Propagation of electromagnetic waves in a rectangular tunnel

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(-2) mho/m. The attenuation below and above the cutoff frequency, both for the two values of sigma 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. (C) 2002 Elsevier Science Inc. All rights reserved.