Where l = physical length of the line; o v = speed of light in
free space. For each line, the respective resonant frequency
must be found and, at that frequency, the wave number in
free space, k0, is obtained. The next step is to propose a unitcell
dimension (or a pattern of unit cells). The structure can
be either a DGS or DMS [5], and this is introduced in the
microstrip line and for such a configuration, the electrical
length, θ, at fr is obtained by EM simulation. From these
results, the SWF is