Outside the photonic bandgap of two-dimensional square lattice photonic crystals, we found spectral regions in which light coupling from the air is forbidden. This uncoupling spectral region originates from the anisotropy of the photonic crystals. A two-dimensional square photonic crystal has a complete total bandgap (forbidden region in both TE and TM modes) with hole radius ranging from 0.15 to 0.45 times a lattice constant.