A generalized model for coupled lines and its application to planar balun synthesis

A network model for unsymmetrical and inhomogeneous coupled lines is derived based on normal mode parameters. The derivation is based on the four-port impedance or admittance matrix which could be found by using normal mode parameters. This model is useful for synthesis of single and multi-layer coupled line circuits. As an example, the model is used for synthesis of a planar balun circuit configuration. The synthesis procedure is verified by comparison with the analysis results.<>