A Flexible 2.45-GHz Power Harvesting Wristband With Net System Output From −24.3 dBm of RF Power

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Abstract-This paper presents a flexible 2.45-GHz wireless power harvesting wristband that generates a net dc output from a −24.3-dBm RF input. This is the lowest reported system sensitivity for systems comprising a rectenna and impedancematching power management. A complete system has been implemented comprising: a fabric antenna, a rectifier on rigid substrate, a contactless electrical connection between rigid and flexible subsystems, and power electronics impedance matching. Various fabric and flexible materials are electrically characterized at 2.45 GHz using the two-line and the T-resonator methods. Selected materials are used to design an all-textile antenna, which demonstrates a radiation efficiency above 62% on a phantom irrespective of location, and a stable radiation pattern. The rectifier, designed on a rigid substrate, shows a best-inclass efficiency of 33.6% at −20 dBm. A reliable, efficient, and wideband contactless connection between the fabric antenna and the rectifier is created using broadside-coupled microstrip lines, with an insertion loss below 1 dB from 1.8 to over 10 GHz. A self-powered boost converter with a quiescent current of 150 nA matches the rectenna output with a matching efficiency above 95%. The maximum end-to-end efficiency is 28.7% at −7 dBm. The wristband harvester demonstrates net positive energy harvesting from −24.3 dBm, a 7.3-dB improvement on the state of the art.

Microwave antennas—An intrinsic part of RF energy harvesting systems: A contingent study about its design methodologies and state‐of‐art technologies in current scenario

“…Prior to it, complete illustration about the microwave antennas in RF energy harvesting are presented with complete design perspective. A comparative study along with performatory analysis of microwave antennas are presented in Table ; keeping intact with rectenna characteristics: operating frequency, realized gain, polarization diversity, input power levels, and RF‐to‐DC power conversion efficiency, which was not in the scope of review papers for RF energy harvesting available in the open literature. Technically, to pursue clear understanding about tradeoffs of modern RF systems; five different cases of planar antennas (monopole antennas) at different bands with reflector surfaces and integrated with rectifier circuits are designed, simulated and analyzed by using FDTD domain solver (CST microwave studio) and circuit solver (advanced design system).…”

“…The relevant theories of basic forms of antennas are available in open literature . It is further classified into high performance antennas, metamaterial antennas, CP antennas, reconfigurable antennas, and array antennas . It is a strong belief that prerequisites need to be cleared before using the implicit technique in proposed antenna models.…”

“…[107][108][109] The relevant theories of basic forms of antennas are available in open literature. 36,65,70,75,80,85,91,96,101,104,107 It is further classified into high performance antennas, [110][111][112][113]159 metamaterial antennas, [114][115][116][117][160][161][162] CP antennas, [118][119][120][121][122][123][124][125][126][127][164][165][166][167][168][169][170][171][172][173][174][175][176][177] reconfigurable antennas,…”

A CMOS RF-to-DC Power Converter With 86% Efficiency and −19.2-dBm Sensitivity

“…Nowadays, ambient WPT is becoming a key enabler for a variety of applications, including biomedical and healthcare devices [6]- [12], RFIDs [13], and remote sensors [14]- [17]. Depending on the application, frequencies ranging from the low megahertz range [6], [7], [18] to the UHF bands [13] are used.…”

Radiation pattern of reconfigurable antenna design for portable device applications

“…Rectangle antenna with Return loss -7dB, Insertion loss 0.7dB, Gain 8.1dBi and 850MHz Bandwidth is reported in ref. (Adami et al, 2018). Pentagon Antenna for frequency reconfiguration is used here.…”