An Input-Impedance-Based Circuit Model for Coplanar Waveguide-to-Slotline T-Junction

In this paper, an analytical input impedance formula is presented to characterize the coplanar waveguide (CPW)-to-slotline T-junction. Based on this impedance formula, one may establish a new circuit model for the T-junction, which may describe both the discontinuity effect and the mode conversion effect between even and odd CPW modes. This circuit model is validated by measurement and is then applied to design the back-to-back CPW-to-slotline and CPW-to-coplanar stripline transition structures.