Zero-n gaps of photonic crystals consisting of positive and negative index materials in microstrip transmission lines

One-dimensional photonic crystals and quasiperiodic structures composed of positive and negative index materials were physically fabricated by using conventional microstrip line units and composite right/left-handed transmission line units. It is theoretically shown that the structures possess zero-(n) over bar gaps which are invariant with a change in the scale length, and the edges of the zero-(n) over bar gap are determined by (epsilon) over bar = 0 and (mu) over bar = 0, respectively. We experimentally demonstrate the independence of the zero-(n) over bar gaps on the scaling by augmenting the respective length by the same factor and confirm the crucial function of (epsilon) over bar = 0 and (mu) over bar = 0 by constructing quasiperiodic structures. The experimental measurements agree well with the simulations.