28 GHz scattering by brick and limestone walls

Even though "bounce" paths are observed to deliver useful signal levels, many researchers think they are too dispersive to support high data rates. Building surfaces are quite rough at LMDS wavelengths, and this roughness should lead to diffuse reflection and a continuum of multipath components rather than the familiar specular reflection and discrete multipath components common to cellular telephone frequencies. To explore these issues, we are making time domain scattering measurements made using nanosecond pulses of 28 GHz RF carrier generated by a novel sampling swept time delay short pulse sounder. In this paper, we present data on the reflection coefficients of the walls and some observations on the pulse width expansion that results from diffuse scattering by the wall rough surfaces.