Designing a resistive ink-dependent microwave frequency selective surface absorber for C, X, and Ka bands

This study proposes a novel design for a compact and wideband absorber that targets microwaves in C, X, and Ka frequency bands. The design involves imprinting a resistive microwave frequency selective surface (FSS) onto an FR-4 dielectric interlayer integrated with a vacuum spacer. The FSS is comprised of a flower-shaped pattern. In simulation studies, the FR-4 substrate has ~ 0.2 mm thickness, with a 4.3 effective permittivity (εr), and a loss tangent (tanδ) of 0.02, whereas the vacuum spacer has a thickness of ~ 4.2 mm and ε=μ=1. A 0.035 mm-thick copper plate used as a bottom plane to reduce the transmission. The pattern was designed using 150 Ω/sq. resistive ink. Simulation results revealed that the absorber could achieve a -10 dB reflection loss over a frequency range of 5 – 15 GHz and 33.1 - 41.3 GHz. This design is obliquely stable from 0°– 70° and polarization insensitive from 0° – 90°; degrees for both modes of polarisation TE as well as TM. These findings make it suitable for realistic stealth applications.