Microsized Graphene Helmholtz Resonator on Circular Dielectric Rod: A Tunable Sub-THz Frequency-Selective Scatterer

A novel miniature THz resonator consisting of a finite-length slotted graphene cylinder wrapped around an infinite circular dielectric rod is proposed. A full-wave 3-D electromagnetic scattering model is built using the method of moments (MoM) solution of the electric-field integral equation (EFIE) in the spectral domain. In order to gain a better understanding of the associated physical effects, the obtained results are compared with a 2-D model where the slotted graphene cylinder is assumed infinite. A good agreement between the 3-D and 2-D models is found. The dependence of the backscattering radar cross section on the frequency is analyzed. It is found that in both cases this scatterer displays quasi-static Helmholtz resonance (HR) response in the sub-THz frequency range, a behavior previously known for perfectly electrically conducting (PEC) slotted cylinders. For both models, in-resonance surface current distributions and far-zone radiation patterns are given. The most important innovation is that due to the use of graphene the Helmholtz-mode resonance becomes electrically tunable.