HILBERT-TRANSFORM SPECTRAL-ANALYSIS OF MILLIMETER-WAVE AND SUBMILLIMETER-WAVE RADIATION WITH HIGH T-C JOSEPHSON-JUNCTIONS

We have demonstrated the first applications of Josephson-effect-based Hilbert-transform spectral analysis using high-T-c Josephson junctions . YBa2Cu3O7-x grain-boundary Josephson junctions have been fabricated on (110) NdGaO3 bicrystal substrates for these measurements. At first, spectra of Josephson radiation have been measured by Hilbert-transfor m technique in the range 60 - 800 GHz. A Lorentzian shape of Josephson radiation and possibility to obtain a spectral resolution as low as 0 .1 cm(-1) in the submillimeter-wave range has been demonstrated at liq uid nitrogen temperature. At second, spectra of high-harmonic content of the radiation coming from commercial millimeter-wave oscillators ha ve been measured by Hilbert-transform technique in the spectral range from 60 to 450 GHz. The comparison of Hilbert-transform spectral analy sis with conventional techniques is given.