JPH05218702A - Polarizer - Google Patents

Abstract

PURPOSE:To make the polarizer small by reducing a quantity of a transmission signal leaked to a reception filter so as to make the reception filter small. CONSTITUTION:A circularly polarized wave generator 11 is formed by plural cavity resonance circuits 13 connected together through plural coupling holes 12 provided symmetrically to a guide wall of a circular waveguide. The resonance frequency fR of the plural cavity resonance circuits 13 is set to a frequency between transmission and reception frequencies fH, fL. When the plural cavity resonance circuits 13 act like a capacitive component, e.g., to the transmission frequency band fH, they act like an inductive component to the reception frequency band fL, the reception signal is converted into a linearly polarized wave signal orthogonal to the transmission signal. A transmission end 15 of a transmission reception branching device 14 and a reception filter 16 are arranged so as to send and receive signals whose polarized wave directions are orthogonal to each other respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization demultiplexer applied to an antenna device for transmitting and receiving by concentric circular polarization in different frequency bands.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, a polarization demultiplexer applied to an antenna device for transmitting and receiving by concentric circularly polarized waves in different frequency bands includes a circularly polarized wave generator 21 and a transmission / reception demultiplexer. And a container 24.

The circularly polarized wave generator 21 has a plurality of cavity resonance circuits 23 connected through a plurality of coupling holes 22 symmetrically provided on the wall of the circular waveguide, and transmits a transmission signal and It acts on each of the received signals to convert the linearly polarized transmission signal into a circularly polarized wave, and converts the circularly polarized reception signal into a linearly polarized wave parallel to the transmission signal.

Further, the transmission / reception branching filter 24 is formed by having a transmission end 25 and a reception filter 26 each formed of a rectangular waveguide in a circular waveguide, and in this case, in the cavity resonance circuit 23. It is provided so as to form an angle of 45 °.

A power amplifier is connected to the transmitting end 25 side, and a low noise amplifier is connected to the receiving filter 26 side. The reception filter 26 is connected to the tube wall of the circular waveguide so as to reduce the coupling with the transmission signal and attenuates the transmission signal.

Next, the operation of the circularly polarized wave generator 21 will be described.

The circularly polarized wave is a wave in which linearly polarized waves whose phases are shifted by 90 ° are orthogonal to each other. Now, as shown in FIG. 5, the direction of the cavity resonance circuit 23 is the Y axis, the direction orthogonal thereto is the X axis, the Y axis component is Ey, and the X axis component is Ex.
Then, the circularly polarized wave is Ey = Ex · exp (± jπ /
2). Here, Ey = Ex · exp (+ jπ /
If 2) is a right-handed circularly polarized wave, Ey = Ex · exp (-j
π / 2) is a left-handed circularly polarized wave.

The circular polarization generator is a kind of phase shifter that gives a phase difference of 90 ° to mutually orthogonal waves. Here, the transmission and reception frequency bands are fH and fL, respectively.
Assuming that the resonance frequency of the plurality of cavity resonance circuits 23 is fR, the transmission and reception frequency bands fH and fL are set lower than fR, for example, as shown in FIG. Therefore, since the susceptance acting on the transmission signal and the reception signal have the same polarity, the reception signal can be converted into a linearly polarized wave parallel to the transmission signal in the duplexer 24.

[0009]

In the conventional demultiplexer described above, since the transmission / reception signals are linearly polarized waves parallel to each other in the transmission / reception demultiplexer 24, the transmission signal input from the transmission end is It leaks to the reception filter side without being sufficiently attenuated. Therefore, the attenuation of the transmitted signal is 8
Since it is necessary to connect a large receiving filter that provides 5 dB or more to the receiving end side, there is a problem in that the size of the demultiplexer becomes large.

An object of the present invention is to provide a polarization splitter capable of reducing the amount of transmission signal leaking to the receiving filter side and downsizing the receiving filter.

[0011]

In the demultiplexer of the present invention, a plurality of cavity resonance circuits are connected to a circular waveguide through which transmission and reception signals of different frequency bands propagate, through a plurality of coupling holes. And a circular waveguide connected to the circular polarization generator, the transmitting end for transmitting the transmission signal is provided on the terminal side of the circular waveguide, and the circular waveguide is provided. A polarization demultiplexer including a transmission / reception demultiplexer in which a reception filter that allows the reception signal to pass through is provided on a tube wall of a waveguide, wherein the resonance frequencies of a plurality of cavity resonance circuits of the circular polarization generator are: ,
Set in the middle of the frequency band of the transmission and reception signals,
Further, the transmission end and the reception filter of the transmission / reception demultiplexer are arranged such that they can transmit and receive signals whose polarization directions are orthogonal to each other.

[0012]

The present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.
It is composed of a circular polarization generator 11 and a duplexer 14.

The circularly polarized wave generator 11 has a plurality of cavity resonance circuits 13 connected to each other through a plurality of coupling holes 12 provided symmetrically on the wall of the circular waveguide. Here, the resonance frequency fR of the plurality of cavity resonance circuits 13 is set in the middle of the transmission and reception frequency bands fH and fL as shown in FIG. Therefore, since the cavity resonance circuit 13 acts on the transmission frequency band fH and the reception frequency band fL with polarities opposite to each other, the reception signal is converted into a linearly polarized signal orthogonal to the transmission signal in the duplexer 14. Can be converted.

That is, as shown in FIG. 2A, assuming that the direction of the cavity resonance circuit 13 is the Y axis and the direction orthogonal thereto is the X axis, the transmission signal Et of the frequency band fH is a circular polarization generator. By passing through 11, the phase of the Y-axis component Ey of the transmission signal Et is delayed by 90 °, so that the signal is converted to the left-hand circularly polarized wave and is transmitted from the antenna. On the other hand, the left-hand circularly polarized wave reception signal Er in the frequency band fL passes through the circular polarization generator 11 to generate the Y-axis component E of the reception signal Er.
Since the phase of y advances by 90 °, it can be converted into a reception signal Er orthogonal to the transmission signal Et.

In this way, the circular polarization generator 11
Since the reception signal of the same circular polarization can be converted into a linear polarization signal orthogonal to the transmission signal, as shown in FIG. 1, the transmission end 15 of the transmission / reception duplexer 14 and the reception filter 16 are polarized. Since the signals can be transmitted and received in directions orthogonal to each other, it is possible to reduce the leakage of the transmission signal to the reception filter side as compared with the conventional one, and thus the reception filter 16 can be downsized. ..

[0017]

As described above, according to the present invention, by setting the resonance frequencies of a plurality of cavity resonance circuits of a circular polarization generator in the middle of the transmission and reception frequency bands, the transmission signal and the reception signal are Since the signals can be converted so that they are orthogonal to each other, it is possible to reduce the transmission signal that leaks from the transmission end of the transmission / reception demultiplexer to the reception end side. Therefore, the reception filter can be downsized and the demultiplexer can be downsized. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, in which (a) is a perspective view and (b) is a front view.

FIG. 2 is a diagram for explaining the operation of the circularly polarized wave generator shown in FIG.

3 is a diagram showing a resonance frequency of the circularly polarized wave generator shown in FIG.

FIG. 4 is a diagram showing an example of a conventional polarization splitter, (a)
Is a perspective view and (b) is a front view.

FIG. 5 is a diagram for explaining the operation of the conventional circularly polarized wave generator shown in FIG.

6 is a diagram showing a resonance frequency of the conventional circularly polarized wave generator shown in FIG.

[Explanation of symbols]

 11 circularly polarized wave generator 12 coupling hole 13 cavity resonance circuit 14 transmission / reception duplexer 15 transmission end 16 reception filter

Claims (1)

[Claims] 1. A circular polarization generator comprising a plurality of cavity resonance circuits connected to a circular waveguide through which a transmission signal and a reception signal of different frequency bands propagate via a plurality of coupling holes, and the circular polarization. A circular waveguide connected to the generator is provided, a transmission end for transmitting the transmission signal is provided on the terminal side of the circular waveguide, and the reception signal is passed through the pipe wall of the circular waveguide. A polarization demultiplexer comprising a transmission / reception demultiplexer provided with a reception filter, wherein the resonance frequencies of the plurality of cavity resonance circuits of the circular polarization generator are in the middle of the frequency bands of the transmission and reception signals. A polarization demultiplexer characterized in that the transmission end and the reception filter of the transmission / reception demultiplexer are arranged so as to transmit and receive signals whose polarization directions are orthogonal to each other.