Achieving Spectrum Efficiency with Reconfigurable Antenna, Microwave Circuits and Backscattering Systems

The fast-growing demand for high-speed wireless communication in the modern wireless systems will increasingly require more efficient strategies for use of the available frequency spectrum, which is scarce and very costly. Full-duplex communications use the same frequency resources in a two-way communication thus improving the spectrum efficiency. Furthermore, back-scatter communications (BSCs) and reconfigurable subsystems are one of the most promising candidates for the next-generations of wireless networks and RF systems to enable spectrally efficient techniques to use available resources. In this thesis, novel pattern, polarization reconfigurable antennas and active BSC terminals to benefit in in-band wireless application and adaptable systems have been introduced. In addition, a novel technique to cancel self-interference signals has been developed for in-band full-duplex communication systems.