Introducing the transfer function concept for a complex structure due to electromagnetic wave penetration using FDTD method [EMC applications]

A complex structure (a typical room in this case), considering the heterogeneousness in its geometry and construction materials, is exposed to EM pulses and the response of electric and magnetic fields is obtained by introducing the concept of a transfer function (TF) for the structure as a linear system. The FDTD method is used to calculate the temporal response of EM fields inside the structure due to a Gaussian incident plane wave and then a frequency domain response is obtained via a discrete Fourier transform. In the next step, we assign a TF to each point by dividing its frequency response by the frequency response of the Gaussian incident wave.. This TF can be used to predict the response of the system to any other temporal waveforms with a frequency content near to the input's frequency content. Thus, once we pay the cost of a long-time memory-consuming numerical calculation to obtain the exact solution of the field distribution inside the structure, due to a proper input (Gaussian pulse), we can come up with a very simple and fast way to predict the answer to other similar inputs.