Research on resistor loaded branch substructure and use it in broad-band microwave equalizer designing

Broadband problem is always a difficult problem in microwave equalizer designing. Numerical simulations and experiments show that the branch resonator as substructure is quite suitable to broadband designing. Only one can provide 5-6 Ghz bandwidth. And for a equalizer, in order to match the given attenuation curve respectively, it´s attenuation and quality factor should be adjustable besides the frequency is adjustable. To solve this problem, we choose thin-film resistor loaded resonators to construct microstrip equalizer. Good results were obtained in the experiment and simulation. Microstrip resonator is the basic substructure of microstrip equalizer, it´s dimension may decide frequency change points of the equalizer. Importing a thin-film resistor into the microstrip resonator and changing the location and resistance of the resistor, we can adjust the quality factor and attenuation. The influence of the the resistor and the branch on the microstrip resonator is investigated through numerical simulations and experiments. High Frequency System Simulator (HFSS) is used to show that the microstrip resonator incorporated with the thin-film resistor loaded not only can be frequency adjustable, but also can be attenuation adjustable and quality factor adjustable. In final, a 12 GHz broadband microstrip equalizer using thin-film resistor loaded microstrip resonator is designed, fabricated and measured providing an excellent verification on it´s attractive feature, matching well to the TWTA requirement.