Combined EM field/linear and nonlinear circuit simulation using the FDTD method

A review of several techniques related to the combination of geometrical decomposition of mixed geometry problems coupled with the inclusion of single and multiple linear and nonlinear circuit elements is addressed for use with the FDTD method. As a demonstrator of the algorithmic aspects related to this problem, a slot loop antenna is analysed. Several variants of the antenna are described, the simplest variation consisting of a slot loop antenna fed by a coplanar waveguide line connected via a slotline transition. More elaborate variations include techniques for the inclusion of lumped linear and/or nonlinear elements into the FDTD code. The inclusion of three terminal lumped active devices is demonstrated in order to describe the algorithmic details of the slot loop operated as an active antenna. Where possible, experimental and theoretical predictions are compared in order to validate the methodologies adopted