Broadband Eight-Way Substrate Integrated Waveguide Radial Power Divider/Combiner with High-isolation

A broadband eight-way substrate integrated waveguide (SIW) radial power divider/combiner with high-isolation is presented. The step probes are utilized to achieve broadband impedance matching and improve the return loss. What's more, the star structure based on microstrip circuit is employed to improve the isolation performance. A two-layer SIW radial power divider/combiner is designed, fabricated and measured. Good agreement between simulated and measured results is achieved for the proposed power divider/combiner. The measured results show that both bandwidths of the input and output port are 25% and 20% when their return loss are lower than -15 dB. The measured output isolation is greater than 17.5 dB from 5.75 GHz to 7.85 GHz and greater than 20 dB from 6.8 GHz to 7.9 GHz. The presented eight-way SIW power divider/combiner has the advantage of wider bandwidth, lower return loss and insertion loss, and higher isolation between the outputs.