COMPARISON OF VARIOUS IMAGE INDUCTION .2. METHODS WITH PHYSICAL OPTICS (PO) FOR THE FAR-FIELD COMPUTATION OF FLAT-SECTIONED SEGMENTED REFLECTORS

Kottler's extension of Kirchhoff's diffraction integral to electromagn etic fields yields the copolarized and cross-polarized fields of segme nted reflectors, For flat sections, the Maggi-Rubinowicz potential can be used to transform Kottler's surface integral into a line integral resulting in an expression composed entirely of line integrals, Comput ation is simplified by the use of the Asvestas potential which elimina tes the need to compute a geometrical optics term required by the orig inal Maggi-Rubinowicz potential, In computing far fields, a further si mplification is realized by considering the antenna in reception rathe r than in transmission as an involved dyadic potential is then replace d by a simple vector potential, This is an exact-analysis method in th e context of the image-induction model which, in theory, provides resu lts which are very close to the physical optics (PO) model for the tra nsmitting antenna, An approximate closed-form method is obtained by ap plying the Gordon transform to Silver's vector far held equations.