Mitigating Backside Radiation Issues of Defected Ground Structure Integrated Microstrip Patches

Abstract

This letter addresses a practical issue of excess backside radiation caused by the cross-polarized (XP) fields, which is being faced by all defected ground structure (DGS) integrated patches. Defects or slots on the ground plane (GP) suppresses the H-plane XP fields. These strategic slots cause leakage of XP fields toward the backside of the antenna. This letter, for the first time, explores the physical insight behind this phenomenon with an aim to find a solution. Engineering on the backside of the GP has been conceived and systematically developed in the form of a pair of electric walls with varied geometries. Serrated comb-shaped geometry has been proposed finally. A thorough DGS-based design along with its experimental validation in the X-band ensures a reduction in XP radiation nearly by 10 dB in the backside maintaining its front-side reduction by 16-18 dB. This also reduces the usual backward radiation originated from the copolarized fields. Although the GP engineering makes the structure nonplanar, its advanced features may find potential applications where significantly low XP standalone antennas are required, such as wireless base stations, to onboard satellite systems.