Quad-Polarized Diversity Hollow Cylindrical Dielectric Resonator Antenna

This communication investigates a new quad-polarized diversity dielectric resonator antenna (DRA). The HEM $_{31\delta }^{\mathrm {x}}$ , HEM $_{31\delta }^{\mathrm {y}}$ , TE $_{02\delta + 1}$ , and TM $_{02\delta }$ modes of the cylindrical DRA are utilized. For a solid cylindrical DRA, the TM $_{02\delta }$ -mode frequency is lower than those of the HEM $_{31\delta }^{\mathrm {x,y}}$ and TE $_{02\delta + 1}$ modes, which is an obstacle to the diversity design. In the central DR region, the E-field of the TM $_{02\delta }$ mode is strong, but those of the HEM $_{31\delta }^{\mathrm {x,y}}$ and TE $_{02\delta + 1}$ modes are relatively weak. Therefore, decreasing the relative permittivity of that region by introducing a hollow can increase the TM $_{02\delta }$ -mode frequency, with much smaller effects on the HEM $_{31\delta }^{x,y}$ and TE $_{02\delta + 1}$ modes. In this way, the frequencies of the DRA modes can be made closer to one another. A hollow cylindrical glass DRA is employed to demonstrate this idea. The broadside ${y}$ -polarized HEM $_{31\delta }^{\mathrm {x}}$ and ${x}$ -polarized HEM $_{31\delta }^{\mathrm {y}}$ modes are excited through two groups of notched aperture pairs. These four apertures are equally fed to excite the horizontally polarized omnidirectional TE $_{02\delta +1}$ mode. Finally, a probe is used to excite the vertically polarized omnidirectional TM $_{02\delta }$ mode. The proposed quad-polarized DRA has a minimum isolation of 21.4 dB and a peak gain of 3.57 dBi across the operation band. Additionally, its radiation patterns exhibit symmetry. © 1963-2012 IEEE.