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Sensors 2012, 12(10), 13636-13663; doi:10.3390/s121013636
Article

Optimization of Passive Low Power Wireless Electromagnetic Energy Harvesters

* ,
 and
Department of Microsystems Engineering, Laboratory for Electrical Instrumentation, University of Freiburg, IMTEK, Georges-Köhler-Allee 106, 79110 Freiburg, Germany
* Author to whom correspondence should be addressed.
Received: 13 August 2012 / Revised: 28 September 2012 / Accepted: 28 September 2012 / Published: 11 October 2012
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany 2012)

Abstract

This work presents the optimization of antenna captured low power radio frequency (RF) to direct current (DC) power converters using Schottky diodes for powering remote wireless sensors. Linearized models using scattering parameters show that an antenna and a matched diode rectifier can be described as a form of coupled resonator with different individual resonator properties. The analytical models show that the maximum voltage gain of the coupled resonators is mainly related to the antenna, diode and load (remote sensor) resistances at matched conditions or resonance. The analytical models were verified with experimental results. Different passive wireless RF power harvesters offering high selectivity, broadband response and high voltage sensitivity are presented. Measured results show that with an optimal resistance of antenna and diode, it is possible to achieve high RF to DC voltage sensitivity of 0.5 V and efficiency of 20% at −30 dBm antenna input power. Additionally, a wireless harvester (rectenna) is built and tested for receiving range performance.
Keywords: RF energy harvesting; wireless power transmission; coupled resonators; Schottky diode; RF to DC power converter; impedance matching; PI-matching; L-matching; rectenna RF energy harvesting; wireless power transmission; coupled resonators; Schottky diode; RF to DC power converter; impedance matching; PI-matching; L-matching; rectenna
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.

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MDPI and ACS Style

Nimo, A.; Grgić, D.; Reindl, L.M. Optimization of Passive Low Power Wireless Electromagnetic Energy Harvesters. Sensors 2012, 12, 13636-13663.

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