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A wide-incident angle and polarisation insensitive transparent metasurface is presented for 5G outdoor to indoor coverage enhancement. In order to predict the structural geometry of the unit cell, the Genetic Algorithm (GA) has been applied. The proposed unit cell is arranged in a periodic structure to construct the transmission surface consisting of tow transparent layers of Indium Tin Oxide (ITO) mounted on both sides of Polyethylene Terephthalate (PET) substrate. The proposed transmission metasurface can be simply coated on a glassy windows to empower the outdoor to indoor 5G signals.

This article presents two transmissive metasurfaces coated on a glassy window to enhance the 5G outdoor to indoor (O2I) coverage inside vehicles and buildings. Two different wide-incident angle, and polarization insensitive unit cells are proposed for both single-glazing and double glazing glasses and have been arranged in a periodic structure to construct the transmission surfaces. Both metasurfaces are optically transparent as Indium Tin Oxide (ITO) is used as a conductive part of each unit cell. The proposed transmission surfaces empower the indoor coverage of 5G signals at 3.5 GHz band for wide range of incident angels. Although multi-layer structures are generally more sensitive to angle of incidence, however, both proposed two layered transmissive surfaces offer wide angular stability up to 65 and 75 degrees for double-and single-glazed glass accordingly. In order to achieve wide stable angular response, evolutionary optimization techniques have been used to optimise the proposed unit-cells. Both designs support high transmission coefficient over the operating frequency for wide incident angles which are higher than reported structures in the literature review. The fabricated prototypes have been evaluated experimentally and from measured results, it appears that both metasurfaces offer significant potential to improve propagation into buildings and vehicles.

A metasurface-based thin flat lens operating at millimeter wave frequencies is presented. The three-layered Huygen Metalens indicates collimating/focusing of broadband frequencies from 60 to 74 GHz, with a gain enhancement of 22.5 dBi at a central frequency of 69 GHz while fed by a dipole antenna. The metasurface transmission performance is designed and simulated by numerical and analytical approaches. By integrating multilayered 1-bit Huygens unit cells, the metasurface produced 180 0 phase coverage with constant high amplitude. The proposed design comprised of 50 × 50 unilcells, creating an area of 75 × 75mm 2 . The dipole antenna is applied to illuminate the proposed metasurface where the distance between the feeder and metalens is 27 mm. The result shows that the proposed metalens antenna achieves a maximum gain of 25 dBi at 69GHz GHz. The unique features of the proposed light-weight metalens will be widely used in wireless communication system for mmW wave frequencies.