Metasurface covered millimeter-wave MIMO antenna array

This paper describes the design of a unique 26 GHz Multiple-Input, Multiple-Output (MIMO) antenna array for 5G millimeter-wave (mm-Wave) broadband applications. The antenna comprises a 2×1 array of radiating elements excited through a T-junction power divider. The antenna array, with dimensions of 12×18mm2, offers a wide operational bandwidth between 25.05 and 27.8 GHz, corresponding to a fractional bandwidth of 10.4%. It is a modified four-element MIMO system, in which the radiating elements are arranged in parallel with an inter-element spacing of 1.5λ0 at 26 GHz and oriented orthogonally to one another. To further enhance the gain, isolation, and overall performance, a metasurface layer comprising a 5×6 array of rectangular split-ring resonators (RSRs) is strategically placed above the antenna. This metasurface acts as a passive spatial filter and phase modulator, enabling wavefront shaping and polarization control. Constructed on a Rogers RT/duroid substrate with a thickness of 0.8 mm, the proposed MIMO system achieves an average gain of 7.85 dBi, a peak gain of 9.1 dBi at 25.8 GHz, an inter-element isolation of –24 dB, and an ECC of less than 0.0005.