Investigation of antennas with non-reciprocal radiation characteristics

Antennas are essential in all wireless systems, serving as the link between a guided signal and free space. Since their invention in the late 1880s, antennas have been designed almost exclusively as reciprocal devices. This assumption of reciprocity allows us to design an antenna from a transmit perspective and have confidence that it will work just as well as a receiver. However, as wireless systems become more advanced, the routine assumption of reciprocity denies us of a useful degree of freedom. This work explores a new paradigm in antenna engineering by investigating antennas deliberately designed to display non-reciprocal behavior. Specifically, unidirectional true-time delays are explored as a means to achieve non-reciprocal radiation. The result is a wideband and low-loss method to induce non-reciprocity into an antenna system, supported by several design-focused models and experimental results. Additionally, an excitation-dependent electromagnetic modal analysis technique is developed. This analytical method builds on previous work to mathematically separate the surface currents responsible for radiation and energy storage. This methodology is validated by analyzing the modal results of simple wire antennas and connecting the results back to known behavior. More complex geometries, such as planar single-element antennas and small arrays, are also discussed. This modal analysis work supports the overarching goal of developing non-reciprocal antenna systems because of its excitation-dependent formulation, which makes it uniquely appropriate for systems that exhibit distinct transmit and receive behavior.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Cain, Sasha Seneca Yamada

Contributors dc:contributor

• Bernhard, Jennifer T
• Ilie, Raluca
• Schutt-Ainé, Jose
• Zhao, Yang

• antennas
• electromagnetics
• non-reciprocal antennas
• modal analysis

Statement dc:rights

• Copyright 2025 Sasha Seneca Yamada Cain

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129690

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129690