Determination of the input impedance of lossless periodic transmission line structures with negative characteristic resistances using Meta-Smith charts

This paper presents the method to determine the input impedance of conjugately characteristic-impedance transmission lines (CCITLs), implemented by multi-section lossless transmission lines (TLs), which can exhibit both non-negative (NNCR) and negative characteristic resistances (NCR). Meta-Smith charts are effectively employed to solve CCITL problems with both NNCR and NCR cases. An example of finite multi-section lossless TLs providing both NNCR and corresponding NCR cases is given. It is found that Meta-Smith charts for the NNCR and corresponding NCR cases with proper propagation constants provide the identical input impedance as expected.