Reciprocal Resonance Effects in the Scattering from Layered Cylindrical Luneburg Lens Partially Coated with Graphene

This study examines how a partially graphenecoated layered cylindrical Luneburg lens behaves in the scattering and focusing regimes under the H-polarization illumination. To represent the graphene strip through its effective surface impedance, we use the Kubo-based conductivity model. We reduce the problem to a hyper-singular integral equation, discretized with a Nystrom method ensuring numerical stability and convergence. Two reciprocal excitation scenarios are considered: plane wave incidence and line current source radiation. The study evaluates both the focusing ability and the radiated power and reveals the plasmon-mode resonances, whose frequencies depend on the graphene chemical potential.