JP6316076B2 - Polarization splitter - Google Patents

Description

  The present invention relates to a demultiplexer mainly used in the VHF band, UHF band, microwave band and millimeter wave band.

  In satellite communications, two orthogonal polarizations are often used in order to effectively use frequencies. For this reason, in a power supply circuit for satellite communication, a circuit that separates two orthogonal polarized waves is indispensable.

As a circuit that separates two orthogonal polarizations, for example, a side-coupled polarization splitter is known.
FIG. 25 is a perspective view showing a side-coupled polarization splitter disclosed in Patent Document 1 below.
FIG. 26 is a cross-sectional view showing the demultiplexer of FIG. 25, and FIG. 27 is a side view showing the demultiplexer of FIG.
The waveguide 101 is a main waveguide that transmits two polarized waves to the short-circuit end 105 when two orthogonal polarized waves (TE11 mode) are input from the horn side terminal 102.

A rectangular waveguide 103 is provided on the side surface of the waveguide 101 so that the wide direction is parallel to the tube axis direction of the waveguide 101.
Further, on the side surface of the waveguide 101, the wide direction is parallel to the tube axis direction of the waveguide 101, and an angular difference of 90 degrees from the rectangular waveguide 103 (perpendicular to the tube axis direction of the waveguide 101). The rectangular waveguide 104 is provided with an angle difference on a simple cross section.
Since the rectangular waveguide 103 and the rectangular waveguide 104 are disposed with an angle difference of 90 degrees, the propagation characteristics of the polarization due to asymmetry (particularly, the degradation of the cross polarization discrimination) is reduced. Arise.
Therefore, in this demultiplexer, the rectangular waveguide 103 and the rectangular waveguide 104 are offset in the tube axis direction of the waveguide 101 in order to reduce the deterioration of the propagation characteristics of the polarization due to asymmetry. Arranged. That is, the rectangular waveguide 103 is provided near the short-circuit end 105 of the waveguide 101, but the rectangular waveguide 104 is provided closer to the horn side terminal 102 than the rectangular waveguide 103. .

The two polarized waves transmitted to the short-circuit end 105 of the waveguide 101 are reflected by the short-circuit end 105 and coupled to the rectangular waveguide 103 or the rectangular waveguide 104 according to the direction of the polarization.
Accordingly, the rectangular waveguides 103 and 104 function as branch terminals that output either one of the polarized waves.
Here, FIG. 28 is an explanatory diagram showing the relationship between the position of the rectangular waveguide 103 and the electric field distribution of the coupled TE11 mode, and FIG. 29 shows the position of the rectangular waveguide 104 and the electric field of the coupled TE11 mode. It is explanatory drawing which shows the relationship with distribution.
In the case where the rectangular waveguide 103 and the rectangular waveguide 104 are arranged with an angle difference of 90 degrees in the cross section perpendicular to the tube axis direction of the waveguide 101, 2 orthogonal to each other from FIGS. It can be seen that the two polarizations are coupled to separate branch terminals and separated. That is, it can be seen that one of the two polarized waves is output from the rectangular waveguide 103 and the other of the two polarized waves is output from the rectangular waveguide 104.

Japanese Unexamined Patent Publication No. 60-1902 (FIG. 1)

  Since the conventional demultiplexer is configured as described above, one of the two polarized waves is output from the rectangular waveguide 103, and the other of the two polarized waves is output from the rectangular waveguide 104. A wave is output. However, since the rectangular waveguide 103 and the rectangular waveguide 104 are offset in the tube axis direction of the waveguide 101 in order to reduce the deterioration of the propagation characteristic of the polarization due to the asymmetry, There has been a problem that the axial length of the waveguide 101 becomes long.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a demultiplexer capable of obtaining a good tolerance polarization discrimination even when the axial length of the main waveguide is shortened. To do.

A demultiplexer according to the present invention includes a main waveguide that transmits two orthogonally polarized waves input from one end to the other end, and one of the two polarized waves provided on a side surface of the main waveguide. A first rectangular waveguide that outputs a polarized wave of the first and a second rectangular waveguide that is provided on a side surface of the main waveguide and outputs the other polarized wave of the two polarized waves, The wide direction of the first rectangular waveguide is parallel to the tube axis direction of the main waveguide, the wide direction of the second rectangular waveguide is the direction orthogonal to the tube axis direction of the main waveguide, and the main waveguide The first rectangular waveguide and the second rectangular waveguide are arranged so as to face each other in a cross section perpendicular to the tube axis direction of the tube, and output from the first and second rectangular waveguides. A coaxial terminal that transmits polarized waves in a frequency band higher than the polarization is connected to the other end of the main waveguide, and is connected to the connection surface of the coaxial terminal at the other end of the main waveguide. , In which grooves around the coaxial terminals has to have been subjected.

  According to this invention, the width direction of the first rectangular waveguide is parallel to the tube axis direction of the main waveguide, and the width direction of the second rectangular waveguide is perpendicular to the tube axis direction of the main waveguide. And the first rectangular waveguide and the second rectangular waveguide are arranged so as to face each other in a cross section perpendicular to the tube axis direction of the main waveguide. It is not necessary to dispose the rectangular waveguide and the second rectangular waveguide in an offset direction in the tube axis direction of the main waveguide, and deterioration of the propagation characteristics of the polarization due to asymmetry is reduced. As a result, even if the axial length of the main waveguide is shortened, there is an effect that good tolerance polarization discrimination can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a polarization demultiplexer according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing the polarization demultiplexer of FIG. 1. FIG. 2 is a side view showing the polarization demultiplexer of FIG. 1. It is explanatory drawing which shows the relationship between the position of the rectangular waveguide 3, and the electric field distribution of TE11 mode to couple | bond. It is explanatory drawing which shows the relationship between the position of the rectangular waveguide 4, and the electric field distribution of TE11 mode to couple | bond. It is explanatory drawing which shows the electric field distribution of TE11 mode in a polarization splitter. 4 is a cross-sectional view showing an example in which four rectangular waveguides are provided on the side surface of the waveguide 1. FIG. It is a side view which shows the polarization branching filter by Embodiment 2 of this invention. It is sectional drawing which shows the demultiplexer by Embodiment 2 of this invention. It is explanatory drawing which shows the electric field distribution of TE11 mode in a polarization splitter. It is a side view which shows the other demultiplexer by Embodiment 2 of this invention. It is sectional drawing which shows the other polarized-wave splitter by Embodiment 2 of this invention. It is a side view which shows the polarization demultiplexer by Embodiment 3 of this invention. It is sectional drawing which shows the demultiplexer by Embodiment 3 of this invention. It is a side view which shows the other demultiplexer by Embodiment 3 of this invention. It is a side view which shows the polarization demultiplexer by Embodiment 4 of this invention. It is a side view which shows the other demultiplexer by Embodiment 4 of this invention. It is a side view which shows the other demultiplexer by Embodiment 4 of this invention. It is a perspective view which shows the demultiplexer which has the groove structure which calculated the electromagnetic field. It is explanatory drawing which shows the cross polarization discrimination degree by which the electromagnetic field calculation was carried out. In the conventional side coupling type | formula demultiplexer / divider, it is explanatory drawing which shows the calculation result of the cross polarization discrimination | determination at the time of aligning the position of the rectangular waveguide 103 and the rectangular waveguide 104 to a tube-axis direction. It is a side view which shows the polarization branching filter by Embodiment 5 of this invention. It is a side view which shows the other polarization separator by Embodiment 5 of this invention. It is a perspective view which shows the demultiplexer by Embodiment 6 of this invention. FIG. 11 is a perspective view showing a side-coupled polarization splitter disclosed in Patent Document 1. FIG. 26 is a cross-sectional view showing the polarization demultiplexer of FIG. 25. FIG. 26 is a side view showing the polarization demultiplexer of FIG. 25. It is explanatory drawing which shows the relationship between the position of the rectangular waveguide 103, and the electric field distribution of TE11 mode to couple | bond. It is explanatory drawing which shows the relationship between the position of the rectangular waveguide 104, and the electric field distribution of TE11 mode to couple | bond.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a demultiplexer according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view showing the demultiplexer of FIG. 1, and FIG. 3 is a side view showing the demultiplexer of FIG.
1 to 3, when two orthogonally polarized waves (TE11 mode) are input from the horn side terminal 2 (one end), the waveguide 1 transmits the two polarized waves to the short-circuited end 5 (the other end). The main waveguide.
The rectangular waveguide 3 is provided on the side surface of the waveguide 1 and functions as a branch terminal that outputs one of the two polarized waves. The rectangular waveguide 3 constitutes a first rectangular waveguide.
The rectangular waveguide 4 is provided on the side surface of the waveguide 1 and functions as a branch terminal that outputs the other of the two polarized waves. The rectangular waveguide 4 constitutes a second rectangular waveguide.

The rectangular waveguide 3 and the rectangular waveguide 4 are provided on the side surface of the waveguide 1 as described above, but the width direction of the rectangular waveguide 3 is parallel to the tube axis direction of the waveguide 1. The rectangular waveguide 3 and the rectangular waveguide 3 are arranged so that the wide direction of the rectangular waveguide 4 is perpendicular to the tube axis direction of the waveguide 1 and is opposed to the tube 1 in the cross section perpendicular to the tube axis direction of the waveguide 1. A rectangular waveguide 4 is arranged.
In addition, the rectangular waveguide 3 and the rectangular waveguide 4 are disposed at a position in contact with the short-circuit end 5 of the waveguide 1.
The branch terminal is generally connected to the waveguide 1 through a coupling hole different from the terminal shape in general, but is omitted here for the sake of simplicity.

Next, the operation will be described.
In the first embodiment, a case where two orthogonal polarized waves (TE11 mode) are input from the horn side terminal 2 of the waveguide 1 will be described.
When two orthogonally polarized waves (TE11 mode) are input from the horn side terminal 2, the two polarized waves propagate inside the waveguide 1 and are reflected by the short-circuit end 5.
The two polarized waves reflected by the short-circuit end 5 are coupled to the rectangular waveguide 3 or the rectangular waveguide 4 depending on the direction of the polarized waves.
Of the two polarized waves reflected by the short-circuited end 5, the polarized wave coupled to the rectangular waveguide 3 is output from the rectangular waveguide 3, and the polarized wave coupled to the rectangular waveguide 4 is a rectangular waveguide. Output from the tube 4.

4 is an explanatory diagram showing the relationship between the position of the rectangular waveguide 3 and the electric field distribution of the coupled TE11 mode, and FIG. 5 shows the position of the rectangular waveguide 4 and the electric field of the coupled TE11 mode. It is explanatory drawing which shows the relationship with distribution.
FIG. 6 is an explanatory diagram showing the electric field distribution of the TE11 mode in the demultiplexer.
The electric field distribution of the TE11 mode in the polarization demultiplexer is as shown in FIG. 6, and one of the two polarized waves is coupled to the rectangular waveguide 3 and the other polarized wave is coupled to the rectangular waveguide 4. The reason for coupling is that the wide direction of the rectangular waveguide 3 is parallel to the tube axis direction of the waveguide 1, the wide direction of the rectangular waveguide 4 is perpendicular to the tube axis direction of the waveguide 1, and This is because the rectangular waveguide 3 and the rectangular waveguide 4 are disposed so as to face each other in a cross section perpendicular to the tube axis direction of the waveguide 1.

In the first embodiment, since the two rectangular waveguides 3 and 4 are arranged with an angular difference of 180 degrees (arranged so as to face each other), the two rectangular waveguides 103 and 104 are arranged at 90 degrees. Compared with the case of arranging with an angular difference of (see FIGS. 25 and 26), the asymmetry is reduced and the influence of the mutual terminals is reduced.
Therefore, the two rectangular waveguides 3 and 4 can be disposed close to each other with respect to the tube axis direction of the waveguide 1. For this reason, the rectangular waveguide 3 and the rectangular waveguide 4 do not need to be arranged offset in the tube axis direction of the waveguide 1, so that the cross-polarization discrimination is not degraded and the waveguide 1 is not degraded. Short axis can be achieved.

The length in the wide direction in the rectangular waveguide 3 and the length in the wide direction in the rectangular waveguide 4 may be the same or different.
When the length in the wide direction in the rectangular waveguide 3 and the length in the wide direction in the rectangular waveguide 4 are different, the two rectangular waveguides 3 and 4 separate polarized waves in different frequency bands. Can do. Moreover, since it is only necessary to achieve matching for each frequency band, good reflection characteristics can be obtained.

In the first embodiment, the example in which the rectangular waveguides 3 and 4 are provided on the side surface of the waveguide 1 having a circular cross-sectional shape is shown. However, the rectangular waveguide is provided on the side surface of the waveguide 1 having a rectangular cross-sectional shape. The wave tubes 3 and 4 may be provided.
When the cross-sectional shape of the waveguide 1 is rectangular, an unnecessary higher-order mode cut-off frequency is higher than when the cross-sectional shape is circular, which makes it easier to match and obtain good reflection characteristics. There is an effect.

In the first embodiment, the rectangular waveguide 3 and the rectangular waveguide 4 are paired, and the two rectangular waveguides 3 and 4 are provided on the side surface of the waveguide 1. Two or more rectangular waveguides may be provided on the side surface of the waveguide 1.
For example, as a variation in the case of providing two sets of rectangular waveguides on the side surface of the waveguide 1, as shown in FIG. In addition to providing in the same manner, a set of rectangular waveguide 3 and rectangular waveguide 4 is provided in the horizontal direction, a set of rectangular waveguide 3 and rectangular waveguide 4 as shown in FIG. 1 is provided in the same manner as in FIG. 1, and a set of the rectangular waveguide 3 and the rectangular waveguide 3 is provided in the horizontal direction. As shown in FIG. 7C, the rectangular waveguide 3 and the rectangular waveguide are provided. In addition to providing a set of 4 in the same manner as in FIG. 1, a mode in which a set of rectangular waveguide 4 and rectangular waveguide 4 is provided in the horizontal direction is conceivable.

Embodiment 2. FIG.
FIG. 8 is a side view showing a demultiplexer according to Embodiment 2 of the present invention, and FIG. 9 is a cross-sectional view showing the demultiplexer according to Embodiment 2 of the present invention.
8 and 9, the same reference numerals as those in FIGS.
The short-circuited end 5 of the waveguide 1 is provided with a protrusion 6 protruding toward the inside of the waveguide 1.
In the example of FIGS. 8 and 9, the shape of the protrusion 6 is a conical shape, and the length of the protrusion changes continuously in the radial direction of the waveguide 1.

FIG. 10 is an explanatory diagram showing the electric field distribution of the TE11 mode in the polarization demultiplexer.
By providing the protrusion 6 at the short-circuit end 5 of the waveguide 1, the same effect as that of the first embodiment can be obtained. In addition, as shown in FIG. The coupling of the tubes 4 is facilitated, and the effect of improving the propagation characteristics of each polarization is obtained.

8 and 9 show an example in which the length of the protrusion in the protrusion 6 continuously changes in the radial direction of the waveguide 1, but as shown in FIG. 11 and FIG. 6 may have a shape in which the length of the protrusions 6 changes stepwise in the radial direction of the waveguide 1.
In the example of FIGS. 11 and 12, the shape of the protrusion 6 is a shape in which cylindrical shapes are stacked in multiple stages, and the length of the protrusion changes stepwise in the radial direction of the waveguide 1.
In the case of such a shape, in the manufacture, excavation by a drill from the tube axis direction of the waveguide 1 becomes easy, and the cost can be reduced.

Embodiment 3 FIG.
FIG. 13 is a side view showing a demultiplexer according to Embodiment 3 of the present invention, and FIG. 14 is a cross-sectional view showing the demultiplexer according to Embodiment 3 of the present invention.
13 and FIG. 14, the same reference numerals as those in FIG. 8 and FIG.
The short-circuited end 5 of the waveguide 1 is provided with a protrusion 7 protruding toward the inside of the waveguide 1.

In the example of FIGS. 13 and 14, the shape of the protrusion 7 is a conical shape, and the length of the protrusion changes continuously in the radial direction of the waveguide 1. However, the shape of the protrusion 7 is asymmetric in the cross section perpendicular to the tube axis direction of the waveguide 1 (the shape of the protrusion 6 in FIGS. 8 and 9 is symmetric). That is, the inclination of the cone in the protrusion 7 is gentler in the lower part than in the upper part in the figure.
Since the shape of the protrusion 7 is asymmetrical, in addition to the same effects as those of the second embodiment, the effect of further improving the propagation characteristics of polarization can be obtained.

  13 and 14 show an example in which the length of the protrusion in the protrusion 7 continuously changes in the radial direction of the waveguide 1, the protrusion in the protrusion 7 as shown in FIG. 15. The length may be changed stepwise in the radial direction of the waveguide 1. For example, the column shape may be a multi-layered shape.

Embodiment 4 FIG.
16 is a side view showing a demultiplexer according to Embodiment 4 of the present invention. In FIG. 16, the same reference numerals as those in FIG.
In the first to third embodiments, an example in which the other end of the waveguide 1 is the short-circuited end 5 is shown. However, in the fourth embodiment, the other end of the waveguide 1 is not used as the short-circuited end 5. A coaxial terminal 8 is connected to the other end of the waveguide 1 for transmitting a polarized wave having a higher frequency band than the polarized wave output from the rectangular waveguides 3 and 4.
The diameter of the coaxial terminal 8 is smaller than the diameter of the horn side terminal 2.
A groove 9 is formed around the coaxial terminal 8 on the connection surface of the coaxial terminal 8 at the other end of the waveguide 1. The depth of the groove 9 continuously changes in the radial direction of the waveguide 1.

In the fourth embodiment, by appropriately selecting the diameter of the coaxial terminal 8, only polarized waves in a frequency band higher than the cutoff frequency determined by the diameter are output to the coaxial terminal 8.
On the other hand, polarized waves in a frequency band lower than the cut-off frequency determined by the diameter of the coaxial terminal 8 are reflected and output after being coupled to the rectangular waveguide 3 or the rectangular waveguide 4.

  By connecting a coaxial terminal 8 that transmits polarized waves in a higher frequency band than the polarized waves output from the rectangular waveguides 3 and 4 to the other end of the waveguide 1, the same as in the first embodiment. Besides having the effect, the low frequency band polarization and the high frequency band polarization are separated, and the low frequency band polarization is output to the rectangular waveguides 3 and 4, and the high frequency band polarization is It can be output to the coaxial terminal 8. Therefore, an effect that can be used in two frequency bands is obtained.

  FIG. 16 shows an example in which the depth of the groove 9 continuously changes in the radial direction of the waveguide 1, but as shown in FIG. It may change stepwise in the radial direction of 1.

  FIG. 16 shows an example in which the right end face of the rectangular waveguide 3 in the drawing coincides with the connection face of the coaxial terminal 8 at the other end of the waveguide 1, but as shown in FIG. The rectangular waveguide 3 may be disposed so that the right end face in the drawing straddles the connecting surface of the coaxial terminal 8 (in the case of FIG. 18, the rectangular waveguide 3 is disposed on the right side of FIG. 16). Have been).

In the operation of the polarization demultiplexer, when only one polarization is used in the low frequency band, one of the rectangular waveguide 3 and the rectangular waveguide 4 may be a non-reflective terminal.
In this case, since the polarization orthogonal to the polarization to be used is absorbed at the non-reflective terminal, the influence is reduced, and an excellent axial ratio can be obtained.

Here, the effect of the present invention will be confirmed using the calculation result of the electromagnetic field calculation.
FIG. 19 is a perspective view showing a demultiplexer having a groove structure calculated by an electromagnetic field.
In the example of FIG. 19, the depth of the groove 9 has a shape that changes stepwise in the radial direction of the waveguide 1.
The rectangular waveguide 3 and the rectangular waveguide 4 are connected to the side surface of the waveguide 1 through a coupling hole having a narrower width than the rectangular waveguides 3 and 4.

FIG. 20 is an explanatory diagram showing the cross polarization discrimination degree calculated by the electromagnetic field.
A cross polarization discrimination degree of −60 dB or less is obtained in a specific band of 16%.
FIG. 21 is an explanatory diagram showing the calculation result of the cross polarization discrimination when the positions of the rectangular waveguide 103 and the rectangular waveguide 104 are aligned in the tube axis direction in the conventional side-coupled polarization demultiplexer. .
In the case of a conventional side-coupled polarization demultiplexer, a cross polarization discrimination degree of only about −20 dB is obtained.
Therefore, in the present invention, the cross polarization discrimination can be improved by 40 dB or more as compared with the conventional example.

Embodiment 5. FIG.
22 is a side view showing a demultiplexer according to Embodiment 5 of the present invention. In FIG. 22, the same reference numerals as those in FIG.
In the fifth embodiment, similarly to the fourth embodiment, the other end of the waveguide 1 is not used as the short-circuited end 5 and has a frequency band higher than the polarization output from the rectangular waveguides 3 and 4. A coaxial terminal 8 that transmits polarized waves is connected to the other end of the waveguide 1.
In the fifth embodiment, as in the fourth embodiment, the groove 10 is provided around the coaxial terminal 8 on the connection surface of the coaxial terminal 8 at the other end of the waveguide 1. The depth of the groove 10 continuously changes in the radial direction of the waveguide 1, but unlike the fourth embodiment, the depth of the groove 10 in the cross section perpendicular to the tube axis direction of the waveguide 1 is different. The shape is asymmetric (the shape of the groove 9 in FIG. 16 is symmetric). That is, the inclination of the groove 10 is gentler in the lower part than in the upper part in the figure.
Since the shape of the groove 10 is asymmetric, in addition to the same effects as those of the fourth embodiment, the effect of further improving the propagation characteristics of the polarization can be obtained.

  FIG. 22 shows an example in which the depth of the groove 10 continuously changes in the radial direction of the waveguide 1. However, as shown in FIG. The shape may change stepwise in the radial direction.

Embodiment 6 FIG.
24 is a perspective view showing a demultiplexer according to Embodiment 5 of the present invention. In the figure, the same reference numerals as those in FIG.
In the sixth embodiment, similarly to the fourth embodiment, the other end of the waveguide 1 is not used as the short-circuited end 5, and the polarization in the frequency band higher than the polarization output from the rectangular waveguide 4 is used. Is connected to the other end of the waveguide 1. The rectangular waveguide 3 has a shape that transmits polarized waves in the same frequency band as that of the rectangular waveguide 11, and the tip thereof is a non-reflective terminal. Further, two rectangular waveguides 12 (fourth rectangular waveguides) having the same shape are provided in a direction orthogonal to the rectangular waveguide 4, and the rectangular waveguide 12 and the rectangular waveguide 4 are provided in the rectangular waveguide 12. Is loaded with a low-pass filter, and the end of the rectangular waveguide 12 is a non-reflective terminal.

Due to the low-pass filter 13, the rectangular waveguide 12 and the rectangular waveguide 4 function as electric walls in the high frequency band, and the polarized waves in the high frequency band are the rectangular waveguide 3 and the rectangular waveguide 11. Is output.
The low frequency band polarized wave functions as an electric wall by being cut off by the rectangular waveguide 3 and the rectangular waveguide 11, and the low frequency band polarized wave is coupled to the rectangular waveguide 12 and the rectangular waveguide. It is output to the tube 4. In addition, polarized waves in the same direction in the low frequency band and the high frequency band are absorbed by the non-reflective terminal in each frequency band. With the above functions, the effect of further improving the propagation characteristics of polarization can be obtained.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Waveguide (main waveguide), 2 Horn side terminal (one end), 3 Rectangular waveguide (1st rectangular waveguide), 4 Rectangular waveguide (2nd rectangular waveguide), 5 Short circuit End (other end), 6, 7 Protrusion, 8 Coaxial terminal, 9, 10 Groove, 11 Rectangular waveguide (third rectangular waveguide), 12 Rectangular waveguide (fourth rectangular waveguide) ), 13 low-pass filter, 101 waveguide, 102 horn side terminal, 103, 104 rectangular waveguide, 105 short-circuited end.

Claims (6)

A main waveguide that transmits two orthogonally polarized waves input from one end to the other end;
A first rectangular waveguide provided on a side surface of the main waveguide and outputting one of the two polarized waves;
A demultiplexer including a second rectangular waveguide provided on a side surface of the main waveguide and outputting the other polarized wave of the two polarized waves;
The width direction of the first rectangular waveguide is parallel to the tube axis direction of the main waveguide, and the width direction of the second rectangular waveguide is a direction perpendicular to the tube axis direction of the main waveguide; And the first rectangular waveguide and the second rectangular waveguide are arranged so as to face each other in a cross section perpendicular to the tube axis direction of the main waveguide ,
A coaxial terminal that transmits polarization in a higher frequency band than the polarization output from the first and second rectangular waveguides is connected to the other end of the main waveguide,
A demultiplexer according to claim 1, wherein a groove is formed around the coaxial terminal on a connection surface of the coaxial terminal at the other end of the main waveguide . Polarization separator of claim 1, wherein the depth of the groove varies continuously in the radial direction of the main waveguide. Polarization separator of claim 1, wherein the depth of the groove varies stepwise in the radial direction of the main waveguide. In a cross section perpendicular to the tube axis direction of the main waveguide, polarization separator according to any one of claims 1 to 3, wherein the shape of said grooves is asymmetric. Polarization separator according to any one of claims 1 to 4, wherein the first rectangular waveguide or said second rectangular waveguides are non-reflective termination. A main waveguide that transmits two orthogonally polarized waves input from one end to the other end;
A first rectangular waveguide provided on a side surface of the main waveguide and outputting one of the two polarized waves;
A demultiplexer including a second rectangular waveguide provided on a side surface of the main waveguide and outputting the other polarized wave of the two polarized waves;
The width direction of the first rectangular waveguide is parallel to the tube axis direction of the main waveguide, and the width direction of the second rectangular waveguide is a direction perpendicular to the tube axis direction of the main waveguide; And the first rectangular waveguide and the second rectangular waveguide are arranged so as to face each other in a cross section perpendicular to the tube axis direction of the main waveguide,
A third rectangular waveguide that transmits polarization in a frequency band higher than the polarization output from the first and second rectangular waveguides is connected to the other end of the main waveguide; and Two fourth rectangular waveguides having the same shape are provided on the side surface of the main waveguide in a direction orthogonal to the second rectangular waveguide, and the second and fourth rectangular waveguides are provided. the tube, polarization separator, characterized in that the low-pass filter for blocking passage of polarization of the higher frequency band is loaded.

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