Wideband optically transparent conformal miniature polarization-insensitive metasurface absorber

A miniaturized, ultrathin, wideband, high-efficiency, optically transparent, and conformal metasurface absorber (MSA) with a simple sandwich structure is proposed in this paper. The MSA consists of a top square-ring resonator fabricated from indium tin oxide (ITO) on a low-cost, highly transparent, and flexible polyethylene terephthalate (PET) substrate, a polydimethylsiloxane (PDMS) dielectric layer, and a continuous ITO ground layer. The proposed absorber achieves an absorption exceeding 90% over the frequency range of 3.5–21.7 GHz, corresponding to an absolute bandwidth of 18.2 GHz and a fractional bandwidth of 144%. This outstanding performance is realized using commercially available ITO films with a sheet resistance of 180 ohm/sq, while maintaining a high measured optical transmittance of 80.5%. The angular stability and polarization insensitivity of the proposed MSA are investigated under both transverse electric (TE) and transverse magnetic (TM) polarization modes, demonstrating stable absorption performance over a wide range of incident angles. In addition, the absorber provides more than 10 dB radar cross-section (RCS) reduction from 6.2 to 18.9 GHz, corresponding to a fractional bandwidth of 101%. The absorption and RCS reduction performances are further validated under conformal configurations with different bending radii, demonstrating excellent mechanical flexibility and robust electromagnetic performance. Owing to its wide operating bandwidth, high optical transparency, compact profile, and conformal capability, the proposed MSA is a promising candidate for applications in low-observable platforms, conformal antennas, and electromagnetic cloaking.