  In this paper, we have proposed ultra-broadband terahertz absorber with three
layers of periodic graphene disks arrays (PGDAs). A gold layer was utilized as
backside reflector and TOPAS as dielectric spacers. Circuit model of PGDAs and
the developed Transmission Line Model (TLM) for the absorber is utilized to
design the structure using impedance matching concept. The validity of the
results of the device was confirmed by Finite Element Method (FEM). The
structure absorbs both TE and TM polarizations. Furthermore, the obtained
normalized absorption bandwidth is 148% with a bandwidth of 2.64 THz in 1.78
THz central frequency which is to best of our knowledge the best report in
two-dimensional graphene-based structures.
