Development of Superconducting Spectroscopic Array Receiver: A Multibeam 2SB SIS Receiver for Millimeter-Wave Radio Astronomy

We have developed a 3×3 multibeam sideband separation superconducting receiver-Superconducting Spectroscopic Array Receiver (SSAR)-for the 85-115 GHz frequency band. The receiver employs 2SB superconductor-insulator-superconductor (SIS) mixers with a typical single sideband (SSB) noise temperature of 60 K and image rejection ratio above 10 dB over the frequency band. Digital techniques are extensively applied in this receiver system for excellent operational stability and efficiency. They include fast Fourier spectrometers, digital LO and digital bias supplies. In our knowledge this is the first 2SB multibeam millimeter wavelength receiver in the world. This receiver has been successfully put into observation and its considerable enhancement of mapping speed has been demonstrated.