Adaptive beam forming using a cascade configuration

A new technique for adaptive beam forming based on the Davies cascade array configuration [11] is presented. First of all it is shown that an n-element linear array can be reconfigured as a number of subarrays of two elements each. This two-element array is capable of steering one null in an arbitrary direction while maintaining a desired gain in some other prespecified look direction. To adaptively perform this function at any cascade stage, the inverse of a (2 × 2) correlation matrix of the signal vector at a subarray is computed and substituted in the expression for the constrained optimum weight vector. Similar processing is performed at subsequent stages of the cascade configuration. At each stage of adaptation a noise source contributing maximum power at that stage is nulled out. Simulation studies carried out verify the validity of this approach and demonstrate the fast convergence property of the proposed technique.