Additive Manufacturing and Electroless Metallization of a 4X4 V-Band Contorted Waveguide Butler Matrix
Abstract
This dissertation presents an investigation of high-performance antennas and beamforming networks with complex geometric features that are uniquely enabled by distinct design spaces created from the intersection of microfluidics, applied electromagnetics, and additive manufacturing. Each design space is explored by a demonstration vehicle that can be used to test key concepts relevant to the types of structures and challenges to current fabrication techniques they are targeted to address. The first demonstration vehicle involves the development of structurally embedded vascular antennas to provide reconfigurable electromagnetic antenna properties in multilayer and complex curved surfaces. The second investigates the development of compact multi-port contorted waveguide networks that provide signal routing and a discrete Fourier transform of the signal for beam switching applications. Each vehicle provides a distinct pathway that leverage design for additive manufacturing whose goal is to develop new high frequency components and devices.
Structurally embedded vascular antennas are functionalized by embedding sacrificial materials into the layup of a structural composite and formed using a mandrel to set the desired geometric structure. After the composite has been cured microvascular structures with desired geometric patterns are embedded between composite lay-ups. Controlled transport of liquid metal through these embedded capillaries enables functionalization of the additively manufactured structure into an antenna or antenna array reconfigurable over a wide range. Two distinct structures have been pursued as a demonstration vehicle to leverage these concepts. These are, a multilayer structure with distinct geometrical patterns positioned in separate layers and a complexly curved composite shaped to resemble the leading edge of an Unmanned Aerial Vehicle. Advances in additive manufacturing and microfluidics enable the design and electromagnetic functionalization of these structures, which is otherwise difficult to accomplish using conventional fabrication techniques.
The “contorted waveguide” topologies are electromagnetically functionalized through a pressure-driven electroless metallization process that deploys fluid-flow through the structure as a means of chemically depositing the conductive layer required to support low-loss wave propagation and guidance. The resulting workflow developed for these components provide a novel low-cost and low-waste-generating process for realizing millimeter-wave volumetric structures that would be challenging if not impossible to fabricate through conventional techniques. The design, fabrication, and experiment of a four-input and four-output beamforming network referred to as a butler matrix is used as a demonstration vehicle to showcase the capabilities and study the limitations of contorted waveguide structures. This includes the compact design of its multi-port constituent components and their assembly into a design capable of being fabricated using consumer-grade additive manufacturing systems.
Structurally embedded vascular antennas demonstrate the capability to engineer multilayer and complexly curved antennas enabled by transport of liquid metal in structurally embedded vascular networks. These structurally embedded antennas are capable of frequency reconfiguration over a decade range. The complexly curved antenna array also offers beam scanning. The “contorted waveguide” beam forming network demonstrates the capability to analyze, design, and fabricate non-planar three-dimensional structures using a selective pressure driven flow of low-cost and low-waste generating metallization process. This beamforming system also establishes the design of complex structures maintaining rotational symmetry and preserving polarization. The challenging structures that have been described above are employed and pursued in this work in order to demonstrate the opportunities offered by the design, fabrication and electromagnetic functionalization methods described in this dissertation.
Citation
Bal, Amrita (2021). Additive Manufacturing and Electroless Metallization of a 4X4 V-Band Contorted Waveguide Butler Matrix. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /195396.