Experimental Study of a Planar-Integrated Dual-Polarization Balanced SIS Mixer

A dual-polarization balanced superconductor- insulator-superconductor mixer operating at 2 mm wavelength is realized in the form of a monolithic planar integrated circuit. Planar orthomode transducers and local oscillator (LO) couplers are enabled by using silicon membranes that are locally formed on the silicon-on-insulator substrate. The performance of the balanced mixer is experimentally investigated. Over the entire RF band (125-163 GHz), the balanced mixer shows an LO noise rejection ratio of about 15 dB, an overall receiver noise about 40 K, and a cross polarization <;-20 dB. The demonstrated compactness and the performance of the integrated circuit indicate that this approach is feasible in developing heterodyne focal plane arrays.