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Access Type
WSU Access
Date of Award
January 2023
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Electrical and Computer Engineering
First Advisor
Dimitrios Sounas
Abstract
Communication systems play pivotal role in the state-of-the-art technologies. There are two prevalent communication systems, which are half duplex and full duplex. In full duplex communication systems both receiving and transmitting modules work simultaneously, while in half duplex systems they work one by one. Here we focus on full duplex communication systems. One of the key components in full duplex systems is circulator, which is a nonreciprocal microwave component. There are some attempts in the literature to realize circulator, but most of them were based on magnetic biasing of circulators by using ferrite as the magnetic material. These types of circulators are bulky, expensive, non-integrable with other microwave components in transceiver chain. Hence, STM gyrator, which is a fundamental nonreciprocal component, based on Wheatstone bridges of varactors is presented in this dissertation to deal with these hurdles. We present an implementation of the proposed approach based on a double-balanced circuit with Wheatstone bridges of varactors, which provides large isolation between the input signal and the sidebands. Weprovide a theoretical and an experimental analysis of the circuit with excellent agreement to each other. In addition to introducing a topology of STM gyrators with improved bandwidth compared with existing designs, our results highlight a potential connection between the bandwidth of STM devices and their harmonic order, which might also find applications in other STM systems, like isolators, circulators, and photonic topological insulators.
Moreover, the other part of the dissertation is dedicated to microwave topological insulator, which plays important role in recent academic research for its unique features, including bandgaps in the dispersion diagram, and robust edge mode propagation, which are immune to discontinuities. In this dissertation, a microwave topological insulator based on a dual lattice of differential transmission lines is presented. The operation principle of the proposed unit cell along with the related theoretical and simulation results for infinite and truncated lattice are presented to verify that the structure has topological property. It is worth mentioning that the proposed microwave topological insulator has potential applications in various microwave components as well as phased array antennas and leaky wave antennas.
Recommended Citation
Keshavarz, Saeed, "Time-Modulated And Topological Microwave Components For Wireless Communication Systems" (2023). Wayne State University Dissertations. 3952.
https://digitalcommons.wayne.edu/oa_dissertations/3952