JPS6017262B2 - Branching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a branching circuit that converts two arbitrary polarized waves into a required linearly polarized wave, and particularly aims to improve the response characteristics of the branching circuit.

When an antenna receives two circularly polarized waves that are in an anti-rotating relationship with each other, if there is an asymmetrical factor such as rain in the propagation path space, the orthogonality between these two polarized waves will be broken and interference between different polarized waves will occur. do.

Various methods have been devised to improve this problem. 1st
The figure shows an example of this. In FIG. 1, when two polarized waves (referred to as solar polarization and V polarization) as shown in FIG. The polarized wave in the state 29 of the device 6 is input to the receiver 7 as an error signal, and the phase difference between the reference signal and the error signal and the amplitude of the error signal are detected and output to terminals 31 and 32, respectively. ^/4 plate 2 and ^/2 plate 3 via servo mechanisms 8 and 9 so that both become zero.
By controlling
Only the Vy polarized wave is split into the terminal 26 of the polarization splitter 4.

Also, since the polarized wave of 10 Vx is branched to the terminal 27 of the polarization splitter 4, the signals 30 and 31 of the splitters 5 and 6 are separated by the splitters 10 and 11, respectively. When the wave is applied to the Y terminal and the X terminal of the polarization splitter 12, the same polarization state as shown in FIG. 8 can be reproduced at the terminal 34.

Here, with the same configuration as above, after the terminal 34 of the polarization splitter 12, there is an input/4 plate 13, a ^/2 plate 14, a polarization splitter 15, a splitter 16, 17, a receiver 18, and a servo mechanism. 19 and 20 and control the ^/4 board 13 and the ^/2 board 14 so that the signals at terminals 38 and 37 of the receiver 18 are both zero.
The V-stripe wave becomes a straight line and can be output to the terminal 36 of the polarization splitter 15. Therefore, the terminal 4 of the duplexer 16 can receive only the sun polarized wave, and the terminal 39 of the duplexer 10 can receive only the sun polarized wave.
Since only polarized waves can be received, cross polarization compensation becomes possible. In addition, a dummy load 21 is installed in the branching filters 11 and 17.
, 22 are connected. However, according to this method, making the phase difference between the reference signal and the error signal zero means that the input quarter plate 2 is aligned with either the shortest axis or the shortest axis of the incident circularly polarized wave. ^/4 If the incident polarization to plate 2 is bridge circular polarization, control is possible; When it comes to polarized waves, the insertion angle of the input/four plate 2 can be any angle, and the phase error sensitivity becomes zero, so the input/four plate 2 can be inserted at any angle.
The disadvantage is that the rotational position of the Therefore, when the received polarization becomes a camellia circular polarization due to rain, etc., the difference between the long axis or short axis direction and the rotational position where the input/fourth plate 2 is present can be as large as 900 degrees. This has the disadvantage that it deteriorates the polarization conversion characteristics of the circuit and, for example, increases the response time until the input/quarter plate 2 rotates to compensate for cross polarization. This invention was made to eliminate these drawbacks,
The present invention provides a branching circuit that improves the response of polarization conversion in automatic cross-polarization compensation.

In this invention, a variable phase shifter 23 is provided at the front stage of the input/fourth plate 2 as shown in FIG. The controller 42 detects the angle formed by the ^/4 plate 2 in sunny weather and the angle formed by the long axis of the circularly polarized wave in rainy weather, and calculates this difference. The above-mentioned phase shifter 23 is controlled so that 4.

Such control is performed during clear weather (initial setting) before the start of operation, or when the control pilot frequency is changed, and is maintained at a constant value until the next setting change. An embodiment of the present invention shown in FIG. 4 will be described below.

In FIG. 4, if the polarized wave incident on the antenna 1 is a circularly polarized wave, the variable phase shifter 23 actively converts the incident polarized wave into a camellia circularly polarized wave as shown in FIG. Output. Therefore, the solar polarized wave at the terminal 28' of the duplexer 5 is used as a reference signal, and the solar polarized wave at the terminal 29 of the duplexer 6 is inputted to the receiver 7 as an error signal. , the amplitude error signal is supplied to the servo mechanisms 8 and 9, and the input/fourth board 2 is input so that each error signal becomes zero.
, the input/second plate 3 is controlled, the solar polarized wave is converted into the linearly polarized wave shown in FIG. We have now assumed that the polarized wave incident on the antenna is circularly polarized, but if this becomes a camellia circularly polarized wave as shown in Figure 2 due to rain, etc., the variable phase shifter 23 should be fixed in the above-mentioned state. If this is done, the wave will become a camellia circularly polarized wave as shown in FIG. 5, and only the Vy polarized wave will be branched to the terminal 26 of the polarization splitter 4 using the same operating principle as described above. In this way, even if the incident polarization to antenna 1 becomes circularly polarized due to clear weather,
By using the variable phase shifter 23, the incident polarization to the input/quarter plate 2 can always be made into a camellia circular polarization, and therefore,
The control system for the ^/4 plate 2 is always driven to the optimum rotational position without the phase error sensitivity becoming zero, enabling highly accurate cross-polarization automatic compensation. Here, the configuration and control of the variable phase shifter 23 will be described in more detail.

The variable phase shifter 23 is connected between the ^/4 plate 2 and the antenna 1, and has a function of converting input polarized waves. If a circularly polarized wave is input now, this circularly polarized wave is converted to a bridge circularly polarized wave. 42 is an initial setting controller that controls the variable phase shifter 23. Before starting operation, it detects the angle 8^ that the ^/4 plate 2 makes with respect to the horizontal axis during clear weather, and Equipped with a function to calculate the difference ac (=0^1OB) between the long axis of the camellia circularly polarized wave generated by the horizontal axis and the angle OB, and send a control signal to the variable phase shifter 23 to reduce this difference ac. ing.

Here, the angle OB that the bridge circular polarization caused by rain etc. makes with the horizontal axis is the sum of the angle 450 made by the equivalent slow surface caused by rain etc. with the horizontal axis, but since a is small, it is about 4
It can be considered as 50. Therefore, the variable phase shifter 23 is controlled so that the value becomes 0^3450, and thereafter this setting is kept constant until it is necessary to change it. With the above configuration, the circularly polarized wave input from the antenna 1 is forcibly converted into a camellia circularly polarized wave by the variable phase shifter 23, and this camellia circularly polarized wave is rotated over a predetermined angle.

According to the embodiment of the present invention, the response of the ^/4 plate 2 can be improved, and the cross-polarization automatic compensation characteristics can be improved. The above explanation was given for the case where the incident polarized wave is a circularly polarized wave in a clear sky, but when the incident polarized wave in a clear sky is a camellia circularly polarized wave with its long axis in the direction shown in Figure 6. , due to rain, etc., the long axis of the long axis changes rapidly in the direction shown in FIG. , sudden changes in the polarization axis due to rain, etc. will not occur in the variable phase shift output.

Therefore, even in such a case, the input/quarter plate 2 does not need to be rotated by a large angle, and the response characteristics during automatic cross-polarization compensation are extremely good. As described above, according to the present invention, by appropriately adjusting the variable phase shifter for the incident polarized wave that changes due to rain, etc., the camellia circularly polarized wave whose axis of polarized wave is always within a certain rotation range is generated. Since it can be converted and applied to the ^/4 board, the response characteristics of the ^/4 board can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional cross-polarization compensation circuit,
FIG. 2, FIG. 3, FIG. 5, FIG. 6, and FIG. 7 are diagrams showing the states of input waves, and FIG. 4 is a block diagram showing an embodiment of the present invention. In the figure, 1 is the antenna, 2 and 13 are the ^/4 boards, and 3
, 14 is an input/2 board, 4, 12, 15 is a polarization splitter, 5, 6
, 10, 11, 16, 17 are duplexers, 7, 18 are receivers, 8, 9, 19, 20 are servo mechanisms, 21, 22 are dummy loads, 23 is a variable phase shifter, 25, 26, 27, 28
,29,30,31,32,33,34,35,36,
37, 38, 39, 40, and 41 are terminals, and 42 is a controller. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 4 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 Conversion means for converting at least one of the elliptically polarized waves generated in the propagation space of polarized waves due to rain and having an anti-rotation relationship to each other into linearly polarized waves, and a polarization splitter for separating both polarized waves after the conversion. In the branching circuit having the above, the angle formed by the long axis of the elliptically polarized wave with respect to the horizontal axis and λ forming the conversion means.
A branching circuit in which a variable phase shifter, which is set in advance so as to reduce the difference from the angle formed by the /4 plate, is provided upstream of the conversion means.