Analytical Investigation of Ultrabroadband Plasma–Graphene Radar Absorbing Structures

In this paper, for the first time, the combinational use of plasma medium and graphene sheets is theoretically proposed for stealth applications. The designed structure is a perfect-electric-conductor-backed thin composite material, including a foam layer, multilayer graphene sheets, and a plasma slab, which is topped by a monolayer graphene. The simultaneous use of the lossy characteristics of plasma and graphene layers in the lower and upper parts of the frequency band, respectively, results in a new type of broadband radar absorbing structures. An analytical approach based on the transmission line theory has been utilized to demonstrate the effects of structural parameters on the reflection/absorption specifications. The performance of the designed structures is significantly improved in terms of both the total thickness and bandwidth compared with the previously published plasma-based absorbers. The role of each layer in the final absorption behavior is also investigated by an impedance transformation method. The structure exhibits good performance at oblique incidences for different polarizations. Therefore, according to different advantages such as lower thickness, wider bandwidth, and additional flexibility in design, this new type of absorbers has a positive future for the design of stealth military platforms.