A filling-factor engineered, perfect metamaterial absorber for multiple applications at frequencies set by IEEE in C and X bands

In this paper, by engineering the filling factor of the resonator of a hybrid frequency selective surface (FSS), a low-profile and application-targeted microwave metamaterial absorber is proposed with polarization and angle insensitivity. The proposed hybrid FSS of the absorber on FR4 substrate comprises four identical concentric copper sub SRRs and a defected copper ground. The square-cut area at the center of the ground and the filling factor of the resonator were tuned to get desired absorption peaks at some IEEE defined frequencies at C and X bands, which any other available perfect metamaterial absorbers cannot obtain. The measurement of the array absorber in anechoic chamber and the equivalent circuit analysis has demonstrated that the filling factor engineering technique illustrated an efficient way to achieve maximum absorptivity with the negative refractive index for perfect absorptions at the desired frequencies. The Wide-angle and polarization insensitivity to both co- and cross-polar waves are described by numerical analysis and EM responses. The thickness and dimension of the unit cell at the lowest operating frequency are 0.022 l and 0.22 l, respectively, and make it subwavelength compact. Besides normal and oblique incidence up to 80 degrees and 180 degrees, respectively, the absorber showed similar performance for cross-polar waves with an average of 99.5% absorptivity at 4.196 GHz, 5.24 GHz, 8.632 GHz, 9.264 GHz, and 10.152 GHz. The absorber has the potential for real-life RCS reduction, stealth, and sensing applications at C and X band antenna, satellite, and fighter aircraft stealth systems. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).