A Numerical Study of Moving Reference Planes Associated with Unit Cells of Reciprocal Lossy Periodic Transmission-Line Structures by Using the Equivalent BCITL Model

A moving reference plane of unit cell of reciprocal lossy periodic transmission-line (TL) structures (RLSPTLSs) by using the equivalent bi- characteristic-impedance transmission line (BCITL) model is studied numerically in this paper. Applying the BCITL theory, only the equivalent BCITL parameters, characteristic impedances for wave propagating in forward and reverse directions and associated complex propagation constant, are of interest. In this study, a unit cell of an infinite RLSPTLSs is obtained by shifting a reference position of unit cells along TLs of interest. For illustration, an example of symmetrical RLSPTLSs is initially considered. Then, unsymmetrical structures are subsequently investigated by shifting a reference position of unit cells. It is found that the equivalent BCITL complex propagation constant remains unchanged as expected, while the equivalent BCITL characteristic impedances are generally different, depending on the reference position of unit cells. Numerical results will be provided and discussed in this paper.