A Flexible 2.45-GHz Power Harvesting Wristband With Net System Output From-24.3 dBm of RF Power

作者：Adami Salah Eddine^*; Proynov Plamen; Hilton Geoffrey S; Yang Guang; Zhang Chunhong; Zhu Dibin; Li Yi; Beeby Steve P; Craddock Ian J; Stark Bernard H

来源：IEEE Transactions on Microwave Theory and Techniques, 2018, 66(1): 380-395.

DOI：10.1109/TMTT.2017.2700299

• Boost converter
• fabric antenna
• fabric-to-PCB connector
• Internet of Things
• power management
• rectenna array
• rectenna impedance matching
• rectennas
• RF energy harvesting
• RF power transfer
• smart fabric
• T-resonator method
• textile antenna
• two-line method

This paper presents a flexible 2.45-GHz wireless power harvesting wristband that generates a net dc output from a -24.3-dBm RF input. This is the lowest reported system sensitivity for systems comprising a rectenna and impedance-matching power management. A complete system has been implemented comprising: a fabric antenna, a rectifier on rigid substrate, a contactless electrical connection between rigid and flexible subsystems, and power electronics impedance matching. Various fabric and flexible materials are electrically characterized at 2.45 GHz using the two-line and the T-resonator methods. Selected materials are used to design an all-textile antenna, which demonstrates a radiation efficiency above 62% on a phantom irrespective of location, and a stable radiation pattern. The rectifier, designed on a rigid substrate, shows a best-in-class efficiency of 33.6% at -20 dBm. A reliable, efficient, and wideband contactless connection between the fabric antenna and the rectifier is created using broadside-coupled microstrip lines, with an insertion loss below 1 dB from 1.8 to over 10 GHz. A self-powered boost converter with a quiescent current of 150 nA matches the rectenna output with a matching efficiency above 95%. The maximum end-to-end efficiency is 28.7% at -7 dBm. The wristband harvester demonstrates net positive energy harvesting from -24.3 dBm, a 7.3-dB improvement on the state of the art.

• 出版日期2018-1