Alternate backward and forward waves in a coupled nonlinear transmission line Jean Emac Ndecfo, Guy Roger Deffo, Serge Bruno Yamgoué and François Beceau Pelap Eur. Phys. J. Plus, 135 1 (2020) 57 Published online: 13 January 2020 DOI: 10.1140/epjp/s13360-019-00080-5