Wideband MIMO Antenna with Orthogonal Polarization

In this paper, we investigate small diameter and low profile wideband orthogonal polarization MIMO antennas. A combination of a wideband Halo antenna with four parasitic elements and a sleeve antenna with an upper sleeve structure is proposed, and its antenna characteristics are confirmed using simulation analysis. The antenna is loaded with short elements on the opposite side of the gap between the Halo antenna and the parasitic element to improve the directivity deviation between the both polarizations. As a result, an orthogonally polarized omnidirectional antenna with a relative bandwidth of 10 % has been obtained with
$\vert \mathbf{S}_{11}\vert, \vert \mathbf{S}_{22}\vert \leq-10\mathbf{dB}$
.