A theoretical study of a mulit-element scanning feed system for a parabolic cylinder

This paper is a theoretical investigation of a method of scanning a beam of an antenna consisting of a fixed reflector and an array of elements illuminating the reflector by appropriately controlling the phase and amplitude of the signal radiating from each element. For the purpose of determining the feasibility of such a systems the two-dimensional problem is explored where a specific antenna geometry and an element radiation pattern are assumed. It was found that although the system exhibits similar performance to a system with a single radiating element when radiating a beam on axis, it could be scanned some eight beamwidths off axis without significant deterioration in characteristics. Interestingly, it was discovered that there is a separation (about0.7lambdain this case) between the feed elements where the sidelobes become dramatically high, analogous to grating lobes in a phased array.