On the reduction of wave propagation loss in tunnels

The reduction of radio wave attenuation in two-dimensional tunnels is discussed. The attenuation of the dominant mode due to its field penetration into the lossy dielectric side wall is reduced by means of the attachment of periodically aligned metallic strips on the wall surface. The electric field distributions in tunnels with and without strips are illustrated to show the effect on the attenuation characteristics. The efficiency of attenuation reduction rate by the metallic-wall stripping method is summarized. The calculation results based on the boundary element analysis are verified by a laboratory experiment.<
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