Double-layer carbon-tiled hexagonal stealth metamaterial utilizing absorptive and radiative surface plasmon polaritons generated by both transverse-electric and transverse-magnetic polarizations

An ultra-wideband and wide-angle hexagonal electromagnetic stealth metamaterial is designed by optimally combining rhombus-carbon tiles on the top of and on the intermediate surface of a foam substrate by utilizing the genetic algorithm. For the first time, a stealth mechanism is unveiled that converts parts of absorptive surface plasmon polaritons induced in an ultra-wide bandwidth from three axial periodic edges and slots for both the transverse electric (TE) and the transverse magnetic (TM) polarizations into radiative ones that have undetectable polarized states for conventional antenna systems. From the measurement, the − 10 dB reflectance bandwidth (BW) is achieved from 1 to 11.66 GHz of which the fractional BW is 168.4% for the normal incidence. Besides, the − 10 dB fractional BW of 49.95% is confirmed for both the TE and the TM polarizations with the incident angle θ from 0° to 45°. Most importantly, the fractional BW is reached to 64.83% for the TE polarization with θ from 0° to 60° which has not been achieved based on square-shape metamaterial absorbers. The design strategy could pave the way to escape from long captivated stealth concepts, i.e., absorbing power, changing the angle of reflection, or shifting the frequency band.