Revisiting composite right-/left-handed transmission lines and symmetric couplers

In this paper, some hidden aspects of composite right-/left-handed (CRLH) transmission lines (TLs) and couplers are clarified. Complete and detailed dispersion analysis of an isolated CRLH TL is presented including lossless and lossy cases based on a conventional unit cell, devised formerly. Dispersion analysis of CRLH TLs is extended form the conventional to an accurate unit cell. Capability of TLs consisting of such unit cells in supporting RLH waves is demonstrated. A pure analytical strategy is proposed for parameter extraction of CRLH TLs and symmetric couplers based on accurate circuit models. It is shown that by including loss parameters in the circuit model, there is no need to make use of curve fitting methods for parameters extraction of said couplers.