DOUBLE STEP-EDGE WEAK LINKS INTEGRATED WITH SPIRAL ANTENNA STRUCTURE IN EPITAXIAL TL2CABA2CU2O8 FILMS FOR MILLIMETER-WAVE MIXING

High-temperature superconducting mixers have been fabricated from epit axial films of Tl2CaBa2Cu2O8 utilizing surface double step-edge juncti ons on LaAlO3 substrates. These mixers were integrated with spiral ant enna structure designed for broadband millimeter wave coupling of the radiation into weak links. Under the optimum bias current condition he terodyne mixing of signals at W band (94 GHz) frequencies has been mea sured, and noise performance operating at V band (60 GHz) has been cha racterized both at liquid nitrogen and liquid helium temperatures. By using an etching technique, two orders of magnitude improvement in noi se performance over the earlier results have been obtained. Strong mix ing signals were achieved right up to T(c) (102 K).