A Novel Reciprocity Based Theory for Extraction of Scattered Field under Plane Wave Incidence from that of Near-field Illumination

Abstract

ABSTRACT A novel theory based on the reciprocity theorem is presented for computing the plane wave scattered field of an arbitrary target, from its scattered field due to near-field illumination. The target is supposed to be illuminated by a transmitter probe on a cylindrical surface and the scattered near-field data is recorded in the near-field. The presented theory constructs a bridge between the scattered field due to the near-field illumination by a transmitter probe and that of plane wave illumination. Thus, referring to the definition of Radar Cross-Section (RCS) that assumes the incident field to be a plane wave, the RCS of the target can be analytically evaluated. For the verification of the proposed method, it is applied to an infinite conducting circular cylinder, which has an analytic solution for the infinite line source as a near-field source. Using the proposed theory the scattered field of such a target under plane wave incidence is evaluated, which is exactly identical to the same analytical scattered field under plane wave illumination.