Broadband Microwave Attenuator Based on Few Layer Graphene Flakes, Pierantoni, L., Mencarelli D., Bozzi M., Moro R., Moscato S., Perregrini L., Micciulla F., Cataldo Antonino, and Bellucci S. , IEEE Transactions on Microwave Theory and Techniques, Volume 63, Number 8, p.2491-2497, (2015)