Date of Award
Doctor of Philosophy (PhD)
Electrical, Computer & Energy Engineering
Dejan S. Filipovic
This thesis focuses on a design methodology for low-power non-directional far-field wireless powering. The power receiver consists of one or more antennae which receive plane waves transmitted by the powering source, and deliver the RF power to a rectifying element. The resulting DC power is optimally transferred to the electronic application via a power management circuit. The powering is independent of the electronic application which can include wireless transmission of sensor data.
The design and implementation of an integrated rectifier-antenna at low incident power densities (from 25-200μW/cm2) is presented. Nonlinear source-pull measurements and harmonic balance simulations are used for finding the optimal rectifying device RF and DC impedances for efficient rectification. Experimental results show that an antenna design with a specific complex impedance reaches the highest rectification efficiency. Several examples of the design methodology are shown. In specific, characterization of a linearly polarized rectifying patch antenna at frequency of 1.96 GHz is detailed, with an optimal RF impedance of 137+j149Ω and an optimal DC load of 365Ω resulting in RF to DC conversion efficiency of 63% (simulated) for the rectifier alone and 54% (measured) for the total rectifying antenna. A compact design (eliminating SMA connector) of a dual-polarized rectifier antenna integrated with two rectifiers, one for each polarization is detailed. The complications and issues of combining the powers from the two polarizations are addressed. A analysis of required RF and DC isolation in multiple-rectifier integrated rectifier-antenna is developed and confirmed. Measurement results of a 2.45 GHz integrated rectifier antenna show conversion efficiency of 56% and very small dependance on rotation angle between powering polarization and receiving rectifier antenna (ratio of maximum to minimum power as the antenna is rotated of 1.09).
Falkenstein, Erez Avigdor, "Characterization and Design of a Low-Power Wireless Power Delivery System" (2011). Electrical, Computer & Energy Engineering Graduate Theses & Dissertations. 93.