Air box Dimensions

pmcardle

  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?

 

 

Mel

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.