A Low-Profile Dual-Polarized Omnidirectional Antenna for WLAN/UWB Applications

A novel ultrawideband (UWB) dual-polarized omnidirectional antenna with a low profile has been proposed for wireless local area networks (WLAN) and UWB applications. The antenna is comprised of two components: a vertically polarized (VP) sheet-like tapered monopole and a horizontally polarized (HP) tightly coupled circular connected array with Vivaldi antennas. The HP structure functions as the metal ground of the VP structure to overcome match deterioration when the HP structure is placed near to the metal ground of the VP structure. This design results in a low profile of only 0.08 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_min</i> for the dual-polarized antenna ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ_min</i> represents the wavelength at the lowest frequency within the working band). The antenna provides an overlapped bandwidth of 2.4-10.6 GHz (126%) and an isolation greater than 20 dB within the band. Meanwhile, high efficiency and uniform omnidirectional radiation patterns with a gain variation of less than 3 dB in the horizontal plane are obtained. These appealing properties enable the antenna an ideal choice for UWB applications and wireless communication systems.