An Ultrawideband Vertically Polarized Omnidirectional Patch Antenna With Low Profile

Abstract

An ultrawideband omnidirectional patch antenna with vertical polarization and low profile is proposed. It composes of a circular patch, eight short pins and a circular ground plane. Two propagation modes of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> are produced when the circular patch is excited by a 1-to-8 power divider, while other two propagation modes of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> are additionally excited by embedding two ring slots in the ground plane. A circular slot is then loaded in the circular patch to enhance the impedance matching at the higher frequency band, thus widening the operating bandwidth. By using such a new mechanism, the multiple modes are combined to realize good impedance matching and omnidirectional radiation with vertical polarization during an ultrawide bandwidth of 110% (1.57-5.39 GHz). Besides the ultrawideband operation, our design achieves simple and planar structure, as well as very low profile of 0.06 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> is the guided wavelength at the lowest frequency of the operating band). These performances make the proposed design competitive for indoor mobile communications.