A low noise 230 GHz sis receiver

We report the construction of a 230GHz superconductor insulator superconductor (SIS) tunnel junction receiver utilizing a full height rectangular waveguide mixer with two tuning elements i.e. an E plane and backshort tuner. Preliminary results indicate that the receiver exhibits a best double side-band response of 114K±15K (averaged over a 500 MHz IF bandwidth) at a frequency of 228GHz and at an ambient temperature of approximately 2.4K. With the exception of a region in the vicinity of 250GHz, the receiver shows an excellent response over an RF input range of 200 to 290GHz. Finally, the receiver has been successfully employed on the new Caltech Submillimeter Observatory 10m antenna on Mauna Kea, Hawaii.