Equivalent Lumped Element Network Synthesis for Distributed Passive Microwave Circuits

In this paper, two compact lumped element models synthesis methods for distributed passive electromagnetic structures are presented. The first method is based on the canonical Foster representation while the second method uses the Brune’s synthesis procedure which is a more general approach capable to account for lossy structures. Both methods, used in combination with a system identification approach, generate equivalent network models that can be analyzed using circuit simulators. In addition, two decomposition techniques, allow to reduce complexity in the network model synthesis by exploiting the structure’s symmetry are presented. The accuracy and efficiency of the proposed methods are demonstrated on two examples: a lossless branch-line directional coupler and a lossy lowpass microstrip filter.