Abstract
This paper introduces a new polarization-insensitive graphene-based
frequency selective absorber (FSA) with a reflective notch designed
for terahertz applications. The proposed structure features two
absorption bands on either side of a central reflection band. The
design composes a lossy frequency selective surface (FSS), a bandstop
FSS with a metal backing, and an air spacer between. A wideband
absorber structure is developed in the first step, leveraging graphene
as an absorbent material in the lossy layer to achieve wideband
absorptive characteristics. Subsequently, a reflection band is
introduced by integrating a bandstop, lossless FSS layer into the
absorber structure. The overall structure demonstrates two distinct
absorption bands, characterized by absorptivity exceeding 80% within
the frequency ranges of 0.30 to 0.57 and 0.67 to 0.90 THz.
Simultaneously, a reflection notch is achieved at 0.60 THz.
Extensive simulations assessed the performance of the designed FSA.
The proposed structure exhibits stability under oblique incidence up
to 40 deg and allows tunable absorption specifications by
adjusting the chemical potential of graphene. It is noteworthy that
the FSA reflector offers advantages such as eliminating the need for
complicated, high-cost 3-D structures and welding of the lumped
resistors.