Optimisation and comparison of three diplexers based on a new slot to microstrip junction

In this paper, a microstrip to slotline transition using different quarter wavelength stubs is proposed and defined as inhomogeneous. The bandwidth of each stub is separately studied and the microstrip to slotline junction is considered as a band-pass filter controlled by design rules. The DOE optimisation and comparison of three different diplexers using this type of junction is achieved by using new design rules implemented in a new CAD tool. Finally, simulations and measurements confirm the theoretical approach of this study.