Design of a Wideband Horizontally Polarized Omnidirectional Antenna With Mutual Coupling Method

Abstract

A wideband horizontally polarized (HP) omnidirectional antenna is proposed in this communication, which consists of 12 printed arc dipole units, a wideband 1-to-12 feed network, 2 rows of parasitic arc strips, and a row of director elements. Based on the tightly coupled dipole array design, 12 printed arc dipoles (about $0.2 \lambda_{\rm L}$ , $\lambda_{\rm L}$ : effective wavelength at low frequency) are formed as a ring with their edge overlap for strong mutual coupling. Meanwhile, the two rows of parasitic arc strips are radially placed around these arc dipoles as an impedance matching layer. Owing to the strong mutual coupling and impedance matching layer, the proposed HP omnidirectional antenna has a wideband operating band. Additionally, a row of director elements is utilized to enhance the radiation in horizontal plane. The printed arc dipoles are fed by a wideband 1-to-12 power divider with identical magnitude and phase. Experimental results show that this antenna has a wide 10-dB return loss operating bandwidth of 70.2% (1.7–3.54 GHz) and good omnidirectionality performance with gain variation in horizontal plane being less than 1.2 dB among 1.7–3.2 GHz.