A Highly Efficient Design of Triple-Band Flexible Rectenna for Ambient RF Energy Harvesting in Passive IoT Applications

This article proposes a highly efficient flexible rectenna for ambient radio-frequency (RF) energy harvesting, accomplished with the broadband omnidirectional receiving antenna and a novel design of triple-band rectifier with high power conversion efficiency (PCE). The rectenna has the efficient energy harvesting ability of multi-band and wide input power range (from -30 dBm to 0 dBm). At an input power of -20 dBm, the PCE achieves <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{3 2 \%, 2 5 \%}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{2 2. 5 \%}$</tex> at the communication frequency bands of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.8,2.1$</tex> and 2.45 GHz respectively. Compared to planar surface state, the PCE of the rectenna decreases no more than 5% at different bending state, proving the stability of its flexibility. Therefore, the proposed rectenna is expected to address the challenge of sustainable power supply, which has the potential to be applied to battery-free passive Internet of Things.