Omnidirectional Retroreflectors for Microwave Applications

Abstract

A retroreflector is a device which reflects an incoming electromagnetic wave predominantly back to the source. The reflection should be strong, predictable and largely independent of the incidence direction. At microwave frequencies, retroreflectors are used for calibrating radars, guiding air vehicles, marking buoys and small boats to enhance their radar visibility, etc. Conventional microwave retroreflectors are metal spheres and plates, corner reflectors and Luneburg lenses. This work describes a new class of microwave retroreflectors omnidirectional but reflecting substantially stronger than the metal sphere. Two basic designs are proposed: a homogeneous sphere from silica glass and a spherical dielectric shell with an optimally chosen shell thickness.