Propagation of electromagnetic waves in a rectangular tunnel

摘要

A study of radio communication in the underground metero tunnel of the city of Cairo, Egypt was carried out. A part of this tunnel was selected, which has a rectangular shape. Its dimensions are 8.85 m wide, 5.9 m height and 4.5 km long. The walls are made of concrete which have conductivity between 10−1 and 10−2mho/m. The attenuation below and above the cutoff frequency, both for the two values of σ are accounted for and graphically drawn. The results are plotted versus selected frequencies ranging between 30 and 300 MHz show the attenuation for TEmn and TMmn (m,n=0,1) modes. It is found that the attenuation constant for 30 MHz is smaller than for 300 MHz.