Wideband Passive Electromagnetic Skin Assisted 5G Base Station in Urban Areas at mmWave

A novel wideband, single-layer passive smart electromagnetic skin (EMS) is designed to significantly enhance 5G network coverage and ensure stable beam steering. The proposed EMS establishes a virtual line-of-sight (VLoS) between 5G base stations (BS) and mobile users (MUs) in urban environments, where various obstacles, such as buildings and vegetation, might obstruct a direct LoS. The proposed smart EMS operates across the full 5G mmWave spectrum, specifically targeting the n258 (24.25 – 27.5 GHz) and n257 (26.5 – 29.5 GHz) bands. Its design features an upper layer of copper sub-wavelength unit cells, providing the necessary phase compensation, with periodicities of 0.43 and 0.46 times the free-space wavelength (λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>) at 26 and 28 GHz, respectively. The 2D phase-compensating EMS aperture is composed of 40 × 40 unit cells, measuring 200 mm × 200 mm × 1.5 mm. It is engineered to improve signal quality in areas prone to signal degradation, with a 5G BS assumed to be 10 meters away in the far-field region. The BS 5G signal impinges on the EMS with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ_i</i> = −15° and reflects in the direction of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">θ_r</i> = 30°. Simulations and measurements demonstrate the 5G signal strength improvement from the EMS and extended area coverage with obstructed LoS, ensuring consistent beam streaming across the 24 to 30 GHz band.