Xiaofei Ren, Shuai Zhang, Hu Li, and Shuxi Gong. “Direction Finding Using Uniform Circular Array of Horizontal Log-Periodic Dipole Antennas”. Applied Computational Electromagnetics Society Journal (ACES), vol. 34, no. 03, Mar. 2019, pp. 434-43, https://journals.riverpublishers.com/index.php/ACES/article/view/8561.