FVTD analysis of radiowave propagation in two-dimensional tunnels with arbitrary bending angle

The problem of electromagnetic wave propagation in a two-dimensional tunnel with an arbitrary bending angle is numerically analyzed by the FVTD method . The FVTD representations for the electromagnetic field in a lossy medium and the PML absorbing boundary condition are formulated and a procedure for the numerical analysis of the two-dimensional tunnel is provided, Next, as specific numerical examples, the electromagnetic propagation characteristi cs near the bend of tunnels with bending angles of 30 degrees, 45 degrees, and 60 degrees are computed. It is confirmed that the results agree well wi th those of the model experiment using microwaves. Detailed numerical calcu lations are performed for the case in which the width of the tunnel is much larger than the wavelength. In this way, the propagation characteristics a re predicted for an electromagnetic wave in the mobile communication freque ncy band, used inside a tunnel. (C) 1999 Scripta Technica, Electron Comm Jp n Pt 1, 82(9): 1-9, 1999.