Aperture area enhancement in circularly polarized microstrip patch arrays using square patches with shorting pins

Circular polarization has always been very effective for many radio systems, such as communications, remote sensing, navigation and radar systems. In these systems, it is desirable for the ground terminal to have a low-profile and lightweight antenna. Additionally, high gain, electronic beam scanning, beam shaping, and low sidelobe-radiation patterns are often required [1]. Microstrip patch arrays satisfy all of the above requirements along with low cost of fabrication. Circular polarization in microstrips is achieved by different methods some of which include: use of multiple feeds, corner feeds, tilted slot placed on the element, elliptical patch element, square patch with slanted corners, circular patch with perturbations, etc. In these methods, two orthogonal modes of equal amplitude and a differential phase of ±90° degrees are excited. In this paper, circularly polarized arrays with shorted metallic patches (SMP) placed in the vicinity of the radiating element are studied. It is shown that the implementation of the SMP in a four element array can have significant improvements on the gain as well as the matching of the elements. All the results have been simulated on infinite ground using Ansoft Ensemble 8.