Development of a Waveguide-Type Dual- Polarization Sideband-Separating SIS Receiver System in 100 GHz Band for the NRO 45-m Telescope

We developed a waveguide-type dual-polarization sideband-separating SIS receiver system of the 100-GHz band for the 45-m radio telescope at the Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho- mode transducer and two sideband-separating SIS mixers, which are both based on the waveguide technique. The receiver has four intermediate frequency (IF) bands of 4.0--8.0 GHz. Over the radio frequency range of 80--120 GHz, the single- sideband receiver noise temperatures are 50--100 K and the image rejection ratios are greater than 10 dB. The new receiver system was installed in the telescope, and we successfully observed the 12 CO, 13 CO, C 18 O and the other emission lines simultaneously toward the Sagittarius B2 region to confirm the performance of the receiver system.