  An eight element, compact Ultra Wideband-Multiple Input Multiple Output
(UWB-MIMO) antenna capable of providing high data rates for future Fifth
Generation (5G) terminal equipments along with the provision of necessary
bandwidth for Third Generation (3G) and Fourth Generation (4G) communications
that accomplishes band rejection from 4.85 to 6.35 GHz by deploying a Inductor
Capacitor (LC) stub on the ground plane is presented. The incorporated stub
also provides flexibility to reject any selected band as well as bandwidth
control. The orthogonal placement of the printed monopoles permits polarization
diversity and provides high isolation. In the proposed eight element
UWB-MIMO/diversity antenna, monopole pair 3-4 are 180o mirrored transform of
monopole pair 1-2 which lie on the opposite corners of a planar 50 x 50 mm2
substrate. Four additional monopoles are then placed perpendicularly to the
same board leading to a total size of 50 x 50 x 25 mm3 only. The simulated
results are validated by comparing the measurements of a fabricated prototype.
It was concluded that the design meets the target specifications over the
entire bandwidth of 2 to 12 GHz with a reflection coefficient better than -10
dB (except the rejected band), isolation more than 17 dB, low envelope
correlation, low gain variation, stable radiation pattern, and strong rejection
of the signals in the Wireless Local Area Network (WLAN) band. Overall, compact
and reduced complexity of the proposed eight element architecture, strengthens
its practical viability for the diversity applications in future 5G terminal
equipments amongst other MIMO antennas designs present in the literature.
