JPS59112705A - Multibeam antenna - Google Patents

Abstract

PURPOSE:To easily obtain a multibeam antenna for satellite mounting which has characteristic beam width for every beam by realizing simple constitution and setting the beam width of each beam independently. CONSTITUTION:Optimum aperture diameters of main reflection mirrors which are assumed to be provided individually are calculated from given beam width. In this case, a signal corresponding to a large optimum diameter is denoted as T and a signal corresponding to a small optimum diameter is denoted as R. Then, the kind of a frequency selection plate 9 is determined. Further, the aperture diameter D of a main reflection mirror 1'' is set so that the optimum diameter Dr corresponding to the signal T is realized, and the size of the selection plate 9 is determined so that the optimum aperture diameter DR (<Dr) corresponding to the signal R is realized. The selection plate 9 is a little bit smaller than the shape size corresponding to the whole of the main reflection mirror 1'' geometrically and optically, and its iradiation area is as large as the DR. Consequently, irradiation areas on the main reflection mirror corresponding to the signals R and T are set independently and their beam widths are fixed individually.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-beam antenna in which the beam widths of a plurality of beams can be set independently.

FIG. 1 is a diagram showing a configuration example of a multi-beam antenna in which a conventional primary radiator is shared by multiple beams, in which 1 is a main reflector, 2 is a frequency band common feeding horn, 3 is a splitter, and 4 ，
5 is an input terminal.

In FIG. 1, when a signal with frequency fl is input to input terminal 4 and a signal with frequency f2 is input to input terminal 5, these signals are multiplexed by demultiplexer 3 and then sent to frequency band common power supply hole 7.
Emitted from 2. Furthermore, these irradiate almost the entire surface of the main reflecting mirror 1, and the radio waves of frequency f1 and radio waves of frequency f2 are each radiated as beams having specific beam widths.

In this type of antenna, the beam widths of both the radio waves of frequency f1 and the radio waves of frequency ft are restricted by the aperture diameter of the main reflector 1, so there is a drawback that the beam widths of each cannot be selected independently.

FIG. 2 is a diagram showing an example of the configuration of a multi-beam antenna that radiates multiple beams using a frequency selection plate, where 1' is the main reflector, 41.5/ is an input terminal, and 6 is a feeder operating at frequency fl. A horn, 7 is a feeding horn that operates at frequency f2, and 8 is a frequency selection plate that reflects radio waves of frequency f1 and transmits radio waves of frequency f2. In the antenna of this configuration, a signal of frequency f1 is inputted to input terminal 4', radiated as a radio wave from feeding horn 6, and then reflected by frequency selection plate 8, while a signal of frequency f2 is inputted to input terminal 5'. After being radiated as a radio wave from the power feeding horn 7, it passes through the frequency selection plate 8 and illuminates the main reflecting mirror 1'.

Even with this antenna configuration, as in the case of the configuration shown in FIG. 1, it was not possible to independently select the beam width of each beam.

In the above explanation, we have talked about antennas that share multiple beams with different frequencies, but antennas that share multiple beams with different polarizations (orthogonal) also have the same structure. As in the case of , there was a drawback that the beam width of each beam could not be set independently.

In order to solve the drawback that the beam width of each of the plural beams in these conventional multi-beam antennas cannot be set independently, the present invention uses a selection plate with a shape and size different from the conventional one, and uses a selection plate to adjust the radio waves reflected by the selection plate. The beam width of the corresponding beam can be set independently of the beam width of the beam corresponding to the transmitted radio wave, and the drawings will be explained below.

FIG. 3 is a diagram showing the configuration of a multiple beam antenna according to an embodiment of the present invention, where I'' is a main reflecting mirror, 4' and 5'' are input terminals, 9 is a frequency selection plate, and 10 is a signal R. 11 is a feeding horn for the signal T. C is the aperture diameter of the portion of the main reflecting mirror 1'' that is irradiated by the reflected wave of the frequency selection plate 9, and D is the main reflecting mirror 1''. is the aperture diameter.

In the antenna of this configuration, if the beam width of radio waves for each signal is given, the configuration parameters can be determined as follows. First, the optimum aperture diameter of each main reflecting mirror is calculated from the given beam width, assuming that each main reflecting mirror has a single main reflecting mirror. In this case, the signal corresponding to the larger optimum aperture diameter is assumed to be R, which is the signal corresponding to the smaller T1. Then, the type of frequency selection plate 9 is determined. Furthermore, the aperture diameter of the main reflecting mirror 1' is set so as to realize the optimum aperture diameter DT for the signal T, and then the dimensions of the frequency selection plate 9 are determined so as to realize the optimum aperture diameter DR (<DT) for the signal R. . The frequency selection plate 9 is set to be smaller in shape and size (in this case, an ellipse whose major axis is AB in the figure) that geometrically and optically corresponds to the entire main reflecting mirror 1'', and its irradiation area C is equal to D8. do it like this.

By adopting such a configuration, it is possible to independently set the irradiation areas on the main reflecting mirror for the signals R and T, resulting in the advantage that the beam widths of each can be determined individually.

In this case, the shape and dimensions of the frequency selection plate 9 are the same as that of the main reflecting mirror 1.
The -order radiator is set to be smaller than the shape of the surface formed as the locus of the point where the straight line connecting the periphery of the aperture of ' and the focal point of the main reflecting mirror 1'' intersects the plane containing the frequency selection plate 9. There is a possibility that the transmitted waves of the radio waves radiated by the frequency selection plate 9 will be scattered by the frequency selection plate 9. However, in such a case,
This can be countered by a method such as loading a dielectric plate having approximately the same amount of phase delay as the amount of phase delay caused by the frequency selection plate 9, etc. In the general case where the phase retardation by the frequency selection plate is small, a multi-beam antenna that can be used in practical use can be obtained without any special method.

In this brief explanation, a frequency selection board is used as the selection board, and a multi-beam antenna with different frequencies is constructed using a feeding horn for the reflection frequency band and a feeding horn for the transmission frequency band of the selection board as the -order radiator. Although we are talking about an example, if we use a polarization selection plate as the selection plate and a feeding horn that emits mutually orthogonal polarization as the -order radiator, it is easy to realize a multi-beam antenna with different polarizations. In either case, the beam width of each of the shared beams can be set independently.

FIG. 4 is a diagram showing the effect of changing the size of the frequency selection plate in the example, and the vertical axis is the level deviation;
The horizontal axis is the shape and size ratio of the frequency selection plate (10 in the conventional case).
0chi), 12 shows the characteristics, and S band (2
, 6/2.5 G H, ) optimized aperture diameter 1
．． Band (30/25G)l with 8m main reflector
This figure shows the reception level around the service area of the band when an antenna is designed to share the S band and the S band and the size of the frequency selection plate is changed.

In Fig. 4, when the frequency selection plate of the conventional size is used, the size is about 60% smaller than when the reflected wave from the K-band frequency selection plate irradiates the entire main reflecting mirror surface (corresponding to 100 inches on the horizontal axis). %, the reception level is about 2.
It can be seen that it increases by 5 dB.

Note that if the selection plate is made smaller in this way, only a part of the radio waves radiated from the feeding horn will be covered by the frequency selection plate for the S band, and there is a concern that the radiation pattern will be deformed, but this design example It has been confirmed that since the amount of phase delay with respect to the S band is small, its radiation characteristics hardly deteriorate.

FIG. 5 is a diagram showing changes in the S-band radiation pattern when using the small frequency selection plate according to the present invention,
13 is a radiation pattern when the shape and size of the frequency selection plate is sufficiently large, and 14 is a radiation pattern when the frequency selection plate has a small shape set to be optimal for the band according to the present invention, and the change in both is small. .

As described above, according to the configuration of the present invention, it is possible to improve the peripheral reception level of the K-band beam while maintaining the original optimum characteristics of the S-band beam.

As explained above, the multiple beam antenna according to the present invention has a simple configuration and the beam width of each of the multiple beams can be set independently. There are advantages that can be easily realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of a multi-beam antenna in which a conventional primary radiator is shared by multiple beams, and FIG. 2 is a diagram showing an example of the configuration of a multiple-beam antenna that radiates multiple beams using a frequency selection plate. Fig. 3 is a diagram showing the configuration of a multiple beam antenna according to an embodiment of the present invention, Fig. 4 is a diagram illustrating the effect of changing the size of the frequency selection plate in the embodiment, and Fig. 5 is a diagram illustrating the invention. FIG. 3 is a diagram showing changes in the S-band radiation pattern when using a small frequency selection plate according to the present invention. 1.1', 1"... Main reflecting mirror, 2...
...Multi-beam shared power feeding horn, 3...
...Branch filter, 4 * 4/. 4", 5.5', 5''...Input terminal,
6......Feeding horn that operates at frequency f1, 7......Feeding horn that operates at frequency f2, 8......Radio wave at frequency f1 Frequency selection plate that reflects radio waves and transmits radio waves of frequency f2, 9...
...Frequency selection board, 10... Signal R
Feeding horn for signal T, 11...Feeding horn for signal T, 12...Characteristics, 13
......Radiation pattern when the shape and size of the frequency selection plate is sufficiently large, 14......The small shape set to be optimal for the band according to the invention Radiation pattern with frequency selection plate

Claims (4)

[Claims] (1) A selection plate is provided between the main reflector and the primary radiator that transmits or reflects the radio waves depending on the characteristics of the radio waves, and the radiated radio waves are transmitted through the selection plate and used as the primary radiator. Arrange the reflector so that it irradiates, and then add another primary radiator to the area.
In a multi-beam antenna arranged so that the radio waves radiated by the secondary radiator are reflected by the selection plate and irradiated to the main reflection mirror, the area around the aperture of the main reflection mirror on a plane including the surface of the selection plate and the main reflection A multi-beam antenna characterized by having a selection plate having a smaller surface shape than the shape surrounded by the trace of the intersection of the straight line connecting the focus of the mirror and the plane. (2) The selection plate is composed of a selection plate part and a dielectric part, and the selection plate causes the transmitted wave to have a phase change equal to the amount of phase change given by the selection plate part to the radio waves passing through the selection plate part. A multi-beam antenna as claimed in claim (1), which has a structure in which a dielectric portion is added to provide a function to the antenna. (3) The selection board is a frequency selection board.
1) The antenna is the multiple beam antenna described in item (2). (4) The selection plate is a polarization selection plate.
) or (2) multiple beam antenna 0