A microwave diffraction system includes two plates, a lattice model, a transmitter and a detector. The two plates are electrically conductive and configured in a parallel manner so as to form a planar waveguide. The lattice model includes a plurality of cylinders arranged in regular order and is placed between the two plates. The transmitter is arranged at an outside edge of the planar waveguide and configured for providing a microwave towards the lattice model. The detector is arranged at outside edge of the planar waveguide and configured for detecting the microwave reflected from the lattice model. The diffraction pattern obtained by the above-mentioned microwave diffraction system is similar to theoretical value. |