Wideband Gain Enhancement of a Dual-Polarized MIMO Vehicular Antenna

Abstract

A compact dual-polarized multiple-input-multiple- output (MIMO) Vivaldi antenna with a wide bandwidth, high gain, and high isolation is proposed for wireless communications in intelligent Internet of Vehicles (IoV). It consists of four identical orthogonally-crossed Vivaldi radiators, crossed-fishbone-shaped slot, metasurface lens, parasitic stubs, electromagnetic (EM) wave reflector, and three-dimensional (3D) printed radome with dielectric resonator (DR) array. These functional modules jointly contribute to optimized antenna performance. Four identical antenna elements are rotationally symmetrical. To reduce the inter-element mutual coupling, the crossed-fishbone-shaped slot is etched to reduce the surface current flowing in adjacent radiators. To raise the gain, the metasurface lens, parasitic stubs, and DR array are loaded to guide the EM wave in the frontward radiation. An EM wave reflector located underneath the Vivaldi radiators could increase the boresight gain and reduce the influence of the vehicle body on the antenna performance. Diversity performance analysis indicates the proposed antenna could offer better MIMO capability. Besides, the impact of weather conditions on the antenna is analyzed. As a proof of concept, an expanded 8-element antenna array prototype is designed, fabricated, and tested. A good agreement is observed between measured and simulated results. It achieves an -10-dB impedance bandwidth of 7.55-22.85 GHz (100.66% FBW) with port isolation of higher than 18.05 dB. The realized gain is 6.98-11.54 dBi, and the radiation efficiency is 85.05-90.27%. The proposed antenna could be used in wireless communications between vehicles and the satellite/infrastructure.