Extended composite right/left-handed (E-CRLH) metamaterial and its application as quadband quarter-wavelength transmission line

A novel extended composite right/left-handed (E-CRLH) transmission line (TL) metamaterial structure, constituted by the combination of the conventional CRLH (C- CRLH) and the recently introduced dual CRLH (D-CRLH) prototypes, is proposed. This E-CRLH metamaterial is characterized by eight LC parameters (four C-CRLH and four D-CRLH parameters), which allow unprecedented diversity in the manipulation of the dispersion relation of the resulting TL structure. In particular, an E-CRLH TL metamaterial, under an extended balance condition, exhibits two frequencies of infinite wavelength propagation. In addition, the E-CRLH is intrinsically a quadband (arbitrary quadruplet of frequencies) structure. The latter property is exploited here into the design of a quadband quarter- wavelength transformer, and may be applied in principle to any TL-based microwave component.