JPS593041B2 - circular polarization generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circularly polarized wave generator having narrow band filter characteristics.

The configuration of a conventional circularly polarized wave generator of this type is shown in FIG.

FIG. 1a is a front view of a conventional circularly polarized wave generator, and FIG. 1b is a side view.

1 is a transmission signal input end, and 2 and 3 are waveguides 4□, 4° into which the transmission signal is branched into halves.

43.44 is a coupling hole, 5□, 52 is a cavity resonator, 6 is a circular waveguide, 7 is a circularly polarized signal output end, 8 is a reflection plate, 91
, 9□, 93.94 are coupling holes, 100, 10° are cavity resonators in which the received signals resonate, 11.12 are waveguides in which two received signals having mutually orthogonal polarization planes are coupled, 1
3 is an output end for a signal obtained by combining two received signals.

Generally, in satellite communications, circularly polarized waves with opposite rotations are used for transmission signals and reception signals.

The transmission signal input from the transmission signal input terminal 1 is transmitted through the coupling hole 4.
The signal passes through a filter composed of □, 4° and a cavity resonator 51, is coupled to the circular waveguide 6, and becomes a signal having a polarization plane in the A direction.

In addition, the signal branched to the waveguide 3 is transmitted through the coupling holes 43 and 44.
The signal passes through a filter consisting of a cavity resonator at 5 degrees, and is coupled to the circular waveguide 6 to become a signal having a polarization plane in the B direction.

At this time, by changing the length of the waveguide 2.3 and creating a 90° phase difference between the signal A coupled from 42 and the signal B coupled from 44, circularly polarized waves are generated. It is occurring.

The circularly polarized signal generated here is divided into equal amounts to the terminal γ side and the reflecting plate 8 side.

The signal traveling toward the reflector 8 is reflected by the reflector 8 and travels toward the terminal 1.

The distance between the positions of the coupling holes 42 and 44 and the reflection plate is selected so that the signal that goes directly to the terminal γ side from the coupling holes 42 and 44 and the signal reflected by the reflection plate are in phase.
All transmission signals are sent out from terminal 1 without loss.

A received signal which is counter-rotating to the transmitted signal is input from terminal I.

A signal component having a polarization plane A passes through a filter consisting of coupling holes 9□, 92 and a resonator 10, and is guided to a waveguide 11.

A signal component having polarization plane B passes through a filter consisting of coupling holes 93 and 94 and a resonator 102, and is guided to the waveguide 12.

Since the received signal is a circularly polarized wave, there is a phase difference of 90° between the signal guided to the waveguide 11 and the signal guided to the waveguide 12.

By selecting the lengths of the waveguides 11 and 12 so as to eliminate a 90° phase difference, the two received signals become in phase, are combined without loss, and are extracted from the output end 13.

At this time, there is a drawback that the transmitted signal leaks into the receiving terminal because the transmitted signal includes the receiving signal that advances toward the reflector side and the signal component of the circularly polarized wave.

Since the transmitted signal has a different frequency from the received signal, it is attenuated by the filter, but since the power of the received signal is small compared to the power of the transmitted signal, the influence of the leaked transmitted signal on the received signal is large, and the received signal The C/N ratio of

Particularly in satellite communication systems, the difference in power between the transmitted signal and the received signal is large, and this effect is significant, to the extent that a separate filter must be used to absorb the transmitted signal.

As explained above, the conventional circularly polarized wave generator has the drawback that the amount of leakage of the transmitted signal to the received signal output end is large.

In order to eliminate these drawbacks, the present invention provides a directional coupler with a coupling degree ObB that has filter characteristics that use a coupling element that has a narrow band in which a strong coupling degree can be obtained and whose coupling degree largely changes with frequency. The purpose is to realize a circularly polarized wave generator in which the transmitted signal leaks less into the received signal output terminal.

The features of the present invention to achieve this object are as follows: A circular waveguide is joined at a position 90 degrees apart in the circumferential direction of the circular waveguide with the tube axis parallel to the surface of the circular waveguide. OdB directional filter with narrow band filter characteristics, which has two rectangular waveguides, a plurality of coupling holes arranged in the tube axis direction on each joint surface, and a dielectric inserted into the coupling holes. a coupler; and a connecting part that connects one end of each of the two rectangular waveguides to a Y-branch waveguide by means of two twisted rectangular waveguides having mutually different phase shifts at the center frequency of the filter characteristic. and a circularly polarized wave generator in which conversion between a fundamental mode of a rectangular waveguide and a circularly polarized wave is performed between one end of the Y-branch waveguide and one end of the circular waveguide. be.

Examples will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which 14 is a waveguide through which a transmission signal passes, 15 is a branching section that divides the transmission signal into two parts, and 1
6.17 is the waveguide 18□ through which the transmission signal divided into two is passed,
Coupling elements 182 to 183 and 184 constitute a directional coupler having a coupling degree of O dB and having filter characteristics through which a transmission signal passes, and are composed of a coupling hole and a dielectric inserted into the coupling hole.

191° 19°, 193, 194.19s are non-reflection terminators, 201° 20°, 203, 204 are coupling elements that constitute a directional coupler with a coupling degree of OdB that has filter characteristics through which the received signal passes, and coupling holes. and a dielectric material inserted therein.

21 is a waveguide to which a received signal component having a polarization plane A is coupled; 22 is a waveguide to which a reception signal component having a polarization plane B is coupled; and 23 is a branching portion where the two received signals are combined. .

FIG. 3 shows an example of the characteristics of a directional coupler with a coupling degree of O dB having filter characteristics, and 24 is the frequency characteristic of the coupling degree.

The transmission signal input from the transmission signal input terminal 1 is transmitted through the waveguide 1.
4 and is divided into two equal parts at a branching part 15.

The signal branched to the waveguide 16 is connected to coupling elements 181 and 18.
The signal passes through a directional coupler having filter characteristics composed of 2 and is coupled to the circular waveguide 6, and becomes a signal having a component of the polarization plane A.

Further, the signal branched to the waveguide 11 is transmitted to the coupling element 183
, 184, and is coupled to the circular waveguide 6 to become a signal having a component of polarization plane B.

At this time, by changing the length of the waveguides 16 and 17, the distance between the transmitted signal of the polarization plane A component and the transmission signal of the polarization plane B component is 90°.
By creating a phase difference of °, circularly polarized waves are generated.

A received signal which is counter-rotating to the transmitted signal is input from terminal I.

Among the received signals, those having a component of the polarization plane A are transmitted to the coupling element 20. ．． The signal is coupled to the rectangular waveguide 21 through a directional coupler with a coupling degree of O dB consisting of 20□.

The one having a component of polarization plane B is a coupling element 203°20
The signal is coupled to the rectangular waveguide 22 through a directional coupler with a coupling degree of O dB made up of 4 directional couplers.

Since the received signal is circularly polarized, there is a 90° phase difference between the signal guided to the waveguide 21 and the signal guided to the waveguide 22.

By selecting the lengths of the waveguides 21 and 22 so as to eliminate the phase difference, the received signals of the two components become in phase, are combined without loss at the branching section 23, and are taken out from the output end 23.

In FIG. 3, a solid line 24 shows the coupling characteristic of a narrowband OdB coupler having filter characteristics.

It can be seen from the figure that narrow band filter characteristics can be obtained.

In the method of the present invention, by using this coupler, filter characteristics are obtained, and the directionality of the coupler prevents the transmission signal component from proceeding through the circular waveguide 1 toward the non-reflection terminator 195. There is.

Therefore, compared to conventional circularly polarized wave generators, there is an effect that the leakage of the transmission signal to the reception signal terminal is reduced by the amount of directionality.

As explained above, in the present invention, since a circularly polarized wave generator is constructed using a narrowband OdB coupler, it is possible to obtain filter characteristics, and the directionality of the coupler allows
It is possible to reduce the transmitted signal component traveling in the same direction as the received signal.

As a result, there is an advantage that leakage of the transmitted signal to the received signal output end can be reduced, and deterioration of the C-ratio of the received signal can be prevented.

In satellite communication systems where the power difference between the transmitted signal and the received signal is large, it is an important issue to prevent the deterioration of the C ratio of the received signal, and the circularly polarized wave generator of the present invention can be used in such fields. Very effective.

[Brief explanation of the drawing]

FIG. 1a is a front view of a conventional circularly polarized wave generator, FIG. 1 is a side view of the same figure, and FIGS. FIG. 3 is an example of the characteristics of a narrow-band directional coupler with a coupling degree of O dB having filter characteristics. 1... Transmission signal input end, 2, 3... Waveguide where the transmission signal is branched into halves, 41, 4°, 43
, 44...Coupling hole, 5□, 52...Cavity resonator, 6...Circular waveguide, 1...
Circularly polarized signal input/output end, 8...Reflector, 91,
92,93,94...Binding hole, 107,102
...Cavity resonator that resonates the received signal, 1L12
. . . Waveguide where two received signals having mutually orthogonal polarization planes are coupled; 13 . . . Output end of a signal obtained by combining the two received signals. 14... Waveguide through which the transmission signal passes, 15...
・Branch section that divides the transmitted signal into two equal parts, 16.17...
...Waveguide through which the transmitted signal divided into two passes, 18. ．． 18
□, 183.184...Coupling element constituting a directional coupler with a coupling degree of OdB having filter characteristics through which a transmission signal passes, 191.192.193°194.1
95...Non-reflection terminator, 200, 20°, 20
3゜204... A coupling element constituting a directional coupler with a coupling degree of OdB having filter characteristics through which the received signal passes, 21... A received signal component having a polarization plane A is coupled. waveguide, 22... waveguide to which the received signal component having polarization plane B is coupled, 23...
A branching section where two received signals are combined, 24...
Frequency characteristics of coupling degree.

Claims (1)

[Claims] 1. A circular waveguide and two square guides that are joined at positions 90° apart in the circumferential direction of the circular waveguide with their tube axes parallel to the surface of the circular waveguide. An Od having narrow band filter characteristics that includes a wave tube, a plurality of coupling holes provided in each joint surface and arranged in the tube axis direction, and a dielectric inserted into the coupling holes.
The B directional coupler and one end of each of the two rectangular waveguides are connected to the Y branch waveguide by two twisted rectangular waveguides having mutually different phase shifts at the center frequency of the filter characteristic. a connecting portion, and conversion between the body mode of the rectangular waveguide and circularly polarized wave is performed between one end of the Y-branch waveguide and one end of the circular waveguide. circularly polarized wave generator. Claim 1, wherein a non-reflection termination means is provided at the other end of each of the 22 rectangular waveguides and at the other end of the circular waveguide.
circularly polarized wave generator.