Additive manufacturing of graded dielectrics

Roper, David A., Jr.
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University of Delaware
The ability to fabricate electromagnetic (EM) materials with graded dielectric properties would benefit a variety of interesting applications, such as low profile antennas, antireflective surfaces, passive beam formers (e.g. Luneburg lenses), graded index lenses, and structural and armored radomes. Recently there has been a surge in commercial 3D free-forming printing technologies. These systems employs additive manufacturing methods to create complicated 3D structures using a host of different techniques, including stereo lithography (SLA), fused deposition modeling (FDM) and selective laser sintering (SLS). While popular for a wide range of applications, commercial 3D printers use a limited library of materials that make them unsuitable for many EM applications including the fabrication of graded dielectrics. In this thesis, I present a custom developed printer that is designed specifically for realizing materials with integrated three dimensionally varying dielectric properties is described. This system utilizes an ultrasonic dry powder deposition head to pattern high dielectric powders onto a low loss dielectric substrate. After stacking and processing, the result is a mechanically rigid composite plate with an embedded 3D variation in dielectric properties. Specifically, I will present detailed methods for fabricating (i.e. system design), calibrating and characterizing composite panels with graded dielectric properties. I will also present several practical applications of this new methodology.