Abstract
Printed circuit boards, chemical etching, and computer numerical control milling currently dominate industrial processes for manufacturing microwave components. However, these manufacturing methods do not provide the flexibility for customization possible with additive manufacturing. Additive manufacturing (AM) has the potential to fabricate microwave components for desired frequency ranges with less effort in prototyping and fabrication. Relative permittivity (εr) of materials is a critical parameter in microwave component design, yet the value changes during the AM process. This article investigates how relative permittivity for nylon substrates, created with AM, changes with different infill densities and infill patterns. The measurement method and procedure can be used to design AM microwave components like antennas or dielectric-filled waveguides with desired characteristics. The two-microstrip-line method was used and improved for the accurate and convenient measurement of the relative permittivity of AM nylon substrates. Several nylon substrates with different infill patterns, including rectangular, hexagonal, triangular, and solid, were fabricated with AM to demonstrate how the relative permittivity value changes as the infill density increases. A linear relationship between the infill density of the rectangular pattern and the substrate permittivity was found. The permittivity data were applied to the design of a rectangular patch antenna for use in the 2.5-GHz WiMAX band. The fabricated antenna with AM, which was tested using a vector network analyzer, showed good agreement with simulation results. The method and procedure of permittivity measurements are specially designed to be applied in the design of microwave components with AM dielectric substrates.
Highlights
Additive manufacturing, often referred to as 3D printing, builds geometrically complex objects from a series of layers, each “printed” on top of the previous one
This linear relationship between the infill density and the permittivity value gives an understanding of the relationship between manufacturing parameters and electromagnetic behavior, which are necessary in the design of microwave components
We have developed a procedure for measuring the permittivity of Additive manufacturing (AM) nylon substrates with low volume material cost and investigated relations between the variation of permittivity and different print parameters such as infill density, infill pattern, and the number of roof and floor layers
Summary
Often referred to as 3D printing, builds geometrically complex objects from a series of layers, each “printed” on top of the previous one. The flexibility of AM technology allows design modifications to be immediately implemented, enabling new paradigms within the manufacturing process. One unique advantage offered by AM is the fact that it provides users with access to every point of the part’s volume during manufacturing. This advantage enables the possibility of incorporating functional components, such as electronics, during the process of a build operation [3,4]. Multifunctional AM is still in its relative infancy; for the technology to Designs 2020, 4, 39; doi:10.3390/designs4030039 www.mdpi.com/journal/designs
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