Dual‐linear polarisation reconfigurable broadband omnidirectional antenna

Abstract

A dual-linear polarisation reconfigurable broadband omnidirectional antenna is proposed. The radiating structure consists of a slotted ring and an inner square loop, which can generate omnidirectional radiation based on characteristic mode analysis. A dipole feeding network is designed and four PIN diodes are loaded into the feeding network to change the current flow direction. The final dimensions of the proposed antenna are 0.2 × 0.2 λ 0 ( λ 0 is the free-space wavelength), with a low profile of 0.006 λ 0 . The measured results show that the antenna achieves an overlapped bandwidth of 49.6% (from 480.2 to 797.5 MHz) with | S 11 | < −10 dB and a gain variation between −1 and 0.4 dBi. The proposed antenna can be applied to a digital terrestrial television service and an unmanned aerial vehicle pattern measuring system.