An iterative small perturbational method for fast steering of the prescribed nulls in large perturbations cases

In order to steer nulls in the directions of interference fast and efficiently, the small perturbation method (SPM) has been studied by many researchers. The SPM requires the assumption of relatively small element perturbations for deriving an analytic solution based on the linearisation of a nonlinear problem. We have developed the iterative small perturbation method (ISPM) for a linear array antenna based on the assumption of a small perturbation phase at each iterative step. Our proposed method finally extend the SPM since the first iteration result of ISPM is exactly the same as the SPM. Numerical results are very effective in fast steering and deep nulling in the case of requiring large perturbations. The proposed scheme may be applied to the steering nulls by controlling the element positions.