Phase locking a 3 mm waveband Gunn oscillator with a high <i>T</i> <i>c</i> superconducting Josephson junction at 77 K

Abstract

Using a high-temperature superconducting YBa2Cu3O7−δ Josephson-junction harmonic mixer operated at 77 K and an analog phase-locking loop, we have locked a 3 mm waveband Gunn oscillator to a synthesizer for harmonic numbers ranging from 10 to 52. The spectrum of the phase-locked intermediate frequency reveals good phase-locked quality even for the 48th harmonic mixing between the signal at 104.3 GHz and the local oscillator at about 2 GHz. Our experimental results show that a high Tc superconducting harmonic mixer can work efficiently with high harmonic number for phase locking in the millimeter waveband.