An efficient technique for spherical near-field to far-field transformation and evaluation of far fields of perfectly conducting scatterers

An efficient technique for probe-directivity-uncompensated, spherical, near-field-to-far-field (NF-FF) transformation is presented. The technique does not make use of the spherical vector waver functions (SVWF) in the conventional manner, but seeks to obtain the NF-FF transformation exactly, viewing it as an electromagnetic scattering problem. The problem is formulated by considering the NF-FF transformation, when the FF observation points are restricted to a single φ-plane at a time. The analytical expressions derived toward this end assume a considerably simplified form offering a high level of computational efficiency. The technique is validated by considering arrays as test antennas with a maximum dimension of 150 λ. Based on the principles employed for the spherical NF-FF transformation, an efficient technique for computing the FF patterns of a perfectly conducting scatterer illuminated by an arbitrary source using the technique of physical optics (PO) is also developed. In order to validate this, typical numerical computations are performed, and the results are discussed