Planar rectennas for wireless power harvesting

Capturing and harvesting RF energy, using small antennas with an effective conversion of RF energy to DC energy with minimal losses, presents a significant research problem. The project addresses the opportunity to harvest RF energy from dedicated or ambient sources using a rectenna. The overall objective of this project is to successfully design, create and implement and effective rectenna system for low-cost, low-power operation at the 2.45GHz ISM band, the aim is to manufacture a prototype of an optimal rectenna design that is effective. The prototype is used to demonstrate the operating principle of the rectenna, its effectiveness and real world performance. This thesis presents two rectenna systems designed to harvest RF energy. Rectenna system 1 comprises of sybsystem 1, a single microstrip patch antenna, while rectenna system 2 comprises of subsystem 3, a microstrip patch antenna array. Both rectenna systems utilise subsystem 2, the two stage Cockcroft Walton rectifier and multiplier circuit. The rectenna systems and their related subsystems achieved exceptional effectiveness and real world performance with the ability to harvest a significant amount of RF power at 2.45GHz. As a result, the operating principle of the rectenna systems, their effectiveness and real world performance are demonstrated, harvesting enough energy to operate a selection of typical electronic devices such as a 2.1v green LED, digital clock timer and digital humidity sensor, up to a range of 3.5 meters.