**4. Conclusion**

A novel approach for RF energy harvesting is presented in this chapter. Unlike previous works, we exploit spectrum sensing as a pre-processing procedure to find the frequency in which the maximum power more than a predefined threshold exists. After that, using a filter, this signal with maximum power is fed to a charger circuit. In simulation, a DC output voltage of 8.8 V is obtained using input RF power of 0 dbm. In practice and as our experimental results, our fabricated charger circuit test led to 450*μ* W output power for battery charging.

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**Author details**

Naser Ahmadi Moghaddam1

provided the original work is properly cited.

1 Tarbiat Modares University, Tehran, Iran

2 K.N. Toosi University of Technology, Tehran, Iran

\*Address all correspondence to: n.moghaddam1990@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\* and Alireza Maleki2

*RF Energy Harvesting System and Circuits for Charging of Wireless Devices Using Spectrum…*

*DOI: http://dx.doi.org/10.5772/intechopen.84526*

*RF Energy Harvesting System and Circuits for Charging of Wireless Devices Using Spectrum… DOI: http://dx.doi.org/10.5772/intechopen.84526*
