JPS6151802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reflector antenna device designed to reduce the side rope level of a reflector antenna in a wide angle direction.

As shown in FIG. 1, a conventional reflector antenna device of this type includes a feeding horn 1, a sub-reflector A2, a sub-reflector B3, and a main reflector 4. The sub-reflecting mirrors A2 and B3 are rotational quadratic curved surfaces, and the main reflecting mirror 4
is a paraboloid of revolution. Phase center F of feeding horn 1
Among the radio waves from , the radio waves along the horn axis are shown in the figure.
Points A, B, C on each mirror surface as shown by the dashed line
is radiated into space. Most of the radio waves head in the direction of this radiation and form the main beam, but some of them are diffracted towards the edges of the mirror surface and head in the radiation direction that is quite far away from the main beam, i.e. in the wide angle direction, where they eliminate radio wave interference. cause This situation is also shown in FIG. Here, a point on the edge of sub-reflector A2
The case of _A1 is shown. The radio waves incident on this point _A1 are not only spherical waves from point F, but also from the sub-reflector B3.
Diffracted waves from points B ₁ and B ₂ on the edge of are also incident. These incident waves generate diffracted waves, which has the disadvantage of deteriorating wide-angle radiation characteristics.

This invention improves wide-angle radiation characteristics by connecting and integrating the main reflecting mirror and the sub-reflecting mirror on the feed horn side with a smooth mirror surface, thereby removing diffracted waves due to the edge portions of the main and sub-reflecting mirrors. The present invention provides a reflector antenna device having the following features. The drawings will be described in detail below.

FIG. 2 is a diagram showing an embodiment of the present invention. In the figure, 1 is a feed horn, 2 is a sub-reflector A, 3 is a sub-reflector B, 4 is a main reflector, and 5 is a continuation of the feed horn 1. This is a connecting mirror surface provided between the sub-reflector A2 and the main reflector 4. Again, point F is the phase center of the feeding horn 1, and the sub-reflectors A2 and B3 are rotational quadratic curved surfaces, but the types of mirror surfaces are different from those in FIG. Further, the main reflecting mirror 4 is a paraboloid of revolution. Connection mirror surface 5
is determined as follows. Here, shown in the figure,
The method of obtaining the curve A ₁ D ₁ C ₁ on the cross section of the connecting mirror surface 5 will be shown. Let point D ₁ be approximately the center of points A ₁ and C ₁ . As mentioned above, radio waves incident on the area A ₁ D ₁ are considered to be radio waves from points F, B ₁ and B ₂ . In this case, the level of the incident wave from point F is considered to be the highest, although it changes depending on the selection of the parameters of the reflecting mirror system, so the level of the incident wave from point F is
The mirror surface A 1 D ₁ can be designed so that the incident wave from A ₁ D 1 is directed toward an angular direction close to the main beam. Similarly, the mirror surface C ₁ D ₁ can be designed so that the incident wave from point B ₂ is radiated near the main beam. In this mirror design, edges are formed at points C ₁ , D ₁ , and A ₁ , but the shape of these edges is not as sharp as in the past and is almost flat, so
The diffracted waves can be ignored. This will be explained with reference to FIG. In the figure, 6 is a rotationally symmetrical mirror surface, and 7 is a flat plate. This mirror surface 6 and flat plate 7 create an edge
FIG. 4 shows the level of diffracted waves from the edges when a plane wave is incident on these edges forming E ₁ and E ₂ and having the angles. In this way, it can be seen that when is small, the diffracted wave level can be ignored.

FIG. 5 shows details of the connecting mirror surface 5. The angles _a and c of the connecting mirror surface 5 measured from the tangential direction at points A ₁ and _{C 1} on the cross-sectional curve may be determined from FIG. 4 so as to be within the permissible level. Connecting mirror surfaces 5 other than those on the cross-sectional curve can also be designed using the same concept.

As described above, according to the present invention, the sub-reflector A2,
This has the advantage that the diffracted waves on some edges of the main reflecting mirror 4 can be almost eliminated, and the wide-angle radiation characteristics can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional reflector antenna device, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, and FIGS. 3, 4, and 5 explain the operation of the present invention. This is a diagram. In the figure, 1 is a feeding horn, 2 is a sub-reflector, 3 is a sub-reflector, 4 is a main reflector, 5 is a connecting mirror surface, 6 is a rotationally symmetrical mirror surface, and 7 is a flat plate. Note that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1 In a reflector antenna device in which two sub-reflectors are provided between a main reflector and a feeding horn, the main reflector and the sub-reflector on the side of the feeding horn are connected by a mirror surface of a predetermined shape. A reflector antenna device characterized in that the edge part of the reflector and the edge part of the sub-reflector are smooth.