Array factor approximation using physical optics and simple line integration

The computation of the array factor of a large two-dimensional (2D) array aperture can result in a large number of computations; this is prohibitive when implemented in a real or semi-real time environment for modeling or simulation purposes. The Fast Fourier transform (FFT) is commonly used where zero-padding is required to minimize aliased spectral leakage. This paper presents a method of fast computation of the array pattern of a large uniformly distributed excitation of the antenna elements within an arbitrarily shaped aperture. The large 2D array factor may be approximated using physical optics and the Navier-Stokes (NS) closed-line integral (NSLI) provided that the array elements are spaced by less than λ/2. Beam steering is still accommodated utilizing this method. With this method, a uniformly excited array with any aperture shape may be evaluated. Both radiation and monostatic scattering may be addressed using the NSLI method.