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Electronics 2018, 7(2), 25;

Design of a Low-Cost Microstrip Directional Coupler with High Coupling for a Motion Detection Sensor

R&D Labs, CIAS Elettronica, 20158 Milano, Italy
Dipartimento di Ingegneria Elettrica ed Elettronica, Università degli Studi di Cagliari, 09123 Cagliari, Italy
EMC Research and Measurement Center of Navy, Shanghai 200235, China
Author to whom correspondence should be addressed.
Received: 2 January 2018 / Revised: 21 February 2018 / Accepted: 22 February 2018 / Published: 24 February 2018
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A coupled-line coupler based on the asymmetric cascade connection of two coupled line sections is used to achieve a high coupling factor using low-cost material and technology in the X frequency band, and its performance is compared with a standard quarter-wave, coupled-line coupler, showing an increase in the coupling factor of about 3 dB. The proposed coupler can be effectively used in a Doppler motion detection sensor, due to its strong coupling and relatively high isolation. The coupler is designed through a simple, yet rigorous, equivalent circuital model. Then, an optimization procedure was performed using the commercial software Ansys HFSS in order to compensate for losses and second order effects. A prototype of the designed coupler was realized, and the measured data show very good agreement with simulations. View Full-Text
Keywords: coupled lines; directional coupler; motion detection systems coupled lines; directional coupler; motion detection systems

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Sanna, G.; Montisci, G.; Jin, Z.; Fanti, A.; Casula, G.A. Design of a Low-Cost Microstrip Directional Coupler with High Coupling for a Motion Detection Sensor. Electronics 2018, 7, 25.

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