Hybrid power tapered/space tapered multi-beam antenna

Abstract

An antenna system producing a multi-beam antenna pattern having reduced sidelobe levels with a uniform beam pattern includes an antenna having a plurality of co-linear arrays of radiating elements including central co-linear arrays each of which has an identical number of radiating elements and a pair of outermost co-linear arrays each having a single radiating element. Each of the central co-linear arrays receives the full power output from a corresponding output of a Butler-matrix feed network except for two of the central radiating elements adjacent to the two outermost co-linear arrays, which each share the output power from a corresponding one of the outputs from the Butler-matrix feed network with one of the outermost co-linear arrays. In particular the power is shared between one of the outermost co-linear arrays and a corresponding one of the central co-linear arrays adjacent to the other outermost co-linear array utilizing a power splitter which splits the power between the corresponding central co-linear array and the outermost co-linear array. Each co-linear array includes a feed strap interconnected to each element in the co-linear array. The feed straps for the central co-linear arrays implement an identical trim configuration, and the feed straps for the outermost co-linear arrays introducing a phase shift of .lambda./2, where .lambda. is the wavelength of the electromagnetic energy to be received or transmitted.