Study and Design of Bandstop Filtres Based on a Multiple Co-Directional Complementary Split Ring Resonator (CSRR)Mouhssine Elbathaoui, Nawfal Jebbor and El-Mahjoub BoufounasE3S Web of Conf., 469 (2023) 00014DOI: https://doi.org/10.1051/e3sconf/202346900014