Polarization independent triple band ultrathin conformal metamaterial absorber for C- and X-frequency bands

Abstract

A triple-band polarization-independent conformal absorber for C- and X-frequency bands have been presented. The designed absorber comprises a Jerusalem cross resonator at the center, surrounded by a quarter part of a square rings resonator with different sizes at each corner on a metal grounded dielectric substrate. The unit cell size is 0.23λo × 0.23λo and thickness of λo/153 at frequency 6.16 GHz. The absorption peaks were obtained at frequencies 6.16 GHz, 9.22 GHz, and 11.6 GHz with absorptivity 95%, 96%, and 97%, respectively. It exhibited full wave at half maximum (FWHM) bandwidths of 160 MHz bands (6.04 GHz–6.20 GHz, 240 MHz (9.09 GHz–9.33 GHz), and 260 MHz (11.57 GHz−11.83 GHz), respectively. The designed absorber is shown four-fold symmetry, which makes it polarization independent. Normalized impedance and surface current distributions for all three absorption frequencies are analyzed for understanding the absorption phenomenon. The designed absorber has been tested for the curved surfaces with different central angles to show its conformal behavior, and it is perceived that measured results and simulated results have good agreement between them.