Leakage Phenomena in Planar Arrays

Abstract

A review of some recent results concerning radiative characteristics of phased arrays of planar leaky-wave antennas is presented, with particular reference to end-of-scanning effects and to the occurrence of grating lobes. On the bas is of a full-wave numerical simulation of infinite linear arrays of microstrip lines, performed via a spectral-domain moment-method approach in the unit cell, the phase and leakage constants of the involved modes have been determined as a function of the physical parameters of the structure and of the phase shift between elements. A transition region between a leaky-wave range and a guided-wave range is reported for the operating mode in correspondence to array radiation at endfire. Moreover, the excitation of anew, additional leaky mode is shown to be responsible for the presence of grating lobes in widely-spaced arrays. Numerical simulations performed on realistic array structures are presented to validate the proposed analysis.