Microstrip Line Fed Wideband Circularly-Polarized Dielectric Resonator Antenna Array for Microwave Image Sensing

A high-gain circularly-polarized (CP) wideband rectangular dielectric resonator antenna (DRA) array, fed by microstrip lines, has been proposed for microwave image sensing. Initially, two orthogonal microstrip lines have been used to feed a single element DRA for obtaining circular polarization. A four element linear array has been conceived with such CP-DRA for obtaining higher directive gain, as well as circular polarization. Both single element DRA and four elements DRA array have been fabricated with Arlon AD270 substrate and Emerson & Cuming make Eccostock HIK materials. A 17% (6.2-7.35 GHz) measured impedance bandwidth and 10% (6.2-6.85 GHz) measured axial-ratio have been noticed for the proposed DRA array. The peak gain of the proposed DRA array varies between 12.1-13.6 dBi over the entire axial-ratio bandwidth with a maximum gain of 13.6 dBi. The simulated and measured results show good agreement.