Design of Broadband Radar Absorbing Corrugated Hybrid Core SandwichNickel-Coated Glass/PEEKThermoplastic Composites

Abstract

This study aims to design and manufacture a low-density hybrid corrugated core sandwich structure, employing a nickel-coated glass fiber (NCF)/polyether ether ketone (PEEK) thermoplastic matrix, which demonstrates exceptional radar absorption performance and lightning resistance within the C~Ku (4-18 GHz) band. To modify the electromagnetic (EM) characteristics of glass fibers (GF), a nickel electroless plating technique was employed to plate the surface of the GF with nickel. The complex permittivity (ε = ε' - jε'') of the GF/PEEK and NCF/PEEK composites was measured using a free space measurement (FSM) technique within the C~X-band (5.8-12.4 GHz) to assess their EM properties. The measurement results revealed that at 10 GHz, the ε of GF/PEEK was 4.69 - j0.079, whereas the ε of NCF/PEEK increased to 18.50 - j15.32, indicating improved dielectric properties. To design a broadband radar absorbing structure (RAS) with exceptional microwave absorption performance, the optimal shape of the corrugated core was determined through the utilization of CST Microwave Studio. The designed RAS demonstrated absorption performance exceeding 90% within the C~Ku band (4-18 GHz). Additionally, to improve the lightning protection effectiveness in RAS designs, a polyimide (PI) film coated with patterned silver paste was applied to the facesheet of corrugated core sandwich panel. Through lightning experiments, it was observed that the lightning protection effect was enhanced in the presence of the dedicated lightning strike protection film. The outcomes of this study indicate that the developed corrugated core sandwich structure for RAS holds potential for applications in stealth technology.