Microstrip/Slotline-Coupling Substrate Integrated Waveguide Power Divider With High Output Isolation

Based on the microstrip/slotline-coupling circuits, a four-way substrate integrated waveguide (SIW) power divider with high output isolation is presented. The presented power divider is constructed by using two substrate layers and three metal layers. Five microstrip lines located on the top metal layer are coupled with the SIW through three slotlines located on the middle metal layer of the SIW. Good impedance matching between the microstrip lines and SIW can be obtained. To improve the output isolation, three isolation resistors are used in the presented power divider. Moreover, the even- and odd-mode equivalent-circuit method is applied to the presented power divider. An X-band four-way power divider has been designed, simulated, fabricated, and measured. The measured results show areasonable agreement with the simulated ones.