JPH0124962Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention separates the transmission waves of both horizontal and vertical polarization, which coexist independently in the main waveguide, into transmission waves of a single horizontal or vertical polarization component in each of the two branch waveguides. or, conversely, a polarization demultiplexer that has the function of combining single polarized transmission waves in two branch waveguides so that they coexist independently as mutually orthogonal polarizations in the main waveguide. It is about improvement.

A conventional polarization splitter of this type has a structure shown in FIG. As shown in Figure 1, the main waveguide 1 of this type of polarization splitter is generally a circular waveguide or a square waveguide that can coexist and transmit both horizontal and vertical polarized waves. The wave tubes 2 and 3 are rectangular waveguides that transmit only a single polarized wave in the basic configuration.

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 reflecting plate 6 installed parallel to the electric field of the wave. It is transmitted as a wave with vertical polarization E ₁ in the opposite direction.
Similarly, the incident wave from the branch waveguide 3 is reflected by the metal reflecting 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 reflecting 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 of radio waves can be ignored.

As described above, the two horizontal and vertical polarized waves incident from the two branch waveguides coexist in the main waveguide in FIG. 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 waves of E ₁ and horizontally polarized wave E ₂ are separated into a branch waveguide 2 and a branch waveguide 3 as single polarized waves by following a path opposite to the above-mentioned transmission path.

In this way, the processes of multiplexing and demultiplexing in the polarization demultiplexer can be described reversibly, and there is no difference in transmission characteristics between each process.

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,
The radio waves incident on the main waveguide 1 from the branch waveguides 2 or 3 cause electric field disturbance in the vicinity of each coupling hole 4, generating unnecessary waves with polarization components orthogonal to the polarization plane of each incident wave. do.

In particular, the unnecessary wave having the polarization plane E′ ₂ generated by the incident wave from the branching waveguide 3 has a factor of deteriorating the VSWR characteristic of the polarization splitter for the transmitted wave having the polarization plane E ₂ .

That is, the unnecessary wave of 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. Moreover, the metal reflecting plate 7 is installed perpendicularly to this unnecessary wave, so there is little reflection and loss, and the unnecessary wave is further transmitted to the left, reflected by the short circuit plate 5 at one end of the main wave pipe, and then Conversely, it is transmitted to the right in FIG. In this way, the unnecessary waves with polarization plane E′ ₂ are transmitted through the metal reflector 6 and the shorting plate 5.
It is repeatedly reflected between the two and causes a resonance phenomenon.

As described above, in the conventional polarization splitter having the structure shown in _FIG . The drawback was that it caused a non-negligible deterioration in the VSWR characteristics of the duplexer.

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

FIG. 2 shows an embodiment of this invention, which is a polarization splitter characterized by having a radio wave absorber 8 provided on the side of the shorting plate 5 facing the main waveguide 1. In FIG. 2, the radio wave absorber 8 has the polarization plane explained above.
It absorbs and attenuates unnecessary waves with E′ ₂ incident in the direction of the short-circuit plate, suppresses reflection from the short-circuit plate, and prevents resonance, thereby reducing transmission from the branch waveguide 3 to the main waveguide 1. This improves the VSWR characteristics of waves.

Note that the shape, thickness, and other dimensions of the radio wave absorber are set with sufficient consideration given to electrical performance such as obtaining effective radio wave absorption characteristics.

In addition, in the above explanation, we have only described the transmission characteristics when a circular waveguide is used as the main waveguide and the effects of providing a radio wave absorber, which is a feature of this invention, but the main waveguide is a square waveguide. Needless to say, the same holds true even when a waveguide is used.

As mentioned above, the polarization splitter of this invention is characterized in that a radio wave absorber is provided on the side facing the main wave pipe of the shorting plate provided at the opening at one end of the main wave pipe. , unnecessary waves generated near the coupling hole between the branch waveguide and the main waveguide and transmitted toward the shorting plate are absorbed and attenuated by the above-mentioned radio wave absorber, suppressing reflection from the shorting plate and preventing resonance, resulting in a good VSWR. It maintains its characteristics. Moreover, it is a simple structure that can prevent resonance and is extremely effective economically.

[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 radio wave absorber. 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] The two branch waveguides are each connected to the main waveguide through a coupling hole, and a shorting plate is provided at the opening at one end of the main waveguide. , in a polarization splitter that separates vertically polarized waves into each of the two branching waveguides as transmission waves of a single polarization component, a radio wave absorber is provided on the side of the shorting plate facing the main waveguide. A polarization demultiplexer characterized by being provided with.