1,721,068 research outputs found
Efficient design of frequency selective surfaces for the design of dichroic sub-reflectors for space applications
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Analytical model of a metasurface consisting of a regular array of sub-wavelength circular holes in a metal sheet
No full textIn this work, a metasurface consisting of an array of circular holes in a metal conducting sheet with a sub-wavelength periodicity is considered. The surface partially reflects the incident field according to the shape and geometrical dimensions of the inclusions and, due to this property, is widely employed in antenna systems to improve the radiation pattern of regular radiators. Since the reflection properties of the metasurface are determined by the current density distribution on the metal, we inspect this distribution and coherently develop a new, easy, and accurate analytical model to describe the grid impedance of the metasurface. In order to validate the model, we compare the reflection coefficient of the array obtained through our approach to the one resulting from full-wave numerical simulations and to other accurateanalytical methods available in the open technical literature
Light propagation through metamaterial temporal slabs: reflection, refraction, and special cases
No full textTime-varying metamaterials are artificial materials whose electromagnetic properties change over time. Similar to a spatial medium discontinuity, a sudden change in time of the metamaterial refractive index induces the generation of reflected and refracted light waves. The relationship between the incident and emerging fields at one temporal interface has been subject of investigation in earlier studies. Here, we extend the study to a temporal slab, i.e., a uniform homogeneous medium that is present in the whole space for a limited time. The scattering coefficients have been derived as a function of the refractive indices and application time, demonstrating that the response of the temporal slab can be controlled through the application time, which acts similarly to the electrical thickness of conventional spatial slabs. The results reported in this Letter pave the way to creating novel devices based on temporal discontinuities, such as temporal matching networks, Bragg grating, and dielectric mirrors, which exhibit zero space occupancy by exploiting the time dimension, instead of the spatial dimension
Equivalent Analytical Model of High-Impedance Surfaces made by Circular Metallic Patches
No full textIn the open technical literature, accurate models for the electromagnetic properties of high impedance surfaces made by square metallic patches have been developed and presented. In this contribution, accurate design formulas for high impedance surfaces made by an array of circular, metallic patches are presented. The analytical model takes into account the coupling between adjacent patches in the array in the case of normally incident plane waves. The results obtained using the analytical model are compared with numerical simulations showing a very good agreement with an accuracy to within 4%
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