A 5-frequency millimeter wave antenna for a spaceborne limb sounding instrument
Several spaceborne Earth observation missions such as the European Space Agency's (ESA) atmospheric chemistry instruments Millimeter wave Acquisitions for Stratosphere/Troposphere Exchange Research (MASTER), Soprano or Piramhyd require the development of complex millimeter and submillimeter wave range spectroradiometers. These instruments place stringent requirements on antenna electrical performance due to the low-noise signal levels and the high-vertical resolution involved. This paper focuses on the electromagnetic (EM) design and analysis of a 2.2-m diameter Cassegrain antenna operating in 5-frequency bands between 200 and 500 GHz. The primary feed network is an essential part. It has to provide not only the low-loss frequency separation of the bands but also the antenna illumination with nearly perfect amplitude and phase patterns for high-beam efficiency. Quasi-optical techniques are extensively used for the overall antenna design and focal plane demultiplexer breadboarding and testing.