UCLA

Recent research advances based on periodic structures and antenna array systems are presented. In the first part of the dissertation, state-of-the-art retrodirective array (RDA) capable of retransmitting predictable polarization with respect to any received polarization state is proposed. RDAs have the unique ability to retransmit the received signal back to the interrogator without prior knowledge of the source location. In addition to this unique feature, the proposed system can receive any polarization and always backscatter the signal that is orthogonally polarized with respect to its received polarization state. This added feature helps to maintain a more secure communication link between the RDA and the interrogator by mitigating the polarization mismatch loss. The second half of the dissertation is dedicated to frequency scanning phased-array feed network and frequency selective surface (FSS) spatial filters based on metamaterial concept. Composite Right/Left-Hand (CRLH) metamaterial transmission lines provide not only phase delay but also phase advance response that can be systematically engineered. This allows the design of an all-passive phased-array feeding network that supports dual-band and broadband frequency scanning capability over wide spatial angle. In addition, decoupling the radiating antenna elements from the array factor enables better controllability of the radiated characteristics in comparison to the widely known CRLH based leaky-wave antennas. Conventional periodic structures based on purely right-handed unit structures also exhibit metamaterial behaviors when the periodicities are much smaller than the operating wavelength. Incorporating this concept and the coupled filter theory, high performance multi-pole FSS is designed that is less sensitive to incident angles, polarizations, and separation distances between the FSS layers.