiment.

Next, FIG. 3 shows a multi-beam antenna according to a third embodiment of the present invention. In this third embodiment,
In the second embodiment, a flat reflector 4 is arranged between the main reflector 1 and _the two focal points F _b ,
The primary radiators 21 and 22 have focal points F a and F _a
It is arranged facing the plane reflection plate 4 at the position of the mirror image point of the plane reflection plate 4 at F _b .

With this configuration, the radio waves radiated from the primary radiators 21 and 22 are reflected by the flat reflector 4 and then directed to the main reflector 1, and then reflected by the main reflector 1 and sent to different 2 radiated in the direction.

The plane reflector 4 simply serves to bend the path of radio waves, and the principle of operation as a multi-beam antenna is the same as in the first embodiment. By using the plane reflector 4, the length of the antenna in the axial direction can be shortened.

Next, FIG. 4 shows a multi-beam antenna according to a fourth embodiment of the present invention. In this fourth embodiment, 3
The case of a beam antenna is shown. The principle in this case is the same as that in the first embodiment, and the main reflecting mirror 1 includes primary radiators 21, 22,
It is a weighted average based on the radiated electric field from 23.

Here, the paraboloids of revolution A', B', and C' have central axes Z _a , Z b , and _Z c that point in different directions from the focal points F _a , F _b , and F _{c ,} respectively. are doing.

As can be seen from the above description, the present invention can be similarly applied to the case of four or more beams.

In the above explanation, we have explained the case where the central axes of the multiple focal points and the multiple paraboloids of revolution are on the same plane, but this is not necessarily the case. For example, the paraboloids of revolution A′ and B′ The central axis Z _a and the same Z _b
may be in a twisted relationship with each other.

That is, the central axis Z _a and the central axis Z _b may extend in any direction other than within the same plane. Further, the angles formed by each central axis and each primary radiator do not need to be equal.

Further, the focal lengths of the respective paraboloids of rotation may not be equal. Further, the outer peripheral shape of the main reflecting mirror may be arbitrary.

(Effects of the Invention) As explained above, according to the multi-beam antenna of the present invention, the plurality of irradiation areas of one main reflecting mirror have appropriate overlapping portions between adjacent irradiation areas; The curved surface shape of each irradiation area can be made into a paraboloid of revolution which is approximately equal to the curved surface shape of the irradiation area in the case of one main reflecting mirror and one irradiation area by a weighted average operation. Each irradiation region can be regarded as a mutually independent paraboloid of revolution reflector. Therefore, according to the present invention, a highly efficient multi-beam antenna can be constructed.

Further, by indirectly transmitting the irradiated radio waves from the plurality of primary radiators to the main reflecting mirror via one plane reflecting mirror, there is an effect that the antenna axis length can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing a second embodiment of the present invention, and FIG. 3 is a diagram showing a third embodiment of the present invention (an embodiment using a plane reflector). ), FIG. 4 is a diagram showing a fourth embodiment (three-beam antenna) of the present invention, and FIG. 5 is a diagram showing a conventional multi-beam antenna. DESCRIPTION OF SYMBOLS 1... Main reflecting mirror, 4... Plane reflecting plate, 5... Paraboloid of rotation reflector, 6... Power feeding section, 7... Low noise amplifier, 21, 22, 23... Primary radiator, A ,B
...Irradiation area, Z... Central axis of the antenna, Z _a ... Central axis of paraboloid of revolution A', Z _b ... Central axis of paraboloid of revolution B', Z _c ... Paraboloid of revolution C' central axis.

Claims (1)

[Claims] 1. A plurality of primary radiators; a plurality of irradiations that respectively receive the radiation of radio waves emitted from each of the plurality of primary radiators directly or indirectly through one plane reflector; There is an appropriate overlap between adjacent irradiation areas among the plurality of irradiation areas, and each of the plurality of irradiation areas emits radio waves in different directions. A multi-beam antenna comprising: one main reflecting mirror that emits radiation in a specific direction determined by the curved shape of the area; A paraboloid of revolution is set in advance corresponding to each of the plurality of irradiation areas, and the curved surface coordinates giving the curved shape of each irradiation area are set as the coordinate values of the corresponding paraboloid of revolution corresponding to the irradiation area. The radiated electromagnetic field of each of the plurality of primary radiators is set by a weighted average of the coordinate values of the corresponding paraboloid of rotation corresponding to the adjacent irradiation area, and the weight of the weighted average is set so that the radiated electromagnetic field of each of the plurality of primary radiators is the main reflecting mirror surface. A multi-beam antenna characterized in that it is formed by setting the intensity of the radiated electromagnetic field in the aperture distribution formed above.