UWB CPW fed 4-port connected ground MIMO antenna for sub-millimeter-wave 5G applications

This paper embodies the design and development of a compact Coplanar Waveguide (CPW) fed connected ground Multiple- Input-Multiple-Output (MIMO) antennas operating in the sub-millimeter-wave 5G New Radio (NR) n257/n258/n261 bands. The planar geometry leads to a small and compact structure while achieving a wide operating bandwidth, high gain, and better radiation efficiency. The top surface of the antenna comprises a modified CPW in the form of two circular structures that feeds the centrally slotted circular patch. The single antenna structure is arranged in a rotational orthogonal manner forming a 4-port structure. The ground plane on the bottom of a 4-port structure is connected using a circular ring which is carefully optimized for achieving isolation levels>20 dB across the band of interest. The sub-mm-wave resonating 4-port antenna achieves a compact size of 24 × 24 mm2, a wide bandwidth of 24.8–44.45 GHz (79.35%), the maximum gain of 8.6dBi, and minimum efficiency of 85% across the bands of interest. The proposed antenna element is fabricated over Rogers 5880 substrate and experimental tests are carried out, where a good correlation between the scattering parameters, transmission parameters, gain, and MIMO diversity performance is achieved that makes the antenna a potential candidate for its application in sub-millimeter wave 5G applications.