JPS6322103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a cross-polarization compensator in a communication system using two circularly polarized waves having an anti-rotating relationship with each other or two orthogonal linearly polarized waves.

For convenience of explanation, a cross-polarization compensator in a communication system using two circularly polarized waves having an anti-rotating relationship will be described as an example.

When two orthogonal linearly polarized waves are radiated into space through a 90° phase difference plate (circularly polarized wave generator) and an antenna, they become two circularly polarized waves with anti-rotation relationships and propagate in space.

Therefore, if these two circularly polarized waves are received by another antenna and passed through a 90° retardation plate, then again,
Since it can be exchanged with two orthogonal linearly polarized waves, it is possible to separate the two linearly polarized waves using a polarization splitter or the like. This communication method uses orthogonality of polarization to separate two waves, so even if two orthogonal polarized waves have the same frequency, separation is possible, and effective frequency utilization can be achieved.

However, in general, the propagation space exhibits anisotropy due to rain or the like, so the orthogonality between the two polarized waves is lost, and cross-polarized components are generated, which become interference waves.

The anisotropy of the rainfall area is caused by Differential Phase Shift (hereinafter abbreviated as DPS) and Differential Attenuation (hereinafter abbreviated as DA) that occur because raindrops become ellipsoidal. For this reason, the conventional cross-polarization compensator was constructed as shown in FIG.

In Figure 1, 1 is a transmitting and receiving antenna, 2 is a group splitter that separates the transmitting and receiving waves, and 3 is a rain area
Two rotatable 90° retarders or each rotatable 90° retarder to compensate for DPS.
A polarization conversion circuit configured in combination with a 180° phase difference plate, 4 is a polarization splitter, 5 is a coupler, 6 and 7 are variable attenuators, 8 is a 90° phase shifter, and 9 is a splitter. , 10, 11
12 is a cross-polarization compensation device for the transmission band based on the same operating principle as that for the reception band; 13 is a control device; 14
is an interference wave cancellation circuit composed of a coupler 5, a variable attenuator 6, and a 790° phase shifter 8.

Now, consider a case where circularly polarized waves, polarized waves A and B, which are in a counter-rotating relationship with each other, are transmitted from opposing antennas. When polarized waves A and B pass through the rain area,
Due to DPS and DA in rainy areas, the waves incident on antenna 1 become two elliptically polarized waves with anti-rotating directions, as shown in Figure 2. In the figure, X and Y indicate the directions of two orthogonal terminals of the polarization splitter 4.

At this time, the polarization conversion circuit 3 is controlled by the receiving terminals 10 and 11 of the polarization A and B according to the phase information of the control device 13.
When controlled so that the phase difference between them is opposite, the state after passing through the polarization conversion circuit 3 becomes two concentric elliptically polarized waves whose long axes are perpendicular to each other, as shown in FIG.

Further, according to the amplitude information of the control device 13, a polarized wave B signal is transmitted to the receiving terminal 10, and a polarized wave A signal is transmitted to the receiving terminal 11.
By controlling the variable attenuators 6 and 7 so that the signals do not appear, only the polarized wave A component can be extracted to the receiving terminal 10, and only the polarized wave B component can be extracted to the receiving terminal 11. It is possible to improve the degree of cross-polarization discrimination.

However, in the conventional method shown in Figure 1,
The control device 13 is configured to prevent unnecessary polarization components from occurring at the terminals of the duplexer 9 in both rainy and sunny conditions.
is operating, it is not possible to distinguish between rain and sunny weather at each instant, and the polarization conversion circuit 3 and variable attenuators 6 and 7, which require constant high-speed rotation, must operate, and the entire control system The disadvantage was that the frequency of failure was high.

The above also applies to the transmission cross-polarization compensator 12.

In order to eliminate these drawbacks, the present invention operates the control device only when interference waves occur at the terminals of the polarization splitter 4 after passing through the polarization conversion circuit 3, and fixes the control device in other cases. The purpose of the invention is to extend the life of the control device and reduce the frequency of failure.

FIG. 4 shows one embodiment of this invention, and in the figure, 1
14 are the same as those in FIG. 1, and 15 determines whether it is raining or sunny based on the signal from the duplexer 9 newly installed at each terminal of the polarization duplexer 4, and instructs the control device 13. This is a control device for rainfall identification.

Now, rainfall is a factor in the deterioration of orthogonality in DPS.
In addition to DA, it is always accompanied by DA. Now, if we consider the case where orthogonality is degraded only by DPS, circularly polarized waves with counter-rotating rotation become elliptically polarized waves with equal elliptical polarization coefficients, which are counter-rotating with each other and whose long axes are orthogonal to each other. Such two ellipses can be converted into two orthogonal bilinear polarized waves that match each terminal of the polarization splitter 4 by controlling the polarization conversion circuit 3. However, since DA always accompanies rainfall, the polarized wave incident on the polarization splitter 4 becomes an elliptically polarized wave as shown in FIG.

Therefore, if the control device 13 is operated by the rain discrimination control device 15 only when the incident wave to the polarization splitter 4 becomes an elliptically polarized wave as in the embodiment of the present invention, the compensator 13 is operated mainly only when it is raining. can be operated.

As a result, the compensator operates for a shorter time,
It is possible to extend the service life and reduce the frequency of failures.

FIG. 5 shows another embodiment of this invention,
This is a case where a control device 16 having a rainfall identification function that is an integral part of the control device 13 and the rainfall identification control device 15 shown in FIG. 4 is used.

In the embodiment shown in FIG. 5, the control devices are installed in one central location, which is convenient for maintenance and management.

The above is the two polarized waves A after passing through the polarization conversion circuit 3,
Although the case has been described in which the polarization conversion circuit 3 is controlled so that the long axis of B coincides with the two terminals of the polarization splitter 4, the present invention is not limited to this. It can also be used in a cross-polarization compensator that controls the polarization so that it becomes a linearly polarized wave that matches the terminal of the polarization splitter 4.

As described above, the cross-polarization compensator according to the present invention can identify rain and operates the compensation circuit only when compensation is required due to rain, which has the advantage of extending the life of the compensator.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional cross-polarization compensator, FIGS. 2 and 3 are state diagrams of elliptically polarized waves, and FIG. 4 is a block diagram of a cross-polarization compensator showing an embodiment of the present invention.
FIG. 5 is a block diagram showing another embodiment of the present invention. In the figure, 3 is a polarization conversion circuit, 4 is a polarization splitter, 13
14 is a control device, 14 is an interference wave canceling circuit, 15 is a control circuit for rain recognition, and 16 is a control device having a rain recognition function. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A polarization conversion circuit that can convert the polarization state of the received wave from the antenna, a polarization splitter that separates the radio wave that has passed through this polarization conversion circuit into two linearly polarized waves, and a polarization splitter that can convert the polarization state of the received wave from the antenna. an interference wave canceling circuit for canceling interference waves generated by cross-polarized components from the output; a rainfall identification means for determining that it is raining when interference waves are generated from the output from the polarization splitter; When the discrimination means determines that it is raining, the polarization conversion circuit and the interference wave canceling circuit are controlled to compensate for cross polarization, and when the rain discrimination means determines that it is sunny, the control is fixed. A cross-polarization compensator characterized by comprising: means.