Three-dimensional modal transmission-line method for radio wave propagation through periodic building structures

The modal transmission-line (MTL) method is used to study the transmission and reflection characteristics of a periodic building structure under the most general condition of oblique incidence (three-dimensional incidence). The presented method extends a previous analysis for the two-dimensional incidence case. Using a coordinate transformation, the reflection and transmission coefficients for an electromagnetic plane wave obliquely incident onto a periodic building structure can be solved rigorously by combining the 2-D incidence result for TE and TM polarisation, respectively. The transmission and reflection properties of concrete block and reinforced concrete walls are also analysed. Simulation findings are compared with those obtained by other researchers and the good agreement validates the extended MTL method.