JPS63146502A - Multi-beam antenna - Google Patents

Abstract

PURPOSE:To constitute a multi-beam antenna with high efficiency by selecting the shape of a curved face of each radiation region to be a paraboloid of revolution nearly equal to a paraboloid of revolution being a curved face of the radiated region in the case of one major reflection mirror provided to one radiated region. CONSTITUTION:If the curved face of the main reflection mirror 1 is concident with the paraboloid of revolution A', then a ray radiated from a focus Fa is reflected in the main reflection mirror 1 and is in parallel with a center axis Za (radiation direction of beam A). If the curved face of the main reflection mirror 1 is coincident with the paraboloid of revolution B', a ray radiated from a focus Fb is reflected in the main reflection mirror 1 and is in parallel with the center axis Zb (radiation direction of beam B). Thus, the curved face of the main reflection mirror 1 is decided in a way that the curved face is nearly coincident with the paraboloid of revolution within the radiated region A except the overlapped part alpha and nearly coincident with the paraboloid of revolution B' within the radiated region B except the overlapped part alpha and the overlapped part alpha is subjected to gradual transition from the paraboloid of revolution A' to the paraboloid of revolution B'. Thus, the multi-beam antenna radiating a radio wave in two different directions as shown in center axes Za and Zb is realized.

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 has a plurality of (for example, three) primary radiators 21, 22,
23, and a paraboloid of revolution reflector 5 that reflects the radio waves emitted by these primary radiators in different directions.
The secondary radiators 21, 22, and 23 are arranged in the vicinity of the focal point F of the paraboloid of revolution at appropriate distances 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. 21, 22, 23
It is necessary to widen the arrangement interval, but then the arrangement position will move away from the focal point F, which will cause disturbance in the wavefront at the aperture surface of the paraboloid of revolution reflector 5 and reduce the antenna gain.

Furthermore, since the feed section 6 and the low noise amplifier 7 that are directly connected to the primary radiator 21 and the like extend in the axial direction of the antenna axis, there is a problem that the axial length of the antenna axis 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 radiates 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 for each of the plurality of primary radiators. This multi-beam antenna is characterized in that the radiated electromagnetic field is formed by setting it as a function of 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 irradiation radio waves in a different direction to a specific direction determined by the curved shape of the irradiation area, that is, to the central axis of a predetermined paraboloid of rotation that gives the curved shape of the irradiation area. Radio waves can be emitted in parallel directions.

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, disturbances in the wavefront at the aperture surface can be significantly reduced, thus improving antenna efficiency.

In addition, when irradiating the main reflector from the primary radiator, if irradiation is done directly, each primary radiator will be placed facing the main reflector, so the antenna axis length will remain the same as before. becomes longer.

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 has a focal point position (
If a flat reflector is used, the primary radiators are placed at mirror image point positions, but since the multiple irradiation areas can each have different curved shapes, the arrangement of the multiple primary radiators is not constant. It can be in any form.

As explained above, according to the multi-beam antenna of the present invention, the plurality of irradiation areas of one main reflecting mirror are
Although there is some overlap between adjacent irradiation areas, the curved shape of each irradiation area can be adjusted to a uniform value by weighted average operation.
Since the irradiation area of the upper reflector 1 can be a paraboloid of revolution that is approximately the same as the curved surface of the irradiation area, each irradiation area can be formed as a paraboloid of revolution that is independent of each other. It can be considered. 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.

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

In FIG. 1(a), the main reflecting mirror 1 has two irradiation areas A and B with appropriate overlapping parts (A) in the center.
has. The curved surfaces of the irradiation areas A and B are substantially paraboloids of revolution formed by a weighted average method, which will be described later.

Here, axis Z is the central axis of the antenna.

Further, the axis Z and the axis Zb are the central axes of a paraboloid of revolution having a curved surface shape in the irradiation area A and the same day, and points F1 and Fb on these axes indicate focal points, respectively.

In the illustrated example, the focal lengths of the rerotating paraboloids are equal. The central axes Z and Z are each inclined at an angle δ/2 with respect to the central axis Z, and the focal points F and Fb are separated by a distance of 2d. The primary radiator 22 is placed at the focal point F to irradiate the
is arranged at the 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 (A). As shown in FIG. 1(b), the paraboloid of revolution A' that defines the irradiation area A and the paraboloid of revolution B' that defines the irradiation area B are slightly shifted from each other. will be set. However, if the main reflecting mirror 1 is a paraboloid of revolution A
', then the light ray emitted from the focal point F becomes a light ray parallel to the central axis Z1 after being reflected by the main reflecting mirror 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 after being reflected by the main reflecting mirror 1 (beam B radial direction).

Therefore, as the curved surface shape of the main reflecting mirror 1, the overlapping portion (
In the irradiation area A excluding the area A), it almost coincides with the paraboloid of revolution A', and in the irradiation area B excluding the overlapping area (A), it almost coincides with the paraboloid of revolution B', and in the overlapping area (A) If the shape is set so that it gradually changes from the paraboloid of revolution A' to the paraboloid of revolution B', it is possible to realize a multi-beam antenna that emits radio waves in two different directions of the central axis Z and Zb.

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

That is, the X-axis, Y-axis, and Z-axis are determined as shown in FIG. X, Y)
−・−=−−−−(1') Z= f b (X,
Y) ~---・-1・----(2). In addition, the radiated electric field intensity 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 two axes by the radio waves radiated from the primary radiators 21 and 22, is E respectively.

(X, Y), Eb (X, Y), the curved surface coordinates Z (X, Y) of the main reflecting mirror are f, (X, Y) and fb (X,
As a weighted average of Y) by E, (X, Y), and Eb (X, Y), for example, Z (X, Y) = Embryo U Ox Old Hikikan Kiya Plate ----------=- (3) It can be determined that

According to the above equation (3), the main reflecting mirror 1 is used in areas where the radiated electric field from the primary radiator 21 is stronger than the radiated electric field from the primary radiator 22, that is, the irradiation area A excluding the overlapping portion (A).
In the area, the area is close to the paraboloid of revolution A', and conversely, the area where the radiated electric field from the primary radiator 22 is stronger is the overlapping area (
In the irradiation area B except for a), it is close to the paraboloid of revolution B',
In addition, where the two electric fields are equal, that is, the overlapping part (
In a), it becomes a curved surface intermediate between paraboloids of revolution 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 prior art.

Note that in the above equation (3), a function of the electric field strength is used as the weighting of the weighted average, but a function of the radiation power of the primary radiator may also be used.

In other words, it is determined as follows. Generally, the curved shape of the main reflecting mirror 1 is determined by . Here, gl and g2 are the primary radiator 2
1 and 22, or a function of the +i radiation electric field E and other parameters, or a function of the radiation electric field Eb and other parameters. For example, if the operating frequencies of the primary radiators 21 and 22 are different from f and f2, then gt(E,)=f IEa'
-m-・---(6)ga(Eb)=fzEb
--m-(7).

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 are on the same side with respect to the antenna center axis Z. In contrast, in this second embodiment, the primary radiators and their corresponding irradiation areas are set on opposite sides with respect to 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. A flat reflector 4 is arranged at the primary radiator 21 and the primary radiator 2.
2 is arranged facing the plane reflection plate 4 at the focal point F and the mirror image point of the plane reflection plate 4 at the focal point Fb.

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

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. This fourth embodiment shows the case of a three-beam antenna. The principle in this case is also the same as that of the first embodiment. The main reflecting mirror 1 is one of paraboloids of revolution A', B', and C'.
Next radiator 21. Same 22. It is a weighted average based on the radiated electric field from 23.

Here, the paraboloids of revolution A', B', and C' have different focal points F1, Fb, and F0, respectively, and central axes Z□Zb and Z0 facing in different directions.

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

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

That is, the central axes Z and Zb may extend in any direction other than within the same plane, and 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 revolution do not have to be equal, and the outer peripheral shape of the main reflecting mirror may also 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 are
Although there is some overlap between adjacent irradiation areas, the curved shape of each irradiation area can be adjusted to a uniform value by weighted average operation.
Since the irradiation area of the main reflector 1 can be made into a paraboloid of revolution that is approximately the same as the curved surface of the irradiation area, each irradiation area can be formed as a paraboloid of rotation that is independent of each other. It can be considered. Therefore, according to the present invention, a highly efficient multi-beam antenna can be constructed.

By indirectly transmitting the irradiated radio waves from a plurality of long primary radiators to the main reflector via one plane reflector, 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 (
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. 1... Main reflecting mirror, 4... Planar reflecting plate, 5... Paraboloid of revolution reflecting mirror, 6......
Power feeding unit, 7...Low noise amplifier, 21, 22.
23...Primary radiator, A, B...irradiation area, Z...antenna center axis, Z,...
.... Central axis of paraboloid of revolution A', Zb .... central axis of paraboloid of revolution B', Zc .... central axis of paraboloid of revolution C'. Agent Patent attorney Yoshi Hachiman Hiromoto's 1st missing column II multi-A antenna
Figure top view (b)

Claims (1)

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