JPS61154205A - Antenna system - Google Patents

Abstract

PURPOSE:To receive simply a left rotaroty and a right rotatory circularly polarized wave with a simple method by arranging a primary radiator for right/left rotatory circularly polarized wave at a different position relatively to a reflector having geometrical unsymmetry. CONSTITUTION:A right rotatory circularly polarized wave primary radiator 3R is arranged to the right side of a focus F (upward in figure) on a plane comprising Z and Y axes by downward view, and a left rotatory circularly polarized wave primary radiator 3L is arranged to the left of the focus F (downward in figure) fixedly by an angle theta cancelling the shift of beam due to a circularly polarized wave from a rotatory symmetric axis respectively. Thus, the right rotatory circularly polarized wave and the left rotatory circularly polarized wave incoming for the same front direction (i.e., the Z axis direction) are reflected on the reflector 2 to change the direction of main beam respectively and received by the primary radiators 3L, 3R at the same time or individually.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an antenna system capable of receiving or transmitting left and right circularly polarized waves.

<Prior Art> In recent years, satellite broadcasting has begun to be put into practical use in many countries, and various antennas for receiving satellite broadcasting have been developed.

In particular, in satellite broadcasting using the 12 GHz band, circularly polarized waves are used to avoid interference between channels and interference between broadcast signal waves of the same amount. In addition, frequency usage allocation has been determined. Furthermore, the positions of satellites in geostationary orbits are determined for many countries, and different satellites transmitting left-handed and right-handed circularly polarized waves may be placed at the same location.

Under these circumstances, if left-handed and right-handed circularly polarized signals can be received simultaneously or individually using one satellite receiving antenna system, more satellite broadcasting signals can be received, which is useful for use. Extremely effective.

Generally, a satellite receiving antenna system consists of one antenna reflector and one primary radiator, and the primary radiator beam is fixed at one focal point of the reflector. Conventionally, as a primary radiator for receiving the signals simultaneously or individually, there is a type shown in FIG. 5 which is composed of a waveguide phone.

The input side of the circularly polarized wave is composed of a circular waveguide 11, within which a dielectric plate 12 is placed at a specific position to delay the wavelength (λ) of the signal passing through the waveguide by S/4. Fixed. Furthermore, the circular waveguide I+ is converted into a rectangular waveguide I3, and for example, the left-handed circularly polarized wave LC is output from the output terminal 14 as a linearly polarized wave signal! - is taken out. On the other hand, the above circular waveguide 11
A rectangular waveguide 15 is connected perpendicularly to the output terminal 14, and the right-handed circularly polarized wave is taken out from the output terminal I6 of the waveguide.

In this conventional method, circular waveguide I+, rectangular waveguide +3
．． 15. Since the waveguide converting part I7 and the dielectric plate 12 are required, the shape becomes very large and heavy, and since polarized waves are extracted on both days with one circular aperture, the output terminal 14° The manufacturing process is extremely difficult due to the positional relationship between the parts 16 and the fixing position of the dielectric plate 2.

Therefore, if an antenna system that can easily receive left-handed and right-handed circularly polarized waves can be realized using a very simple method, it would be a very effective means.

<Object of the Invention> The present invention has been made in view of the above points, and combines a reflector having a geometrically asymmetrical shape such as an offset parabolic reflector with a primary radiator for left-handed and right-handed circularly polarized waves. The polarized primary radiators are arranged at different positions relative to the reflector, and left-handed and right-handed circularly polarized waves are extracted from each primary radiator. In other words, by utilizing the difference in the reflection direction (beam) angle of left-handed circularly polarized waves and right-handed circularly polarized waves by an asymmetric reflector, left-handed and right-handed circularly polarized primary radiators are placed at different positions, and Both circularly polarized signals reflected by the tail flap are extracted by the radiator.

In this case, the primary radiator may be any primary radiator specific to left-handed or right-handed circularly polarized waves, but if a simple one such as a helical antenna or batch antenna is used, the antenna The system is configured.

In addition to being used for reception, the present invention can also be configured as a transmission antenna system based on the same principle.

<Example> As a typical example of the present invention, an antenna system using an asymmetric offset parabolic antenna in which a part of a paraboloid of revolution is removed will be described.

Figure 3 shows a normal offset parabolic antenna, with 1
is a paraboloid of revolution, 2 is a reflector (reflection plate) consisting of a part thereof, 3 is a primary radiator, B is an incoming radio beam, F is the focal point of the paraboloid of revolution 1, and primary radiator 3 is the focal point of the paraboloid of revolution 1. Focus F
Fixed.

This offset parabolic antenna uses a reflector (reflector) 2 that is not rotationally symmetrical, as shown in Figure 3, to place the primary radiator 3 outside the aperture where the radio waves enter, thereby avoiding blocking by the primary radiator 3. This is an antenna designed like this. In the case of this antenna, when excited with linearly polarized waves, cross-polarized components are generated due to the asymmetry of the reflecting surface. On the other hand, in the case of circularly polarized waves, there is a 90° phase shift and it becomes a positive polarized wave component, so there is no cross-polarized wave, and the direction of the main beam changes between right-handed and left-handed circularly polarized waves. do.

[References: ゝゝDeclarization Pro
parties of 0ffsetReflecto
r Antennas'', TA-5HINGCHU
and R, H, TURRIN, IEEE tran
s.

Antennas Propagat, , vol.
AP-, 21.

May +973 or [Antenna Engineering Handbook]
Institute of Electronics and Communication Engineers network.

+Page 16-117] FIG. 4 explains how the direction of the main beam changes. Here, assuming that radio waves are emitted from focal point F,
FIG. 4 shows the offset parabolic antenna viewed from above in FIG. Irradiates right-handed and left-handed circularly polarized waves from focal point F! ~, then reflected by the reflector 2, the main beam of right-handed circularly polarized waves points in the direction of the solid arrow (■), and the main beam of left-handed circularly polarized waves points in the direction of the dotted arrow (■).

The dashed-dotted arrow ■ is the direction of the main beam in the case of linearly polarized waves, which is oriented parallel to the Z-axis of the offset parabolic antenna.

The present invention applies the above-mentioned difference in reflection characteristics of circularly polarized waves, and a specific example thereof is shown in FIG. FIG. 1 is also a top view of the offset parabolic antenna.

In Figure 1, 2 is the same glue reflector (reflector) as mentioned above, F
is the focal point of the paraboloid of revolution (1, see FIG. 2), 3R is a right-handed circularly polarized primary radiator, and 3L is a left-handed circularly polarized primary radiator.

The right-handed circularly polarized primary radiator 3R is on the right side of the focal point F (upper side in the figure) on the plane consisting of the Z-axis and the Y-axis when viewed from above, and the left-handed circularly polarized primary radiator 3L is on the plane consisting of the Z-axis and the Y-axis. Focus F on the same plane as the axis
They are fixedly placed on the left side (bottom side in the figure) of the rotational symmetry axis, separated by an angle θ that cancels out the beam deviation due to circular polarization. This angle is the same as the angle θ formed by the Z-axis and the solid arrow (■) or the dotted arrow (■) explained in FIG.

With the above configuration, the right-handed circularly polarized wave and the left-handed circularly polarized wave arriving from the same direction in front (i.e., the Z-axis direction) are reflected by the reflector 2, change the direction of the main beam, and simultaneously or individually transmit the primary radiation. The signals are received by the receivers 3R and 3.

When used as a transmitting antenna, due to the arrangement of the primary radiators 3R and SL as shown in 1 to 3 above, the direction of the main beam of the dual-day polarization reflected by the reflector 2 can be right-handed circularly polarized or left-handed circularly polarized. Both waves are radiated in the same direction in front (ie, the Z axis).

The primary radiators 3R and 3L may be any primary radiators that are unique to right-handed or left-handed circularly polarized waves;
Small devices such as J-tube elements can also be used, and by using these, the system can be configured even more compactly.

In addition, as shown in FIG.
If the asymmetry of the reflector is emphasized by bringing the angle closer to .theta., the angle .theta. in FIG. 1 can be made larger. This is very convenient when fixing the arrangement of both primary radiators 3R and 3L (see FIG. 1).

The above explanation uses a paraboloid of revolution, but
The same method can be applied to something that uses a parabolic cylindrical surface.

<Effects of the Invention> As explained above, in the present invention, the radiation beam directions of both left-handed and right-handed polarized waves are different in a flefter having a geometrically asymmetrical shape, such as an offset +7 laboratory antenna. Taking advantage of the can be separated and transmitted or received using a radiator.

Therefore, in particular, signals with different circular polarization characteristics sent from one or more satellites can be simultaneously received by a single flaper, which is extremely effective in broadcasting satellite receivers, etc. can be used.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a diagram illustrating changes in reflection characteristics showing another embodiment of the present invention, and Fig. 3 is a diagram illustrating a general Hiko offset parabolic antenna. ,
FIG. 4 is a diagram illustrating the reflection characteristics of circularly polarized waves in an offset parabolic antenna, and FIG. 5 is a schematic configuration diagram of a primary radiator showing a conventional example. 1... Paraboloid of revolution, 2... Reflector (reflector), 3
R: right-handed circularly polarized primary radiator, 3L: left-handed circularly polarized primary radiator, F: focal point, θ: angle of change of main beam. Agent Patent attorney Aihiko Fuku (and 2 others) Procedural amendment (method) May 1, 1985

Claims (1)

[Claims] 1. Consists of a part of a paraboloid of revolution or a parabolic cylinder,
A reflector (reflector) having a geometrically asymmetrical shape to give radio wave reflection characteristics different radiation characteristics for right-handed circularly polarized waves and left-handed circularly polarized waves; a right-handed circularly polarized primary radiator; and a left-handed circularly polarized primary radiator, and near the focal point of the curved surface of the reflector (reflector), the right-handed circularly polarized wave is placed at two positions having a direction change angle of the main beam of right-handed circularly polarized wave and left-handed circularly polarized wave. An antenna system comprising a circularly polarized primary radiator and a left-handed circularly polarized primary radiator, each of which is fixedly arranged. 2. Receiving right-handed or left-handed circularly polarized waves arriving at the reflector (reflector plate) from the same direction by the right-handed circularly polarized primary radiator and the right-handed circularly polarized primary radiator simultaneously or individually. An antenna system according to claim 1, characterized in: 3. Both circularly polarized waves emitted simultaneously or individually from the right-handed circularly polarized primary radiator and the left-handed circularly polarized primary radiator are reflected by the reflector (reflector plate) and radiated in the same direction. An antenna system according to claim 1.