JPH0116046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a primary radiator that introduces electromagnetic waves in multiple frequency bands in circularly polarized waves.

In order to simplify the explanation, we will limit the explanation to two frequency bands, and of these two frequency bands, we will refer to the electromagnetic waves in the lower frequency band _{as L} , and the electromagnetic waves in the higher frequency band as L.
This will be explained as _H.

A conventional primary radiator of this type is shown in FIG.

In the figure, 1 is a rectangular waveguide introducing _L , 2
is a polarization demultiplexer that separates orthogonal polarized waves _L 8a and _H 8b, 3 is a main waveguide, 4 is a high-pass waveguide using the low-cut characteristics of a rectangular waveguide, and 5 is _H 8b is a rectangular waveguide that introduces it, 6 is a polarization converter that converts the linearly polarized wave and circularly polarized wave of _L 8a and _H 8b, and 7 is an electromagnetic horn.

Now, when _L is introduced into the polarization demultiplexer 2 as a transmitting wave 8a and _H as a receiving wave 8b, the electromagnetic wave of _L is converted into a circularly polarized wave by the polarization converter 6 and is fed to the antenna from the electromagnetic horn 7. . By the way, since the size of the aperture of this electromagnetic horn 7 cannot usually be made sufficiently large compared to the wavelength of the frequency band _L , reflected waves are generated at the aperture. The reflected wave of _L at the aperture is reflected as an opposite circularly polarized wave,
It is converted into a linearly polarized wave by the polarization converter 6, and propagates through the main waveguide 3 as the same polarized wave as _H , and is transmitted through the high-pass waveguide 4.
leading to. However, since it is necessary to introduce only _H as a received wave into the rectangular waveguide 5, _{L is} It is reflected and reaches the polarization converter 6. Therefore, two _L electromagnetic waves having different phases are introduced into the polarization converter, which causes deterioration of the elliptical polarization coefficient.

This conventional primary radiator is configured as described above, so in order to obtain the desired elliptical polarization, the reflection of the electromagnetic horn must be reduced, and in particular, the aperture size of the electromagnetic horn must be made small. When it is necessary to do this, even if a matching element is used, it is not possible to reduce reflection over a wide band, so there is a drawback that a desired elliptic polarization cannot be obtained.

This invention was made to solve this drawback, and is a primary radiator that has a small aperture size and can obtain a desired elliptical polarization without using a matching element in the electromagnetic horn. It provides:

An embodiment of the present invention shown in FIG. 2 will be described below.

In Figure 2, 1 is a rectangular waveguide that introduces _L , 2 is a polarization splitter, 3 is a main waveguide, 4 is a high-pass waveguide, 5 is a rectangular waveguide that introduces _H , and 6 is a polarization converter, 7 is an electromagnetic horn, and 11 is E of the main waveguide 3.
A coupling hole provided in the surface, 12 is a resonant element, 13
14 is a branch waveguide, and 14 is a radio wave absorber provided in the branch waveguide.

Now, when _{the H wave} and the _L wave reflected from the electromagnetic horn 7 are propagating in the main wave tube 3, the resonant element 12 attached to the coupling hole 11 responds to _{the L} wave as follows.
Although it has almost no effect, the dimensions are such that it will be in a series resonance state for _H waves. On the other hand, the high-pass waveguide 4 is selected so that the H-plane cross-sectional dimension 9 becomes a cutoff region at the frequency _L , and the position from the coupling hole 11 of the high-pass waveguide 4 is selected so that the cutoff region is at the frequency _L. approximately λ _L /4(1+2N) where λ _L : tube wavelength at the center frequency of _the frequency band L N: 0 or any positive integer, which is a dimension of 10.

Therefore, _{the L} wave introduced into the main waveguide 3 is reflected by the high-pass waveguide 4 and enters the branch waveguide 13 via the coupling hole 11.

Further, since the branch waveguide 13 is provided with a radio wave absorber 14, _{the L} wave entering the branch waveguide is absorbed. On the other hand, _{the H} wave introduced into the main waveguide 3 is electrically short-circuited at the position of the resonant element 12 of the coupling hole 11, and _{the H} wave enters the coupling hole 11.
It reaches the high-pass waveguide 4 with almost no influence from the waveguide and is introduced into the rectangular waveguide 5.

Since the primary radiator according to the present invention operates in this way, it is possible to realize a primary radiator that obtains the desired elliptical polarization without deteriorating the elliptical polarization even if a reflected wave is generated by the electromagnetic horn 7. Additionally, the opening size of the electromagnetic horn 7 can be reduced, and there is no need to use a matching element.

FIG. 3 shows another embodiment of this invention,
Instead of providing the coupling hole 11 shown in FIG. 2 on the E surface of the main wave tube 3, it is provided on the H surface of the main wave tube 3, and has the same effect.

The above explanation is based on the case where the main waveguide 3 and the high-pass waveguide 4 are rectangular waveguides, but even in the case of circular waveguides, the inner diameter of the high-pass waveguide _{is L.}
A similar effect can be obtained if the cutoff range is selected for the frequency of .

Also, instead of the resonant element 12, the passband is _L ,
A similar effect can be obtained by using a Watsuful waveform generator selected so that the stopband is _H.

Furthermore, although the case in which the number of electromagnetic horns 7 is one is described above, similar effects can be obtained in the case of a configuration using a plurality of electromagnetic horns.

[Brief explanation of drawings]

Figure 1 shows a conventional primary radiator; Figure 2;
FIG. 3 is a diagram showing each embodiment according to the present invention. In the figure, 1 and 5 are rectangular waveguides, 2 is a polarization splitter,
3 is a main waveguide, 4 is a high-pass waveguide, 6 is a polarization converter, 7 is an electromagnetic horn, 11 is a coupling hole, 12 is a resonance element, 13 is a branch waveguide, and 14 is a radio wave absorber. be. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

Claims (1)

[Claims] 1. A polarization demultiplexer that introduces electromagnetic waves _L in a low frequency band and electromagnetic waves _H in a high frequency band in a multifrequency band, and separates the electromagnetic waves _L and _H with orthogonal polarization, and a polarization demultiplexer installed in the polarization demultiplexer. a rectangular waveguide connected to the coupling hole and introducing the electromagnetic wave _L ; a polarization converter connected to one end of the polarization splitter and converting the polarization between linear polarization and circular polarization; In a primary radiator composed of an electromagnetic horn connected to a polarization converter and a main waveguide connected to the other end of the polarization splitter, the same polarization of multiple frequency bands propagating through the main waveguide is used. A coupling hole is provided in the main wave tube so as to separate and absorb electromagnetic waves in a low frequency band from the electromagnetic waves of the waves, and the coupling hole in the main wave tube serves as a cutoff area for electromagnetic waves in a low frequency band. A high-pass waveguide is provided at a distance close to a quarter of the internal wavelength of the main waveguide or an odd multiple thereof, and a branch waveguide is connected to the main waveguide through a coupling hole. A primary radiator characterized by having a wave transmitter and a radio wave absorber installed in the pipe section.