Extension of the multi-frequency ECRH system at ASDEX upgrade D. Wagner, J. Stober, M. Kircher, F. Leuterer, F. Monaco, M. Münich, M. Schubert, H. Zohm, G. Gantenbein, J. Jelonnek et al. (19 more) EPJ Web Conf., 149 (2017) 03004 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714903004