Electronic Theses and Dissertations

Date of Award

1-1-2025

Document Type

Dissertation

Degree Name

Ph.D. in Engineering Science

First Advisor

Winn Elliott Hutchcraft

Second Advisor

Richard K. Gordon

Third Advisor

Byron Villacorta

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

Additive manufacturing, commonly known as 3D printing, is revolutionizing radio frequency engineering. Along with rapid prototyping and fabricating complex structures, it enables varying substrate thickness and dielectric properties, which are highly beneficial for radio frequency research. However, despite its growing popularity, there’s a gap in understanding how 3D printing process parameters affect the electrical properties of the 3D printed structure. In radio frequency design, where device performance and characteristics heavily depend on electrical parameters such as relative permittivity, this hinders the consistency, repeatability, and reliability of 3D printed radio frequency devices.

This research addressed this gap by investigating the relationship between relative permittivity, an electrical property, and infill density, a key 3D printing process parameter. It further explored the relationship in various infill patterns and examined the effect of solid layers on the relative permittivity of 3D printed substrates. The relationship was investigated in 3D printed dielectric slabs utilizing both simulation and experimental methodologies.

The findings indicate that the relationship is linear for the infill layers, however, the solid layers impact the linear relationship. Based on this, two separate equations were developed to calculate the effective relative permittivity for 3D printed substrates without and with solid layers. The linear relationship was validated for the various infill patterns, and the significance of this relationship is demonstrated through 3D printed patch antennas with varying infill densities, reinforcing infill density as a crucial design parameter.

A valuable application of this research is presented by fabricating a cloaked antenna. This novel antenna required dielectric slabs with specific permittivity values that were unavailable in commercial filaments. The development of such an antenna was only possible by leveraging the established relationship between relative permittivity and infill density.

The knowledge of this relationship enables the development of novel substrates with tailored electrical properties by adjusting the infill density. Additionally, it allows obtaining a range of permittivity values from a single filament material. These advancements are crucial in radio frequency design, expanding the applicability of additive manufacturing for fabricating novel radio frequency devices.

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