JPH02288706A - Reflecting mirror antenna - Google Patents

Abstract

PURPOSE:To install a primary radiator to an optimum position to obtain a shaped beam and to avoid the loss of the electric characteristic for a cross polarized wave or the like by using a corrugated horn as the primary radiator supplying maximum power and using a step horn as the other primary radiator. CONSTITUTION:A corrugated horn 21a is employed for a primary radiator supplying a maximum power and one parabolic reflecting mirror and step horns 21b, 21c are employed for other two primary radiators. As a result, in comparison with the case with employing corrugated horns for all primary radiators, the interval among the primary radiators is made narrow and the desired shaped beam is easily obtained. Moreover, the cross polarized wave level is suppressed lower than the case of employing conventional horns for the step horns 21b and 21c. Furthermore, the antenna is applied to an antenna using plural reflecting mirrors such as a Cassegrain antenna or Glegory antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reflector antenna having a plurality of primary radiators and forming a shaped beam, and particularly to a reflector antenna with an improved -order radiator system.

[Prior Art] Conventionally, one method of obtaining a shaped beam using one or more reflecting mirrors is to arrange a plurality of radiators such as horns in a -order radiator system. .

As a conventional technique for obtaining a shaped beam, there is a method in which a corrugated horn is used as the primary radiator that supplies the maximum power, and an ordinary horn such as a conical horn is used as the other primary radiator (for example, Japanese Patent Publication No. 6L-34282 ).

[Problems to be Solved by the Invention] However, although the above-mentioned conventional reflector antenna has good cross-polarization characteristics in the front direction of the secondary radiation pattern, it suddenly exhibits cross-polarization characteristics at a slightly distant angle. The disadvantage is that it worsens the sex.

In particular, for antennas mounted on broadcasting satellites, for which the cross-polarization level with respect to the territory of another country is determined by the 2 International Telecommunications Treaties, it is necessary to maintain a low cross-polarization level over a wide range.

In view of the above drawbacks, one technical object of the present invention is to provide a reflector antenna that does not impair cross-polarized wave characteristics.

[Means for Solving the Problems] The reflector antenna of the present invention uses a corrugated horn that has a small cross-polarized wave component and a wide band frequency characteristic of cross-polarized waves in the -order radiator that supplies maximum power. A step horn is used as the other primary radiator.

Although the frequency characteristics of the cross-polarized waves of the step horn are not as wide as those of the corrugated horn, the power supplied is about 8 dB lower than that of the corrugated horn that supplies the maximum power, so -3
Even with a cross polarization level of 2 dB, a cross polarization level of -40 dB equivalent to that of a corrugated horn can be obtained.

[Example] Next, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a reflector antenna according to an embodiment of the present invention.

In this embodiment, one parabolic reflector and a corrugated horn 21a are used as the primary radiator that supplies maximum power, and step horns 21b and 21c are used as the other two primary radiators.

As a result, compared to the case where corrugated horns are used as all the primary radiators, the interval between the -order radiators can be narrowed, and a desired shaped beam can be easily obtained.

Further, the level of crossed polarization can be lowered than when normal horns are used for 21b and 21c.

In the above embodiment, a case was described in which one reflecting mirror was used, but the present invention can also be used in an antenna using a plurality of reflecting mirrors, such as a Cassegrain antenna or a Gregorian antenna.

Furthermore, the corrugated horn is not limited to a specific shape.

The shape and number of step horns are not limited either.

[Effects of the Invention] As explained above, the present invention uses a corrugated horn as a primary radiator that supplies maximum power.

By using a step horn as the other primary radiator, it is possible to install the primary radiator in the optimal position to obtain a shaped beam, and the reflection does not impair electrical characteristics such as cross polarization. You can get a mirror antenna.

Margin below

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a reflector antenna according to an embodiment of the present invention, and FIG. 2 is a perspective view of a primary radiator system according to an embodiment of the present invention. 1... Reflector, 21a... Corrugated horn, 21
b...Step horn, 21C...Step horn.

Claims (1)

[Claims] 1) In a reflector antenna that uses a reflector and a plurality of primary radiators to obtain a shaped beam, a corrugated horn is used as the primary radiator that supplies maximum power, and a step horn is used as the other primary radiators. Features a reflector antenna.