Abstract
The study discusses the polarization-frequency diversity for microstrip patch antennas by grounding pin and slot. Clearly, the specific polarization design is one of significant issues for radio frequency applications. The effective current path can be varied via slot or grounding pin so that the operating frequency are shifted higher or lower. The TM10 and TM_01 modes are excited with the feeding probe closed diagonal line on a square patch. The hybrid linear polarization also can be separated into two individual linear polarization governed by TM_10 and TM_01 modes or be transformed to circular polarization by slot and grounding pin applied. In this paper, we discuss the characteristics of mode and polarization when both slot and grounding pin are applied. There are two main structures. One of these structures is destructive type which has two polarizations governed by TM_10 and TM_01 modes. The other structure is constructive type which has circular polarization based on the original resonant mode. These designs demonstrate the circular-polarization performance and linear-polarization diversity with only one layer and a single feed. The simulation result matched the theoretic proof and real instrument measurement. The overall tolerance is less than 3%.The study could deliver the valuable principle for multi-mode and switchable polarization RF components design.