Università Roma Tre

Introduction to metamaterials. Negative index metamaterials. Classification and terminology. Engheta’s resonator. Pendry’s lens. Metamaterial transmission lines. Miniaturized components. Miniaturized antennas. 2D metamaterials: metasurfaces. Design of metamaterial particles at microwaves. Simulations and experiments. Design of metamaterial transmission lines and design of miniaturized components (unit-cells, phase-shifters, rat-races, etc.) Simulations (and experiments).

Electromagnetic invisibility. Reduction of radar observability. Basic principles of EM invisibility. Radar and scattering cross sections. Figure of merit for EM cloaks. Basic principles of the transformation EM. Invisibility cloak based on transformation EM. Other EM invisibility techniques. Basic principles of the scattering cancellation. Scattering cancellation through volumetric metamaterials. Scattering cancellation through metasurfaces (mantle cloaking). Mie theory for spherical and cylindrical cloaked objects. Mie theory on Mathematica. Implementation of single and dual polarization cloaking devices working at microwave frequency. Applications of the EM invisibility at microwave frequencies: cloaking passive objects, cloaking receiving antennas and sensors, cloaking transmitting antennas. Non-linear and waveform selective cloaking devices and related applications. Full-wave simulations of actual cloaking devices.

Metasurfaces at optical frequencies based on proper arrays of nanoparticles. EM characterization of metals at optical frequenices. Drude model. Size correction of the Drude formula. Volumetric homogenization techniques for arrays of nanoparticles: Maxwell Garnett and Clausius-Mosotti formulas. 2D homogenization techniques: the surface impedance model. Homogenization techniques on Mathematica. Application of optical metasurfaces: EM invisibility, absorbers, anti-reflection coatings, transparent screens. Extension of the 2D homogenization to arrays of dielectric nanoparticles. Application of dielectric metasurfaces. Full-wave simulations and practical examples.

Introduction to EM non-reciprocity based on natural and artificial materials. Introduction to space-time modulated metamaterials. Analysis of a resonator loaded with a space-time modulated metamaterial: coupled mode theory, resonant modes and frequency response. Applications. Free-space and slab propagation in space-time modulated materials. Time-domain propagation in a dielectric slab. Space-time modulated metasurfaces. FDTD simulations of space-time modulated materials and surfaces.

Topological properties of structured fields. Introduction to the concept of orbital angular momentum, phase singularity and topologiocal charge. Generation of EM fields with phase singularities at optical and microwave frequencies. Generation of composite vortices and related topological properties (robustness with respect to the interaction with opaque objects and vortex-less fields). Application examples: patch antenna with Moebius polarization, shaping of the direction pattern, sectorial and saddle radiation patterns. Full-wave and analytical simulations.

Radiation and transmissive components based on metamaterials. Examples of multifunctional and miniaturized antennas. Filters for horn antennas based on metamaterial particles: pass-band behavior (linear and circular polarization, single-band and dual-band), notch-band (narrow-band and broad-band). Waveguide components based on electrically small resonators (orthomode transducer, curved components, power dividers). Full-wave simulations.

Course notes.