Quasioptical system of the dual channel SIS receiver for TRAO telescope

Abstract

A quasioptical system of 100/150GHz band for dual channel receiver is developed for the simultaneous observation for both bands. The frequency independent Gaussian beam matching is applied to design the quasioptical system for wide band operation. A beam measurement system is constructed to measure the quasioptical system and to align its components. The beam from Cassegrain focus is divided into two polarizations by the beam splitter and then fed to corrugated feed horns of their bands through their quasioptical system. The intensity distributions near the Cassegrain focus and the variations of the beam widths along the propagation are measured in the laboratory. The performances of the developed quasioptical system are evaluated by comparing the measured results with theoretical calculations. The dual channel receiver with this quasioptical system is installed in the 14m telescope. The relative pointing offset between two bands is 3 inches. We have successfully observed the various sources with both bands using this receiver since October 1998.