Optimal rectenna design for textile, flexible, and printed radio frequency energy harvesting

The growing energy demands of the Internet of Things (IoT) highlight the need forbattery-free methods to remotely power pervasive IoT devices. Emerging electronics fabrication techniques such as electronic textiles (e-textiles) and additive manufacturing canbe utilized to realize low-cost Radio Frequency (RF) components. Far-field propagationof radio waves enables the remote delivery of power using rectifying-antennas (rectennas).Rectennas emerged in the 1950s for drone-powering, and more recently for harvestingambient RF power and for wireless-powering IoT networks. Optimizing a rectenna is amulti-variate problem imposing constraints on the materials, fabrication process and sizeof the rectenna. This work investigates and optimizes different rectenna architecturesfor wearable and flexible electronics, achieving Power Conversion Efficiencies (PCEs)surpassing State-of-the-Art (SoA) rectennas of higher complexity.Rectennas are proposed based on 50 Ω matching networks and matching networkelimination, showing that material properties do not hinder high-PCE rectennas.Antenna-rectifier co-design is proposed as an antenna-based solution for simultaneous wireless information and power transfer (SWIPT), demonstrating high PCE anduncompromised off-body radiation properties. The scalability of low-cost textile-basedrectennas for millimeter-wave (mmWave) bands is then demonstrated through a novelbroadband microstrip antenna design and analytical analysis showing up to an orderof magnitude performance gains at mmWave bands compared to Ultra High Frequency(UHF) bands. The first implementation of a textile-based mmWave rectenna is presentedbased on a novel broadband antenna with high efficiency based on a compact radiator.At UHF, the proposed design methodologies are applied to two application-orientedimplementations. Firstly: an e-textile coplanar waveguide thin and flexible rectennaintegrated with a textile supercapacitor is presented, showing the highest reported endto-end efficiency; secondly: a compact rectenna is proposed for low-resolution printing,representing the first meshed co-designed rectenna and showing PCE-improvements overSoA while having the lowest complexity. It is concluded that rectennas can be demonstrated with SoA PCEs using low-cost materials and components, presenting RF energyharvesting as a highly-practical solution for powering future IoT