RF Energy Harvesting System Based on an Archimedean Spiral Antenna for Low-Power Sensor Applications

Abstract

This paper presents a radiofrequency (RF) energy harvesting system based on an ultrawideband Archimedean spiral antenna and a half-wave Cockcroft-Walton multiplier circuit. The antenna was proved to operate from 350 MHz to 16 GHz with an outstanding performance. With its use, radio spectrum measurements were carried out at the Telecommunication Engineering School (Universidad Politécnica de Madrid) to determine the power level of the ambient signals in two different scenarios: indoors and outdoors. Based on these measurements, a Cockcroft-Walton multiplier and a lumped element matching network are designed to operate at 800 MHz and 900 MHz frequency bands. To correct the frequency displacement in the circuit, a circuit model is presented that takes into account the different parasitic elements of the components and the PCB. With an input power of 0 dBm, the manufactured circuit shows a rectifying efficiency of 30%. Finally, a test is carried out with the full RF energy harvesting system to check its correct operation. Thus, the RF system is placed in front of a transmitting Vivaldi antenna at a distance of 50 cm. The storage capacitor has a charge of over 1.25 V, which is enough to run a temperature sensor placed as the load to be supplied. This demonstrates the validity of the RF energy harvesting system for low-power practical applications.

Ultrawideband inkjet‐printed monopole antennas for energy harvesting application

“…Nowadays, the most relevant power contributions in the radio spectrum can be found from 0.8 to 5 GHz 26 . In particular, it was pointed out in Reference 27 that more than an 80% of the harvested power had its origin in the mobile bands of 0.8 and 0.9 GHz. Additionally, part of the 5G mobile communications will occupy the frequency bands of 0.6 and 0.7 GHz in the near future 28 .…”

Parasitics Impact on the Performance of Rectifier Circuits in Sensing RF Energy Harvesting

“…The most significant power contribution normally comes from mobile network (0.8, 0.9, 1.8, and 2.1 GHz) and WiFi frequency bands (2.4 and 5.2 GHz). Specifically, previous works have demonstrated that most part of the incoming RF power has its origin in mobile bands [3,4,5]. Concretely, Ref.…”

“…Concretely, Ref. [5] points out that more than an 80% of the power harvested is located in 0.8 and 0.9 GHz frequency bands.…”

“…The low input power level provokes the diodes into dissipating an important part of the incoming power. Specifically, RF harvesting systems must operate with lower power densities [3,4,5] compared to other harvestable sources, such as the sun, wind or vibrations [11]. Moreover, the nonlinearity associated with the diodes represents an added difficulty [12]: the performance of the entire system is dependent, among other parameters, on the input power, which unfortunately hampers the design of the matching circuit.…”

“…However, the steps followed in the document can be extrapolated, without loss of generality, to any other configuration. According to the estimations of the incoming power provided in [3,4,5], the circuits are designed to operate within 800–900 frequency bands, the center frequency being 870 MHz. Several combinations of components were tested in both circuits.…”