JPH11308004A - Polarization demultiplexer - Google Patents

Abstract

(57) [Problem] To improve isolation of horizontal and vertical two-polarization of LNB with a simple structure. SOLUTION: A cylinder 2 following a primary radiator 1 and a chassis.
A circular waveguide is formed by the cylindrical portion 2 'formed by the shield cover 13 and the substrate 12, and the substrate 11 is arranged in the tube axis direction. 5
Is converted into a rectangular waveguide 7 (formed of the chassis and the conductor surface on the back surface of the board) by the slot 6 formed at the position of the short face 4, and is erected on the board at a position of λg2 / 4 from the short face 9. The probe 10 receives the vertically polarized wave. From the connection part 3 (discontinuous part) of the circular waveguide to the short surface 4 (2n + 1)
× λg1 / 4, N × λg2 / 2 from the input end face 8 to the short face 9 of the rectangular waveguide (n and N are natural numbers), so as not to hinder the current of both polarized waves on the tube wall of the connection part; Reduces radio wave leakage from the connection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization demultiplexer, and more particularly to an LNB (low noise frequency converter) for receiving satellite radio waves.
For improving horizontal / vertical dual polarization isolation.

[0002]

2. Description of the Related Art A primary radiator-integrated LNB or the like for receiving both horizontal and vertical polarizations has, for example, a single substrate 21 orthogonal to the tube axis of a circular waveguide 2 as shown in FIG. Although there are two probes 22 and 23 for vertical polarization reception and horizontal polarization reception on the top, the two probes are close to each other and interfere with each other, and the electric field distribution is disturbed. There is a problem that the isolation deteriorates and, for example, only about 17 dB to 18 dB can be obtained for a required level of 25 dB (decibel) or more.
If two probes are three-dimensionally arranged, the isolation is improved, but the structure becomes complicated because two substrates are required.

[0003]

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to improve the isolation between horizontal and vertical polarized waves with a simple structure.

[0004]

In order to achieve the above object, in the polarization demultiplexing device according to the present invention, a substrate is provided in a tube axis direction on a circular waveguide and a rectangular waveguide following the circular waveguide. The first waveguide in the circular waveguide provided on the substrate receives one of the orthogonal polarized waves, and converts the other polarized wave converted into the rectangular waveguide into the rectangular waveguide provided on the substrate. Second in the tube
Make the probe receive.

[0005] The other polarized wave is converted into a rectangular waveguide by a slot provided on the short surface of the circular waveguide.

The circular waveguide is formed by a cylindrical portion following the primary radiator and a portion following the cylindrical portion formed by a chassis and a shield cover with the substrate interposed therebetween, and The waveguide is formed by the chassis and the ground conductor on the back surface of the substrate.

The connection between the cylindrical portion following the primary radiator of the circular waveguide and the cylindrical portion formed by the chassis and the shield cover is (2n + 1) × λg1 from the short surface of the circular waveguide. / 4 (when n = 1, 3λg1 /
4, λg1 is the wavelength in the circular waveguide) and N × λg2 / 2 (N =
In the case of 1, λg2 / 2 and λg2 are set to the wavelengths in the rectangular waveguide (n and N are natural numbers) so as to reduce the leakage of the radio wave from the connection part (the discontinuous part of the circular waveguide). .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a configuration diagram of a main part of an embodiment of a polarization demultiplexing device according to the present invention.
2B is a side view, and FIG. 2 is an exploded perspective view of a main part. In the figure, 1 is a primary radiator, 2 is a cylindrical portion of a circular waveguide,
2 'is a cylindrical portion, 3 is a connection portion of a circular waveguide, 4 is a short surface of a circular waveguide, 5 is a first probe, 6 is a slot, 7 is a rectangular waveguide, and 8 is a rectangular waveguide. 9 is the short end of the rectangular waveguide, 10 is the second probe, 11 is the substrate,
12 is a chassis and 13 is a shield cover.

The circular waveguide comprises a cylindrical portion 2 following the primary radiator 1, a chassis 12 and a shield cover 13 with a substrate 9 interposed therebetween.
And a portion 2 'formed into a cylindrical shape. The substrate 11 is arranged in the tube axis direction of the circular waveguide 2 + 2 'and the rectangular waveguide 7. Then, from the short surface (rear end surface) 4 of the circular waveguide 2 + 2 'to λg1 / 4 (λg1 is the wavelength in the circular waveguide).
The first probe 5 provided at the position (1) receives one polarized wave (polarized wave in the vertical direction), and converts the polarized wave into a rectangular waveguide 7 at the slot 6 formed at the position of the short surface 4. The other probe (horizontal polarization) is received by the second probe 10 erected on the substrate 11 at a position of λg2 / 4 (λg2 is a wavelength in the rectangular waveguide) from the short surface (rear end surface) 9 of FIG. The rectangular waveguide 7 is formed by a chassis 12 and a ground conductor surface on the back surface of the substrate 10 mounted on the chassis 12.

Since the circular waveguide (2 + 2 ') is formed by the cylindrical portion 2 following the primary radiator 1 and the cylindrical portion 2' formed by the chassis 12 and the shield cover 13 as described above, The connection portion 3 becomes discontinuous, from which radio wave leakage occurs. In order to reduce this radio wave leakage, the distance L1 between the connection portion 3 (discontinuous portion) and the short surface 4 of the circular waveguide is set to (2n +
1) × λg1 / 4 (3λg1 / 4 for n = 1), the distance L2 from the input end face 8 of the rectangular waveguide 7 to the short face 9 is N × λg2 / 2 (for N = 1, λg2 / 2)
The current of the tube wall of the connection part 3 of both polarizations is not prevented.
At the same time, since the positions of the two probes are separated from each other, no mutual interference occurs, the disturbance of the electric field distribution is eliminated, and the isolation is improved. In addition, since the two probes are provided on one substrate, the connection to the subsequent LNB circuit is easy, so that the embodiment can be implemented with a simple structure.

[0011]

As described above, according to the polarization demultiplexer according to the present invention, one of the polarized waves is received by the first probe provided in the circular waveguide on the substrate, and the circular waveguide is received. Since the other polarized wave converted into a rectangular waveguide by the slot formed on the short surface is received by the second probe erected in the rectangular waveguide on the substrate, only one substrate is required. With a simple structure, good isolation can be obtained. In addition, since the circular waveguide is composed of a cylindrical portion following the primary radiator and a cylindrical portion formed by the chassis and the shield cover, the connection portion becomes discontinuous and radio wave leakage is likely to occur. Since the connection portion is set at an appropriate position, currents of both polarized waves on the tube wall of the connection portion are not hindered, and radio wave leakage can be reduced.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an embodiment of a polarization demultiplexer according to the present invention.

FIG. 2 is an exploded perspective view of a main part of one embodiment of the polarization demultiplexer according to the present invention.

FIG. 3 is a main part configuration diagram of an example of a conventional polarization splitter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary radiator 2 Circular waveguide 3 Connection part of circular waveguide 4 Short surface of circular waveguide 5 First probe 6 Slot 7 Rectangular waveguide 8 Inlet end face of rectangular waveguide 9 Square waveguide Short surface 10 Second probe 11 Board 12 Chassis 13 Shield cover

Claims (6)

[Claims] A substrate is arranged in a tube axis direction on a circular waveguide and a rectangular waveguide following the circular waveguide, and one of orthogonally polarized waves is provided on a first side in a circular waveguide provided on the substrate. A polarization demultiplexer, wherein the other polarization received by a probe and converted into the rectangular waveguide is received by a second probe in a rectangular waveguide erected on the substrate. 2. The polarization demultiplexer according to claim 1, wherein the other polarization is converted into the rectangular waveguide by a slot provided on a short surface of the circular waveguide. 3. The circular waveguide is formed of a cylindrical portion following a primary radiator, and a portion following the cylindrical portion formed by a chassis and a shield cover with the substrate interposed therebetween. 3. The polarization demultiplexer according to 1 or 2. 4. The rectangular waveguide is formed by the chassis and a ground conductor on a back surface of the substrate.
Or the polarization demultiplexer according to 3. 5. A connecting portion between a cylindrical portion following the primary radiator and a cylindrical portion formed by a chassis and a shield cover with the substrate interposed therebetween is (2n + 1) from the short surface of the circular waveguide. 4. The method according to claim 3, wherein the distance from the input end face to the short face of the rectangular waveguide is set to N.times..lambda.g2 / 2, and the leakage of the radio wave from the connection part is reduced. Or the polarization demultiplexer according to 4. 6. A connecting portion between a cylindrical portion following the primary radiator and a cylindrical portion formed by a chassis and a shield cover with the substrate interposed therebetween is 3λg1 / 4 from the short surface of the circular waveguide. 5. The polarized wave according to claim 3, wherein the distance from the input end face to the short face of the rectangular waveguide is set to be .lambda.g2 / 2 to reduce radio wave leakage from the connection part. Demultiplexer.