Dual-layer square-ring antenna (DLSRA) for circular polarization

In this paper, a dual-layer square-ring antenna is studied. The ring configuration is achieved by removing the central conducting portion from the patch which reduces the resonance frequency. The stacked configuration gives wide impedance bandwidth, compared to the regular microstrip patch antenna. To achieve significant axial ratio bandwidth, diagonal corner truncation of only top or bottom square-ring is not enough; rather a combination of corner truncation in both layers is necessary. Simulated and measured results show wide impedance and axial ratio bandwidths, compared to a single microstrip antenna. This antenna can be used in a GPS system or mobile communication.