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This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.

This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.

Modeling of spherical metasurfaces using generalized sheet transition conditions (GSTCs) and vector wave function (VWF) expansion is presented. The fields internal and external to the metasurface are expanded in terms of spherical VWFs and unknown coefficients. The GSTCs are used to obtain linear relationships between the unknown coefficients. An overdetermined system of equations is then solved by point matching. The method is quasi-analytical, and hence there is no need for meshing, which is encountered in conventional computational electromagnetic methods. This results in the method being extremely fast and hence useful for metasurface optimization. The method is validated by two examples. The formulations presented here can be easily extended to multilayered spherical metasurfaces.

In magnetic resonance imaging (MRI), several studies have demonstrated that the metamaterial-based structures can effectively improve the sensitivity, and thus the signal-to-noise ratio (SNR), of receiving radio-frequency (RF) coils. However, the use of metamaterials for this type of the MRI application is often limited due to the bulkiness of the metamaterial structure at RF wavelengths and a lack of frequency tunability of the final design. In this work, we propose a planar compact sub-wavelength (1- field at the depth of 30mm into a load experimentally. Even at a penetration depth as much as 60 mm (deep brain in the case of head imaging), an enhancement of 9% was observed. Moreover, the magnetic field enhancement comes with a decrease (10%) in specific absorption rate (SAR). In terms of tuning, by controlling the water level in the cavity, the proposed spiral resonator shows a wide tuning range of 35MHz, centered around 64 MHz, with high tunability sensitivity (2.4-0.75 MHz/ml or 15-4.8 MHz/mm), which is due to the fact that the tuning cavity is located between the two spirals, where the fields are highly confined.

Modeling of circular cylindrical metasurfaces using the method of moments (MoM) based on generalized sheet transition conditions (GSTCs) is presented. GSTCs are used to link the integral equations for fields on the inner and outer contour of the circular cylindrical metasurface. The GSTC-MoM is validated by two examples: 1) anisotropic and gyrotropic metasurface capable of two field transformations; and 2) nongyrotropic metasurface capable of transforming the field generated by an infinite electric line source at origin to the field generated by a displaced electric line source. The formulations presented here can be used as a platform for deriving GSTC-MoM for 3-D spherical and conformal metasurfaces.