Measured performance of matched dielectric lenses

Two microwave lenses whose surfaces have been matched respectively by embedded capacitive walls and by simulated quarter-wave transformers were built and compared experimentally to an unmatched lens of identical aperture and focal length. At the design frequency, the matched lenses exhibited reductions in side-lobe level of 14 and 10 db with respect to the unmatched lens, and increases in over-all gain of 0.35 and 0.1 db. The input vswr of the feed horn was reduced from 1.6 for the unmatched case to 1.02 and 1.05 for the matched cases. The bandwidth of good performance for the two lenses ranged from lö per cent to at least 44 per cent