An ultra-thin, polarization free wide-angle stable quad-band metamaterial absorber for applications in C, X, and Ku bands

This study proposes and examines an ultrathin, wide-angle stable and polarization-insensitive metamaterial absorber (MMA) with quad-band functionalities. The proposed MMA exhibits four absorption peaks of 95.67%, 99.16%, 95.97%, and 97.02% at 5.026 GHz, 8.582 GHz, 11.73 GHz, and 15.036 GHz, respectively. The corresponding full width at half maximum (FWHM) bandwidth observed from simulations of the proposed MMA is found to be 180 MHz, 360 MHz, 420 MHz, and 580 MHz. It has a thickness of 0.0134 20 and the dimension of the unit cell is 0.167 20 x 0.167 20 at 5.026 GHz. Moreover, it does not display any variations in absorption per-formance when polarization angle (0) is changed, justifying its polarization insensitive behavior. When changing the incident angle (0) in case of oblique incidence, the proposed MMA is able to maintain the absorptivity above 90% for transverse electric (TE) mode up to 30 degrees and for transverse magnetic (TM) mode up to 60 degrees at all four frequency, which demonstrates its angular stable characteristics. Analyses of the variation in structural parameter, complex permittivity, complex permeability, surface current density, absolute electric field, and normalized input impedance have also been carried out to authenticate the proposed MMA unit cell structure.