Analysis of Electromagnetic Field Distribution in Tunnels with Partition Walls.

A method of formulation based on the boundary element method is provided for the electromagnetic field in a two-dimensional impedance tunnel with partition walls excited by the fundamental mode. The impedance boundary condition used often for the analysis of the electromagnetic scattering problem from a lossy dielectric and of the wave propagation in a tunnel is based on the characteristic impedance for an infinitely thick medium. Since there is no provision on the transmitted wave behind the dielectric plate, this boundary condition cannot be applied directly if the dielectric plate used is thinner than the skin depth. This paper derives first a new boundary condition in which the values of the electro-magnetic field in the region opposite to the wall surface are considered. in the case of a plane wave (TE wave) incidence on an infinitely wide than dielectric plate, the computed values by the boundary element method with the new boundary condition are compared with the rigorous solutions. It is found that the results agree with each other for both the reflection and transmission coefficients so that the impedance boundary condition introduced here can be used as the boundary condition for a thin dielectric plate. Further, assuming a tunnel with a thin partition wall, we carried out a micro-wave simulation experiment with a Bakelite plate so that the validity and usefulness of the present method are confirmed. [ABSTRACT FROM AUTHOR]