High-Q High-Isolation Resistor-Less Filtering Power Dividing SIW-Cavity for High-Power Applications

A high-power resistor-less filtering power divider is proposed in this paper. It consists of a substrate-integrated-waveguide (SIW) cavity resonator, with two centered posts in it. Two high unloaded quality factor ($Q_u$) evanescent-modes, mode 1 and mode 2, are excited at different resonant frequencies. The posts are loaded with two capacitive loads, ($C_{res}$) and ($C_{shift}$), embedded in the structure. Controlling these capacitances, the resonant frequency of the proposed power divider is tuned. Moreover, the resonant frequency of mode 2 is shifted to its equivalent of mode 1, obtaining an isolation between the output ports. The proposed power divider is designed to operate at 4.5 GHz. A good agreement is obtained between the simulated and the measured results. The proposed SIW-cavity has a size of ($0.55{\lambda }_g\times 0.55{\lambda }_g$) without its feeding lines. A filtering bandwidth of 166 MHz and a 528 MHz 20-dB roll off bandwidth, are measured. Also, a high unloaded quality factor of 296 is obtained. Moreover, a measured insertion loss and an isolation of 0.9 dB and 32 dB are achieved, respectively. The proposed resistor-less SIW-cavity power divider is suitable to operate with high-power applications up to 10 Watts, due to its capability to handle high input power levels.