A compact frequency-selective absorber with optical transparency

This article proposes a new method for designing an optical transparent frequency-selective surface absorber using indium tin oxide (ITO) conductive film with different sheet resistances. This novel optical transparent frequency-selective absorber exhibits excellent optical transparency, ensuring a visible light transmittance exceeding 76%. Simultaneously, it exhibits broadband absorption characteristics covering the entire X-Ku band, with an absorption rate exceeding 90%. Due to the simplicity of the design, the overall structure is easily processable, and the desired product can be rapidly fabricated using laser etching equipment without adding any lumped elements in the design. Simulation and experimental results indicate that the S11–10 dB frequency range of the frequency-selective absorber is 7.7–18.4 GHz, with a transmission frequency range below −3 dB between 26.7–29.4 GHz. The findings suggest that this structure holds potential applications in microwave stealth design requiring optical transparency and high-throughput satellite communication scenarios.