Millimeter-Wave ME-Dipole Array Antenna Decoupling Using a Novel Metasurface Structure

A novel customized $\pi $ -shaped split-ring resonator metasurface arranged in two configurations is presented to decouple $1\times 2$ and $1\times 4$ Millimeter-Wave (MMW) Magneto-Electric (ME) Dipole in the H-Plane with 1.6 mm ( $0.32\lambda $ at 60 GHz) inter-element spacing. The metamaterial unit cell is first designed to inhibit the propagation of coupled surface waves within the bandwidth of interest. A $5\times 2$ arrangement of this unit cell is carefully positioned on the top and bottom of the superstrate with 1 mm spacing ( $0.2\lambda $ at 60 GHz) between the antenna and the superstrate. In the $1\times 2$ array, a maximum measured mutual coupling reduction of 53 dB is observed within the 52–66 GHz bandwidth (23.7%). To further demonstrate the uniqueness of the metasurface, an $11\times 2$ configuration of this unit cell is arranged as a superstrate for the $1\times 4$ ME-dipoles. A maximum measured mutual coupling reduction of 40 dB is achieved without a considerable effect on the radiation characteristics. Parametric analysis is performed to confirm the uniqueness of this new decoupling structure. The proposed antenna exhibits measured high total efficiency (>89%), high gain (>8 dB), low envelope correlation coefficient ( $ < 0.0003$ ), and very good radiation characteristics throughout the entire bandwidth. The fabricated prototype antenna is measured to validate the simulation results. The proposed antenna is a good recommendation for V-band millimeter-wave MIMO applications like radar research.