JP2002232202A - Converter for satellite broadcast reception - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converter for satellite reception having a satisfactory cross polarization characteristic by securing separation between a right hand circular polarization and a left hand circular polarization. SOLUTION: A horn part 1a for radio introduction is provided at the front end of a waveguide 1, and a waterproof cap 6 is attached to cover the open end of the horn part 1a. A pair of ridges (90 deg. phase shifting part) 2, a probe 4 for main polarization reception and its reflection surface 5a are sequentially arranged from the waterproof cap 6 toward the rear end of the waveguide 1, and the opening of the rear end of the waveguide 1 is closed by a wave absorber 3. In the converter for satellite broadcast reception of such a configuration, when a left hand circular polarization is inputted during receiving a right hand circular polarization signal, for instance, in the cast the main polarization is a right hand circuit polarization, the left hand circular polarization signal is converted into a vertical polarization by the ridges 2 and subsequently absorbed by the wave absorber 3 on the rear end side of the waveguide 1 without being combined by the probe 4, polarization is, therefore, hardly returned to the waveguide 1 by being reflected against the waterproof cap 6, and it is possible to prevent an undesired polarization signal from being combined as a leaked polarization by the probe for the main polarization reception.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite broadcast which is installed at the focal point of a reflector of a satellite broadcast reflective antenna and converts a right-handed or left-handed circularly polarized wave transmitted from a satellite into a linearly polarized wave and receives it. Related to a receiving converter.

[0002]

2. Description of the Related Art FIGS. 3 and 4 illustrate a conventional example of this type of satellite broadcast receiving converter. FIG. 3 is a sectional view and FIG. 4 is a front view as viewed from a horn.

As shown in these figures, a conventional converter for receiving satellite broadcasting has a waveguide 10 having a conical horn portion 10a at one end and a closed surface 10b at the other end. A pair of ridges 11 projecting from the inner wall surface of
A probe 12 is provided between the ridge 11 and the closed surface 10b of the waveguide 10, and a waterproof cap 13 is provided so as to cover the open end of the horn 10a. A circuit housing (not shown) is connected to the rear end side.

The waveguide 10 is formed of a material having good conductivity such as a zinc die cast or an aluminum die cast.
Both ridges 11 are formed integrally with the waveguide 10. These ridges 11 have a predetermined height, width, and length, and function as 90-degree phase shifters that convert circularly polarized waves entering the waveguide 10 from the horn 10a into linearly polarized waves. Waveguide 10
Assuming that a plane including the center axis of and the ridges 11 is a reference plane,
The probe 12 intersects the reference plane at an angle of about 45 degrees, and the distance between the probe 12 and the closed surface 10b is separated by about １ ／ wavelength of the guide wavelength. The waterproof cap 13 is made of a material having a low relative dielectric constant and excellent weather resistance, such as an AES resin or an ABS resin, to prevent foreign matters such as rainwater and dust from entering the inside of the waveguide 10.

[0005] In the thus configured satellite broadcast receiving converter, when the circularly polarized wave transmitted from the satellite is reflected by the reflector of the antenna and input to the waveguide 10, the circularly polarized wave is converted into the waterproof cap. The ridge 11 enters the horn 10 a through the horn 13, and is converted into linearly polarized light by the ridge 11 when propagating in the waveguide 10. That is, since the circularly polarized wave is a polarized wave in which the composite vector of two linearly polarized waves having the same amplitude and a phase difference of 90 degrees from each other is rotating, the circularly polarized wave is the two ridges.
By passing through 1, the phases shifted by 90 degrees become in-phase and are converted into linearly polarized waves. Therefore, if this linearly polarized wave is coupled to the probe 12 and received, the received signal can be converted into an IF frequency signal by the converter circuit and output. The received circularly polarized signal includes right-handed circularly polarized light and left-handed circularly polarized wave. For example, in the case of receiving a BS broadcast in Japan, the right-handed circularly polarized wave transmitted from the satellite is transmitted to the ridge 11. Is converted into a horizontally polarized wave, and this horizontally polarized wave is coupled to the probe 12 and received.

[0006]

In the above-described conventional converter for receiving satellite broadcasting, for example, if a left-handed circularly polarized wave is input during reception of a right-handed circularly polarized wave, the left-handed circularly polarized wave becomes The ridge 11 converts the light into vertically polarized light and travels toward the closed surface 10b without being coupled to the probe 12. The vertically polarized light reflected on the closed surface 10b returns inside the waveguide 10 to the waterproof cap 13 side. This vertically polarized wave passes through the ridge 11 and is converted into a left-handed circularly polarized wave. A part of the vertically reflected wave is reflected by the waterproof cap 13 and returns to the ridge 11 to become a right-handed circularly polarized wave. When the polarized wave passes through the ridge 11 again, it is converted into a horizontally polarized wave. As a result, the polarization signal reflected by the waterproof cap 13 is applied to the probe 1 for horizontal polarization.
2, the ratio of the input level of the leakage to the input level of the normal signal is increased,
There is a problem that the isolation deteriorates by several dB.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances of the prior art, and has as its object to ensure isolation between right-handed circular polarization and left-handed circular polarization and to provide good cross polarization. It is an object of the present invention to provide a satellite broadcast receiving converter having wave characteristics.

[0008]

To achieve the above object, a satellite broadcast receiving converter according to the present invention comprises a waveguide having a horn for introducing radio waves at a front end thereof, and a horn attached to the horn. A waterproof cap, a 90-degree phase shift portion provided inside the waveguide, a probe and a reflection surface sequentially disposed behind the 90-degree phase shift portion, and a reflection surface disposed behind the reflection surface. With a radio wave absorber, one of the right-handed or left-handed circular polarization transmitted from the satellite is converted to linear polarization in the 90-degree phase shift unit and detected by the probe, and either of the other is used. The circularly polarized wave is converted into linearly polarized wave by the 90-degree phase shifter and is absorbed by the radio wave absorber.

[0009] In the satellite broadcast receiving converter thus configured, for example, when a right-handed circularly polarized wave transmitted from a satellite is input, the circularly polarized wave enters the horn through the waterproof cap, After being converted to horizontal polarization by a 90-degree phase shifter in the waveguide, the signal is received by a probe for horizontal polarization. When the left-handed circularly polarized wave is input while receiving the right-handed circularly-polarized signal, the left-handed circularly polarized wave is converted into a vertically polarized wave by a 90-degree phase shifter and then coupled to the probe. Without being absorbed by the radio wave absorber toward the rear end side of the waveguide, it is possible to reduce coupling of an undesired polarized signal as a leak to the main polarized wave receiving probe.

In the above configuration, it is preferable that a circuit board is disposed at a predetermined interval in front of the radio wave absorber, and that the main polarization receiving probe and its reflection surface are provided on the circuit board. Then, the structure can be simplified and the assembly workability can be improved.

In the above configuration, the radio wave absorber may be disposed inside the waveguide as long as the radio wave absorber is behind the reflecting surface. In this case, the radio wave absorber can be easily attached to the waveguide, which is preferable.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a satellite broadcast receiving converter according to an embodiment of the present invention; FIG.
FIG. The converter for receiving satellite broadcasting according to the present embodiment converts a right-handed circularly polarized signal transmitted from a satellite into a horizontally polarized wave and receives the signal. The converter has a horn 1a at one end and an open end at the other end. A waveguide 1, a pair of ridges 2 projecting from the inner wall surface of the waveguide 1, and a radio wave absorber 3 installed so as to close the opening at the rear end of the waveguide 1. A probe 4 installed between the radio wave absorber 3 and the ridge 2;
And a circuit board 5 installed between the electromagnetic wave absorber 3 and a waterproof cap 6 attached so as to cover the open end of the horn 1a. A circuit housing (not shown) is connected.

The waveguide 1 is formed of a material having good conductivity such as zinc die cast or aluminum die cast, and both ridges 2 are formed integrally with the waveguide 1. These ridges 2 have a predetermined height, width and length, and when a plane including the center axis of the waveguide 1 and both ridges 2 is set as a reference plane, the probe 4 has an angle of about 45 degrees with respect to this reference plane. Intersect at These ridges 2 function as 90-degree phase shifters for converting circularly polarized waves (right-handed circularly polarized waves) entering the waveguide 1 from the horn 1a into linearly polarized waves (horizontally polarized waves). Alternatively, a dielectric plate may be used as the 90-degree phase shifter instead of the ridge 2. The radio wave absorber 3 is made of a rubber material mixed with carbon, a ferrite-based magnetic material, or the like. The opening at the rear end of the waveguide 1 is closed by the radio wave absorber 3. In this case, for example, a metal cap (not shown) is attached to the rear end of the waveguide 1,
If the radio wave absorber 3 is laid on the inner surface of this metal cap,
The radio wave absorber 3 can be easily attached to the waveguide 1. The probe 4 is a pin member bent in an L shape, and its base is soldered to the circuit board 5 outside the waveguide 1. The circuit board 5 is formed in an elongated shape so as to extend in parallel with the probe 4, and a reflection surface 5a is patterned on one of both surfaces thereof. Inside the waveguide 1, the probe 4 and the reflection surface 5a are separated by about １ ／ of the guide wavelength.
They are separated by the wavelength. The waterproof cap 6 is formed of a material having a low relative dielectric constant and excellent weather resistance, such as an AES resin or an ABS resin, to prevent foreign matters such as rainwater and dust from entering the inside of the waveguide 1.

When a right-handed circularly polarized wave, which is the main polarized wave transmitted from a satellite, is input to the satellite broadcast receiving converter thus configured, the right-handed circularly polarized wave passes through the waterproof cap 6. After entering into the horn portion 1a and propagating in the waveguide 1, it is converted into a horizontally polarized wave by the ridge 2;
Since the signal is received by the horizontally polarized probe 4, the received signal is converted into an IF frequency signal by a converter circuit and output, whereby a right-handed circularly polarized signal can be received. When a left-handed circularly polarized wave is input while receiving such a right-handed circularly polarized wave signal, the left-handed circularly polarized wave is converted into a vertically polarized wave by the ridge 2 and then coupled to the probe 4. Instead, it goes toward the rear end of the waveguide 1 and most of it is absorbed by the radio wave absorber 3 at the rear end of the waveguide 1.
Therefore, the reflection of the vertically polarized light on the rear end face of the waveguide 1 is greatly reduced, and the polarization reflected by the waterproof cap 6 and returned to the waveguide 1 is almost eliminated. Undesired polarization signals can be prevented from being coupled to the probe 4 as leakage, and isolation between right-handed circular polarization and left-handed circular polarization can be ensured, resulting in good cross-polarization characteristics. Is achieved.

In the above embodiment, a converter for receiving a satellite broadcast receiving a circularly polarized signal whose main polarization is right-handed has been described. However, a case where a circularly polarized signal whose main polarization is left-handed is received. Is basically the same. That is, in this case,
A probe for vertical polarization is installed in the waveguide, and the left-handed circular polarization transmitted from the satellite is converted to vertical polarization by a 90-degree phase shifter and coupled to the probe. Polarization is 90
After being converted into a horizontally polarized wave by the phase shift unit, it is absorbed by the radio wave absorber toward the rear end of the waveguide without being coupled to the probe.

[0016]

The present invention is embodied in the form described above, and has the following effects.

A 90-degree phase shifter, a main polarization receiving probe and its reflection surface are sequentially disposed inside the waveguide toward the rear, and a radio wave absorber is disposed at a position farthest from the waterproof cap. For example, if the main polarization is a right-handed circularly polarized wave, and a left-handed circularly polarized wave is input while receiving a right-handed circularly polarized signal, the left-handed circularly polarized wave is converted by a 90-degree phase shifter. After being converted into a vertically polarized wave, it is absorbed by the radio wave absorber toward the rear end of the waveguide without being coupled to the probe. Therefore, the reflection of vertically polarized waves at the rear end face of the waveguide is greatly reduced,
Along with this, there is almost no polarization reflected by the waterproof cap and returning to the waveguide, so that it is possible to prevent unwanted polarized signals from being coupled to the main polarized wave receiving probe as leakage, and to make a right-handed rotation. Good cross polarization characteristics are realized by securing isolation between circularly polarized waves and left-handed circularly polarized waves.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a satellite broadcast receiving converter according to an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a sectional view of a satellite broadcast receiving converter according to a conventional example.

FIG. 4 is a front view of the satellite broadcast receiving converter of FIG. 3 as viewed from a horn unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waveguide 1a Horn part 2 Ridge (90 degree phase shift part) 3 Radio wave absorber 4 Probe 5 Circuit board 5a Reflection surface 6 Waterproof cap

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Doumotoju 1-7 Yukitani Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd. F-term (reference) 5J012 FA04 5J045 AA14 BA02 CA02 CA04 DA01 EA02 EA05 EA07 EA17 EA18 HA06 JA15 KA03 NA02 NA08 5J046 AA04 AB09 CA10

Claims (3)

[Claims] 1. A waveguide having a horn portion for introducing a radio wave at a front end, a waterproof cap attached to the horn portion, a 90-degree phase shift portion provided inside the waveguide, and 90
A probe and a reflecting surface thereof sequentially disposed behind the phase shift unit, and a radio wave absorber disposed behind the reflecting surface, and whichever of right-handed or left-handed circularly polarized waves transmitted from the satellite is provided. Either one is converted to linear polarization by the 90-degree phase shifter and detected by the probe, and the other circular polarization is converted to linear polarization by the 90-degree phase shifter and is converted by the radio wave absorber. A converter for receiving satellite broadcasting, characterized in that it is configured to absorb. 2. The circuit according to claim 1, wherein a circuit board is disposed at a predetermined interval in front of the radio wave absorber, and the reflection surface and the probe are provided on the circuit board. Converter for satellite broadcasting reception. 3. The converter according to claim 1, wherein an opening at a rear end of the waveguide is closed by the radio wave absorber.