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Highly accurate computations of surface plasmons in metallic nanostructures with various geometries are presented. Calculations for cylinders with irregular cross section, coupled structures, and periodic gratings are shown. These systems exhibit a resonant behavior with complex field distribution and strong field enhancement, and therefore their computation requires a very accurate numerical method. It is shown that the multiple multipole (MMP) method, together with an automatic multipole setting (AMS) procedure, is well suited for these computations. An AMS technique for the two-dimensional MMP method is presented. It relies on the global topology of each domain boundary to generate a distribution of numerically independent multipole expansions. This technique greatly facilitates the MMP modeling.

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Abstract-A meshless numerical technique based on radial point interpolation is introduced for electromagnetic simulations in time domain. The general class of meshless methods presents very attractive properties for addressing future challenges of electromagnetic modeling. Among the interesting aspects, the ability to handle arbitrary node distributions for conformal and multi-scale modeling can be mentioned first. Furthermore, the possibility of modifying the node distribution dynamically opens new perspectives for adaptive computations and optimization. The mathematical background of the radial point interpolation method and a two-dimensional implementation are presented here. The advantages of this meshless method are discussed and applied to a model consisting of a 90 degree H-plane waveguide bend. It is shown that solutions converge much faster using the ability of conformal modeling compared to a similar analysis in rectangular grids.

Abstract-A cross-slot-coupled cylindrical dielectric resonator antenna (DRA) is studied theoretically and experimentally. In previous papers, a cross-slot of unequal slot lengths was centered under the dielectric resonator (DR), resulting in circular polarized operation of the antenna. In the present study, the design is enhanced by setting the centers of the two slots at different positions and taking into consideration the partial independence of the slot modes from the DRA mode. Thus, circular polarization (CP) bandwidth of up to 4.7% is attained experimentally in the broadside direction. It is also shown that a largely asymmetrical structure results in a very high bandwidth, but with the tradeoff of distorted CP operation off-broadside.