High-efficiency Waveguide Tunable Leaky-wave Antennas and Phase-shifters

In this thesis, we discuss several ways that one can increase the radiation efficiency of leaky-wave beam-steerable antennas. In this effort, both frequency and fixed frequency scanned leaky-wave antennas are considered. Specifically, we discuss the design and implementation of a slow-wave frequency-scanned leaky-wave antenna that can achieve a high radiation efficiency with a split-block structure. The concentration of the current distribution in the middle of the waveguide due to the proposed design results in reducing the Ohmic loss in the gap of the split-block antenna and maximizing its efficiency. The antenna has a much smaller width compared to its serpentine waveguide counterparts which makes it possible to place several of them side-by-side to narrow the beam or perform beam-steering in the non-scanning plane. We also study the design and implementation of a slotted waveguide with impedance walls as a fixed-frequency beam-steerable leaky-wave antenna. This antenna can be used when a high radiation efficiency is required for fixed-frequency beam steering at relatively high frequencies where the quality factor of electrical tunable elements decreases considerably. In the designed antenna, the power loss in the varactors on the tunable impedance walls is the least compared to the other loss mechanisms. This is because of locating the varactors where the electric field strength is reduced in the reconfigurable waveguide. Using the designed impedance surfaces with reduced power dissipation in varactors, we introduce a new tunable phase shifter based on surface waves with high efficiency. The proposed phase shifter can be used for the implementation of phased arrays with low loss at high frequencies. The design of the proposed phase-shifter is based on maximizing its figure-of-merit (FOM) for achieving 360\textsuperscript{o} of phase shift.

Department dc:contributor.department

Electrical and Computer Engineering

Year dc:date.issued

2022

Author dc:creator

• Ohadi, Amirmasoud

Advisor dc:contributor.advisor

• Eleftheriades, George V

• Antennas
• Leaky-waves
• Metasurfaces

Handle dc:identifier.uri

http://hdl.handle.net/1807/125279

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/125279