Effects of cage on electromagnetic wave cutoff frequency in mine tunnel

The effects of cage in mine tunnel on the cutoff frequency is analyzed by the finite-element method when the tunnel is regarded as a waveguide, and the numerical results are obtained. The cage in tunnel lower TE mode cutoff frequency and raise TM mode cutoff frequency. AS the area of cage becomes larger,the TE mode cutoff frequency falls slowly and TM mode cutoff frequency raises rapidly. When the cross-section ratio of cage and tunnel is close to one, the model degeneration of TM mode appears.