A more rigorous UTD-based expression for multiple diffractions by buildings

The paper derives and analyses a more rigorous UTD-based expression for multiple diffractions caused by buildings. The previous expression was addressed in the open literature. This new expression is more appropriate for numerical calculation as well as for theoretical analysis. The previous expression applied to the vertically polarised electric field. As a theoretical extension, the new expression applies to the horizontally polarised electric field as well. These suggest that the new expression be utilised in the propagation prediction for cellular mobile radio communications