JPS6057721B2 - Demultiplexer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a demultiplexing device used in a communication system using two circularly polarized waves having anti-rotating relationships.

In wireless communications that use two circularly polarized waves with the same frequency and opposite rotation, one of the polarized waves has degraded cross-polarization discrimination due to anisotropy in the propagation path due to rain, etc. The waves can be split without containing cross-polarized components by a splitting device consisting of a circularly polarized wave generator, a polarization plane rotator, and a polarization splitter that are rotatable around the tube axis.

Here, for convenience of explanation, the right-handed circularly polarized transmitted wave is referred to as R, the left-handed circularly polarized transmitted wave is designated as L, and of the transmitted waves R and L whose cross-polarized wave discrimination has deteriorated due to rain etc., L is It is assumed that demultiplexing is performed in a state where there is no interference wave of R.

In addition, in controlling such a branching device, a pilot wave of a frequency not included in L is required at least for R.

Let this pilot frequency be fRp) and the pilot wave be Rp. First, FIG. 1 shows an example of a conventional demultiplexing device.

In FIG. 1, 1 is a horn, 2 is a circular waveguide, and 3a and 4a are couplers that couple with electric field components parallel to the Y-axis and the X-axis in the circular waveguide 2 at a frequency fRp, respectively;
5 is a circular polarization generator, 6 is a polarization plane rotator, 7 is a polarization splitter,
8 and 9 are branching waveguides that separate electric field components parallel to the Y-axis and X-axis in the polarization splitter, 10 is a rotary joint, and 11 and 12 are circularly polarized wave generator 5 and polarization plane rotation, respectively. A drive device that rotates the device 6, 13 is a coupler 3a and 4a
This is a signal processing device that calculates optimal angles for the circularly polarized wave generator 5 and the polarization plane rotator 6 from the amplitude and phase of each component of the pilot wave Rp coupled to the pilot wave Rp, and provides a drive signal.

The transmitted waves R and L have their cross-polarized wave discrimination degraded by rain or the like, and become elliptically polarized waves Rl and Ll, respectively, and enter the demultiplexer.

At this time, if the amplitude ratio (elliptical polarization index) of the long axis direction component and the short axis direction component of the electric field of the elliptically polarized wave is r1 and the angle that the long axis makes with the X axis is φ, then the X axis direction component of the electric field and the Y The phase difference of the axial component (ZEx-ZEY) is given by the following equation.

Here, it is 1 for right-handed polarization and + for left-handed polarization.

In this equation, as φ=0, the elliptically polarized wave R
In Ll and Ll, the phase difference between the long axis direction component of the electric field and the short axis direction component perpendicular to this is 90 degrees, so in the above duplexer, first, the circularly polarized wave generator 5 is rotated and the phase difference is 90 degrees. R the slow phase surface
By placing it parallel to the long axis of the electric field ellipse R1, the long axis direction component and the short axis direction component of R1 can be made to be in phase or out of phase.

That is, at this time, R1 becomes the linearly polarized wave R2 of the electric field, which is the vector sum of the long axis direction component and the short axis direction component. on the other hand! is another elliptically polarized wave! is converted to Next, by rotating the polarization plane rotator 6 and placing its 180 degree slow phase at an angle that is half the angle that the electric field of the linearly polarized wave R2 makes with the X axis, the electric field of this linearly polarized wave R2 is It becomes a linearly polarized wave R, which is parallel to .

At this time, L2 is an elliptically polarized wave with only the long axis angle changed! becomes. In this way, in the polarization splitter 7, R3 is
Since it is a linearly polarized wave parallel to the axis, it is coupled only to the branch waveguide 9 and not to the branch waveguide 8.

On the other hand, since L, is coupled to both branch waveguides 8 and 9, branch waveguide 8 has ! is split without including the cross-polarized component R3. However, in the conventional demultiplexing device described above, it is necessary to calculate and determine the angle of the long axis before and after the circularly polarized wave generator 5 from the amplitude and phase of the R components coupled to the couplers 3a and 4a. be.

Therefore, as a signal processing device of this demultiplexing device, R
, as well as amplitude and phase detection equipment, it requires a fairly complex arithmetic unit, which has the disadvantage of being expensive. next,
Another example of the conventional demultiplexing device is shown in FIG. The demultiplexing device with the control method shown in this figure is Electronics Le Terrs, VOl. l2, positive. 25, pp. Seki 6-6
87 (December 197). In Figure 2, 1 and 5 to 13 are the same as in Figure 1, 3b and 4
b is the pilot wave R after being split into branch waveguides 8 and 9.
This is a combiner that combines p. In such a demultiplexer shown in FIG. 2, the circularly polarized wave generator 5 is driven and controlled so that the components of the pilot wave Rp coupled to the couplers 3b and 4b are in phase. Further, the polarization plane rotator is driven and controlled so that no component is coupled to the coupler 3b. However, the demultiplexing device shown in FIG. 2 has the disadvantage that it is difficult to accurately detect the phase difference because the levels of the components of the pilot waves Rp coupled to the couplers 3b and 4b are significantly different. There is.

In order to eliminate these drawbacks, the present invention provides a coupler for the pilot wave Rp in a circular waveguide that rotates together with the circularly polarized wave generator, and will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, in which 1 to 13 are the same as in FIGS. 1 and 2, 14 is a flexible line, and 15 is a pilot wave Rp coupler 3a and 4a. The phase difference between the components Rpx″ and Rpx″ (ZRpx″−
This is a second signal processing device that generates a voltage proportional to the cosine of ZRpy''). However, the circular waveguide 2 of the demultiplexing device of the present invention is connected to a circularly polarized wave generator 5 as shown in FIG. rotates with

At this time, the coupler 4a couples with the electric field component parallel to the 9[3 slow phase plane of the circularly polarized wave generator 5, and the coupler 3a couples with the component orthogonal to this electric field component, and these electric fields Coordinate axes parallel to the components are indicated by x'' and Y'' in FIG. 3, respectively. Further, in FIG. 3, the drive device 11 rotates the circularly polarized wave generator 5 clockwise with a negative voltage and counterclockwise with a positive voltage.

Next, FIG. 4a shows the relationship between the polarization state of the incident pilot wave R in the circular waveguide 2 and the x'' and Y'' axes.

In addition, FIG. 4b shows the angle φ (9 positive clockwise in FIG. 4a) that the long axis of the pilot wave Rp makes with the X'' axis as shown in FIG. component R of R,
The relationship between the phase difference (ZRpx''-ZRpy'') between py' and Rp/ is shown. In other words, the right-handed elliptically polarized pilot wave Rp has a phase difference (ZRpx'' - ZRpy
'') is larger than 90 degrees when φ is positive, and smaller than 90 degrees when φ is negative. Therefore, when φ is positive, a negative voltage is generated in the second signal processing device 15. , drive device 1
1, the circularly polarized wave generator 5 is rotated clockwise until the 90-degree slow phase plane parallel to the x'' axis coincides with the long axis of the pilot wave Rp.

Further, when 0 is negative, the circularly polarized wave generator 5 is rotated counterclockwise, and 90 is the second rotation when the slow surface coincides with the long axis of R9.
Since the voltage generated in the signal processing device 15 becomes O, the circularly polarized wave generator 5 always has a 90 degree slow phase plane as the pilot wave Rp.
It will be controlled so that it coincides with the long axis of . Therefore, by the above control, the incident wave R1 is converted into a linearly polarized wave R2 as described in the conventional demultiplexing device of FIG.

The driving method of the polarization plane rotator 6 of this invention is exactly the same as the method shown in FIG. It will no longer be done. Therefore, the signal transmitted with the left-handed circularly polarized wave can be branched to the branch waveguide 8 without being interfered with by the signal transmitted with the right-handed circularly polarized wave. In the demultiplexing device of this invention,
As shown in Figure 1, it is inexpensive because it does not require a complex arithmetic circuit like the conventional demultiplexer, and it is not necessary to detect the phase difference between signals with significantly different levels as in the demultiplexer shown in Figure 2. There is an advantage that there is no

Note that in the above description, only the coupler is attached to the circular waveguide that rotates together with the circularly polarized wave generator, but even the detection device included in the signal processing device may be attached.

Further, although the pilot wave is transmitted as a right-handed circularly polarized wave, it may be a left-handed circularly polarized wave.

However, in this case, the signal transmitted with right-handed circular polarization is separated without being interfered with by the signal transmitted with left-handed circular polarization. As described above, the demultiplexing device according to the present invention has the advantage that drive control of the circularly polarized wave generator can be easily performed with a simple circuit configuration.

[Brief explanation of drawings]

1 and 2 are schematic configuration diagrams showing a conventional demultiplexing device, FIG. 3 is a schematic configuration diagram showing one implementation of the present invention, and FIG. 4 shows A and b of the demultiplexing device of the present invention. It is a diagram showing the principle of operation. In the figure, 3a, 3b, 4a, 4b are couplers, 5 is a circularly polarized wave generator, 6 is a polarization plane rotator, 7 is a polarization splitter, 10 is a rotary joint, 11, 12 is a drive device, 13, 15 is a signal processing device, and 14 is a flexible line.

Claims (1)

[Claims] 1 In a demultiplexing device used for communications for two orthogonal polarizations, in which at least one polarization includes a pilot wave of a frequency that is not used in the other polarization, a horn; a first circular waveguide that is coupled to the first circular waveguide; first and second couplers that are provided in the first circular waveguide and separately couple orthogonal polarized waves; a circularly polarized wave generator that is cascaded to the circular waveguide and changes the phase of one polarized wave by 90 degrees with respect to the orthogonal polarized wave; a second rotary joint is connected to this circularly polarized wave generator; a polarization plane rotator that changes the phase of one polarized wave by 180 degrees with respect to the orthogonal polarization; and a polarization plane rotator that is cascaded to the polarization plane rotator via a third rotary joint; a polarization demultiplexer that separates orthogonal polarized waves into separate terminals; a pair of branch waveguides provided in this polarization demultiplexer; , third and seventh couplers that separately couple orthogonal polarized waves; a first signal processing device that processes signals of the pilot waves coupled to the first and second couplers; ;
a second signal processing device for processing the pilot wave signals coupled to the third and fourth couplers; rotationally driving the circularly polarized wave generator by the output of the first signal processing device; third and fourth couplers connected to the terminals of the polarization splitter, respectively; and rotationally driving the polarization plane rotator by the output of the second signal processing device; A second driving device for rotating a circular waveguide together with the circularly polarized wave generator.