JPH0345921B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an improvement in a corrugated horn used as a primary radiator in an aperture antenna. In particular, it relates to the adjacent structure of a plurality of corrugated horns arranged in an aperture antenna.

[Description of prior art]

In an aperture antenna such as a parabolic antenna, when shaping the radiation pattern and creating multiple beams, the most effective method is to use a plurality of primary radiators. In such an antenna, in order to improve the cross-polarization characteristics and increase the aperture efficiency, it is necessary to use a primary radiator with good cross-polarization characteristics and good radiation characteristics.

To achieve this, a corrugated horn is often used as the primary radiator, but when multiple corrugated horns are used, the aperture diameter of the horn is approximately λ/2 larger than that without corrugation, and each horn The center spacing of the beam shaped by However, λ indicates the free space wavelength. For example, even if you try to obtain a shaped beam from a geostationary satellite that can efficiently illuminate a narrow terrain like mainland Japan, it is not possible to obtain an efficient shaped beam because the distance between adjacent horns cannot be close to the same distance as one without corrugation. There were flaws.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a corrugated horn that can improve the above-mentioned drawbacks and easily obtain an efficient shaped beam with fewer cross-polarized components.

[Key points of the invention]

The present invention is configured to use corrugated horns as a plurality of primary radiators, and to shorten the distance between the centers of the corrugated horns by incorporating some of the corrugated parts of each adjacent corrugated horn. Features.

[Explanation based on examples]

This will be explained based on the drawings.

FIG. 1 is a sectional view showing the configuration of a general offset parabolic antenna. 1 is a reflector, 2 is a primary radiator, Fp is a focal point of a parabola, and M is a mirror axis.

FIG. 2 is an enlarged sectional view of the corrugated horn used as the primary radiator 2 in FIG. 1. 3 is a corrugated horn, 31 is a corrugation tooth (convex), 32 is a corrugation groove (concave), 2a is an opening diameter, and 2a+λ/2 is a diameter of the groove 32 at the tip of the opening. Therefore, the outer diameter of a corrugated horn is approximately λ/2 smaller than that of a horn without corrugation.
only becomes larger.

FIG. 3 is a diagram showing the arrangement of the horns as seen from section A-A' in FIG. 1, and 4b, 4c, and 4d are horns without corrugation. Now, assume that the desired antenna shaped beam is obtained with the horn arrangement shown in FIG. However, since a horn without corrugation is used, there is a drawback that the level of crossed polarization becomes high.

FIG. 4 is a diagram showing the arrangement of the horn as seen from cross section A-A' in FIG.
In order to improve the drawbacks of the case shown in the figure, a corrugated horn was used as the primary radiator. 3b, 3
c and 3d are corrugated horns. By using a corrugated horn, the cross polarization level is lowered, but 4c-4b and 4c-4d in Figure 3
Compared to the horn spacing of 3c-3d and 3c-3d of FIG. 4, the horn spacing of 3c-3d and 3c-3d of FIG. , it becomes difficult to obtain the desired antenna shaped beam.

FIG. 5 shows a cross-sectional view of a combination of two corrugated horns according to an embodiment of the present invention, 3b and 3c are corrugated horns, 31 is a corrugation tooth (convex), and 32 is a corrugation groove (concave). be.

FIG. 6 is an enlarged sectional view of FIG. 5. The grooves (concave) 32 of the corrugated horn 3c are placed on the teeth (convex) 31 of the corrugated horn 3b, and the corrugated horn 3 is placed on the teeth (convex) 31 of the corrugated horn 3c.
By inserting the grooves (concave) 32 in b, the distance between the corrugated horns in 3b and 3c can be approximately reduced.
It is possible to set it to 2a+λ/4. however,
The width of the corrugation teeth 31 and the width of the groove 32 must be λ/4 or less.

FIG. 7 is a cross-sectional view of the dielectric 33 inserted into the groove 32 of FIG. Now, if the permittivity of the dielectric is εr, the distance between corrugated horns 3b-3c is approximately
It is possible to approach as close as 2a+λ/ _4√r .

FIG. 8 is a layout diagram of a corrugated horn according to an embodiment of the present invention, as seen from cross section A-A' in FIG. In this way, corrugated horns 3b, 3c
and 3d, the center distance of the corrugated horns can be shortened by λ/4 or more when compared with the conventional corrugated horn arrangement shown in FIG.

Although the above description has been made using an offset type parabolic antenna as an example, the use of the corrugated horn of the present invention is not limited to offset type parabolic antennas. FIG. 9 shows an example of use in a Cassegrain type parabolic antenna. 11 is a sub-reflector. Moreover, FIG. 10 shows an example of use in a normal front-fed parabolic antenna. In addition, it can be used in an aperture antenna equipped with a reflecting mirror, such as a Gregorian parabolic antenna.

[Explanation of effects]

As explained above, by incorporating part of the corrugation of adjacent corrugated horns and shortening the distance between the horn centers, it is possible to obtain almost the same antenna radiation pattern as a horn without corrugation while keeping the level of crossed polarization low. is possible. Further, it exhibits excellent effects such as a greater degree of freedom in horn arrangement than simply arranging corrugated horns, and a greater degree of freedom in shaping the beam.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a general offset parabolic antenna. Figure 2 is an enlarged sectional view of a corrugated horn. FIG. 3 is a sectional view taken along line A-A' in FIG. 1 when three horns without corrugations are arranged.
FIG. 4 is a cross-sectional view taken along line A-A' when three corrugated horns are arranged in FIG. FIG. 5 is a sectional view of a combination of two corrugated horns according to an embodiment of the present invention. FIG. 6 is an enlarged sectional view of the part in which the corrugation shown in FIG. 5 is incorporated. FIG. 7 is a cross-sectional view of a dielectric inserted into the groove of the corrugation shown in FIG. FIG. 8 is a sectional view taken along line A-A' when a corrugated horn according to an embodiment of the present invention is arranged as shown in FIG. FIG. 9 is a sectional view when the corrugated horn according to the present invention is used in a Cassegrain parabolic antenna. FIG. 10 is a sectional view when the corrugated horn according to the present invention is used in a general parabolic antenna. 1... Reflector, 2... Primary radiator, 3... Corrugated horn, 31... Corrugation tooth (convex), 32... Corrugation groove (concave).

Claims (1)

[Scope of Claims] 1. A corrugated horn in which a plurality of corrugated horns are arranged on an aperture surface antenna and have projections and depressions formed on the inner surface, characterized in that the projections and depressions are configured to intertwine with each other at a portion of an adjacent outer periphery. Corrugated horn with surface antenna.