Pencil beam pattern synthesis using perturbation technique and fast Fourier transforms

Using perturbation technique, the linear relation between the array pattern and its parameter (current, spacing) perturbation can be established. In a simple and fast way, the formulas to determine parameter perturbations by FFT (Fast Fourier Transform) algorithms are developed and presented in this paper. These formulas can be generically applied in the array synthesis to approach the specified pattern or to improve the pattern performance. Applying them on the synthesis of pencil beam patterns, for which the lower sidelobe levels and/or narrower main beam width are desired, it is shown that the sidelobe reduction can be easily achieved, meanwhile keeping a desired narrow beam width.