Microwave circuits

We present a general method for the generation of lumped element equivalent circuits for linear passive reciprocal distributed microwave components from time domain scattering signals. The method is based on a field theoretical analysis of the distributed multiport circuit in time domain. For this purpose the three-dimensional transmission-line-matrix method is used. A canonical representation of the multiport admittance matrix Y(p) allows one to extract an equivalent circuit directly after specifying the frequency range of validity. Topology as well as the parameters of the lumped element equivalent circuit are generated by the method. A distributed three-port microwave circuit was modeled and the applicability of the generated circuit model in transient SPICE simulations could be demonstrated.