Even-odd mode of a double-Lorentz metamaterial and its application to a tri-band branch-line coupler Fatima Mazeh, Houssam Ayad, Majida Fadlallah, Kassem Joumaa, Jalal Jomaah and Fabien Ndagijimana EPJ Applied Metamaterials, 3 (2016) 8 Published online: 13 September 2016 DOI: 10.1051/epjam/2016006