Ultra-wideband absorber based on multilayer lossy frequency selective surface

In this letter, a multilayer dielectric with a lossy frequency-selective surface (FSS) absorber is proposed, which is composed of three layers of resistive film-dielectric composite layer and a metal grounded plane. Particularly, each resistive film-dielectric composite layer consists of a polyethylene terephthalate (PET), polymethacrylimide foam (PMI), and resistive film layer. An equivalent circuit model is established to further understand the performance of the absorber based on the impedance matching approach and the transmission line theory. Experimental results reveal that the metamaterial absorber (MMA) covers -10 dB bandwidth of 1.96-21.8 GHz for normal incidence. Meanwhile, the absorption rate can retain more than 80% for both TE and TM polarizations within 55 degrees incidence angles. Furthermore, the fractional bandwidth of the MMA is 167% and its thickness is only 0.108 ?L. The MMA has the characteristics of ultra-wideband, high absorption rate, and polarization stability, making it suitable for communication systems.