Ultra-Wide-Band and Polarization-Insensitive Metamaterial Absorber With Resistive Ink Sheet for RCS Reduction Applications

This proposed work focuses on designing and evaluating planar and optimal metamaterial absorbers for radar stealth applications. The structure of the unit cell is designed using a dielectric FR4 substrate with resistive ink patterns printed on it. With the help of computational optimization using the Ansys HFSS tool, the proposed unit cell's various geometric parameters are fine-tuned to achieve outstanding results. The unit cell, which is designed with resistive ink-based lossy material printed on an FR-4 dielectric substrate, achieves a remarkable $-10$ dB reduction in reflection with a 90% fractional bandwidth between 15 and 28.9 GHz under normal incidence. Additionally, the proposed structure's dual negative feature reduces reflection by $-10$ dB for Both TE and TM polarized waves can be angled up to $60^{\circ }$ across all frequencies. The design has a fourfold rotation symmetry, which enables polarization-insensitive capabilities, enhancing its versatility. Furthermore, the unit cell's various properties, including permittivity, permeability, refractive index, and impedance plots, are analyzed to assess the design. The distribution of surface current and electric field is being investigated, which further bolsters the design's credibility. The prototype is developed with a novel unit cell structure, an assortment of unit cell structures is also fabricated to enhance its functionality further, and the results are measured and presented. The experimental results match the simulated results, indicating that the proposed metamaterial absorber is an optimal solution for radar stealth applications.