A millimeter and sub-millimeter wave multi-channel quasi-optical system for microwave radiometer

In millimeter and sub-millimeter waveband, the quasi-optical multiplexer with very low loss utilized quasi-optical technology also known as Gaussian beam technology could achieve that the detection beams of different frequencies and different polarization share the same transmission path. The quasi-optical multiplexer used to separate the multi-channel beams is composed by number of discrete components, which are combinated according to the pre-designed optical layout, such as beam convergence devices, beam separation devices and feed horns. The five-channel quasi-optical multiplexer are developed and designed in this paper. The operating frequency bands include 54, 118, 183, 380 and 425GHz. the “separating waveband” and “separating polarization” program are developed for the quasi-optical systems. Based the separating beams programs, relativing optical layouts are designed to obtain compact structure and good electrical performances of quasi-optical systems.