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A tunable reflection/transmission coefficient circuit using a 45° hybrid coupler with two orthogonal variables
Kalantari, M ; Sharif University of Technology | 2019
320
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- Type of Document: Article
- DOI: 10.1109/TMTT.2019.2895578
- Publisher: Institute of Electrical and Electronics Engineers Inc , 2019
- Abstract:
- This paper presents a tunable reflection/transmission coefficient (TRTC) circuit based on a 45° hybrid coupler that is potentially useful for leakage cancelation purposes. The analysis of the proposed TRTC circuit shows that the circuit can cover any reflection/transmission coefficient of less than 0.5 on the Smith chart by adjusting only two variable resistors. Meanwhile, the real and imaginary parts of the reflection/transmission coefficient can be tuned independently, facilitating the use of this circuit in feedback systems. To implement the 45° hybrid coupler used in the proposed TRTC circuit, a new wideband planar topology for arbitrary phase and amplitude hybrid coupler is introduced. The circuit is analyzed and closed-form derivations for designing the proposed hybrid coupler are extracted. A prototype of the proposed 45° hybrid and TRTC circuits are fabricated and measured on 1.6-mm FR-4 PCBs at 1 GHz. The measurement results show a fractional bandwidth of 50% for the proposed 45° hybrid and a coverage radius of larger than 0.3 on the Smith chart in a frequency range of 0.8-1.2 GHz for the proposed TRTC circuit, which are well matched to the simulation results
- Keywords:
- cancelation ; impedance tuner ; phase shifter ; reflection coefficient ; transmission coefficient ; Bandwidth ; Electric network analysis ; Microwave circuits ; Phase shifters ; Printed circuit boards ; Reflection ; Timing circuits ; Attenuator ; Hybrid coupler ; Impedance tuners ; Transmission coefficients ; Electric connectors
- Source: IEEE Transactions on Microwave Theory and Techniques ; Volume 67, Issue 4 , 2019 , Pages 1402-1411 ; 00189480 (ISSN)
- URL: https://ieeexplore.ieee.org/document/8642516