Physical interpretation of negative characteristic resistances associated with lossless periodic transmission line structures

This article presents a physical interpretation of negative characteristic resistances (NCRs) associated with lossless periodic transmission line (TL) structures using the model of conjugately characteristic‐impedance transmission lines (CCITLs).Interestingly, the CCITL model of lossless periodic TL structure can exhibit both non‐negative characteristic resistances (NNCR) and NCRs with appropriate propagation constants. Nevertheless, the physical meaning for the NCR case is still ambiguous. To physically interpret the NNCR and NCR cases, it is found that the propagation constant plays an important role. In addition, the suitable definitions of incident and reflected waves for both NNCR and NCR cases are also provided. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1180–1183, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26796