Dual band omnidirectional millimeter wave antenna for 5G communications

A planar dual band millimeter wave printed monopole antenna and a $2\times 2$ MIMO antenna are presented for 28/38 GHz future 5G wireless communications. The shape of the radiating element of the proposed antenna is derived from a 28 GHz rectangular monopole. The radiating element isproducing a second resonance at 38 laterally slimmed in a hemispherical manner to intensify the surface current density along the hemispherical contour, producing a second resonance at 38 GHz. The measured impedance bandwidth confirms its dual band characteristics, covering 26.65–29.2 and 36.95–39.05 GHz where $|S_{11}|\le -10\mathrm{d}\mathrm{B}$. The measured radiation patterns are omnidirectional, with a peak gain value of 1.27 and 1.83 dBi at 28 and 38 GHz, respectively. Moreover, diversity performance of the proposed MIMO antenna is evaluated in terms of MIMO performance metrics. such as envelope correlation coefficient, diversity gain, isolation and channel loss capacity.