State-Space System Representation of Time-Domain Responses from Electromagnetic Simulations

This paper presents a control systems' methodology to derive rational transfer function models from time-domain simulated data, which will be useful to (a) improve the computational efficiency of time-domain simulators, and (b) synthesize distributed equivalent circuits in microwave applications. The method is applied to model FDTD signatures for highly resonant circuits, such as notch filters and patch antennas, and for the first time, a complete signal model is derived, which encompasses the entire signal, including the initial transients. Excellent model corroboration is achieved with published measured data, expending only a fraction of the simulation effort in comparison with previous methods.