On the study of CWP dual band left handed propagation with reciprocal and nonreciprocal characteristics over ferrite substrates

This paper presents, for the first time, a new LH CPW TL, which exhibits dual-band LH passbands with reciprocity and non-reciprocity in addition to the conventional right handed (RH) passband. The proposed TL is composed of a CPW over a ferrite substrate, magnetized in a direction perpendicular to its strip, and periodically loaded with shunt planar strip inductors and series air gap capacitors. The negative permeability of the ferrite substrate allows it to play the role of an additional effective series capacitive loading. The first LH passband at lower frequencies is reciprocal and the second LH passband at moderate frequencies has non-reciprocity. The new TL is also tunable by changing the applied magnetic bias. In comparison with microstrip LH TL, a CPW LH TL requires lower dc magnetic bias since it has much smaller demagnetization factor.