Wideband, High-Gain, and Tri-Polarized Cylindrical Dielectric Resonator Antenna Employing Six High-Order Modes

A wideband, high-gain, and tri-polarized dielectric resonator antenna (DRA) is proposed in this communication. Its three ports employ three sets of high-order modes of the cylindrical DRA: x-polarized HEM $_{31\delta }^{\text {y}}$ and HEM $_{32\delta }^{\text {y}}$ modes, y-polarized HEM $_{31\delta }^{\text {x}}$ and HEM $_{32\delta }^{\text {x}}$ modes, and vertical-polarized TM $_{02\delta }$ and TM $_{03\delta }$ modes. By utilizing high-order modes, the DRA is capable of providing an impressive peak gain, but it also brings the challenge of narrow bandwidth. To address this issue, a unified air-filled method that can almost independently expand the bandwidths of the two HEM ports and the TM port is proposed. Specifically, two air rings are introduced at the edge of the cylindrical DRA for the bandwidth enhancement of two HEM ports, while a cylindrical air region is introduced at the bottom center of the DRA for enhancing the bandwidth of the TM port. With an appropriate aspect ratio of the DRA selected, it was also found that each port exhibited mode merging, thus effectively expanding the bandwidth. The experimental findings indicate that the tri-polarized DRA under consideration attains an overlapping impedance bandwidth of 27.7% and a peak gain of 7.46 dBi, which are new heights for the same type of DRA.