The interaction of electromagnetic fields with a graphene sheet has been the subject of many investigations in recent years, in view of the potential applications of such an exceptional two-dimensional (2-D) material to future high-frequency circuits and systems, and in emerging nanoelectronic and nanoelectromagnetic applications. Examples include graphene nano-interconnects for all-carbon electronic systems, reconfigurable planar antennas, filters and absorbers, and RF shields.
On the other hand, direct time-domain analyses of electromagnetic systems offer both computational advantages and valuable physical insight into the involved wave phenomena, with respect to indirect analyses based on inverse Fourier transformation of the relevant frequency-domain solutions, whenever the frequency spectrum of the source waveform has a large fractional bandwidth or, equivalently, the transient waveform has pulse-like features. This is the case in a number of applications of increasing diffusion and importance, such as ultra-wideband antenna systems, integrated circuits and associated interconnects for ultra-high bit-rate signal processing, etc.
The goal of this research program is the development of suitable analytical tools to evaluate the time-domain shielding performance of promising nanomaterials, such as graphene, through a direct analysis in the time domain, deriving efficient and accurate formula which serve as guidelines to design graphene components as effective shields to protect apparatuses or systems against transient electromagnetic waveforms due to pulsed external sources.
Recently, there has been an increasing interest in solving time-domain problems which called for developing new methods of analysis in addition to classical numerical approaches such as the Finite-Difference Time-Domain (FDTD) method and TD Method of Moments (MoM). This is becasue direct time-domain analyses of electromagnetic systems offer both computational advantages and valuable physical insight into the involved wave phenomena, with respect to indirect analyses based on inverse transformation of the relevant Laplace-domain of frequency-domain solutions, whenever the frequency spectrum of the source waveform has a large fractional bandwidth or, equivalently, the transient waveform has pulse-like features. This is the case in a number of applications of increasing diffusion and importance, such as ultra-wideband antenna systems, integrated circuits and associated interconnects for ultra-high bit-rate signal processing, and electromagnetic shielding where new figures of merit have been recently introduced to deal with transient problems.
On the other hand, the worlwide research on new materials for nanoelectronic and nanoelectromagnetic applications is rapidly exploring all their potentials and limits, starting from artificially modified materials (metamaterials and periodic strucures) to new two-dimensional (2-D) material. In particular, the class of 2-D atomic crystals represents the ultimate embodiment of a metasurface in terms of thinness, and often performance (e.g., tunability, flexibility, and quality factor). Some notable examples of 2-D layered crystals include graphene, transition metal dichalcogenides, trichalcogenides, black phosphorus (BP), boron nitride, and many more.
The time-domain analysis of this new class of materials is still at its initial stage, but it apperas of paramount importance, mainly because their excitation is usually achieved through intense ultrashort pulses: for this reason, it would be much more significant to have a direct time-domain technique to investigate the electromagnetic transient behavior of such nanostructures.
With particular reference to graphene structures (which are at the moment the most promising nanostructure), we will make use of the integral method known as the Cagniard-de Hoop technique to solve transient shielding problems in classical configurations in an analytical or semianalytical form, in order to be able to efficiently perform parametric analyses of the considered structures. More practical configurations will be analyzed by introducing suitable approximate methods, still based on the Cagniard-de Hoop technique and all the results will be compared with those obtained through brute-force numerical codes. It is expected that the analytical formulations will give a tremendous insight into the time-domain behavior of a class of graphene nanostructures, in particular with reference to shielding problems where graphene and time-domain methods are recently gaining a remarkable attention.