Asymptotic transition region theory for edge diffraction. I. Tracing transition regions via reflectors

A new edge-diffraction theory for multireflector antennas is presented. It is based on the uniform geometrical theory of diffraction (UTD) and other well-known asymptotic techniques, but is simplified and extended to cover edge diffraction in the presence of several reflector surfaces. The main emphasis of the theory is placed on the transition region around the boundary of the geometrical optics (GO) field. The theory describes the field near the GO boundary in terms of a standard function and a wavelength-dependent parameter Δρ, where Δρ represents the lateral extent of the transition region. The field around the GO boundary can thereby be constructed solely from knowledge of the single parameter Δρ. Formulas are presented for tracing Δρ along the GO boundary from a diffraction point at a certain edge via other possible reflectors. Existing diffraction theories do not allow such tracing of transition region fields via several reflectors