Near optimal conformal antenna array structure for direction-of-arrival estimation

This article determines the near optimal conformal antenna array structure for direction-of-arrival (DOA) estimation through a comprehensive study on the planar and usual conformal antenna arrays including the cylindrical and hemispherical by using the directive antenna elements in all designs. To model the hemispherical structure, an improved multi-face antenna array with three different tilts is proposed and compared with previous works in order to investigate the tilt effect and obtain the conclusive results. The Cramer-Rao lower bound, multiple signal classification, and root-mean-square error algorithms are utilized to evaluate the estimation accuracy of all conformal structures. Finally, by comparing the estimation precision of all conformal structures it is shown that the purposed multi-face structure as the hemispherical model has a better performance than other conformal structures in terms of the maximum angular coverage of the spatial resource. Moreover, the proposed study method in this article fully examines the impacts of the different conformal antennas geometric structure on the DOA estimation performance by involving the directive antennas radiation patterns.