A Five-Element MIMO Antenna Based on Wideband Triple-Resonance SIW Antenna for Vehicular Communications

The paper presents a wideband triple-resonance substrate integrated waveguide (SIW) rectangular ring slot (RRS) antenna. Three different modes, i.e., half-TE 110 cavity mode, TM 100 and TM 020 patch modes, are excited and merged in the cavity to achieve the wideband triple-resonance performance. The radiation principle of the antenna with its field distributions is also explained. Further, a parametric study is performed to understand the effect of the dimensional parameters of the proposed antenna. Finally, a five-element multiple-input multiple-output (MIMO) antenna has been proposed by arranging the presented single-element antenna in a cubical configuration having five faces. The antenna element achieves 25.95% bandwidth, 7 dBi peak gain, and the total and radiation efficiencies above 85.4% and 92.2%, respectively. The MIMO antenna achieves 26.76% bandwidth, with port-to-port isolation being higher than 25 dB and the envelope correlation coefficient < 0.002 within the operating bandwidth. Also, the peak gain of the MIMO elements is about 7 dBi.