Optically Transparent Metasurface with High RF Transmittance and Wide-Angle Stability for Dual Bands and Dual Polarizations

Glass windows are an important part of indoor-to-outdoor wireless communication channels, but the transmission loss of the normal glass limits the quality of the radio frequency (RF) signals, especially for the transverse-electric (TE) polarized waves incident at large angles due to the impendence mismatch. Although some design methods for wide-angle high RF transmission (WHRT) have been proposed recently, they can only work in a single frequency band. Here, an optically transparent metasurface is presented to realize high RF transmissions for dual polarizations in dual bands (2.2-3.2 and 4.4-5.2 GHz) and wide incidence angles (0-80 degrees). The central frequencies of the two bands can be tuned independently by changing the structural parameters. A theory based on the transmission line (TL) model is proposed to explain the mechanism of the design, and a prototype is fabricated by using flexible printed circuit technology. The measured results of the prototype have good agreement with numerical calculations and full-wave simulations. The design is expected to be beneficial to improve the quality of wireless signals in 5G systems.