Transmission line–periodic circuit representation of planar microwave photonic bandgap structures

Planar photonic bandgap structures have been modeled using the theory of transmission lines and periodic circuits. The method allows for fast and accurate computation of the dispersion diagram, and thus prediction of the stopbands for two directions of propagation. Results obtained by the proposed analytic method are in agreement with previously published numerical data for two structures. Additional numerical evaluations of the reflection phase with the finite‐difference time‐domain (FDTD) method confirm the validity of the analytic model within the limits of its applicability. They also further confirm previous observations that wave propagation in directions other than two principal axes results in a narrower stopband.