With the aid of numerical simulations, we study the tunability of photonic structures, by evidencing the band gaps (BGs) of a particular 2.5D and of a triangular photonic crystals. Several runs were performed for different values of the dielectric constant, ranging from the dielectric constant ε = 15 to ε = 150. Results shown the BGs cover a large intervals. The numerical model with which the numerical simulations were performed is presented too. We conclude these configurations could be used for tunable high – reflectivity and high – directionality antenna. The pioneering work of Yablonovitch [1] and John [2], which emphasized the analogy between electronic waves in a crystal and light waves in a three-dimensionally periodic structure, and evidenced a complete photonic band gap, led to further studies which cover a large range of domains. As mentioned before, the aim of this paper is to demonstrate, with the aid of numerical simulations, large intervals of BGs in a particular photonic crystal with hexagonal and triangular symmetry.figure