Effects of reinforced concrete structures on RF communications

The proliferation of communication systems used in and around man-made stru ctures has resulted in a growing need to determine the reflection and trans mission properties of various commonly used building materials at radio fre quencies typically used in businesses and residential environments. This pa per describes the calculation of reflection and transmission coefficients f or reinforced concrete walls as a function of wall thicknesses and rebar la ttice configuration over a frequency range of 100-6000 MHz. The transmissio n and reflection coefficients were calculated using a finite-difference tim e-domain (FDTD) solution of Maxwell's equations. The rebar structures analy zed include both a two-dimensional (2-D) trellis-like structure and a one-d imensional (1-D) structure, where the reenforcing bars are all oriented in the same direction. In general, the results show that the reinforced concre te structures severely attenuate signals with wavelengths that are much lar ger than the rebar lattice and that the transmitted signal has a complex st ructure with resonances and nulls that strongly depend upon the geometry of the reinforcing structure and the concrete wall thickness.