Compact unidirectional ring dielectric resonator antennas with lateral radiation

A compact unidirectional ring dielectric resonator (DR) antenna (DRA) with lateral radiation patterns is investigated for the first time. The unidirectional patterns are obtained by combining an equivalent horizontal magnetic dipole of the DR HEM_11δ+1 mode and a vertical electric dipole located at the center of the DR. A wideband version of the design is also investigated, in which the higher-order DR HEM_11δ+2 mode is excited and merged with a slot mode to give a wideband magnetic dipole. The wideband electric dipole is obtained by making use of the parasitic effect of the DR. To demonstrate the idea, the original and wideband DRAs were designed in WLAN (2.40-2.48 GHz) and WiMax (3.4-3.7 GHz) bands, respectively. Their prototypes were fabricated and measured, and reasonable agreement between the measured and simulated results was obtained. In each design, the measured and simulated front-to-back radiation ratios are both over 15 dB, with measured and simulated 3-dB beamwidths of at least 117°.