Design of Flexible Hybrid Nanocomposite Structure Based on Frequency Selective Surface for Wideband Radar Cross Section Reduction

This paper presents the design, synthesis, and testing of a novel flexible hybrid nanocomposite (FHN) structure for the wideband radar cross section (RCS) reduction of targets. The proposed FHN structure consists of a frequency selective surface (FSS) pattern printed on a thin flexible polyimide film backed by aluminum foil, which is then integrated with a customized flexible nanocomposite sheet. The nanocomposite sheet consists of graphite fillers combined with zinc oxide powders, which are embedded into the thermoplastic polyurethane matrix. The fabricated nanocomposite sheet is first characterized for the effective permittivity and the dielectric loss tangent using the free-space measurement technique, and the measured electromagnetic properties are then used for the design of an FHN structure. The proposed FHN structure having overall thickness of 1.335 mm shows minimum reflection coefficient (RC) of -28 dB at 10.2 GHz, along with -10 dB RC bandwidth in the entire X -band. Finally, the fabricated FHN structure is applied on a cylindrical target, which provides minimum 10 dB RCS reduction under various polarizations. The proposed work provides an effective way to combine the strength of FSS with that of a customized nanocomposite sheet in order to design an efficient FHN structure for various strategic applications.