Air box Dimensions
pmcardle
Altair Community Member
It is my understanding that when using an FEM simulation decoupled from the MoM, the surrounding airbox should be at a minimum of wavelength/4. Is this the wavelength of the incident light? or is this the effective wavelength of any dielectric media that this airbox is surrounding?
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Answers
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The size should be 1/3 of the free space wavelength at the simulation frequency. The air box forms the absorbing boundary condition for the FEM only solution.
An exception is waveguides that are fully enclosed, e.g. a waveguide filter with FEM modal ports. Here the boundary consists of the PEC walls of the waveguide and you do not need to add an airbox.1