A design of new microstrip-slotline transition structure

In this paper, two improved microstrip-slot transition structures are proposed. The top layer are microstrip lines with two fan-shaped open-circuit terminals, and the bottom layer is the cross-finger slotline which is perpendicular to the microstrip lines, and the short-circuit terminals of the slotline are circular or petal-shaped. These two structures work in the 1–13GHz frequency band. HFSS is used to simulate these two structures, S-parameters and VSWR are compared among the ring slot, petal shaped slot and the original fan-shaped slot. The results show that petal shaped slot transition structure has the best performance. The S11 is less than −19.5 dB and the VSRW is less than 1.23 within 2.5–11.2GHz and 12.4–13GHz.