Design of dispersion-free phase-shifting non-reciprocity in composite right/left handed metamaterials

A composite right/left handed metamaterial with almost dispersion-free phase-shifting nonreciprocity over a wideband is proposed. The difference of refractive indices between forward and backward propagation directions is nearly constant with respect to the operational frequency. To achieve this condition, periodic insertion of asymmetric capacitive stubs for nonreciprocity and symmetric inductive stubs for negative permittivity into a normally magnetized ferrite-based CRLH microstrip line is proposed and designed. Numerical simulation and measurement results clearly show phase-shifting nonreciprocity approximately proportional to the operational frequency in the range over 5-7 GHz.