JPS61234602A - Antenna system - Google Patents

Abstract

PURPOSE:To obtain an excellent cross polarization identification characteristic, by forming plural reflection mirror in such a way that the cross polarization components produced by the reflecting mirrors can be compensated by each other and providing an elliptical waveguide between the horn and polarization coupler of the antenna system of a receiving system. CONSTITUTION:Plural reflection mirrors 5', 6', and 7' are formed in such a way that the cross polarization components produced by the reflecting mirrors 5', 6', and 7' can be compensated geometrically by each other. A waveguide 9 which is rotatable around its axis and has an elliptical internal cross section is provided between the horn 4' and polarization coupler 2' of the antenna system of a receiving system. Then the polarization coupler 2' is adjusted so that the right and left peaks of the cross polarization pattern in the horizontal plane can become the same level. Thereafter, the waveguide 9 is rotated by a prescribed angle. Therefore, an excellent cross polarization identification characteristic can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a transmitting/receiving antenna device that faces each other at a predetermined distance, and that radio waves radiated from the transmitting antenna device have separation characteristics between two orthogonal polarized waves. The present invention relates to an antenna device system that allows reception without loss of signal.

[Conventional technology]

FIG. 4 shows a conventional transmitting/receiving antenna device installed opposite the propagation path [11]. (2'
) is a polarization splitter that separates the polarization of transmitting and receiving antenna equipment, ! 31. (3') is a horn that is the primary radiator of the transmitting system and receiving system antenna device; (71, (7')
) is the main reflector of the transmitting and receiving antenna equipment, +
81° (8') is the direct wave and reflected wave propagating through the spatial propagation path (11).

Conventionally, in such an antenna system, in order to obtain a predetermined degree of polarization separation, that is, a degree of crossed polarization discrimination.

The transmitting system and receiving system antenna devices shown in FIG. Cross polarization component VX of waves and cross polarization component H of horizontal polarization
The above-mentioned 116 branching filter (2) is placed at the position where x is the best.
(By fixing the 2' loop, good cross-polarized wave discrimination characteristics can be obtained.7-c.

[Problem that the invention attempts to solve However, in this method, as shown in FIG.

If the rotation angle of the polarization demultiplexer at which the degree of discrimination between VX and HX is maximized is greatly deviated, there is a drawback that a predetermined crossing polarization viii & dichotomy cannot be obtained over a wide band. Generally, when the reflection coefficient at the reflection point on the propagation path (1) is small, if the transmitting system and the receiving thread antenna device are completely facing each other as described above, 1 beam splitter + 21. (2”)
When rotated, the rotation angles at which the discrimination degree of Vx and Hx becomes maximum are almost the same, and a good 48 property can be obtained.

However, if the 9 reflected wave (8') component is not sufficiently smaller than the direct wave (8) component, 't', that is, if the reflection coefficient at the reflection point of the reflected wave (7') in the propagation path il+ is large. includes a receiving system antenna device vc i-t, a direct wave (
8) and the reflected wave (8') are received at the same time, and here, when the two reflected waves (8') have a slope of r7c waves during reflection, V'C is.

By combining with the direct wave (8), 1 becomes a circularly polarized wave that is normally horizontal and tilted from the vertical.

Furthermore, since the reflecting mirror (7') of the receiving antenna device is non-rotationally symmetrical, the rotation directions of the rainbow and elliptical polarizations are also different depending on the difference in the transmission polarization.

Therefore, as shown in FIG. 5, Vx.

The polarization demultiplexer f2+, (2'
) will shift, and the depth of the drop will become duller. In the figure, the solid line is for Hx and the dotted line is for Vx.

Figure 5(a) shows the polarization splitter (2) of the transmission system antenna device.
FIG. 5(b) shows the cross-polarization discrimination characteristics as seen in the receiving antenna system when the polarization splitter (2') of the receiving antenna system is rotated.

In this case, the setting angle of the partial splitter +21, (2') is usually chosen at the intersection of Vx and Hx, but Vx,
The polarization demultiplexer [2+, (2
Since the rotation angle of ') differs depending on the frequency, it has been difficult to obtain good cross-polarization discrimination characteristics over a wide band.

This invention was made to solve the above-mentioned problems, and aims to convert elliptical polarized waves to linearly polarized waves [7°] to obtain an antenna system having good cross-polarized wave discrimination characteristics. That is.

[Means for solving problems]

The antenna device system according to the present invention is configured such that a plurality of reflecting mirrors of the transmitting and receiving antenna devices cancel out cross-polarized components generated by each reflecting mirror, and the receiving antenna device An elliptical waveguide is inserted between the horn and the polarization splitter.[Function] The antenna system of this invention is designed to cancel the cross-polarized components generated by the two reflecting mirrors. The transmitting/receiving antenna device configured in 1- to obtain good cross-polarization discrimination characteristics.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, (41°(
4') is the primary radiator of the transmitting system and receiving system antenna device, and ideally it is a corrugated horn that does not generate any crossed polarization components. In addition, (51, (5") is the first sub-reflector consisting of a rotating quadratic curved mirror of the transmitting system and receiving system antenna device, (61, (6') is the rotating quadratic mirror of the transmitting system and receiving system antenna device @2 sub-reflectors consisting of curved mirrors,
(71, (7') are the main reflecting mirrors of the transmitting system and receiving system antenna devices, and the reflecting mirrors are configured so as to cancel out the cross-polarized components generated in each reflecting mirror.Furthermore, ( 9) is a receiving system antenna device, a corrugated horn (
The waveguide is rotatable around the tube axis connected to the power feeding end of 4') and has an oval internal cross-sectional shape. In addition, (11
, (2L (2'l.(8)#(8')) are similar to those shown in FIG.

The radio waves fed from the polarization splitter (2) of the transmission antenna device pass through the corrugated horn (4), the first sub-reflector (5) and the second sub-reflector (6), and then reach the main reflector. (7), it is radiated to the propagation path (11) with almost no cross-polarized components generated.

A reflected wave (8') is generated on this propagation path (1).

When the reflection coefficient at the reflection point is large, the receiving system antenna device receives the direct wave (8) and the reflected wave (8') at the same time, and one reflected wave (7') changes polarization during reflection. If there is a tilt, it may be combined with the direct wave (7) to become an elliptical polarized wave. III is tilted from vertical or horizontal. At this time, the receiving system antenna device uses a corrugated horn (4') that does not generate cross-polarized wave components, similar to the transmitting system antenna system, and cancels the cross-polarized wave components generated by each reflecting mirror. is composed of reflecting mirrors (5'), (is'), and (7'), but the size of each reflecting mirror is finite, and the wavelength of the radio waves used is longer than that of light. Therefore, the cross-polarized wave components generated in the antenna system cannot be completely removed, and the cross-polarized wave peak level remains as a residual component of about −30 dB or less. in this case.

The above-mentioned elliptical polarized wave maintains almost the same shape, and the above-mentioned reflecting mirror (
7'), (6'), (5') and corrugated horn (4').

It reaches the polarization splitter (2') via the inner groove wave tube (9).

At this time, the direction adjustment in the horizontal plane of the receiving system antenna device is performed by adjusting the polarization splitter (2') so that the left and right peaks of the crossed polarization pattern are equal. Set a rectangle at the null point. in this case.

Since the received radio waves are elliptical polarized waves, as shown in Figure 2,
Although the maximum value of the discrimination degree of Vx and Hx suddenly disappears, by alternately repeating the adjustment of the inner groove wave tube (9) and the adjustment of the polarization splitter described above, the third
As shown in the figure, even in the propagation path (1) with a large reflection coefficient, it is possible to secure a cross-polarization discrimination of 44 dB or more for the antenna system, which is essential for microwave digital systems.

In the above embodiment, the reception system antenna device has three reflecting mirrors, but any number of reflecting mirrors of two or more may be used.

〔Effect of the invention〕

As described above, according to the present invention, an antenna consisting of a plurality of reflecting mirrors configured to cancel out cross-polarized components generated by the reflecting mirrors in a transmitting system and a receiving system antenna device, a corrugated horn, and a receiving system are provided. By connecting an internal groove wave tube to the feeding end of the corrugated horn of the antenna device, the elliptical polarization generated in the propagation path is converted to linear polarization, and the effect of obtaining good cross-polarization discrimination characteristics can be seen.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an antenna system fM system according to an embodiment of the present invention, FIG. 18142 is a diagram showing crossed polarization discrimination characteristics, and FIG. 4 is a diagram showing a conventional antenna system Figure 5 is a diagram showing the polarization discrimination characteristics of transmission and reception. In Figure 9, (1) is the propagation path, (2) and (2') are the polarization splitters, and +3
1. (5') is a horn, +41. (4') is a corrugated horn, +51. (5') is the first sub-reflector, (61, (6') is the second sub-reflector, (7),
(7') is the main reflector, (8) is the direct wave, (8')
is a reflected wave, (9) i-1 inner groove wave tube. Note that the same or corresponding parts in FIG. 9 are designated by the same reference numerals.

Claims (1)

[Claims] An antenna device consisting of a horn as a primary radiator, an antenna consisting of a plurality of reflecting mirrors, and a polarization demultiplexer that separates polarized waves is a transmitter and an antenna device that faces each other at a predetermined spatial distance.
In the receiving antenna device, the plurality of reflecting mirrors are configured to geometrically and optically cancel the cross-polarized components generated by each reflecting mirror, and the horn of the receiving antenna device and the polarization splitter are A waveguide that is rotatable around the tube axis and has an oval internal cross-section is inserted between them, and the polarization splitter is first set so that the left and right peaks of the crossed polarization patterns on the horizontal plane are at the same level. An antenna device system characterized in that the cross-polarized wave discrimination degree in the front direction of the antenna is set to 44 dB or more by rotating the oval waveguide by a predetermined angle after adjusting.