Ultrawideband Electromagnetic Absorber Using Sandwiched Broadband Metasurfaces

In this letter, we propose an ultrawideband electromagnetic absorber using sandwiched broadband metasurfaces. The proposed absorber consists of three layers. The broadband metasurface for high frequencies is loaded on the upper layer. Another broadband metasurface for low frequencies is loaded on the lower layer. The two broadband metasurfaces form a sandwich with the air space in the middle layer. Each metasurface is realized by a periodic array of circular sector patterns with chip resistors. The fabricated absorber shows higher than 90% absorptivity from 3.87 to 14.84 GHz. Under oblique incidence, the absorber shows higher than 80% absorptivity from 3.78 to 15.63 GHz when the incident angle is less than 40° in the transverse electric mode. In the transverse magnetic mode, the absorber shows higher than 80% absorptivity from 5.11 to 15.13 GHz when the incident angle is less than 50°.