A Way to Address Inherent Weakness in Conceiving the Ground Plane Geometry for a Microstrip Antenna

This work presents an insight into the nature of ground plane (GP) current of a microstrip patch which is truly adverse in terms of generating cross-polar (XP) fields and minimally contributing to the primary radiation.This study also uses a theoretical basis in exploring a simple solution to mitigate the high XP values, specifically over the diagonal planes (D-planes).This actually turns out to be an engineered GP by clipping off its four corners.This has been thoroughly studied for a set of representative patch geometries and experimentally verified.A consistent XP reduction by 12-13 dB over D-planes has been ensured without affecting the impedance matching or antenna gains.This eventually results in cross-polar discrimination (XPD) of the order of 25-31 dB uniformly over the full range of operating bandwidth.In addition, the design is advantageous in terms of reduction in antenna size or the deployment area.Such a simple low-cost design appears as truly improved alternative to a typical standalone microstrip radiator for practical applications.