Analysis of a slot-coupled microstrip line coupler with finite size substrates using surface equivalence principle and multiple network theory (SEMN)

Two slot-coupled microstrip lines each with a finite size substrate are located on a distinct side of a large ground plane. They are analyzed using surface equivalence principle and multiple network theory (SEMN). Four-port scattering parameters are calculated and compared with experimental measurements which exhibit good comparison. This analysis is also used to model a slot fed microstrip antenna.