A comprehensive double knife-edge diffraction computation method based on the complete Fresnel theory and a recursive series expansion method

This paper deals with the mathematical study of the surface Fresnel integral (SFI) which enables a rigorous computation of the double knife-edge diffraction. The proposed method, which is based upon an analytical series calculation for the SFI, becomes valid whatever the conditions of reception. Besides, the mathematical procedure that is proposed here involves the incident shadow boundary neighborhood for both knife-edge obstacles. Results are compared with some reference well-known values which correspond to asymptotic cases, the global system for mobile communications (GSM) and DCS1800 frequency bands, and a set of measurements. The suggested analytical method has been shown to be in very good agreement with these expected particular theoretical values and field-strength measurements, where different shadowing conditions, including frequency dependence such as mobile communications bands, have been considered for the sake of comparisons.