Design and integration techniques for compact, wideband and multi-functional baluns

The prevalence of RF components in 5G communications and the ‘Internet of Things’ (IoT), has resulted in the integration of electronic devices into all facets of life. This has driven the need for RF components with smaller footprints, lower power consumption and less loss, while being more versatile across the ever-more crowded frequency spectrum. RF baluns, being a key front-end passive component in RF communications must meet these requirements, while effectively providing an impedance transformation and converting balanced-to-unbalanced RF signals. However, current balun technologies are typically large in size, lossy, or narrowband, calling for the development new design techniques and integration methods that will overcome these modern challenges. On the basis of the aforementioned limitations, this dissertation investigates RF and EM design methodologies for the realization of broadside-coupled line baluns with highly-miniaturized footprint, ultra-wide bandwidth (BW), and the added RF capability of bandpass filtering. Furthermore, the thesis outlines the performance capabilities and limitations of commercially available streamlined multilayer PCB processes and emerging additive manufacturing technologies using inkjet printing. Specifically, this thesis lays the foundations for; i) maximizing the fractional bandwidth (FBW) of Marchand baluns (MBs) and capacitively-loaded variants, dependant on process constraints, using broadside coupled transmission lines and perforated ground planes, ii) enhanced footprint miniaturization using self-packaged integration concepts enabled by freeform inkjet printing, and iii) RF co-designed bandpass filtering, by utilising the resonant behaviour of the coupled-line sections and exploiting the inkjet printing process to tailor their coupling levels. Experimentally validated results that are presented in this work demonstrate i) FBWs up to 122%, larger than what is achievable with the most common balun implementations, ii) footprints below 0.005 λg2 , which are competitive with state-ofthe-art miniaturised balun designs, and iii) 3rd-order compact RF co-designed filtering baluns, with FBWs from 30-110%, and footprints at least 6x smaller than what is currently presented in the literature.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2024

Author dc:creator

• Steele, Joe

Advisor dc:contributor.advisor

• Psychogiou, Dimitra

• Additive manufacturing
• Baluns
• Low-footprint integration
• RF Co-design
• Wideband communications

Statement dc:rights

• © 2024, Joseph Steele.

Licence dc:rights.uri

• https://creativecommons.org/publicdomain/zero/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/18386

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/18386