Design and Characterization of a 211-275 GHz Sideband Separating Mixer for the APEX Telescope

Journal article, 2008

We present the final results of the development and characterization of the sideband separating superconductor-insulator-superconductor (SIS) mixer for the APEX telescope band 1 (211-275 GHz). The sideband separation is achieved by using a quadrature scheme where the RF and a local oscillator (LO) power are applied to two identical double sideband SIS mixers. All mixer components, including the LO and RF distribution circuitry, are integrated into a single mixer block. To achieve a compact design we developed a superconducting Lange coupler, based on Nb thin film, which is used as an IF hybrid. Typical single sideband noise temperature of 100˚K and sideband rejection ratio of about 12 dB and are measured.