Superdirectivity and the Application of Complementary Split Ring Resonators in Directivity Enhancement of Millimeter-Wave Antennas

The use of millimeter wave frequencies is extending to a variety of applications with the development of 5G/6G networks. Due to the small physical size in addition to atmospheric absorption and material losses, millimeter wave antennas suffer from low radiation performance. Motivated by this limitation, this work investigates superdirectivity for millimeter wave antenna designs. Superdirectivity happens when a radiating body exceeds its maximum theoretical directivity limit. Based on a comprehensive literature review, a recent redirection away from reactive loading and towards geometric optimization of array elements is noticed. However, directivity bandwidth is rarely addressed in modern work. Accordingly, the main aim of this thesis is creating dynamic designs that are easily tuned to different radiation and bandwidth requirements. Initially, a superdirective antenna is developed using a new approach. Complementary split ring resonators are used to enhance directivity and manipulate the complex current distribution over a printed dipole. Systemic design approaches are presented using characteristic mode analysis, small dipole modeling, and transmission line theory for a time efficient design process. Additionally, to overcome matching the high input impedance and improve the directivity bandwidth, a Yagi-like array implementation is developed and verified experimentally. To introduce more degrees of freedom to the design, Low Temperature Co-fired Ceramic technology is used to design a multilayer wideband high gain antenna based on a single fed vertical stack of open ended stubs. Design flexibility is demonstrated through reshaping the radiators for circular polarization or adding more layers for directivity enhancement without changing the total aperture or the feeding setup. Finally, CSRRs are applied to the wideband multilayer antenna for directivity enhancement and are shown to improve directivity with significant reduction in overall antenna thickness. The work presented in this thesis advances superdirective antenna design by refining the single element through multiple fabrication technologies. Additionally, the dynamic geometrical structures accompanied by tunable models enables design flexibility and help overcome bandwidth and radiations limits.

Department dc:contributor.department

Electrical and Computer Engineering

Year dc:date.issued

2026

Author dc:creator

• Sary, Monica Wasfy William

Advisors dc:contributor.supervisor

• Antar, Yahia
• Freundorfer, Alois

• Antenna
• Superdirective
• Complementry Split Ring Resonators
• CSRR
• Millimeter Wave
• Characteristic modes analysis
• Transmission line theory
• Low Temperature Cofired Ceramics
• LTCC
• Small Antenna
• Dipole
• Multilayer Antenna
• Circuit Modeling
• Harrington Limit
• Theoretical Directivity Limit
• Small Dipole modeling

Statement dc:rights

• Attribution-NonCommercial-NoDerivatives 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/36006

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/36006