A Wideband Dual-Polarized Omnidirectional Antenna for Base Station/WLAN

A wideband dual-polarized omnidirectional antenna is proposed for mobile communication base station and 2.4 GHz wireless local area network applications. An integrated design is achieved by combining an inverted-cone monopole for vertical polarization (VP) and a modified cross bow-tie dipole for horizontal polarization (HP). The proposed antenna has a compact size because the HP element acts as the HP radiating element and the ground plane for the VP element simultaneously. The proposed VP and HP antennas are excited by a <inline-formula> <tex-math notation="LaTeX">$50~\Omega $ </tex-math></inline-formula> Sub-Miniature-A connector and a broadband feeding network, respectively. The overall volume of the proposed antenna is only <inline-formula> <tex-math notation="LaTeX">$0.35\lambda _{0}\times 0.35\lambda _{0}\times 0.25\lambda _{0}$ </tex-math></inline-formula> (with <inline-formula> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> being the wavelength of the lowest frequency). Simulation results show that the dual-polarized omnidirectional antenna achieves a bandwidth (for <inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert < -10$ </tex-math></inline-formula> dB) of about 41.5% (1.64–2.5 GHz) with an isolation of at least 25 dB and the gain variations at the center frequency in the horizontal plane are 0.7 dB for VP and 2.3 dB for HP. The good agreements between the simulation and measured results validate the proposed design.