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Compact reconfigurable rat‐race coupler with tunable frequency and tunable power dividing ratio
Author(s) -
Liao ZhenHeng,
Zhang XuChun,
Yang Xiao
Publication year - 2017
Publication title -
international journal of rf and microwave computer‐aided engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.335
H-Index - 39
eISSN - 1099-047X
pISSN - 1096-4290
DOI - 10.1002/mmce.21139
Subject(s) - capacitance , rat race coupler , power (physics) , materials science , phase (matter) , voltage , hybrid coupler , electrical engineering , optoelectronics , physics , engineering , power dividers and directional couplers , electrode , quantum mechanics
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 Ω 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 ∼ 0.81 GHz and 3 dB ∼ 14 dB, respectively with isolation better than 20 dB, phase difference less than 7°and return loss better than 20 dB. The theoretical simulation, electromagnetic simulation, and measured results show good agreement in this design.