Abstract-Making use of mode matching method, a theoretical analysis of a metamaterial layer is presented. The unit cell of the structure is modeled by a TEM waveguide, and the metamaterial element is supposed as a discontinuity in the waveguide. Analyzing the structure using this model, mathematical relations between s-parameters of a metasurface are extracted. It is evident that the variation of each s-parameter is limited to an arc of circle on Smith chart. The key factors determining the location of each circle on plane are specified. Moreover, a discussion on the role of metasurface element in the determination of s-parameters of the structure is given. The variations of scattering transfer parameters on the plane are determined, too. The steps needed to derive these relations are described. Using these relations, simple and straightforward formulas are devised which can be used to predict the response of the metasurface. Finally, some metasurfaces will be analyzed by full-wave method. The new relations are well-agreed with simulation results.
Quantitative techniques to characterize thermomechanical effects of light on canvas paintings are necessary in order to better understand the deleterious effects that light has on precious art collections in museum exhibitions. In this paper, we present advances in the development of a customized laser shearography system for temporal characterization of inplane displacements of canvas paintings when subjected to specific lighting conditions. The shearography system is synchronized with a thermal IR camera and concomitant measurements of derivatives of displacements along two orthogonal shearing directions as well as thermal fields are performed. Due to the nature of the measurements, we have developed real-time temporal phase unwrapping algorithms and high-resolution Fast Fourier Transform (FFT) methods to calibrate applied shearing levels. In addition, we are developing methods to isolate thermally-induced components from randomly-induced mechanical vibrations that occur in museum environments by application of IR imaging data. Representative examples are shown, which illustrate capabilities to measure, detect, and map crack propagation as a function of lighting conditions and time.
In this study, the mode matching method is used to obtain scattering fields due to discontinuity in a uniform waveguide. Unlike the conventional methods, to avoid directly applying the boundary conditions, a new equation is defined in this approach which implicitly involves the boundary conditions. Since employing the boundary conditions directly is not a concern in the authors’ proposed method, it is faster and simpler than other conventional techniques. Next, they derive this equation mathematically. Finally, simulation results with full‐wave softwares confirm the reasonable accuracy of the proposed method with the aid of some examples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.