A Circularly Polarized Antenna Element for Highly IntegratedArray Antennas

In many areas of wireless communications and radar, there is a fast growing demand for antennas to be highly integrated with microwave sub-systems. To achieve this task, there is a considerable interest in reduced-size antennas. However, reducing the antenna size works against operational bandwidth. In particular, a significant challenge is faced when circular polarization has to be accomplished. In this paper, a small size three-strip coupler is proposed as an external polarizer for a dual feed aperture coupled patch to achieve high purity circular polarization over an increased operational bandwidth. Design, development and experimental results for such an antenna element and a linear array are presented.