Design of the Low-Profile, Bandwidth-Enhanced, Omnidirectional, and Polarization-Diversity Dielectric Resonator Antenna Employing a New Mode Combination

A low-profile, bandwidth-enhanced, omnidirectional, polarization-diversity dielectric resonator antenna (DRA) is discussed. The horizontally polarized TE<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{011+}\delta }$ </tex-math></inline-formula> and vertically polarized TM<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{02}\delta }$ </tex-math></inline-formula> modes of the cylindrical DRA are employed in this polarization-diversity antenna. The new mode combination is found to provide a small height-to-radius ratio of ~0.14, which is well suited for the low-profile design. In order to simultaneously expand the bandwidth of these two modes, an air ring covering the strong E-field regions of both modes is introduced into the lower portion of the cylindrical DRA. In this way, the bandwidths of the TE<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{011+}\delta }$ </tex-math></inline-formula> and TM<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{02}\delta }$ </tex-math></inline-formula> modes can be efficiently increased by 2.6 and 3.1 times, respectively, and the overlapping bandwidth of the diversity DRA also increases accordingly. The measured outcome demonstrates that the suggested omnidirectional polarization-diversity DRA exhibits strong performance, which can achieve a 25 dB minimum isolation and a 4.2 dBi maximum gain within a 12% overlapping bandwidth. Significantly, it necessitates a DR height of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.08\lambda _{\text {o}}$ </tex-math></inline-formula>, a new record for the omnidirectional polarization-diversity DRAs. The proposed DRA can be applied to the WLAN-5.8 GHz (5.725–5.85 GHz), ISM-5.8 GHz (5.725–5.875 GHz), V2X-band (5.905–5.925 GHz), and Wi-Fi 6E (5.925–6.125 GHz).