Design methods for ULA-based directional antenna arrays by shaping the Cramér-Rao bound functions

This study focuses on the design methods for uniform linear array (ULA) based directional antenna arrays by optimising the radiation characteristics of elements. To improve the performance of direction-of-arrival (DOA) estimation in a predetermined objective spatial sector which includes all the potential directions of incidence, Cramér-Rao bound based optimisation models are established by utilising the least squares fitting technique. Besides, a modified simulated annealing (SA) algorithm with the iteration of parameters is proposed, aiming to solve the optimisation problems when the classic SA is invalid. Compared with the corresponding conventional ULA, an optimised array can obtain higher accuracy of DOA estimation in the objective spatial sector with little fluctuation. Additionally, the optimised design of radiation characteristics can also suppress the ambiguities, and remains effective for the arrays with different aperture. Simulation results verify the effectiveness of the proposed methods and the superiority of the optimised arrays.