By using the Transfer-Matrix-Method we have calculated both photonic band structures and transmission coefficients of two-dimensional square macroporous silicon. Results of comparison with a triangular lattice of circular air rods are reported. A study of optimal conditions, such as air rods radius and the material size reveal that two-dimensional square macroporous silicon has a three photonic band gap (PBG) in which the third one is centered at less than 2.90 mu m for both polarization,