Design and analysis of optically transparent energy selective surface for high-power microwave protection

With the wide application of energy selective surface (ESS) in the field of high power microwave (HPM) protection, aiming at the research gap in the optical transparency field of ESS, this paper designed two optically transparent ESS based on metal micron wire and colorless polyimide (CPI) substrate: single resonant and dual-resonant ESS. The field-resonance modes and nonlinear conversion characteristics of optically transparent ESS are explored, and the influence of visible light transmission (VTL) on insertion loss (IL), shielding efficiency (SE) and switching threshold is analyzed. Finally, two ESS prototypes are fabricated and tested. The measurement results show that the VTL of the single resonant ESS is 75.5%, the IL is less than 1dB at 7.3-7.7GHz, and the SE is greater than 20 dB at 5.8-8.2GHz. The dual-resonant ESS has a VTL of 78.1%, the IL is less than 1dB at 6-8.2GHz and the SE is 27 dB at 7.5GHz. The simulation results show that optically transparent ESS has effective field-resonant modes and nonlinear conversion characteristics, angular stability and dual polarization stability from 0 to 60℃. Through the design of the metal microwire structure, under the same electromagnetic indicators, the smaller the metal line-width is, the greater the VTL can be achieved. This indicates the application feasibility of optically transparent ESS, and has certain reference and guiding significance for the research of optically transparent ESS.