JPS62193402A - Reflection mirror antenna system - Google Patents

Abstract

PURPOSE:To facilitate the common use of antenna frequency and the variable adjustment of beam width with simple constitution by providing the 1st primary radiator irradiating the front reflecting face of a sub reflection mirror and the 2nd primary radiator irradiating the rear reflecting face of the sub reflection mirror. CONSTITUTION:The reflecting face of the main reflection mirror 13 is formed to be nearly a part of a parabolic face of rotation and an incoming radio wave is focused onto the front reflecting. The front face of the sub reflection mirror 14 is formed to be nearly a part of the hyperbolic face of rotation and the rear reflecting face is formed to be nearly a part of a parabolic face of rotation. The curvature of the front reflecting face is selected to focus the radio wave from the main reflection mirror 13 onto the 1st primary radiator 15 and the curvature of the rear reflecting face is selected to focus the incoming radio wave onto the 2nd primary radiator 16. Then the 1st primary radiator 15 is connected to a transmitter receiver 17 for 20/30 (GHz) and the 2nd primary radiator 16 is connected to a transiter receiver 18 for 40/50/55 (GHz).

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention is used for satellite communications, etc., and has the function of securing communication lines in multiple frequency bands and changing the beam width of the antenna pattern. The present invention relates to a reflector antenna having a reflector antenna.

(Prior Art) Conventionally, satellite antennas used for satellite communications are required to secure communication lines in a large number of frequency bands depending on the purpose. Additionally, in order to secure a communication service area, a function to change the beam width of the antenna pattern is also required. To this end, it is possible to mount separate antennas for each frequency or to mount separate antennas with different dimensions for each beam width.

On the other hand, equipment mounted on a satellite has weight restrictions and size restrictions due to the storage space of the launch vehicle, making it difficult to mount a large number of antennas. In particular, since the reflector antenna has large dimensions and weight, it tends to have more restrictions.

Conventionally, in response to the above-mentioned conflicting demands, an antenna sharing technique has been considered in which the number of mounted reflecting mirrors is reduced by sharing the reflecting mirrors. The main ones are as follows.

(1) A method of frequency sharing using a -order radiator.

(2) A method of frequency sharing using FSS (frequency selection board).

(3) A method of sharing an antenna using a composite mirror surface.

(4) A method of sharing antennas using a polarization grid.

However, depending on the purpose, it may not be possible to use these conventional techniques. Two such cases will be explained below as examples.

(Example 1) Axis-symmetric Cassegrain antenna, the diameter of the reflector is 1.5
[When ml, 20/30 [GIIzl band and 4
0/50/55 [Sharing GIIzl band, 1st
Consider a case where the required performance of a table is determined. (Note that the gain does not include power supply loss.) Table 1 In this case, if method (1) is applied, the configuration shown in FIG. 3 will be obtained. 1 is the main reflector, 2 is the sub-reflector, 3 is the primary radiator, and the -order radiator 3 is 20/30/40/50/5
5 [It will be shared by 5 frequencies of G11zl. However, since the main reflecting mirror 1 is shared, the ratio of 40/50/
55 [GHz], the beam width becomes too narrow and does not satisfy the beam width requirements in Table 1. moreover,
Another problem is that the primary radiator 3 that is used for five frequencies has an extremely complicated configuration.

Next, when method (2) is applied, the configuration shown in FIG. 4 is obtained. 4 is the main reflector, 5 is the FSS sub-reflector, θ is 20/
30 [GIz] Common-order radiator, 7 is 40150
/ 55 [GIlzl common-order radiator. This is because the FSS sub-reflector 7 works as a reflector in 20/30[G11zl, and becomes transparent in terms of radio waves in 40150155[GIIzl, so 20/30[GIIzl]
Cassegrain antenna, 40150155 [GII
zl operates as a parabolic antenna. This method has the advantage that the configuration of the -order radiators 6 and 7 can be simplified.

However, since it is the same as method (1) in that the main reflecting mirror 4 is shared, the beam width requirement is not satisfied with 40150155[GIIzl.

Furthermore, when method (3) is applied, the configuration shown in FIG. 5 is obtained. That is, 8 is the main reflector, 9 is the sub-reflector, IO is 20
/ 30 [GIIz] Common-order radiator, 11 is 40
/ 50 / 55 [(illzllll-order radiator,
12 is the reference mirror surface for 40150 / 55 [01 (zl). In this case as well, the primary radiator to,
Although it has the advantage of being able to separate the tt into two parts, the composite mirror surface 12
Since the part is no longer an effective reflecting surface for the 20/30 [GIIzl band, it does not satisfy the gain requirements in Table 1.

Method (4) is not applicable to circularly polarized waves.

From the above, it is difficult to apply the conventional shared technology in Example 1, and it is necessary to install another reflector antenna for 40/50/55 [G11zl.

(Example 2) Consider a case where there is a request to change the beam width in the same frequency band. This occurs, for example, when performing antenna pointing control. As shown in FIG. 6, when communicating between a geostationary satellite Sl in a geosynchronous orbit and an orbiting satellite S2 in a low orbit,
It is necessary to direct the antenna A mounted on the geostationary satellite S1 toward the orbiting satellite US2. Normally, as an initial step, the antenna A is generally directed toward the satellite S2 by program tracking so as to be within the capture angle range of the RF sensor of the antenna A itself. As a second step, by switching to monopulse automatic tracking using the RF sensor, it is possible to control the direction of the antenna A with high precision.

However, the capture angle range of the RF sensor becomes narrower as the gain of the antenna A becomes higher. Therefore, if the accuracy of program tracking is low, depending on the program tracking, it may not be possible to track the object within the capture range of the RF sensor.

As a countermeasure to this problem, a method of adding an antenna B having a wide capture angle range (low gain) at the same frequency can be considered. The beam width of the added antenna B is widened so that the antenna B can be brought into the capture range of the RF sensor where the antenna B itself exists by program tracking. Then, the RF sensor of this antenna B captures the satellite N S 2, and after directing the antenna A to within the capture range of the RF sensor, the antenna B
By switching the RF sensor for antenna A to the RF sensor for antenna A, extremely accurate antenna pointing control for antenna A becomes possible.

Here, it is preferable to use the antennas A and B in common because mutual alignment errors can be reduced. However, it is difficult to share any of the methods (1) to (4) described above. Although it is theoretically possible to use an array antenna instead of a reflector antenna, array antennas are extremely heavy and are currently not suitable for use on satellites.

(Problems to be Solved by the Invention) As described above, the present invention improves the difficulties in performance and configuration with conventional sharing technology in frequency sharing and beam tuning, and allows antennas to be easily configured with a simple configuration. One object of the present invention is to provide a reflector antenna that can easily perform frequency sharing and variable beam width.

[Configuration of the Invention (Means for Solving the Problem) That is, the reflector antenna according to the present invention has a main reflector and a sub-reflector, and a first reflector that irradiates the surface of the sub-reflector. The second radiator illuminates the primary radiator and the back surface of the sub-reflector.
a primary radiator, and the sub-reflector forms a skin radiation surface with a curvature such that when the radio waves focused by the main reflection mirror are reflected on the skin radiation surface, they are focused on the first primary radiator. However, the back skin emission surface is characterized by being formed with a curvature such that when an incoming radio wave is reflected on the back skin emission surface, it is focused on the second primary radiation 2.

(Function) In other words, in the above configuration, the incoming radio waves received by the main reflector are focused on the skin projection surface of the sub-reflector and then focused on the first primary radiator, thereby operating as a Cassegrain antenna. . Further, by focusing the incoming radio waves received by the back surface of the sub-reflector on the second primary radiator, it can be operated as a parabolic antenna. Since it has two antenna functions in this way, it can be used for both frequency sharing and variable beam width.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows the configuration when this invention is applied to the above-mentioned Example 1 for the purpose of frequency sharing, where 13 is a main reflecting mirror;
14 is a sub-reflector, 15 is a first primary radiator, [6 is a second
are the primary radiators of , and are arranged on the same straight line l. The main reflecting mirror 13 is formed so that its reflecting surface is almost a part of a paraboloid of revolution, and is designed to focus the incoming radio waves on the epidermal projection surface of the sub-reflecting mirror 14. This sub-reflector 14
The outer skin projection surface is formed to be approximately a part of a hyperboloid of revolution, and the back skin projection surface is formed so as to be approximately a part of a paraboloid of revolution. The curvature of the skin radiation surface is set so as to focus the radio waves from the main reflector 13 onto the first primary radiator 15, and the curvature of the skin radiation surface is set so as to focus the incoming radio waves onto the second primary radiator 16. Set. And the first primary radiator 15 is 2
0/30 [G11z] band, and the second primary radiator 16 is connected to the transmitter/receiver 17 for the 40150155 [G11z] band.
It is connected to a transmitter/receiver 18 for the 11zl band.

That is, for the 20/30 [GIIzl band, the first primary radiator 15 is used to function as a Cassegrain antenna using the skin projection surfaces of the main reflecting mirror 13 and the sub-reflecting mirror 14. On the other hand, 40/50/55 [G11z
For the L band, the second primary radiator 1B is used to function as a parabolic antenna using the back surface of the sub-reflector 14. In other words, this reflector antenna device has 20/
30 [GIIz] Band Cassegrain antenna and 40
/ 50 / 55 [GHz] band parabolic water parabolic antennas can be designed independently.

However, the aperture size of the sub-reflector 14 cannot be chosen freely, and needs to be selected within a range of about 8 to 20% of the aperture size of the main reflector 13 from the viewpoint of blocking the Cassegrain antenna. In the case of example 1, the main reflecting mirror 13
If the diameter of the sub-reflector 14 is approximately 1.5 ml and the diameter of the sub-reflector 14 is approximately 0.2 ml, all of the required characteristics in Table 1 can be satisfied.

FIG. 2 shows a configuration in which the present invention is applied to the above-mentioned Example 2, which aims to change the beam width. However, in FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals. That is, the main reflector 13, the sub-reflector 14, and the first primary radiator 15 of this reflector antenna device are not on the same straight line, but are shifted so that the sub-reflector I4 does not block the main reflector 13. will be placed. In other words, the main reflecting mirror 13, the skin radiation surface of the sub-reflecting mirror 14, and the first primary radiator 15 constitute an offset-type Cassegrain antenna. Further, the back surface of the sub-reflector 14 and the second primary radiator 16 constitute a parabolic antenna. The first primary radiator 15 is connected to a fixed terminal a of the RF switch 19, and the second primary radiator 20 is connected to a fixed terminal a of the RF switch 19. A movable terminal C of this RF switch 19 is connected to an RF sensor 20.

That is, when the movable terminal C of the RF switch 19 is connected to the b side, the RF sensor 20 is connected to a parabolic antenna formed by the second primary emitter IG and the back surface of the sub-reflector 14. Since this parabolic antenna has a small aperture diameter, the beam width is wide, which also widens the capture range of the RF sensor. Therefore, even with program tracking, it can be easily brought into the capture range. In other words, the above example 2
It can be made to function as antenna B in.

When the movable terminal C of the RF switch 19 is connected to the a side, an offset type Cassegrain antenna formed by the first primary radiator 15, the skin radiation surface of the sub-reflector 14, and the main reflector 13 is connected to the RF sensor 20. . This Cassegrain antenna has a large aperture diameter, so the beam width is narrow. Therefore R
Since the capture range of the F sensor 20 is also extremely narrow, highly accurate angular pointing accuracy can be achieved. In other words, it can function as the antenna A in Example 2 described above.

That is, this reflector antenna device has an RF switch 1
After connecting the movable terminal C of the RF switch 19 to the b side and sufficiently directing the antennas A and B to the 1" mark based on the output of the RF sensor 19, switch the movable terminal C of the RF switch 19 to the a side. The target can be easily brought into the capture angle range of antenna A with a narrow beam width.

Therefore, according to the above configuration, since the front and back surfaces of the sub-reflector are used as a Cassegrain antenna and a parabolic antenna, respectively, the frequency sharing and beam width variable functions of the antenna can be achieved extremely easily and without increasing the rRLM and dimensions. It can be realized. This reflector antenna device is small, lightweight, and powerful, so it can be used onboard satellites.
It is very effective as an antenna for satellite communication ground stations or radar.

In addition, in the second embodiment, the beam width variable function can be achieved by connecting the first and second primary radiators 15 and 16 to the RF sensor via RF switches in the antenna device shown in FIG. It can be realized. Also, in the antenna device of FIG. 2, the first and second primary radiators 15.
18 can be connected to a transmitter/receiver with a different frequency band, and can be used as an antenna for a common frequency band.

According to the present invention, as described in ``Effects of the Invention'' (2), it is possible to provide a reflector antenna that has a simple configuration and can easily share the antenna frequency and vary the beam width.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the reflector antenna device according to the present invention, FIG. 2 is a block diagram showing another embodiment according to the present invention, and FIGS. FIG. 2 is a diagram for explaining the configuration of a reflector antenna device. 1.4, 8.18... Main reflecting mirror, 2, 9.14...
Sub-reflector, 3, (i, 10.15...first primary radiator, 5...FSS sub-reflector, 7,1θ...
Second primary radiator, 17, 18... Transmitter/receiver, 19.
...RF switch, 2o...RF sensor. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 ρ Figure 5 Chiku 6 rf! J

Claims (1)

[Claims] It has a main reflecting mirror and a sub-reflecting mirror, a first primary radiator that irradiates the front reflecting surface of the sub-reflecting mirror, and a second primary radiator that irradiates the back reflecting surface of the sub-reflecting mirror, The sub-reflecting mirror has a front reflecting surface with a curvature such that when the radio waves focused by the main reflecting mirror are reflected on the front reflecting surface, they are focused on the first primary radiator, and a back reflecting surface reflects the incoming radio waves. A reflecting mirror antenna device characterized in that a back reflecting surface is formed with a curvature such that when reflected, it is focused on a second primary radiator.