Hsi-Tseng Chou Zong-Chen Tsai Siddhartha Panigrahi Tri-Focal Configuration of Three-Dimensional Metallic Waveguide-Array Lens Antennas of Rotman Lens Concept for Multi-Beam Applications. 144524-144535 2019 7 IEEE Access https://doi.org/10.1109/ACCESS.2019.2945047 db/journals/access/access7.html#ChouTP19