Gaussian beamwaist and radiation pattern measurements of a quasi-optical radiometer

The authors present Gaussian beamwaist and radiation pattern measurements of the breadboard high frequency subsystem (HFSS) of the advanced microwave sounding unit-B (AMSU-B) instrument. The AMSU is a 20 channel microwave radiometer providing temperature and humidity soundings. Channels 16 to 20 which cover the frequency range from 86 GHz to 192 GHz form the basis of AMSU-B which is being provided by the British Meteorological Office. A general description of the test methods is given, and the results are presented. The results show that simple Gaussian equations can be used to design a complex quasi-optical instrument