JPH05191303A - Rf switching type low noise converter - Google Patents

Abstract

PURPOSE:To obtain the RF switching type low noise converter in which the isolation characteristic between a horizontal polarized wave and a vertical polarized wave is improved. CONSTITUTION:A linearly polarized wave from an antenna is divided into a horizontal polarized wave H and a vertical polarized wave V and high frequency signals corresponding to the polarized waves are amplified selectively at low noise amplifiers 35, 36 via microstrip lines 33, 34 and the amplified signal is fed to a mixer 39 via a filter 37. An intermediate frequency signal outputted from the mixer 39 reaches an output terminal 5 via an intermediate frequency amplifier 41 and is fed to a tuner of a receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF switching type low noise converter for receiving horizontally polarized waves and vertically polarized waves sent from a geostationary satellite station.

[0002]

2. Description of the Related Art As a method of receiving linearly polarized waves from a geostationary satellite, after the horizontal polarized waves and vertical polarized waves reflected by the reflector of a parabolic antenna pass through a horn, for example, a representative method is disclosed in No. 2-290305 (1) mechanical system for selecting polarization to be received by using a servo motor, or the action of Faraday rotation of a ferrite rod as disclosed in Japanese Patent Laid-Open No. 52401/1993. (2) Electromagnetic method, and further, JP-A-64-62901
And (3) RF switching system as disclosed in JP-A-3-139901. The RF signal selected by the polarization plane switching method according to the RF switching method is low noise amplified by a low noise converter (LNB) and then converted into the UHF band, and the converted signal is sufficiently amplified to be coaxial. It leads to an indoor receiver via a cable.

The problem here is the RF switching system, which is described in the above-mentioned Japanese Patent Laid-Open No. 64-62901 and Japanese Patent Laid-Open No. 3-1.
As disclosed in Japanese Patent No. 39901, two systems of circuits are provided from orthogonal probes or microstrip elements so that an RF stage, which is an input part of a converter, can receive either of orthogonal polarizations. It is a method of switching and receiving. In addition, as a method of this switching,
For example, it is often due to the potential difference of the DC voltage superimposed on the 75Ω coaxial cable.

[0004]

The conventional RF switching method described above has the advantage that the primary radiator including the converter is downsized and there is no mechanical failure because the converter has a switching unit. However, since the probes are close to each other and are orthogonal to each other, there is a drawback that the isolation between the horizontal polarization and the vertical polarization is poor, and the circuit-divided substrate in the converter is complicated.
An object of the present invention is to maintain the advantages of the conventional RF switching system, to significantly improve the isolation between horizontal polarization and vertical polarization, and to further simplify the inside of the converter. To provide a low noise converter.

[0005]

In order to achieve the above object, the present invention provides a single waveguide and either one of a horizontal polarization and a vertical polarization input to the waveguide. In the low noise converter which is selected and received by switching the circuit of the low noise amplifier, the waveguide is a polarization demultiplexer, and linear polarizations are provided in the output openings of the horizontally polarized wave and the vertically polarized wave in the demultiplexer. A wave radiating element portion is provided.

In a preferred embodiment of the present invention, the output opening of the demultiplexer may be joined to a linearly polarized wave radiating element portion on a dielectric substrate in the same plane.

[0007]

The linearly polarized wave reflected by the reflecting mirror passes through the horn section, and is then split into a horizontal polarized wave and a vertical polarized wave by the demultiplexer, and is provided at each output opening of the demultiplexer. It is directly picked up by the linearly polarized radiation element at the end of the microstrip line of the system and input to the low noise amplifier. Therefore, horizontal polarization or vertical polarization can be selected by switching the circuit of the low noise amplifier.

[0008]

Embodiments of the present invention shown in the drawings will be described below. FIG. 1 is an embodiment of a basic circuit configuration diagram of an RF switching type noise converter (LNB) according to the present invention. In the figure, 1 is a demultiplexer, 2 is a horn unit, 3 is an RF circuit board, and 4 is an IF circuit board. The RF circuit board 3 includes low noise amplifiers 35 and 36, a filter 37, and a mixer 3.
9. The local oscillator 38 is formed, and the IF circuit board 4 is
An intermediate frequency amplifier 41, a power supply 42, and a switching control circuit 43 are formed. 2 (a) and 2 (b) are a sectional view and a sectional view taken along the line AA showing a specific configuration of the above embodiment. FIG. 3 is a circuit pattern principal part diagram of the RF circuit board 3 of the above-described embodiment.

In the embodiment shown in FIG. 1, the linearly polarized wave in the 12 GHz band reflected by the reflector of a parabolic antenna (not shown) is input to the demultiplexer 1 via the horn section, and the demultiplexer 1 The horizontally polarized wave H and the vertically polarized wave V, which have been demultiplexed by the
11a and 12a on the RF circuit board 3 shown in FIG.
Input strip lines 33 and 34 for horizontal and vertical polarization respectively
Are picked up by the radiating element portions 31 and 32 provided at the ends of the.

The high frequency signals picked up by the radiating element portions 31 and 32 pass through horizontal and vertical polarization input strip lines 33 and 34, and low noise amplifiers 35 and 36 composed of amplifying elements T1 to T5 shown in FIG. Is amplified by low noise by the filter 37, and the signal of 12GHz band is passed through the filter 37 to 1G.
After passing through a local oscillator 38 for converting an intermediate frequency signal of Hz band and a mixer 39, it is amplified by an intermediate frequency amplifier 41 formed on the IF circuit board 4 to reach an output terminal 5, and from the output terminal 5 via a coaxial cable. Supplied to tuners, etc.

The output terminal 5 also serves as a DC voltage input terminal for selecting horizontal polarization and vertical polarization, and the DC voltage for switching control superimposed from the tuner or the like on the coaxial cable is switched to the switching control circuit 43. And the low noise amplifiers 35 and 36 are switched in response to the DC voltage to select one of the both waves. As another embodiment, the object of the present application can be achieved even if the above-mentioned horizontal and vertical polarization radiating element portions 31 and 32 are of a probe type.

[0012]

As described above, according to the present invention,
While utilizing the advantages of the conventional RF switching method, the isolation characteristics of horizontal polarization and vertical polarization can be significantly improved by 10 dB or more, and further, the size and cost of the entire device can be reduced. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2A is a schematic cross-sectional view showing a specific assembly structure of the above embodiment. (B) It is the sectional view on the AA line of the figure which shows the said assembly structure.

FIG. 3 is a diagram showing a main part of a circuit pattern of the RF circuit board according to the embodiment.

[Explanation of symbols]

1 Polarizer 2 Horn Unit 3 RF Circuit Board 4 IF Circuit Board 5 Output Terminals 11 and 12 Horizontal and Vertical Polarization Polarization Apertures 11a and 12a Polarizer Splitter Joints on RF Circuit Board 31 , 32 Horizontal and vertical polarization radiating element section 33, 34 Horizontal and vertical polarization input strip line 35, 36 Horizontal and vertical polarization low noise amplifier 37 Filter 38 Local oscillator 39 Mixer 41 Intermediate frequency amplifier 42 Power supply 43 Switching control circuit T1 , T2, T3, T4, T5 amplification element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mamoru Yoshida 4-7-4 Kitamachi, Warabi-shi, Saitama, Japan Atena Co., Ltd. Warabi factory

Claims (2)

[Claims] 1. A low noise converter for selecting and receiving a single waveguide and either horizontal polarization or vertical polarization input to the waveguide by switching circuits of a low noise amplifier. In the RF switching type, the waveguide is a demultiplexer, and a linearly polarized wave radiating element section is provided at each output opening of the horizontally polarized wave and the vertically polarized wave in the demultiplexer. Low noise converter. 2. The RF switching system according to claim 1, wherein the output aperture of the demultiplexer is joined to a linearly polarized wave radiating element portion on a dielectric substrate in the same plane. Low noise converter.