Costa, F., and A. Monorchio. “Electromagnetic Absorbers Based on High-Impedance Surfaces: From Ultra-Narrowband to Ultra-Wideband Absorption”. Advanced Electromagnetics 1, no. 3 (October 14, 2012): 7-12. Accessed October 26, 2020. https://aemjournal.org/index.php/AEM/article/view/22.