Investigation and Enhancement of Radio Frequency Signal Losses of Glassy Window

This paper presents a wide incident angle, wideband, and polarization-insensitive unit cell frequency-selective surface (FSS) on single- and double-glazing glass. The 5G signal losses due to the shielding of building materials lead to high penetration losses that degrade the data rates, energy, and spectral density. The transmission coefficient of glass is lower than that of the materials used in buildings. So, investigating and enhancing radio frequency signal losses on glassy windows at sub-6GHz frequency band is crucial to increase the transmission coefficient. This paper uses three different transparent materials: ITO-PET film, silver nanowires (AgNWs) on a polymer substrate, and silver on a pet substrate as an FSS coating material for glassy windows to enhance the transmission coefficient at the n77 and n78 bands. The optimization of unit cell parameters was implemented using the Trust Region Framework (TRF) algorithm. The investigation for single and double glazing has shown that the thicker the glass, the lower the transmission coefficient. Moreover, the simulation result of the proposed FSS can support up to ${85}^{o}$ and ${75}^{o}$ for single- and double-glazing glass, respectively. A maximum of 17 dB enhancement was obtained from single-glazing glass, and a maximum of 10 dB enhancement was obtained from double-glazing glass. Thus, the designed FSS structure can enhance 5G signal transmission from outdoors to indoors.