Compact reconfigurable rat-race coupler with tunable frequency and tunable power dividing ratio

作者：Liao Zhen Heng^*; Zhang Xu Chun; Yang Xiao

来源：International Journal of RF and Microwave Computer-Aided Engineering, 2017, 27(9): e21139.

DOI：10.1002/mmce.21139

• graphic method
• parallel-strip line
• reconfigurable rat-race coupler
• tunable frequency
• tunable power dividing ratio

A compact reconfigurable rat-race coupler with tunable frequency and tunable power dividing ratio is proposed for the first time. Varactors and two single control voltages are used to obtain both the tunable frequency and the tunable power dividing ratio in this article. The structure of the rat-race coupler involves 50 parallel-strip lines only and a phase inverter is used for size reduction. Theoretical equations for the relationship among S-parameters and the capacitance of varactors are derived. The graphic method is used to choose capacitance for the desired operation frequency and the desired power dividing ratio. For demonstration, a prototype is designed and fabricated. The measured results show that the rat-race coupler's frequency and the power dividing ratio can be effectively tuned in 0.69 GHz approximate to 0.81 GHz and 3 dB approximate to 14 dB, respectively with isolation better than 20 dB, phase difference less than 7 degrees and return loss better than 20 dB. The theoretical simulation, electromagnetic simulation, and measured results show good agreement in this design.

• 出版日期2017-11
• 单位中国人民解放军空军工程大学