Prediction of diffracted field strength in the shadow of a flat roofed building

A modification to previously developed slab diffraction models allows Babinet's principle to be applied to the problem resulting in simpler computation. An extension to the new model allows the case where a flat roof is surrounded by a parapet wall to be considered. Results show that in such cases the diffracted field strength can exceed that for a perfectly absorbing building. Predictions are supported by measurements made using real buildings and scale models.