Time domain modelling: integral equations, finite differences and experimental results

Describes the fundamental assumptions present in two numerical time domain methods based on the electric (or magnetic) field integral equations and Maxwell´s equations. The cause of late time instabilities in the former is analysed, and a practical and effective method of eliminating them is presented. Numerical results of the methods for some idealised problems are presented. Discrepancies in the decay envelope of the backscattered pulses are attributed primarily to the finite thickness of the FDTD (finite difference time domain) plates, as opposed to the infinitely thin structures used in the integral equation representation. Upon modifying the conductivity in the FDTD plate model to make the plate thin, in the sense that its thickness is comparable to its skin depth, significantly improved agreement is obtained. Future work will address the cause of this implied resistivity in the integral equation model