Frequency-dispersive resistance of high impedance surface absorber with trapezoid-coupling pattern

Resonances of the high impedance surface (HIS) absorber with periodic trapezoid-coupling pattern were studied. The theoretical, numerical, and experimental study showed that a frequency dispersion of the equivalent resistance could break the single resonance limitation. The limitation is induced by the non-dispersive feature of the equivalent resistance in simple patterned HIS absorber. Therefore, multi-resonances originated from the trapezoid-coupling pattern effectively expanded the absorption bandwidth. The proposed absorber had a thickness reduced by 41% and a −15 dB absorption bandwidth broadened by 50% compared with Salisbury screen.