A proposed new design for a large radio telescope

Abstract

A new type of radio telescope is proposed which may make very large telescopes more aordable. The tele- scope is considered to be one of several identical elements that form a synthesis array. It is composed of an almost flat primary reflector that is slightly adjustable in shape and made up of identical square flat panels supported by the ground. A very long focal length imposes the unusual condition that the receiver be carried by an airborne vehi- cle such as a powered, helium-lled balloon. The position of the balloon is measured and controlled as accurately as possible and residual errors in the balloon's position are dealt with in two ways. Errors of a few metres are corrected by moving the receiver feed point electronically. Larger errors are corrected by adjusting the primary re- flector so as to move its focal point to follow the balloon. These features maintain telescope eciency and correct pointing so long as the balloon lies anywhere within a large volume surrounding its ideal position. The problem of con- trolling the balloon position is thereby substantially eased. The telescope has the wide sky coverage needed for syn- thesis observations and an estimated optimum diameter in the range 100 to 300 m. It will operate from decimetre to short centimetre wavelengths, or, with smaller panels, millimetre wavelengths.