Time-domain system identification modeling for microwave structures

Some system identification (SI) and spectral analysis (SA) methods for computing the S-parameters and the admittance Foster-represented matrix (AFM) to generate the lumped element equivalent circuits for linear reciprocal distributed microwave circuits are analyzed. The methods, based on the parameter models, use measured or simulated data obtained by the transmission line matrix method (TLM). Applying the time-domain SI and SA modeling allows us to find poles and residues system locations which satisfy AFM restrictions of the equivalent circuits technical feasibility. Furthermore the real-time modeling can avoid long calculation time of the TLM. The behavior of a microelectromechanical (MEMS) capacitive switch, for which the calculation time usually is extremely long, was investigated by using these methods. The advantage of the applied approaches are made obvious in a dramatic reduction of computation time