An Ultrawideband Vertically Polarized Omnidirectional Patch Antenna With Low Profile

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 TM01 and TM02 are produced when the circular patch is excited by a 1-to-8 power divider, while other two propagation modes of TM01 and TM02 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?(L) (?(L) is the guided wavelength at the lowest frequency of the operating band). These performances make the proposed design competitive for indoor mobile communications.