Design of an Optimized Feed for Printed Reflectarray Antenna

A printed reflectarray antenna consists of a feed and a planar array of microstrip patches. The performances of whole antenna system obviously depend on the radiation pattern of the feed. In order to enhance the aperture efficiency, a saddle-shaped pattern of the feed is required. In this paper, a one-dimensional (1-D) pattern synthesis for feed is performed by employing a coupled tapered slot-line antenna (CTSA) operating in the sum-mode, which results in uniform illumination on the array aperture. Compared to a traditional tapered slot-line feed, the optimized one improves the 1-D aperture efficiency from 70.6% to 83.7%. Its available frequency range covers (9.7-10.6) GHz with 9% bandwidth.