JPH0685534A - Reflector Multi-beam antenna device - Google Patents

Abstract

(57) [Summary] [Object] To provide a multi-beam antenna device capable of improving frequency utilization efficiency and giving flexibility to frequency allocation of a system. A reflector multi-beam antenna device having a plurality of cluster feeds each comprising a reflector, a plurality of circularly polarized primary radiators, and a distribution circuit for distributing a signal to the primary radiators. , The primary radiator comprises two feed ports having loose coupling characteristics, and when the primary radiator is shared between the two cluster feeds, the two feed ports are connected to the two clusters. If the primary radiator is used for only one cluster feed, the first feeding port of the primary radiator is non-reflectively terminated and the second feeding port is connected to each of the distribution circuit ports of the feed. Is connected to the distributor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite-mounted reflector multi-beam antenna device for performing satellite communication and satellite broadcasting.

[0002]

2. Description of the Related Art In recent years, with the spread of satellite communication and satellite broadcasting, research and development have been vigorously conducted to improve the performance of satellite antennas for realizing these communications and broadcasting. In satellite communication and satellite broadcasting, (1) how to efficiently use frequency, which is a finite resource, (2) in order to popularize small and low-priced ground stations, A major technical issue is how to increase the gain of a satellite antenna. As a means for solving this, a reflector multi-beam antenna capable of simultaneously forming a plurality of beams with one antenna is most promising from the viewpoint of satellite mountability and feasibility.

FIG. 5 is a block diagram of a general reflector multi-beam antenna, which includes a parabolic mirror surface 100 and a primary feeding system 10.
It consists of 1. In the figure, the primary feeding system 101
Is disposed near the focal point of the parabolic reflector 100, and the radio waves emitted from the primary feeding system 101 are transmitted by the parabolic reflector 1
00, and propagates in the direction of the service area.

Here, the operation principle of the conventional reflector multi-beam antenna, its effect and problems will be described by taking the simplest multi-beam configuration in which the service area as shown in FIG. 6 is covered by three beams as an example. To do. In FIG. 6, the service area is covered with three beams 102, 103 and 104, and each beam has a frequency f.
It is assumed that 1, f2 and f1 are assigned. The advantage of such a multi-beam configuration is that, first of all, a higher gain can be achieved as compared with the case where the entire service area is covered with one beam. This is because the size of each beam of the multi-beam is smaller than that of the case where the entire service area is covered with one beam, so that energy can be concentrated. The second advantage is that by lowering the side lobes of beams 102 and 104,
The interference between the beams 102 and 104 can be reduced, and the same frequency can be effectively reused.

An example of a primary feeding system for forming such three multi-beams is shown in FIGS. 7 and 8. FIG. 7 shows the surface of the primary power feeding system 101 that radiates radio waves, and is composed of a plurality of primary radiators 105, 106, and 107.
Here, one beam is a cluster feed 108, 10 composed of three primary radiators as shown by a dotted line.
9, 110 are used. That is, the cluster feeds 108, 109, 110 are the beams 102, 1 of FIG.
It corresponds to 03 and 104. The reason why cluster feed formation is used is that the side lobes of the antenna can be reduced and the frequency can be reused by optimizing the excitation amplitude and phase of the plurality of primary radiators forming the cluster feed. For the above reasons, the cluster feed type is the basis of the frequency reuse type reflector multi-beam antenna.

Further, as described above, it is indispensable to increase the gain of the beam in the multi-beam antenna, and it is most important to improve the gain (generally called crossover level) in the region where the beams overlap. To achieve this, some primary radiators need to be shared between the cluster feeds, as shown in FIG. In the figure, a primary radiator 107 is used in both of the two cluster feeds 108,109. Generally, in reflector antennas, the physical spacing of the cluster feeds is
In order to correspond to the beam interval, if the primary radiator is not shared, the interval between the adjacent beams will be widened, and as a result, the phenomenon that the crossover level is lowered will inevitably occur. From this fact, in order to improve the crossover level, it is essential to share the primary radiator among the cluster feeds.

FIG. 8 shows a general structure of the primary radiator and the feeding circuit of the primary feeding system 101. Hereinafter, the configuration and the operating principle will be described by taking the case of transmitting radio waves as an example.
(The same applies when radio waves are received, so it is omitted here.) In FIG. 1, primary radiators 105 and 106 are distributors 1 that distribute a transmission signal of frequency f1.
11 is connected. A multiplexer 112 is connected to the primary radiator 107 shared by the cluster feeds. The multiplexer 112 synthesizes the signal of the frequency f1 from the distributor 111 and the signal of the frequency f2 from the distributor 113. The distributors 111 and 113 perform amplitude and phase weighting on the input signal to reduce the side lobe of the antenna and distribute the signal. In this way, the distributor 11
By weighting the amplitude and phase of 1 and 113, the antenna beam is made into a low side lobe, and frequency reuse is possible.

However, the conventional reflector multi-beam antenna described above has the following drawbacks. First of all
In addition, since the multiplexer 112 needs to combine and output the frequencies f1 and f2, a guard band, that is, a frequency band that cannot be used, is necessarily required between the frequencies f1 and f2. That is, it is not possible to use all of the limited and valuable frequency band allocated to the entire service area, resulting in hindering effective use of the frequency.

The second drawback is that the pass-amplitude phase characteristic near the band edge of the multiplexer is not flat, so that an error occurs in the excitation amplitude phase of the cluster feed in this frequency region, and the multi-beam antenna has a low side lobe. Will not be achieved. As a result, the amount of interference from other beams that use the same frequency increases, which greatly affects the quality of communication and broadcasting. In order to avoid this, a method of using only the frequency region in which the pass amplitude / phase characteristics of the multiplexer do not affect the side lobe reduction can be considered. This results in a narrower usable frequency band, which is a serious problem from the viewpoint of effective frequency utilization.

A third drawback is that since the frequency band of the multiplexer 112 is fixed, the satellite communication / broadcasting system has no flexibility in frequency allocation. For example, the frequency allocation of beams is changed after the satellite is launched. You cannot fulfill the demand you want to make. In recent years, the lifespan of satellites has tended to increase to more than 10 years, and even if frequency allocation is performed based on the communication demand assumed at the design stage of a multi-beam antenna system, the area will be operated within a long period of 10 years of satellite operation It is highly conceivable that real communication needs will change and frequency will be reallocated. Due to such a situation, the method of fixedly allocating the frequency by the multiplexer has the effect of greatly reducing the flexibility of the system.

Further, a primary power feeding system in which the multiplexer 112 is replaced with a 3 dB hybrid is also conceivable. In this case, flexibility of frequency allocation and effective use of frequency can be achieved as compared with the multiplexer, but 3 dB. This results in a 3 dB reduction in input power to the primary radiator connected to the hybrid.

[0012]

As described above, in the conventional reflector multi-beam antenna, if it is attempted to reduce the side lobes for frequency reuse and improve the crossover level at the same time, It is necessary to use a cluster feed with wave filters, which results in the ineffective use of the allocated frequencies and the susceptibility to interference from other beams using the same frequency. It was Also, since the multiplexer fixedly determines the frequency band, the flexibility of the entire system is excluded, and at the same time, when a 3 dB hybrid is used instead of the multiplexer, a loss of 3 dB is incurred. There was a problem.

The present invention was devised in order to improve the problems of the above-mentioned conventional example, and can improve the utilization efficiency of frequency which is a finite resource, and achieve high quality of communication / broadcast by reducing interference waves. However, it is an object of the present invention to provide a reflector multi-beam antenna device that can give the system flexibility in frequency allocation and at the same time reduce loss as compared with the case of using a 3 dB hybrid.

[0014]

In order to solve the above-mentioned problems, the first invention comprises a reflecting mirror, a plurality of primary radiators, and a distribution circuit for distributing a signal to the primary radiators. In a reflector multi-beam antenna device having a plurality of cluster feeds, the primary radiator has two feed ports having loose coupling characteristics, and the two feed ports generate circularly polarized waves with the same rotation. When the primary radiator is shared between the two cluster feeds, the two power feed ports are connected to the distribution circuit ports of the two cluster feeds, respectively, and the primary radiator is When used with only one cluster feed, the first feeding port of the primary radiator is non-reflectively terminated, and the second feeding port is connected to the distributor. A reflector multibeam antenna device.

A second aspect of the invention is a reflector multi-beam antenna device characterized in that the number of primary radiators shared between the cluster feeds is the same as the number of feed ports of the primary radiators.

[0016]

According to the present invention, since the circularly polarized primary radiator forming the cluster feed has two feed ports and has the loose coupling characteristic between the two feed ports, it is shared between the cluster feeds. There is no need to connect the primary radiator via the multiplexer, and as a result, the utilization efficiency of the frequency, which has been a problem in the conventional example, can be improved. Further, since the amplitude / phase pass characteristic of the primary radiator is flatter than that of the multiplexer, the excitation amplitude / phase error is small, and the low sidelobe characteristic of the beam can be maintained. As a result, the influence of interference waves from other beams that use the same frequency is reduced, and high quality communication and broadcasting can be achieved. In addition, the frequency allocation of the primary radiator is less restricted than that of the multiplexer, thus providing flexibility in the frequency allocation of the system. Further, since the primary radiator having the loose coupling characteristic is used between the two power feeding ports, the loss can be reduced as compared with the case of using the 3 dB hybrid.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a primary feeding system of a multi-beam antenna device according to an embodiment of the present invention. In the figure, 1, 2 and 3 are primary radiators each having two feeding ports, 4 is a reflectionless termination connected to the second port of the primary radiator 1, and 5 and 6 are excitation amplitudes of the cluster feed. It is a distributor that sets the phase and at the same time distributes the signal of frequency f1 to the primary radiator. The relationship between the reflecting mirror and the primary feeding system is the same as in FIG. 5 shown in the conventional example, and is omitted here for simplicity. Further, FIG. 1 illustrates the simplest case in which three primary radiators form a cluster feed and the primary radiator 3 is shared between the cluster feeds, as in the above-described conventional example.

The operating principle of one embodiment of the present invention will be described in detail below with reference to FIG. However, the operation principle of the primary radiator having two power feeding ports and having loose coupling between the ports will be described later.

In FIG. 1, the distributor 5 weights the input signal of the frequency f1 with the excitation amplitude and phase for lowering the side lobe, and supplies it to the three output ports. This output port is connected to the first power supply ports of the primary radiators 1, 2, 3 and has a frequency f1 distributed by the distributor 5.
Signal is supplied to the primary radiators 1, 2, and 3. As a result, the primary radiators 1, 2, 3 and the distributor 5 form a cluster feed. With this cluster feed
A beam of low sidelobe frequency f1 is formed. Further, the feed ports of the primary radiators 1 and 2 which are not connected to the distributor 5 are connected to non-reflection terminations in order to reduce reflected waves. Furthermore, since the primary radiator 3 is shared between the adjacent cluster feeds, the crossover level can be set high similarly to the conventional example. On the other hand, the cluster feed consisting of the distributor 6 and the primary radiators connected thereto, the distributor 5 and the primary radiators 1, 2,
The cluster feed constituted by 3 forms beams of the same frequency, but since the side amplitude is reduced by the excitation amplitude / phase weights of the distributors 5 and 6, the interference between both beams is reduced. Further, since the amplitude / phase pass characteristic of the primary radiator is flatter than that of the multiplexer described in the conventional example, the excitation error is small and the low side lobe characteristic can be maintained regardless of the frequency. Furthermore, since the same primary radiator is used in the cluster feed, the amplitude and phase pass characteristics of all the primary radiators are the same except the manufacturing error, and the excitation amplitude phasing design and the distributor manufacturing are At the same time, since the deviation between the amplitude and phase pass characteristics due to the frequency between the primary radiators is small, the side lobe can be reduced over a wide band. As a result, the influence of the same frequency interference wave from other beams is reduced, and high quality of communication and broadcasting is achieved.

Furthermore, since the primary radiator can be operated to cover the entire frequency band allocated to the entire service area, there is no restriction on the frequency allocation of the beam. As a result, the frequency allocation of the beam can be easily changed during the satellite operation period, and the flexibility of the system can be increased.

FIG. 2 is characterized in that a general primary radiator 7 having no two feeding ports is used for the primary radiator which is not shared between the clusters in the above embodiment. With such a configuration, since different primary radiators are used in the cluster feed, it is easy to design the excitation amplitude phasing described in the embodiment of FIG. 1 and the amplitude phase pass characteristic deviation due to the frequency between the primary radiators. However, other effects are similar to those of the embodiment shown in FIG.
Furthermore, there is an advantage that the non-reflective termination can be reduced and the configuration can be simplified.

Next, the primary radiator in the embodiment shown in FIGS. 1 and 2 will be described. The primary radiator has two feed ports, and the coupling between the two feed ports has a loose coupling characteristic. An example of such a primary radiator is disclosed in Japanese Patent Laid-Open No. 3-309135. In the above-mentioned published patent, four antenna elements fed by two orthogonal linearly polarized wave probes are used, and these are combined by two sequential feeding circuits to have a feeding port capable of generating two identical circularly polarized waves. . Further, in this publication, it is premised that the two probes of the antenna element are matched at different frequencies, and in this case, the coupling between the feeding ports is -30 dB and loose coupling. It can be seen that the radio waves input from the power feeding port do not couple to other ports so much, and most of the input radio waves are radiated.

The antenna described in the above publication can be used as the primary radiator in the embodiment of the present invention shown in FIGS. As a result, compared to the conventional example using a multiplexer, the excitation amplitude error can be reduced, but since the power supply port is fixed at a different frequency, flexibility of frequency reallocation and frequency utilization efficiency are improved. There are difficulties in improving.

Therefore, the two orthogonal linear polarization probes of the antenna elements described in the above-mentioned publication are matched in the same frequency band, and the sequential feeding circuit for feeding the four antenna elements is 90. ° and 1
Consider the case of being composed of an 80 ° hybrid.

FIG. 3 shows a schematic configuration diagram of the primary radiator in the present invention. In the figure, 10 is an antenna element, 1
Reference numeral 1 is a first linear polarization probe, and 12 is a second linear polarization probe. The antenna element 10 has two linearly polarized probes 11 and 12 which are orthogonal to each other.
From 1 and 12, orthogonal linearly polarized waves are transmitted to the antenna element 10
Is emitted through. The impedances of the two linear polarization probes 11 and 12 as viewed from the antenna element side are matched in the same frequency band. Further, the antenna elements 10 are physically rotated by 90 ° and arranged.

Next, FIG. 4 shows a sequential feeding circuit for generating circularly polarized waves using the four antenna elements 10 of FIG. In the figure, 13 and 14 are 90 °
Hybrid circuit, 15 is a 180 ° hybrid circuit,
Reference numeral 16 is a power feeding port of the final primary radiator. Figure 4
3 shows the sequential power supply circuit connected to the probes A1 to A4 in FIG. 3, but the sequential power supply circuit connected to the probes B1 to B4 has the same configuration and is omitted here.

The operation principle will be described below with reference to FIGS. First, it is assumed that a signal is applied to the power supply port shown in FIG. The signal is distributed by the 180 ° hybrid circuit 15 to the 90 ° hybrid circuit 13 in 0 ° phase, while to the 90 ° hybrid circuit 14 in −180 ° phase. The 90 ° hybrid circuit 13 outputs the signal from the 180 ° hybrid circuit 15 to the A1 port with a −90 ° phase, and to the A2 port with 0 phase.
° Distribute in phase. Similarly, 90 ° hybrid circuit 1
4 receives the signal from the 180 ° hybrid circuit 15 as A3
It is distributed at -90 ° phase to the port and 0 ° phase to A4 port. As a result, the phases of the signals fed to A1 to A4 shown in FIG. 3 are A1 ... -90 °, A2 ... 0 °, A3.
...- 270 [deg.], A4 ... -180 [deg.]. Further, as shown in FIG. 3, the probes A1 to A4 are spatially rotated by 90 °. In this way, by the phase set in the sequential feeding system and the physical rotation of the antenna element 10,
Circular polarization is generated. In the above example, it is a left-handed polarized wave. The same circularly polarized wave can be generated for the probes B1 to B4 with the same sequential power feeding configuration.

Here, the power supply ports of the sequential power supply circuit connected to the probes A1 to A4 are A port and B, respectively.
The power feeding ports of the sequential power feeding circuit connected to the probes 1 to B4 will be referred to as B ports. It will be explained below that the coupling between the A and B ports is loose coupling. First of all, A in the antenna element 10
i and Bi (i = 1, 4) are coupled by the linear polarization probe 1
Since 1 and 12 are orthogonal, there is almost no bond. Next is the coupling of Ai and Bj (i and j are different), which is a mutual coupling between the radiating elements and varies depending on the antenna element spacing, but generally used element spacing is 0.6 wavelength or more. Then, it is about −15 dB, and there is no such coupling. Therefore, the connection between the A and B ports is
It turns out that it is loosely coupled. As a result, it can be seen that the power input to the power supply ports is efficiently radiated even if the power supply ports A and B match at the same frequency. Further, the loss can be reduced as compared with the case where a 3 dB hybrid is used instead of the multiplexer as described in the conventional example. Further, since there is no amplitude / phase pass characteristic as seen in the multiplexer in the frequency band, the occurrence of excitation error is small.

The present invention is not limited to the above embodiment. For example, as the antenna element shown in FIG.
A patch antenna, a waveguide, a horn, etc. can be used. Further, in the embodiments of FIGS. 2 and 3, the case where one cluster feed is composed of three primary radiators is described, but the number is not limited to three, and it is composed of a plurality of primary radiators. The present invention can be applied to a cluster feed. Further, in the embodiments of FIGS. 2 and 3, the example in which one primary radiator is shared between the cluster feeds is shown, but a plurality of cluster radiators may be used. In addition, various modifications can be made without departing from the scope of the present invention.

[0031]

According to the reflector multi-beam antenna apparatus of the present invention, it is possible to construct a primary radiator system in which restrictions on frequencies are relaxed, thereby improving frequency utilization efficiency,
It is possible to provide a reflector multi-beam antenna that achieves flexibility of frequency reassignment, high quality of communication broadcasting, and reduction of loss, and exerts a great effect.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram showing an example of a primary feeding system of a multi-beam antenna device according to the present invention.

FIG. 2 is a conceptual configuration diagram showing a case where a non-reflecting termination is reduced in a primary feeding system of a multi-beam antenna device

FIG. 3 is a diagram showing a configuration of an antenna surface of a primary radiator according to the present invention.

FIG. 4 is a diagram showing a configuration of a sequential feeding system of the primary radiator according to the present invention.

FIG. 5 is a diagram showing a configuration of a reflector multi-beam antenna.

FIG. 6 is a diagram showing spatial arrangement of multi-beams and frequency allocation for explaining the principle of a reflector multi-beam antenna.

FIG. 7 is a diagram showing a configuration of a primary radiator of a reflector multi-beam antenna.

FIG. 8 is a diagram showing a conventional example of a primary feed system of a reflector multi-beam antenna.

[Explanation of symbols]

 1, 2, 3 ... Primary radiator having 2 feeding ports 4 ... Non-reflective termination 5, 6 ... Distributor 7 ... Primary radiator having 1 feeding port 10 ... Antenna element 11 ... First linearly polarized probe 12 ... Second linear polarization probe 13, 14 ... 90 ° hybrid circuit 15 ... 180 ° hybrid circuit 16 ... Feeding port

Claims (2)

[Claims] 1. A reflector multi-beam antenna device comprising: a reflector; and a plurality of cluster feeds each comprising a plurality of primary radiators and a distribution circuit for distributing signals to the primary radiators. The radiator is provided with two feed ports which have a loosely coupled characteristic and generate circularly polarized waves of the same rotation. When the primary radiator is shared between the two cluster feeds, When two feed ports are respectively connected to the distribution circuits of the two cluster feeds and the primary radiator is used for only one cluster feed, one of the feed ports of the primary radiator is non-reflectively terminated. , A mirror multi-beam antenna device, wherein the other feeding port is connected to the one cluster feed distribution circuit. 2. The reflector multi-beam antenna device according to claim 1, wherein the number of primary radiators shared between the cluster feeds is the same as the number of feed ports of the primary radiators.