Abstract
This paper presents a numerical approach to the time-domain analysis of N-branch-line couplers. The approach is based on the modified central difference (MCD) method combined with internal boundary treatments, which consist of the time-domain scattering matrix for the three-port junction discontinuity. The behavior of the signal propagation including multiple reflections on the N-branch-line coupler with and without line loss is analyzed and demonstrated in the time domain. Additionally, the S-parameters obtained from Gaussian pulse responses of the N-branch-line directional couplers are shown. The simulated results are in good agreement with those of the commercial simulator.
