A Comparative Study of GTD and Physical Optics Diffraction Coefficients for Axially Symmetric Reflectors

The diffraction coefficients of the qeometrical theory of diffraction (GTD) and those of the physical optics (PO) are compared. A unified method for calculating the complete scattered patterns of all the axially symmetric reflectors (spheroid, ellipsoid, paraboloid, hyperboloid and plane) is presented; this method is based upon the correction of the PO diffraction coefficients for a straiqht half plane. The presented unified diffraction coefficients are equal to those of Sommerfeld multiplied by transition functions, which remove the singularities at reflection and shadow boundaries, and differ insiqnificantly from those of Kouyoumjian only in the regions of these boundaries. In the vicinity of caustics, the obtained scattered fields, similarly valid for the afore-mentioned reflectors, are indistinguishable from the predictions by the equivalent edge currents method.