A low-profile wideband dual-resonance tri-port MIMO antenna

A low-profile wideband tri-polarized MIMO antenna is proposed in this paper. Based on characteristic mode analysis of a circular patch, four slots are etched symmetrically on the patch to transform the high-order monopole-like modes into broadside modes with lower resonant frequencies. Four sets of shorting pins are also applied to simultaneously adjust the resonant frequencies of the monopole-like modes and broadside fundamental modes of the patch. The effects of the slots and the shorting pins on these modes are analyzed in detail. Three dual-resonance ports with high isolation are achieved by exciting three pairs of orthogonal modes of the patch. The proposed antenna is wideband with respect to its profile (bandwidth/height = 216), as facilitated by the dual-resonance property of each port. Experimental results show that the proposed antenna features high port isolation (> 35 dB) and high gain (> 5.58 dB). The proposed low-profile wideband tri-port antenna can be applied in highly integrated MIMO systems.