A Hybrid Retrodirective Array Based on Delay-Locked Loop Hybrid Phase Conjugators
Type of DegreePhD Dissertation
Electrical and Computer Engineering
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This dissertation discusses the design, construction, and characterization of a new Hybrid Retrodirective Array (HRA) as a possible beamforming technology for 5G wireless communication networks. A Delay-Locked Loop based Hybrid Phase Conjugator (DLL-HPC) capable of functioning as both an actively controlled phase shifter and a closed-loop phase conjugator is presented as the basis for the new HRA. The HRA is shown to be capable of fast acquisition times, ideal transmit and receive beamforming, automatic mobile target tracking, direction of arrival reporting, and array-geometry independent operation. Test results show initial acquisition times up to 50x faster than current beamforming standards and the ability to automatically track mobile users with no communication overhead. This work describes in detail the operation of the HRA system with special attention given to the theory, construction, and testing of a full prototype. Additionally, a novel rollover phase-frequency detector (R-PFD) circuit is presented alongside transistor-level integrated circuit design and simulations as an enabling technology for future implementations of delay-locked loop (DLL) based beamformers. This dissertation serves as the first steps towards HRA-based network architectures through several novel contributions: a new hybrid phase conjugator circuit topology which improves settling time and backwards compatibility over existing hybrid retrodirective arrays and a new R-PFD circuit capable of enabling a new class of DLL-based beamformers.