Phase Shifting Surface (PSS) and Phase and Amplitude Shifting Surface (PASS) for Microwave Applications

Abstract

This thesis describes an electrically thin surface used for electromagnetic applications in the microwave regime. The surface is free-standing and its primary purpose is to modify the phase distribution, or the phase and amplitude distribution of electromagnetic fields propagating through it: it is called phase shifting surface (PSS) in the first case, and phase and amplitude shifting surface (PASS) in the second case. For practical applications, the surface typically comprises three or four layers of metallic patterns spaced by dielectric layers. The patterns of the metallic layers are designed to locally alter the phase (and amplitude in the case of the PASS) of an incoming wave to a prescribed set of desired values for the outgoing wave. The PSS/PASS takes advantage of the reactive coupling by closely spacing of the metallic layers, which results in a larger phase shift range while keeping the structure significantly thin. The PSS concept is used to design components such as gratings and lens antennas which are presented in this document. The components are designed for an operating frequency of 30 GHz. The PSS phase grating gives high diffraction efficiency, even higher than a dielectric phase grating. Several types of lens antennas are also presented, which show comparable performance to that of a conventional dielectric plano-hyperbolic lens antenna with similar parameters. The PASS concept is used in a beam shaping application in which a flat-topped beam antenna is designed. This work demonstrates the potential for realising thin, lightweight and low-cost antennas at Ka band, in particular for substituting higher-gain antenna technologies such as conventional dielectric shaped lens antennas.