Artificial loss in FDTD predictions of high-Q cavities

The penetration of electromagnetic fields into conducting enclosures via apertures is an EMI issue that is relevant to all of aviation. Although there are many possible mechanisms for the penetration of fields into an aircraft it is usually the windows which admit the greatest. Consequently, it is of greatest importance to understand and be able to predict the field penetration through apertures. Contrary to initial intuitive estimations this is not an entirely trivial problem for the finite difference time domain (FDTD) method. Particularly when the aperture is small relative to the size of the enclosure, the decay time of a pulsed excitation can be enormous. However, there may be some advantages to introducing an artificial loss mechanism into the problem space to accelerate the decay of the late-time fields.