Quasioptical Hilbert transform spectrometer

A quasioptical spectrometer using Hilbert transformation of Josephson junction response has been designed, fabricated and experimentally studied. Resistively shunted SIS junctions have been used as the Josephson sensor placed in the centre of a complementary logarithmic spiral antenna. The response was studied in the 75-150 GHz frequency band. A resolution below 1 GHz and noise equivalent power about 10/sup -13/-10/sup -14/ W has been measured for the 0.7 /spl Omega/ junction. The measured spectrum is obtained by means of Hilbert transformation via a novel deconvolution program based on the maximum likelihood approach. This allows one to diminish the measured interval of bias voltage and avoid measurements of the noisy part of the response curve without loss of the spectral resolution.<
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