DUAL-BAND REFLECTOR FEED SYSTEM FOR CLASSICAL CASSEGRAIN RADIO TELESCOPES

The paper describes a dual-band feed system, operating at S- and X-ban d, that can be temporarily mounted and used in a classical Cassegraini an-type radio telescope without removing the existing feed systems. Th e novel feed system, designed to give us high efficiency as possible i n both bands, consists of two offset primary-fed parabolic reflectors, one for each frequency band. The X-band reflector, located behind the S-band reflector, radiates through a plane dichroic surface that repl aces the central part of the S-band reflector. The feed system is to b e used for space geodesy utilizing the very-long-baseline interferomet ry (VLBI) technique and has been tested and used at a radio telescope in Chile. The paper contains results of both a theoretical design stud y and measurements.