Multiband pi-shaped structure with resonators for tri-band wilkinson power divider and tri-band rat-race coupler

This paper presents a novel multiband Pi-shaped structure with resonators. By employing resonators in conventional Pi-shaped structure, multiband quarter wavelength transmission line is achieved. In order to demonstrate our proposed multiband structure, we designed and fabricated tri-band Wilkinson power divider and tri-band rat-race coupler. We can reduce the size by sharing the stub with resonators of two adjacent Pi-shaped structures and making stubs inside the two demonstrated circuits. Measured results show excellent performance comparing to the classical component at single frequency.