Li, J. ., F. . Wang, G. . Wen, Y. . Huang, and W. . Zhu. “Planar Metamaterial for Matched Waveguide Termination”. Applied Computational Electromagnetics Society Journal (ACES), vol. 28, no. 12, Sept. 2021, pp. 1236-43, https://journals.riverpublishers.com/index.php/ACES/article/view/11257.