An Antenna System for an EHF Satellite Earth Terminal and Its Calibration,
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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The antenna system for a 4420 GHz earth terminal to be used to measure on-orbit satellite performance and the facilities used in its calibration are described. Built around a 8-ft. diameter Cassegrain antenna mounted on a pedestal positioner, the entire system is enclosed within a 17-ft. diameter radome. The antenna uses a frequency-selective-surface to diplex the 44-GHz uplink signal from a scalar horn and the 20-GHz downlink signal to a five-horn tracking feed. Mounted directly to the back of the antenna are a 20-GHz receiver front-end, a 5-W 44-GHz transmitter, and a transmit power attenuator used to precisely control terminal EIRP. Individual calibration of each of these units in conjuction with gain measurements on the radome-enclosed antenna allow a prediction of the overall antenna system performance, in terms of downlink GT and uplink EIRP.
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