JPH03250801A - Polarization coupler - Google Patents

Abstract

PURPOSE:To prevent the degradation in the electric characteristic by varying the interruption frequency of other high-order modes without varying the interruption frequency of a fundamental mode. CONSTITUTION:Four ridges 8 are disposed to the inner wall face of a main circular waveguide 1 as shown in figure (b) at the interval of 90 deg. along the axial direction. When the ridges 8a-8b are arranged to the main circular waveguide 1 in such a manner, the interruption frequency of the high-order mode propagated in the main circular waveguide 1 is varied. Thus, the interruption frequency of other modes than the fundamental mode is varied. Then the degradation in the electric characteristic generated when the interruption position of the high-order mode and the coupling hole are overlapped, that is, such as the group delay characteristic, the reflecting characteristic and the identification degree of orthogonal polarized wave is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a polarization splitter, particularly as an antenna device used in a satellite communication earth station.

[Prior art] Conventionally, this type of polarization splitter has a polarization splitter as shown in Fig. 3.
One side of the main circular waveguide l has a short surface 2,
About 1/2 people from this short side 2.

Coupling holes 3a and 3b are provided on the wall of the main circular waveguide 1 at a distance of (input, wavelength of a predetermined frequency band signal), and a rectangular high-frequency branch waveguide is connected via the coupling holes 3a and 3b. 4 and a low frequency branch waveguide 5 are connected.

That is, the high frequency band coupling hole 3a is provided at a position approximately 1/2 wavelength of the high frequency band signal from the sheet surface 2, and the low frequency band coupling hole 3b is provided at a position approximately 1/2 wavelength of the high frequency band signal from the short surface 2. It is provided at a position of 1/2 wavelength. Then, the coupling hole 3
The branch waveguide 4.5 coupled to a and 3b is a filter for blocking unnecessary frequency band signals, that is, the high frequency branch waveguide 4 is a low frequency blocking filter, and the low frequency branching waveguide 5 is a high frequency blocking filter. This makes it possible to separate or combine high-frequency band signals and low-frequency band signals.

[Issue IN to be solved by the invention] In the conventional polarization splitter described above, the coupling holes 3a, 3b
In order to strengthen the coupling between the TE and moat, a magnetic field coupling method is adopted, and an elongated hole is formed in the inner wall surface of the main circular waveguide l in the direction orthogonal to the axis.

Therefore, depending on the frequency setting state, impedance discontinuity may occur in the high frequency band with respect to the cutoff region of unnecessary high-order motes, and as a result, a resonance phenomenon may occur, resulting in group delay characteristics, reflection characteristics, orthogonal polarization discrimination. There was a problem that various electrical characteristics such as temperature deteriorated.

The present invention has been made in view of the above problems, and aims to provide a polarization splitter that can eliminate impedance discontinuity in high frequency bands and prevent deterioration of various electrical characteristics.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides two parallel
Linearly polarized signals of two different frequencies are propagated together, with a main circular waveguide having a short surface on one side, and a wall of the main circular waveguide at a position approximately 1/2 wavelength from the short surface at each frequency. In a polarization splitter including two rectangular branching waveguides connected through a coupling hole provided and having a filter for blocking unnecessary frequency bands, a plurality of rectangular branching waveguides are arranged at predetermined intervals inside the main circular waveguide. The structure is such that a book ridge is provided to change the cut-off area of the higher-order moat.

Preferably, four ridges are provided inside the main circular waveguide at intervals of 90 degrees in the axial direction.

[Function] According to the above configuration, the cut-off frequencies of other higher-order motes can be changed without changing the cut-off frequency of the basic mote, and deterioration of electrical characteristics can be prevented.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the configuration of the polarization splitter of the embodiment, and the main circular waveguide l, which is a common waveguide, has approximately 1/2 person 1. A coupling hole 3a is opened at a position of (λ, 1; wavelength of high frequency band signal), and a high frequency branch waveguide 4 is connected to this coupling hole 3a. Also, short side 2
Approximately 1/2 in from g2 (in, 2; wavelength of low frequency band signal)
A coupling hole 3b is opened at the position , and a low frequency branch waveguide 5 is connected to this coupling hole 3b. Further, the high-frequency branch waveguide 4 has a low-frequency rejection filter, and the low-frequency branch waveguide 5 has a high-frequency rejection filter, and with such a configuration, the high frequency band and the low frequency band can be separated and combined. I will do it.

Note that the high frequency electric field vector 6 and the low frequency electric field vector 7 are parallel to each other.

In this embodiment, four ridges 8 are provided on the inner wall surface of the main circular waveguide 1 at 90 degree intervals along the axial direction, as shown in FIG. 1(b).

When the ridges 8a to 8d are arranged in the main circular waveguide 1 in this manner, the cutoff frequency of the moat propagating within the main circular waveguide 1 changes.

This state is shown in FIG.

Figure 2(a) shows the results of calculations for a typical moat, which is based on the height of the ridge 8 being h and the main circular waveguide as shown in Figure 2(b). Let h/a (when W/a=0.2) be the radius of pipe l, and take h/a (when W/a = 0.2) on the horizontal axis,
The vertical axis represents the ratio of the cutoff frequency f co of the fundamental mote to the required cutoff frequency f, that is, the value of f0/fc0.

According to this figure, it is clear that the cutoff frequencies of the fundamental modes (TE, □ mote) do not change, but the cutoff frequencies of other modes change. Therefore, the size and shape of the ridge 8 can be changed. By selecting, it is possible to change the cutoff frequencies of other higher-order motes without changing the cutoff frequency of the fundamental moat.

When the ridges 8a to 8d are disposed in the main circular waveguide 1 in this way, it is possible to change the wavelength within the guide of the higher order moat, and therefore it is possible to change the cutoff position of the higher order moat. As a result, the cutoff frequency range of the higher-order moat can be moved away from the coupling hole 3 without changing the position of the coupling hole 3.
It is possible to prevent deterioration of electrical characteristics due to impedance discontinuity caused by the coupling hole 3 and the cutoff region of the higher-order moat.

[Effect of the invention] As explained above, according to the present invention, two parallel
In a polarization splitter that separates two different frequency signals,
By attaching a ridge to the main circular waveguide, it is possible to change the cutoff frequency of frequencies other than the fundamental moat, and the electrical characteristics that occur when the cutoff position of the higher-order mode and the coupling hole overlap, that is, the group delay characteristic・It has the effect of reducing deterioration in reflection characteristics, orthogonal polarization discrimination, etc.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a polarization splitter according to an embodiment of the present invention. FIG. 1(a) is an overall perspective view, FIG. Figure 2 shows the change in cutoff frequency in a typical mote in the example, and Figure 2 (a)
3 is a graph showing calculation results, FIG. 3B is a diagram showing ridge setting conditions, and FIG. 3 is a perspective view showing the configuration of a conventional polarization splitter. 1. Main circular waveguide 2. Sides 3a, 3b: Coupling hole 4. High frequency branch waveguide 5: Low frequency branch waveguide 8 (8a to 8d) ・Ridge

Claims (2)

[Claims] (1) Linearly polarized signals of two different frequencies parallel to each other are propagated together, with a main circular waveguide having a short surface on one side, and approximately In the polarization splitter including two rectangular branch waveguides connected via a coupling hole provided at a 1/2 wavelength position and having a filter for blocking unnecessary frequency bands, the main circular waveguide A polarization splitter characterized by providing a plurality of ridges at predetermined intervals inside a tube to change the cutoff range of higher-order modes. (2) The polarization splitter according to claim 1, wherein four ridges are provided in the main circular waveguide at intervals of 90 degrees in the axial direction.