Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

Committee Chair

Maria Pour

Committee Member

David Pan

Committee Member

Tony Gatlin

Committee Member

Sarma Rani

Committee Member

Patrick Reardon


Energy harvesting, Antennas (Electronics)--Design and construction


Harvesting energy from ambient sources allows sensors and systems to become self-reliable and not depend on small batteries or energy sources, which is of paramount importance in space applications. In recent decades, multi-band or wideband energy harvesters have attracted much attention. The main challenge to design such energy harvesters is that they need to efficiently scavenge the electromagnetic waves at multiple bands and deliver the received multi-frequency signals to the rectifier that has a frequency dependent impedance. In this dissertation, a compact dual-band harvesting sensor is developed for space applications at the RF (900 MHz) and the ISM (2400 MHz) frequencies. To design the receiving antenna and tune it to the desired frequency bands, the constitutive parameters of the material, on which the antenna is printed, play a critical role. To this end, a composite non-magnetic material developed by NASA, initially used for the antenna design, is characterized. In particular, the dielectric constant and loss tangent of the materials are determined by employing the composite material as a superstrate on a pre-characterized benchmark antenna. Then, compact dual-band RF energy harvesters, printed on low loss materials, are designed with improved gain and front-to-back ratios at both the RF and the ISM bands. The drawbacks of antenna miniaturization are addressed through the use of quarter-wave choke slots in the ground plane. Additionally, a dual-band impedance matching network with acceptable bandwidth at both frequency bands is developed to reduce the reflection losses between the antenna and the rectifier. To conclude the dissertation, metamaterial unit cells are employed to improve the radiation characteristics of a wideband bowtie antenna. In particular, a wideband split ring resonator (SRR) with negative permeability whose refractive index is lower than the supporting substrate is presented. This will in turn help congregate the radiation and improve the peak gain of the antenna. Finally, the potential of the SRR structure is further investigated to reconfigure the radiation pattern of the designed bowtie antenna.



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