Source: https://www.researchgate.net/profile/Benahmed-Nasreddine/publication/279914630_Conception_et_simulation_de_coupleurs_RF_et_micro-onde_utilisant_la_ligne_a_bandes_symetriques_elliptiques_blindee/links/559dbb1308ae76bed0bb4747/Conception-et-simulation-de-coupleurs-RF-et-micro-onde-utilisant-la-ligne-a-bandes-symetriques-elliptiques-blindee.pdf