Glass Penetrating Transparent Surface with Transmission Improvement for 5G Indoor Communications

A glass penetrating transparent surface (GPTS) is typically implemented using metasurface technology. A GPTS, such as a glass window, must be visually unaffected in environments where propagation control is required. Therefore, we aimed to improve the performance of indoor wireless communication systems for 5G and 6G. In this study, we designed and investigated two different frequency selective surface (FSS) structures, FSS-1 and FSS-2, based on miniaturized elements applied on two separate glasses. FSS-1 was applied on borosilicate glass (GPTS-1), and the results revealed a stable filtering passband around 28 GHz in the Ka band with an impressively low insertion loss of less than 1.7 dB. FSS-2 was applied on conventional glass (GPTS-2), and the measurement results revealed a high insertion loss of 3.7 dB at 30 GHz. However, by adding dielectric slabs to one side and both sides of the conventional glass, the insertion loss improved, reaching 1.7 dB at 30 GHz and 1.08 dB at 27.16 GHz, respectively. To explain this behavior, we introduced a simple equivalent circuit model. Overall, our measured results indicate that the proposed concepts hold potential as viable solutions for signal filtering at millimeter waves on glass windows.