Development of powerful Ka-band FEM-amplifiers with broad frequency tuning A.K. Kaminsky, I.V. Bandurkin, D.E. Donets, S.V. Kuzikov, N.Yu. Peskov, A.V. Savilov, S.N. Sedykh and A.A. Vikharev EPJ Web Conf., 149 (2017) 04011 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714904011