QUASI-OPTICAL HILBERT TRANSFORM SPECTROMETER

A quasioptical spectrometer using Hilbert transformation of Josephson junction response has been designed, fabricated and experimentally stu died. Resistively shunted SIS junctions have been used as Josephson se nsor placed in the centre of complementary logarithmic spiral antenna. The response was studied in 75-150 GHz frequency band. The resolution below 1 GHz and noise equivalent power about 10(-13)-10(-14) W has be en measured for the 0.7 Ohm junction. Measured spectrum obtained by me ans of Hilbert transformation via novel deconvolution program based on the maximum likelihood approach. This allows to diminish the measured interval of bias voltage and avoid measurements of the noisy part of response curve without loss of the spectral resolution.