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Design and experimental validation of multi-section directional coupler with arbitrary coupling and high directivity
Shrawan K Patel1, Rusan Kumar Barik2, Niraj Kumar Dewangan3
1Department of Electronics and Communication Engineering, School of Engineering and Technology, GGV Bilaspur, Chhattisgarh, India.
Plos One
|May 8, 2026
Summary
This study introduces a novel, simple topology for an ultra-wideband directional coupler using microstrip line technology. The new design achieves improved coupling and directivity, enhancing microwave component performance for communication infrastructure.
Area of Science:
- Electrical Engineering
- Microwave Engineering
- Applied Physics
Background:
- Conventional multi-section directional couplers face limitations in achieving both ultra-wideband (UWB) performance and high coupling.
- Improving directivity and maintaining low insertion loss across a wide frequency range remains a challenge in UWB coupler design.
Purpose of the Study:
- To present a geometrically simple topology for an ultra-wideband (UWB) directional coupler with enhanced coupling and directivity.
- To validate the effectiveness of a novel short-ended coupled-line structure for UWB coupler fabrication.
- To demonstrate a microstrip line-based approach for scalable UWB coupler designs.
Main Methods:
- Utilized a short-ended coupled-line structure to create a tightly coupled, symmetric three-section directional coupler.
- Employed microstrip line technology for the fabrication of the proposed coupler design.
- Performed comprehensive analysis including calculation, simulation, and experimental measurement of the coupler's performance.
Main Results:
- The proposed three-section directional coupler achieved ultra-wideband (UWB) response from 0.75 GHz to 3.75 GHz (5:1 bandwidth).
- Demonstrated superior performance with coupling of 8.3 ± 1.4 dB, return loss > 16 dB, isolation > 20 dB, and directivity > 30 dB.
- Achieved approximately 1.2 dB improvement in coupling compared to conventional designs, with bandwidths up to 133%.
Conclusions:
- The presented geometrically simple topology offers a viable solution for developing high-performance ultra-wideband (UWB) directional couplers.
- The short-ended coupled-line structure and microstrip implementation enable improved coupling, directivity, and bandwidth.
- This advancement supports the development of efficient and reliable communication infrastructure, aligning with SDG 9.
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