Application of the slope diffraction method for urban microwave propagation prediction

This paper describes an algorithm for the implementation of the slope diffraction method presented by J.B. Andersen (see IEEE Trans. Antennas Propag., vol.45, no.7 p.1093-7, 1997) for an arbitrary configuration including edges or wedges. Validations against several published results are presented. The validations include examples of wedge configurations for which no validation of the slope diffraction method is available in the literature. Furthermore, an estimation for an urban environment of the gain in accuracy due to the use of the slope diffraction method over the classical uniform theory of diffraction (UTD) was performed. It was found that the gain in accuracy is directly related to a factor we called the transition region width (TRW). TRW depends on the three parameters (the frequency, the separation between two screens d, the difference in building heights Δh) to give a single parameter: Δh²/(λ*d). It was shown that the classical UTD used with power summing of the rays can be accurate in configurations in which it was usually not considered to be valid. The results were obtained from 25 realizations of 10 equally spaced screens with heights distributed according to a uniform distribution U[18-Δh,18+Δh]m