Wideband Center-fed Stacked Patch Circularly Polarized Antenna used in Phased Array

A center-fed circularly polarized stacked patch antenna (CF-CPSPA) with enhanced axial-ratio (AR) bandwidth is proposed in this paper. The antenna is composed of two microstrip patches, the lower patch consists of a circular pad, an elliptical-ring, and two branch lines connecting them, which is used to realize the center-fed condition, and the upper patch is an elliptical patch to achieve the wide band performance. Firstly, two center-fed linearly polarized stacked patch antennas with wide band are designed, one mode radiated with x polarization, and the other generates y polarized radiation. Next, the orthogonal modes of two linearly polarized antennas are combined together by a specific design. Finally, the approximate equal amplitude and quadrature phase difference of the introduced modes are achieved in the operating frequency band with proper parameters analysis. And the impedance bandwidth and 3dB AR bandwidth is improved to 30.4% and 16.5%.