Enhancing Signal Transmission in Energy-Saving Glass through Tri-Bandpass Frequency Selective Surface Design

The use of energy-saving glass (ESG) is widespread in modern architectural designs due to its exceptional thermal insulation properties. However, the coating deposited on the glass can attenuate signal propagation by up to 40-50 dB. To address this issue, this study introduces a tri-bandpass frequency selective surface (FSS) applied to ESG. The design incorporates a square loop and two hexagonal loop slots etched into the metallic coating to enable the transmission of sub-bands of 5G signals and common UMTS signals. Simulation results demonstrate that the -3 dB range effectively encompasses the frequency bands of 700 MHz, 1.9 GHz, and 3.6 GHz. Furthermore, the study also proposes an optimized approach involving the selective removal of additional lines along the middle of both hexagon sides from the coating to alter the current distribution. The bandwidth of the proposed FSS is significantly improved at 1.9 GHz and 3.6 GHz while constraining the total coating removal to a mere 13.5%. This achievement ensures favorable signal transmission of 5G and UMTS signals, and preserves the thermal insulation properties of ESG. The experimental result of the test sample implemented by the PCB technology matches well with the simulation, indicating this design holds significant promise for enhancing the signal transmission performance of ESG.