Asymmetric Geometry of Defected Ground Structure for Rectangular Microstrip: A New Approach to Reduce its Cross-Polarized Fields

Abstract

A shaped defected ground structure (DGS) that is asymmetric in a specific radiating plane of a microstrip element has been explored with a view to addressing the cross-polarization (XP) issues. The asymmetric configuration has been conceived from an insight of the inherent asymmetry of the modal fields underneath a probe-fed microstrip patch and has been experimentally demonstrated as the best possible design compared to its predecessors in terms of the reduction in XP fields, angular span of suppression around boresight, and the space occupied by the defects. Different orientations of the defects with reference to the patches of different aspect ratio values have been thoroughly examined. More than 28-dB isolation between co-pol and cross-pol has been achieved over 190° angular range, which is indeed 140° more if compared with a conventional ground plane. Its superior characteristics with respect to the earlier designs have also been documented.