A Compact Frequency-Reconfigurable Rat-Race Coupler

A compact rat-race coupler with tunable frequency is presented. The frequency-reconfigurable operation is achieved by attaching the frequency-reconfigurable matching network (MN) to each port of the four-port network. The MN composed of a shunt tunable capacitor transforms the port equivalent impeda...

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Bibliographic Details
Published inIEEE microwave and wireless components letters Vol. 30; no. 7; pp. 665 - 668
Main Authors Tan, Xiangguan, Sun, Jiaxing, Lin, Feng
Format Journal Article
LanguageEnglish
Published IEEE 01.07.2020
Subjects
Capacitors
Compact
Couplers
Frequency measurement
frequency reconfigurable
Impedance
Manganese
Power transmission lines
rat-race coupler
Tuning
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Summary:A compact rat-race coupler with tunable frequency is presented. The frequency-reconfigurable operation is achieved by attaching the frequency-reconfigurable matching network (MN) to each port of the four-port network. The MN composed of a shunt tunable capacitor transforms the port equivalent impedance of the four-port network to the port impedance across the entire frequency-tuning range. Closed-form design equations are derived. For demonstration, a compact frequency-reconfigurable 3-dB rat-race coupler is designed and measured. The measured results agree well with simulated ones. The measured frequency tuning range is from 1.0 to 2.96 GHz, with the >20-dB return loss and >35 dB isolation. As compared with state of the arts, the proposed coupler exhibits wide frequency tuning range with smaller size and fewer tuning elements.
ISSN:1531-1309
1558-1764
DOI:10.1109/LMWC.2020.2993369