DESIGN AND ANALYSIS OF A BROADBAND HIGH ISOLATION DUAL-POLARIZED OMNIDIRECTIONAL ANTENNA

A high isolation broadband dual-polarized omnidirectional antenna comprising two low profile orthogonally polarized omnidirectional radiating elements is presented. A modified monopole using loadings to broaden impedance bandwidth is applied to vertical polarization (VP), while four printed concentrically arranged Yagi-Uda-like antennas are employed for horizontal polarization (HP). Both the simulated and measured results indicate that the operating bands of the proposed antenna with its reflection coefficient less than −10 dB are 1.48 to 3.16 GHz for VP and 1.69 to 2.7 GHz for HP. A good port isolation larger than 40 dB and omnidirectional patterns with the out-of-roundness less than 2dB in horizontal plane are obtained. This paper explains the radiation mechanism by investigating the simulated surface current distributions for VP element and establishing a radiation model for HP element, and also analyzes the performance of the proposed antenna. This antenna design can be applied to 4G (LTE) communication system.