Investigation/design of scalable RF metaresonator for building material

Abstract

Globally, governments are building smarter, greener and more sustainable buildings with the help of technological innovations. Deploying embedded WSN in buildings is one of the promising technologies that enables such a vision. However, such sensors face challenges in sourcing long term power, and transmission of wireless signals in and out of building materials. One way to source power is from the ambient RF signals. To harvest such energy, RF energy harvesting antenna is an important component in embedded WSN systems. This antenna can also be responsible for wireless communications. In addition, building materials enclosing the embedded antenna also affects the transmission of RF power for harvesting and communications. In this thesis, a study on the concepts of metamaterial and electrically small antennas is performed to combine both concepts in the design of an electrically small antenna, and a scalable antenna array suitable for RF energy harvesting and wireless communications. Another aspect affecting RF energy harvesting and wireless communications indoors is also investigated in this thesis. Analysis into some commonly used admixtures to compare the effects on the embedded arrays and the resulting materials is done. Combining concepts from metamaterials and electrically small antenna, an electrically small metaresonator is designed. This antenna has a maximum dimension of one-tenth the wavelength of WiFi spectrum at channel 13. Using the stubbed design, the resonant frequency can be tuned to the required centre frequency at channel 7. The resulting antenna Abstract xviii has a S11 of −25 dB, gain of −16 dB and an efficiency of −9 dB, within expectations of an ESA. This electrically small metaresonator is then used as an array element to form into an array using DC combiner topology. Due to its geometry and combining the concepts of