Boundary Metal VS. Structure Metal

What if only metal boundary is being simulated with source?
Will it be a perfect waveguide
Or will it give results to reflect the source

Hi @guanmy17,

Thank you for the question. If you use metal boundary conditions in FDTD Solutions, they will act as perfect electrical conductors and will reflect any fields incident on them. If, for example, the x and y boundaries are set as metal, then in this case the simulation region will act as a perfect metal waveguide propagating in the z direction. If all of the boundaries are set as metal, then the simulation region will act like a cavity.

Please let me know if this answers your question.

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Hello @guanmy17,

Do perhaps mean to use FDE to find the modes of a waveguide? It is pretty standard to start with metal boundary conditions when solving for the modes of a waveguide/fiber etc. See starting with metal BC in FDE. Doing this will ignore scattering losses, which is often correct for waveguides and may be what you mean by ‘perfect waveguide’? It will consider material losses however.

Doing FDTD simulations with Metal BC is not used very often, since as @kjohnson said it would result in a perfect rectangular cavity.


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Yes, this perfectly answered my question. Thank you very much!

Got it! Thanks a lot!

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