A Low-Profile, Wideband, Filtering-Response, Omnidirectional Dielectric Resonator Antenna Without Enlarged Size and Extra Feeding Circuit

A low-profile omnidirectional dielectric resonator antenna (DRA) with wide-bandwidth and high-selectivity filtering response is proposed. Initially, the traditional low-profile DRA has no filtering response. Then, an array of four shorting pins1 is loaded inside the DRA. It proves that the nonradiative pins1 mode could be excited and the radiation-gain null1 in the upper stopband is produced due to the canceled electric fields. Then, the shorting pins2 is loaded to reallocate these modes closely to each other. After that, the additional shorting pins3 is embedded to resonate the nonradiative pins3 mode, thus forming up the radiation-gain null2 in the lower stopband. Finally, the proposed DRA is fabricated and measured. The antenna has simultaneously acquired wide bandwidth (41.2%) and stable omnidirectional patterns in the range of 1.85-2.81 GHz. Besides, the filtering response is generated with a 14 dB out-of-band suppression level. Particularly, it maintains the primary property of the traditional DRA without extra feeding circuit, such as single layer, compact volume, and low profile (0.12 free-space wavelength).