JP2004343654A - Superconducting receiver system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting receiver system of which the miniaturization/simplification is realized by filtering the image side by a waveguide type filter. <P>SOLUTION: In a heterodyne receiving system which receives a spectrum from a heavenly body and atmospheric minute amount molecules, a waveguide type band rejection filter 2A is arranged between a cross guide coupler 2 to be connected with an electromagnetic horn 5 and the superconducting SIS mixer 3 in order to use a superconducting SIS mixer 3 which is a double side band (DSB) receiver as a single side band (SSB) receiver and noise and interference from an image band are eliminated by filtering the image side by the waveguide type band rejection filer 2A. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a superconducting receiver system, and more particularly, to a superconducting (SIS) receiver system using a waveguide type band rejection filter.
[0002]
[Prior art]
In a mixer receiver used in the millimeter-wave and sub-millimeter-wave regions, the magnitude of the sideband ratio is the key to performing stable and accurate observation.
[0003]
Therefore, the present inventors have already proposed a measuring apparatus for measuring the sand band ratio of a superconducting mixer using a comb generator capable of performing stable and accurate observation (see Patent Document 1 below).
[0004]
On the other hand, in a heterodyne receiving system that receives spectra from astronomical objects and atmospheric trace molecules, it is necessary to remove noise and interference from image bands for efficient observation. In addition, since the spectral intensity of celestial bodies changes depending on the sideband ratio of the receiver (the sensitivity ratio between the signal band and the image band), it is extremely important to convert the receiver to one sideband (SSB) for high-accuracy measurement. It is.
[0005]
Conventionally, in order to use a superconducting mixer, which is a double sideband (DSB) receiver, as a single sideband (SSB) receiver, a filter must be provided on the image side using a quasi-optical method such as Martin Parplet or a two-back short method. It was realized by running.
[0006]
[Patent Document 1]
JP-A-2003-57274 (FIG. 1 on page 3-5)
[0007]
[Problems to be solved by the invention]
However, since the conventional method described above always involves a movable part in the system, problems such as poor reproducibility and aging occur.
[0008]
Further, in the above-described conventional method, a side band ratio of only about ２０20 dB has been achieved because a phase difference or the like is used.
[0009]
The present invention has been made in view of the above circumstances, and by applying a filter on the image side with a waveguide type filter, a superconducting mixer can be formed into a single side band (SSB) with a simple configuration, and the side band ratio can be increased. It is an object of the present invention to provide a superconducting receiver system that can be reduced in size and simplified.
[0010]
[Means for Solving the Problems]
The present invention, in order to achieve the above object,
[1] In a heterodyne receiving system that receives spectra from astronomical objects and atmospheric trace molecules, a superconducting SIS mixer, which is a double sideband (DSB) receiver, is used in order to use it as a single sideband (SSB) receiver. A waveguide-type band rejection filter is disposed between the cross guide coupler connected to the horn and the superconducting SIS mixer, and the image is filtered by the waveguide-type band rejection filter. And to eliminate interference.
[0011]
[2] The superconducting receiver system according to [1], wherein switching between SSB reception and DSB reception can be performed without adjusting the superconducting receiver simply by selecting the frequency of the intermediate frequency signal. .
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0013]
FIG. 1 is a block diagram of a superconducting receiver system showing an embodiment of the present invention, and FIG. 2 is a photograph (substitute drawing) showing a main part configuration of the superconducting receiver system showing an embodiment of the present invention.
[0014]
In FIG. 1, 1 is a dewar (4K cryostat), 2, 6 is a CGC (cross guide coupler), 2A is a waveguide band rejection filter, 3 is a superconducting (SIS) mixer to be measured, and 4, 9 are HEMTs. Amplifiers 5, 5 and 7 are electromagnetic horns, 8 is a superconducting (SIS) mixer for comb generator output calibration (with back short), 11 is a temperature calibration device, 12 is a rotating mirror, 13 is a normal temperature black body (300K), 14 is Liquid nitrogen cooled black body (77K), 21 is a signal oscillating device, 22 is a comb generator reference signal oscillator (up to several GHz), 23 is a comb generator, 24 and 26 are directional couplers, 25 is a pseudo comb generator output calibration. An astronomical signal oscillator, 27 is a LO (local oscillation) GUNN oscillator, 31 is a computer, and 32 is a spectrum analyzer. With such a configuration, in order to use the superconducting SIS mixer 3 which is a double sideband (DSB) receiver as a single sideband (SSB) receiver, the cross guide coupler 2 connected to the electromagnetic horn 5 And the superconducting SIS mixer 3, a waveguide band rejection filter 2A is arranged, and the image is filtered by the waveguide band rejection filter 2A so as to remove noise and interference from the image band. I made it.
[0015]
FIG. 3 is a characteristic diagram of a waveguide band rejection filter of a superconducting receiver system according to an embodiment of the present invention. The horizontal axis indicates frequency (GHz), and the vertical axis indicates transmission gain (dB). In the drawing, a is a characteristic diagram of the present invention to which a waveguide band type band rejection filter is applied, and b is a diagram showing a simulation result.
[0016]
As is apparent from this figure, it can be said that the waveguide band rejection filter can be manufactured with good simulation reproducibility.
[0017]
FIG. 4 is a diagram showing the results of observation of the ozone spectrum by the waveguide type band rejection filter of the superconducting receiver system of the present invention, wherein the horizontal axis represents the frequency [MHz] and the vertical axis represents the temperature T [K]. I have. In the figure, ○ indicates the observation result in both sidebands (DSB), and □ indicates one sideband (SSB).
[0018]
At the time of observation with SSB, the frequency of the first LO (local oscillator) is about 103 GHz, the first intermediate frequency (IF) is about 7 GHz [USB: upper (upper) sideband is about 110 GHz, LSB: lower (low) The side band is about 96 GHz, see the BSF characteristic in FIG. 3].
[0019]
Also, at the time of observation with DSB, the frequency of the first LO (local oscillator) is about 106 GHz, the first intermediate frequency (IF) is about 4 GHz (USB: upper side band is about 110 GHz, LSB: lower side band is about 110 GHz). 102 GHz, see BSF characteristics in FIG. 3).
[0020]
In the conventional method, a side band ratio of only about 20 dB was achieved because a phase difference or the like was used. On the other hand, according to the waveguide type filter system of the present invention, the band rejection can be -50 dB or more, so that the achieved side band ratio can be 50 dB or more. Furthermore, it is possible to switch between SSB reception and DSB reception without adjusting the receiver simply by selecting the frequency of the intermediate frequency signal.
[0021]
It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.
[0022]
【The invention's effect】
As described in detail above, according to the present invention, a superconducting SIS mixer, which is a double sideband (DSB) receiver, is connected to an electromagnetic horn for use as a single sideband (SSB) receiver. A waveguide band rejection filter is arranged between the cross guide coupler and the superconducting SIS mixer, and the image side is filtered by the waveguide band rejection filter to remove noise and interference from the image band. be able to. In particular, it is possible to significantly increase the sideband ratio (up to the rejection of the filter) from 20 dB in the conventional method.
[0023]
In addition, it is possible to switch between SSB reception and DSB reception without adjusting the receiver simply by selecting the frequency of the intermediate frequency signal.
[Brief description of the drawings]
FIG. 1 is a block diagram of a superconducting receiver system illustrating an embodiment of the present invention.
FIG. 2 is a photograph as a substitute drawing showing a main part configuration of a superconducting receiver system showing an embodiment of the present invention.
FIG. 3 is a characteristic diagram of a waveguide band stop filter of a superconducting receiver system according to an embodiment of the present invention.
FIG. 4 is a diagram showing an observation result of an ozone spectrum by a waveguide band stop filter of the superconducting receiver system of the present invention.
[Explanation of symbols]
1 Dewar (4K cryostat)
2,6 CGC (cross guide coupler)
2A Waveguide type band rejection filter 3 Superconducting (SIS) mixer for measurement 4, 9 HEMT amplifier 5, 7 Electromagnetic horn 8 Superconducting (SIS) mixer for comb generator output calibration (with back short)
11 Temperature Calibration Device 12 Rotating Mirror 13 Room Temperature Black Body (300K)
14. Liquid nitrogen cooled black body (77K)
21 signal oscillator 22 comb generator reference signal oscillator (up to several GHz)
23 Comb generators 24, 26 Directional coupler 25 Pseudo astronomical signal oscillator for comb generator output calibration 27 GUNN oscillator for LO (local oscillation) 31 Computer 32 Spectrum analyzer

Claims (2)

In a heterodyne receiving system that receives spectra from astronomical objects and atmospheric trace molecules, a double-sideband (DSB) receiver, a superconducting SIS mixer, is connected to an electromagnetic horn for use as a single-sideband (SSB) receiver. By disposing a waveguide type band rejection filter between the cross guide coupler and the superconducting SIS mixer, and filtering the image side with the waveguide type band rejection filter, noise and interference from the image band can be reduced. A superconducting receiver system characterized by removing. 2. The superconducting receiver system according to claim 1, wherein switching between SSB reception and DSB reception can be performed without adjusting the superconducting receiver simply by selecting the frequency of the intermediate frequency signal. system.

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