The use of the expanding grid FDTD technique for simulation of CAD-derived personal wireless telephones

We have previously discussed our use of computer aided design and manufacturing (CAD/CAM) files for use in FDTD simulations of mobile communication devices. We address the problems involved with the description of the internal components of the mobile telephone. These are of particular importance as the other plastic shell of the device is no longer metalized. This exposes the internal components and thus they should be included in the model which is used for numerical compliance testing of the device. The problem size when using CAD derived models can be somewhat larger than using a 'box' design as a higher resolution is required to maintain an accurate representation of the device. We also describe the use of an expanding grid FDTD algorithm to enable this large problem to be solved on a workstation.