Wide-angle Beam-scanning with Squinted Feed Elements

Abstract

In this article we propose the use of feed-element correction lenslets (FCL) in order to significantly reduce scan loss for wide-angle beam-scanning lens antennas. The FCL achieves this improved scan performance by squinting feed beams toward the center of the aperture lens to reduce spillover loss and can optionally predistort feed phase to correct for aperture phase distortions and improve beam quality. To demonstrate the concept we design and simulate a 4" fan-beam gradient-index (GRIN) lens antenna and unique GRIN FCLs for beam angles of 27° and 47°. The aperture lens and FCLs include broadband matching sections and exhibit approximately 50% aperture efficiency across the 26.5–40 GHz (WR28) band. We show that by using FCLs the gain at 47° is increased by 3.3 dB, corresponding to a scan loss exponent decrease from 3.0 to 2.0.