JPH0124963Y2 - - Google Patents

Description

[Detailed description of the device] This device transmits horizontally and vertically polarized waves that coexist independently in the main waveguide, and transmits a single horizontal or vertically polarized wave component to each of the two branch waveguides. The function is to separate the single-polarized transmission waves of two branch waveguides so that they coexist independently in the main waveguide as mutually orthogonal polarization transmission waves. This paper relates to the improvement of a polarization demultiplexer.

Conventionally, there is a polarization splitter of this type having a structure shown in FIG.

Generally, the main waveguide of a polarization splitter is a circular waveguide or square waveguide that can transmit horizontal and vertical polarized waves together, and the branch waveguide is used to transmit a single polarized wave in the basic configuration. A rectangular waveguide is used that transmits only

In FIG. 1, the transmitted wave of the branch waveguide 2 enters the main waveguide 1 through the coupling hole 4, and is reflected by the metal reflection plate 6 installed parallel to the electric field of the wave. It is transmitted as a wave with vertical polarization E ₁ to the right.
Similarly, the incident wave from the branch waveguide 3 is reflected by the metal reflection plate 7 provided parallel to the electric field of the wave, and is transmitted to the right in the figure as a horizontally polarized wave _E2 .
At this time, the metal reflection plate 6 is installed in a direction perpendicular to the horizontally polarized wave E ₂ , and if it is placed at an appropriate position with an appropriate thickness, reflection and loss can be ignored.

As described above, the horizontal and vertical polarized waves incident from the two branch waveguides coexist in the main waveguide in Figure 1 as two orthogonal polarized waves and are transmitted to the right in the figure. .

On the other hand, the principle of reversibility holds true for the above transmission theory, and the vertically polarized waves coexisting and transmitted within the main waveguide 1
The E ₁ and horizontally polarized E ₂ waves follow a path opposite to the above-mentioned transmission path and are separated into a branch waveguide 2 and a branch waveguide 3 as single-polarized waves, respectively. In this way, the process of multiplexing and demultiplexing in the polarization demultiplexer can be described reversibly, and the transmission characteristics do not change.

Therefore, in order to simplify the explanation, only the process in which radio waves enter the main waveguide from the branch waveguide, that is, the case corresponding to multiplexing, will be described below.

In the conventional polarization splitter having the structure shown in Fig. 1,
Radio waves incident on the main waveguide 1 from the branch waveguides 2 or 3 cause electric field disturbance near each coupling hole 4, generating unnecessary waves having polarization components orthogonal to the polarization plane of each incident wave. .

In particular, the unnecessary wave with the polarization plane E ₂ ' generated from the wave incident from the branching waveguide 3 is the polarization plane E ₂ of the polarization splitter.
This is a factor that degrades the VSWR characteristics for transmitted waves with . That is, the unnecessary wave with the polarization plane E ₂ ' is reflected by the metal reflecting plate 6 installed parallel to the electric field of this wave, and is transmitted to the left in FIG. Furthermore, the metal reflector 7 is installed perpendicularly to the electric field of this unnecessary wave, so there is little reflection and loss, and the unnecessary wave is further transmitted to the left and reflected by the shorting plate 5 at one end of the main wave tube. This time, the signal is transmitted in the opposite direction to the right in FIG. In this way, the unnecessary wave having the polarization plane E ₂ ' is repeatedly reflected between the metal reflecting plate 6 and the shorting plate 5, causing a resonance phenomenon.

As described above, in the conventional polarization splitter having the structure shown in FIG. 1, the unnecessary wave with the polarization plane E ₂ ' generated from the radio wave incident on the main waveguide 1 from the branch waveguide 3 causes resonance. The drawback was that it caused a non-negligible deterioration in the VSWR characteristics of the polarization demultiplexer.

The purpose of this invention is to improve the above-mentioned drawbacks and provide a polarization demultiplexer with a simple structure and excellent VSWR characteristics.

FIG. 2 is a diagram showing an embodiment of this invention, in which the main wave is connected between the short-circuit plate 5 at one end of the main waveguide 1 in a polarization splitter and the branch waveguide 3 near the short-circuit plate. This polarization splitter is characterized in that a metal post 8 is provided on the tube in parallel to the tube axis of the branch waveguide 3.
A screw, bolt, or the like is used for the metal post 8 in view of ease of installation on the main waveguide 1 and ease of changing the insertion amount.

The metal post 8 provided on the main waveguide is electrically equivalent to a susceptibility element loaded in parallel to the circuit, and by changing the amount of insertion into the main waveguide, the plane of polarization E ₂ ' explained above can be changed. The frequency at which resonance occurs due to unnecessary waves can be changed arbitrarily. Therefore, if we focus on the frequency band in which the polarization demultiplexer is used, it is possible to shift the resonance that appears within this band to a frequency that does not pose a problem when using the polarization demultiplexer, thereby maintaining good VSWR characteristics. be able to.

Note that the exact position of the metal post 8 in the main waveguide 1, the shape and size of the post, etc. are determined with sufficient consideration given to electrical characteristics such as the ability to effectively move the resonance frequency outside the frequency band used. It is set.

Also, in the above explanation, the effect of the metal post 8 was described only when a circular waveguide is used as the main waveguide, but it goes without saying that the same holds true even when a square waveguide is used as the main waveguide. .

As mentioned above, in the polarization splitter of this invention, the branch waveguide is connected to the main waveguide between the short-circuit plate at one end of the main waveguide and the branch waveguide near the short-circuit plate. This device is characterized by a metal post installed parallel to the tube axis, and by changing the insertion amount of the metal post into the main wave tube, the resonance frequency of unnecessary waves can be moved outside the frequency band used by the polarization splitter. can be made, economical and easy with simple structure, good
This is an extremely effective device that can contribute to providing a polarization demultiplexer with VSWR characteristics.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional perspective view showing a conventional polarization splitter, and FIG. 2 is a partial cross-section perspective view showing the polarization splitter of this invention, where 1 is a main waveguide, and 2 is a branch. waveguide, 3 is a branch waveguide, 4 is a coupling hole, 5 is a short circuit plate,
6 is a metal reflecting plate, 7 is a metal reflecting plate, and 8 is a metal post. It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of utility model registration request] Each of the two branched waveguides is connected to the main waveguide through a coupling hole provided in the main waveguide, and a shorting plate is provided at the opening at one end of the main waveguide to coexist within the main waveguide. In a polarization splitter that separates transmitted waves of both horizontal and vertical polarization into transmission waves of a single polarization component to each of the two branching waveguides, the shorting plate and the branch nearer to the shorting plate are used. A polarization splitter characterized in that a metal post is provided in the main waveguide between the waveguide and parallel to the tube axis of the branch waveguide closer to the shorting plate.