230GHz 冷却受信機の試作

抄録

The purposes of this research are to make a cooled receiver at 230GHz, to examine its efficiency and to obtain a key for the realization of low noise receiver at submillimeter wavelength. Thus the most significant point of this research is a trial which enables the application at submillimeter range. (1) Since it is difficult at submillimeter range to obtain high local oscillator power, we used a diode with epitaxial layer of less than 1000A for the mixer. As a result, we got the conversion loss of 9dB at the low input power of -5dBm, and this value is good enough for the utility. (2) We used the gaussian beam mode as the transmission system to decrease the transmission loss. And the frequency mixing by beamsplitter was also tried. The residuary loss of less than 2.4dB is enough for utility. (3) The multiplier which we tried to make as a source of local oscillator shows the conversion loss of 12dB, and we can tell the realization in the near future. (4) The cryostat that we made has an ability to be cooled down to 25K even if we settle two mixers in it. The problem that it is a little unstable for heat cycles. But the stabilization is possible by the improvement of the FET amplifier etc. In conclusion, we could obtain a good prospect for the realization of submillimeter low noise receiver.