Determination of multiple-diffraction ray paths for arbitrary oriented straight edges

A new method for determining the ray path of multiple diffractions is presented. The method is based on the Keller´s law of diffraction derived from Fermat´s least-time principle: the incident angle is equal to the diffraction angle at a diffraction point. Furthermore, the number of nonlinear equations to be solved is reduced to about half of the conventional method. Because of this, the number of iterations of Newton´s method is also reduced. Finally, an appropriate initial guessing technique is adopted to guarantee the convergence and efficiency of the Newton´s method. Our approach has the potential of speeding up the radio propagation modeling in urban and ridged mountain area.