Wideband Dielectric Resonator Antenna With Dual Circular Polarization

Abstract

In this communication, two wideband dual-polarized dielectric resonator antennas (DRAs) for X-band radar applications are presented. The design procedure is started with designing a linear polarized DRA fed by a microstrip line. The feedline is optimized to excite the hybrid electromagnetic (HEM) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{11 \delta }$ </tex-math></inline-formula> modes of DRA which corresponds to magnetic monopole-like radiation. Then, a novel quadrature hybrid is designed in the feeding structure to provide both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Finally, two antenna prototypes are fabricated and tested: a dual (right hand and left hand) circular polarization DRA with omnidirectional pattern and an enhanced gain version of dual-polarized circular polarized (CP) DRA with a directive pattern. The measurement results of antennas confirm wideband impedance bandwidth (34% and 38.8%) as well as wideband axial ratio (AR) ones (23% and 30%) in element and array structures, respectively. The antennas also provide both RHCP and LHCP radiation. The first antenna contains monopole-like radiation which is aimed at wireless systems with omnidirectional pattern requirements. The second antenna, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> antenna array, presents around 9 dB across the entire band. The presented antennas are good candidates for radar applications such as weather monitoring, air traffic control, and vehicle speed detection.