Textile-Based Band-Stop FSS Design for X-Band Applications

This paper reports the practical implementation and planar experimental characterization of a cross-shaped band-stop frequency selective surface (FSS) on denim for X-band filtering. The contribution comprises a proof-of-concept prototype using low-cost self-adhesive copper foil, quantitative free-space evaluation against an empty-path reference, and transmission measurements under different incidence angles and polarization orientations. An established resonator topology is used. A 15 × 15 mm2 unit cell was analyzed and optimized through full-wave simulations in CST and a parametric study, then extended to a 15 × 15 array measuring 225 × 225 mm2. The periodic model predicts a transmission notch near 10.0 GHz, with a minimum transmission coefficient of approximately −45 dB and a 10 dB rejection band of 9.3–10.7 GHz, corresponding to a fractional bandwidth of approximately 14%. The finite-array model shows a comparable response. Free-space measurements yield a maximum additional insertion attenuation of approximately 16 dB at 10.3 GHz relative to the empty-path reference. This attenuation characterizes the complete denim–adhesive–copper panel under the measurement setup. Since no unpatterned denim control or separate adhesive control was measured, the contributions of the individual components could not be quantified. The measured band with at least 10 dB additional attenuation extends from approximately 9.8 to 11.0 GHz, corresponding to a fractional bandwidth of approximately 11.5%. Additional measurements characterize the dependence of the transmission response on incidence angle and polarization under planar conditions. The results provide prototype-level validation of a planar textile-integrated selective filtering panel. Conformal and wearable performance has not been validated.