Design of an Adaptive Wideband Beamforming Algorithm for Conformal Arrays

Wideband conformal arrays are increasingly used in modern communication systems due to their flexibility in attaching to arbitrary surfaces. However, designing such arrays has been limited to pattern synthesis techniques because of the complexity of their geometrical analysis and the different contribution of each sensor in the array response. These techniques are basically non-adaptive data independent methods and are not suitable for dynamic environments. In this letter, the conventional Frost space-time wideband beamforming method and its associated Linearly Constrained Minimum Variance (LCMV) algorithm are employed to develop an adaptive wideband beamforming method for an arbitrarily shaped conformal array. The constraint matrix used in the LCMV algorithm is modified to include the pattern of each individual sensor, thereby incorporating the element responses into the weight adjustment algorithm. A set of angle-frequency constraints are used in the proposed LCMV formulation to achieve the desired frequency-invariant beampattern. It is shown by a comprehensive example of a typical conical array that the desired beampattern can be obtained in an adaptive manner for a time-varying target.