Measurement of Amplitude and Phase Patterns of 110 GHz and 183 GHz Corrugated Horns

摘要

Radiation patterns (amplitude and phase) of two corrugated feed horns designed for a 2 m single offset reflector antenna have been measured. The measured amplitude and phase patterns can be used to calculate the far-field radiation patterns and finally the beam efficiencies of the 2 m antenna. To reach the required accuracy of + or - 1% for the beam efficiency, accurate amplitude and phase patterns of the feed horns have to be known. The center frequencies of the horns are 110 and 183 GHz. The measurement set-ups are based on phase-locked InP Gunn oscillators (followed by frequency doublers at 183 GHz), Schottky mixers and a Scientific Atlanta 1783 receiver. Dynamic ranges are limited by room reflections to about 50-60 dB. Phase patterns and phase center positions are measured by the novel differential phase method. Problems as phase changes in rotary joints and flexible cables associated with conventional methods can be avoided by using this method. The measured amplitude and phase patterns agree excellently with patterns calculated by using the modal matching technique.