Comparative study of backward directional couplers using ENG and coupled line

In this paper, the performance of Epsilon Negative Transmission line (ENG) coupler and coupled line coupler with tight coupling have been investigated. The two structures are simulated using two main field simulators HFSS that is based on finite element method FEM, and CST that is based on finite integration technique FIT and one circuit simulator (ADS). The simulated results are compared with the measured ones and very good agreement has been obtained.