Comparison of absorbing boundary conditions for numerical analysis of periodic structures
DOI:
https://doi.org/10.1109/ICATT.2007.4425170Keywords:
absorbing boundary condition, Floquet waveguide, Klein-Gordon equation, mode basis method, perfectly matched layerAbstract
Periodic structures like gratings or frequency selective surfaces are widely met in antenna design and applications. Some problems require calculating reflectivity in a wide frequency band. Time domain methods like FDTD are beneficial in such problems since they provide the whole spectrum in a single simulation. A periodic structure is modeled as a Floquet waveguide. In FDTD the simulation region needs to be bound with absorbing boundary condition that imitates a semi-infinite waveguide. We tested several such conditions, which are widely used, and reveal that none of these performs well near cutoff frequencies. The problem is demonstrated on a simple illustrative diffraction problem. Some possible ways of improving ABC to overcome the difficulty are discussed.References
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