Development of Resistive-Ink Based Planar and Conformal Metasurfaces for RCS Reduction

This work reports design, development and characterization of both planar and conformal Metasurfaces using resistive Ink based lossy pattern printed on top of FR-4 dielectric substrate for RADAR stealth application. Different geometrical dimensions of the proposed unit cell have been optimized numerically using CST-Microwave Studio, to achieve 20 dB reflection reduction with 60% fractional bandwidth in frequency range 10.5-19.5 GHz under normal incidence with 0.12 lambda(L) thickness (where lambda(L) corresponds to lower operating frequency) and 10 dB reflection reduction up to 40 degrees oblique angle of incidence in the given frequency spectrum for both TE and TM polarized wave. An equivalent circuit analytical modelling has also been performed to understand and verify the numerical findings which are nearly in agreement. Polarization insensitive characteristics of developed surfaces is achieved using fourfold rotation symmetry of the designed unit cell. The designed absorbers are fabricated in form of planar, cylindrically bent and 90 degrees dihedral Metasurfaces and are characterized using ABmm Vector Network Analyzer (VNA) system and free space measurement method. A thorough different experimental measurements are performed and it is found that measured characteristics are in agreement with numerical-analytical findings.