Considerations for the Design and Implementation of Ambient RF Signal Rectifiers in the 2.45 GHz WiFi Band

Abstract

Ambient RF energy harvesting (RF-EH) is a particular case of wireless power transfer (WPT), which is characterized by ultra-low power operation. This work points out theoretical and practical aspects that should be considered in the design of RF rectifiers for ambient RF energy harvesting systems. The most common RF rectifier circuits are compared and discussed using simulations and experimental data. The efficiency is analyzed in terms of the input power and load resistance. It is demonstrated that the most efficient RF rectifier in ultra-low power conditions is the simple diode capacitor structure. As an illustrative example, an RF rectifier has been fabricated by designing an impedance-matching network to operate into the WIFI band. The fabricated prototype shows a measured 12% efficiency working at 2.47 GHz with around −30 dBm ambient input power, which is higher than the reported efficiencies in the literature. The fabricated energy harvesting system delivers power between 25.6 nW and 129.6 nW to a resistive load. The obtained results are applicable to ambient RF up to 6 GHz.

Energy Harvesting Fractal Antenna for Charging Low Power Devices

“…The RF-EH relies on the scavenging of RF signals in the vicinity of the system; there are two types of RF signal sources: ambient and specialized [7].…”

“…In this paper, a new distinct shape for the energy harvesting antenna is presented by relying on cutting-edge design methodologies to absorb the highest energy from many frequencies simultaneously using the fractal antenna, where can significantly enhance antenna array performance using fractal geometric methodologies. The usage of an array fractal antenna (FA) enhances multi-beam and multi-band features and enhances the behaviour of the array factor, but one of the research challenges of FA's is among huge antenna elements at higher level frequencies, such as four to N iterations [7]. The rest of this research is organized as follows: Section 2 presents the related works.…”

A 915 MHz Closed-Loop Self-Regulated RF Energy Harvesting System for Batteryless Devices

“…The differences between them are related to the levels of derivation to reduce parasitic effects and the resulting power conversion efficiency. In [9], a comparison is made between these topologies operating at 2.4 GHz, taking into account features that limit efficiency.…”