Design of wideband circularly polarized cylindrical dielectric resonator antennas

A compact wideband circularly polarized (CP) cylindrical dielectric resonator antenna (DRA) with an underlaid 90° couplers is presented. The HEM
_11Δ
(1<; Δ <;1) and HEM
_11Δ
(1<; Δ <;2) modes of the cylindrical DRA are utilized to design the wideband CP DRA. The underlaid coupler is used to generate two quadrature signals, which are fed to two vertical excitation strips stuck on the side wall of the DRA. Since no extra footprint is needed for the coupler, the proposed antenna is very compact. With this compact configuration, loss of the feed network and, hence, reduction in the antenna gain, can be minimized. It was found that the 3dB axial-ratio bandwidth of the proposed antenna can be as wide as 22.5%. The reflection coefficient, radiation pattern, and antenna gain of the proposed antenna are studied, and reasonable agreement between the measured and simulated results is observed.