This dissertation gives guidelines for state-of-the-art power harvesters and for optimizing its components, e.g., rectifier, matching network, and antenna, in various applications. A single diode rectifier using a quarter-wave matching circuit with a measured efficiency of 73.7% is also presented. Several experimental demonstrations are included for powering a number of sensors and devices, such as a clock, computer mouse, calculator, thermometer, medical insulin pump, and super capacitor with power management circuitry.
To increase the amount of RF harvested power, an array of rectifying antennas (rectennas) is presented and used in experiments up to 60 meters. Wireless power transfer demonstrations at near field distances are also presented. For the latter, we show a strong tolerance to misalignment while delivering high levels of power (1.2 mW over 42 cm). As an application, a medical pump is successfully powered over this distance. Further, bandwidth widening techniques are presented along with rectifier optimizations.
To reduce the overall dimensions of the rectenna, miniaturization techniques are discussed. This leads to a rectenna size of 1.5 x 2.5 cm^2, making it ideal for medical or on-body applications. This rectenna was used to successfully activate a body-worn thermometer across 65 cm. In the case of implantable devices, a dielectric matching layer was found useful and validated using pig skin. A related SAR analysis ensured the safety of the proposed RF powering harvesting techniques.