Choice of optimal frequency for radio communication in mine tunnel

Researched influence of frequency on characteristic of electromagnetic wave transmission in tunnels, and analyzed characteristic of electromagnetic wave transmission in circular, arches and curved tunnels by method of metal wave guide, and gives approximate formulas of attenuation rate. Main conclusions we obtain are as follows: in circular,rches tunnels, if frequency is higher, attenuation rate is smaller, it is beneficial for EM waves to transmit, in curved tunnel, higher frequency, more attenuation rate is smaller,it is unfavorable for EM waves to transmission. By contrast with data of experiment, obtain conclusion 900MHz is optimal frequency for radio communication in mine tunnel.