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Interferometry And Synthesis In Radio Astronomy

This paper provides an overview on the main additive manufacturing/3D printing technologies suitable for many satellite applications and, in particular, radio-frequency components. In fact, nowadays they have become capable of producing complex net-shaped or nearly net-shaped parts in materials that can be directly used as functional parts, including polymers, metals, ceramics, and composites. These technologies represent the solution for low-volume, high-value, and highly complex parts and products.

Overview on Additive Manufacturing Technologies

Antenna is one of the key components onboard small satellites as its design determines the performance of all the wireless systems including telemetry, tracking and control, high-speed data downlink, navigation, intersatellite communications, intrasatellite communications, wireless power transfer, radars and sensors, etc. This paper presents a review of recent development in advanced antennas for small satellites (MiniSat, MicroSat, NanoSat, CubeSat, etc.). A number of recent examples of antennas for small satellite applications are shown and discussed. A conclusion and future development in antennas for small satellites are given in the end.

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Advanced Antennas for Small Satellites

3D printing is disrupting the design and manufacture of electronic products. 3D printing electronics offers great potential to build complex object with multiple functionalities. Particularly, it has shown the unique ability to make embedded electronics, 3D structural electronics, conformal electronics, stretchable electronics, etc. 3D printing electronics has been considered as the next frontier in additive manufacturing and printed electronics. Over the past five years, a large number of studies and efforts regarding 3D printing electronics have been carried out by both academia and industries. In this paper, a comprehensive review of recent advances and significant achievements in 3D printing electronics is provided. Furthermore, the prospects, challenges and trends of 3D printing electronics are discussed. Finally, some promising solutions for producing electronics with 3D printing are presented.

Additive manufacturing frontier: 3D printing electronics

2-D printed electronics have been the focus of intense research for the past two decades primarily focused on implementing electrical interconnect by dispensing conductive binder-based inks. More recently, traditional printed electronics processes have been leveraged within 3-D printed structures where components and interconnect are introduced during fabrication interruptions. The dielectric performance of 3-D printed materials compares well with traditional printed circuit board (PCB) dielectrics but one remaining challenge is the low conductivity of printed ink traces. The performance degradation is due to curing temperature limits imposed by the properties of the polymer substrates. Thermoplastics, such as ULTEM, can maintain form at over 200 °C, but production ink curing processes require 850 °C to provide an appropriate conductivity. Previous reports have described submerging wires with selective energy within a thermoplastic substrate upon which 3-D printing can continue uninhibited. As copper wires have the same conductivity as PCBs and can be implemented in a wide range of cross-sectional areas, 3-D printed electronics are now in a position to transform the electronics industry. This paper describes an inter-layer process to insert metal connection between layers—allowing for improved routing density and leveraging the geometries brought to bear by 3-D printing. Minimum placement distance between these 3-D printed vias was initially 1.5 mm, and the vias can connect layers separated by as much as 2.8 mm in the vertical build direction (z-axis). As the number of wires layers that can be fabricated is not as limited as traditional board lamination, complex routing can be realized within mass customized, arbitrary shapes.

3D Printed Electronics With High Performance, Multi-Layered Electrical Interconnect

This work describes the design, fabrication, and testing of an Archimedean spiral or spiral antenna using polymer extrusion 3D printing of polycarbonate base material. The spiral antenna design was simulated using CST Microwave Studio (R), and the resulting 3D printed antenna characterized in terms of return loss, directivity, and polarization. The antenna design was embedded into a 3D printed structure using a unique ultrasonic method while a ground plane was inserted through a thermal embedding process. These fabrication methods provide process flexibility, which allows multiple conductive antenna layers to be additively constructed in a single build sequence. The method described can be used to create unique electromagnetic structures such as waveguides directly in a 3D printed dielectric part. The spiral antenna was tested with three variations of microstrip feed line used to match 50 impedance and introduce a 180 degrees phase shift between the two arms of the spiral. These include a Duroid balun attached to feed of the antenna after fabrication, a Duroid balun embedded into the polycarbonate during fabrication, and the same microstrip design fabricated out of copper mesh and embedded into the structure using the polycarbonate as a dielectric substrate. The results of these three approaches will be discussed. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1662-1666, 2016

Multi-layer archimedean spiral antenna fabricated using polymer extrusion 3D printing

In the last decade, the proliferation of new 3D printing technologies has enabled the fabrication of complex geometries in manifold materials for novel applications. One discipline that has been explored extensively in the context of additive manufacturing is electromagnetic devices such as antennas. Difficult-to-fabricate geometries are now possible and can deliver new antenna functionality and extend performance (e.g., lower frequency resonance in small volumes, wider bandwidth, narrow-beam directionality, and so on). Coupled with accurate 3D electromagnetic simulations, a new paradigm is emerging for antenna design and manufacture. Starting from a seed geometry, the state space can now be explored to identify new combinations and permutations of electromagnetically-beneficial shapes through multiple simulation iterations. Subsequently, the identified structures can be further validated and improved through rapid manufacturing using 3D printing for hardware evaluation in an anechoic chamber. However, to fully benefit from this emerging paradigm, an up-to-date survey of the most recent metal processes is required. This survey would determine which processes are well suited for building the next generation of antennas. For this purpose, a variety of metal 3D printing was employed to fabricate benchmark antennas with pathological geometries, including thin walls, overhanging features, and large aspect ratios. This survey can inform designers about potential structures to serve in novel antennas. A total of five processes have been preliminarily explored including selective laser melting, binder jetting, and plated vat photopolymerization, all of which delivered different advantages and disadvantages in terms of mechanical and electromagnetic performance.

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Digital Manufacturing of Pathologically-Complex 3D Printed Antennas

Significant research and press has recently focused on the fabrication freedom of Additive Manufacturing (AM) to create both conceptual models and final end-use products. This flexibility allows design modifications to be immediately reflected in 3D printed structures, creating new paradigms within the manufacturing process. 3D printed products will inevitably be fabricated locally, with unit-level customization, optimized to unique mission requirements. However, for the technology to be universally adopted, the processes must be enhanced to incorporate additional technologies; such as electronics, actuation, and electromagnetics. Recently, a novel 3D printing platform, Multi3D manufacturing, was funded by the presidential initiative for revitalizing manufacturing in the USA using 3D printing (America Makes - also known as the National Additive Manufacturing Innovation Intuitive). The Multi3D system specifically targets 3D printed electronics in arbitrary form; and building upon the potential of this system, this paper describes RF antennas and components fabricated through the integration of material extrusion 3D printing with embedded wire, mesh, and RF elements.

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3D printing multi-functionality: Embedded RF antennas and components

Printing Multi-Functionality: Additive Manufacturing for CubeSats

The utilization of frequency spectrum for space-to-ground communications applications has generally progressed from the lowest available bands capable of supporting transmission through the atmosphere to the higher bands, which have required research and technological advancement to implement. As communications needs increase and the available spectrum in the microwave frequency bands (3 30 GHz) becomes congested globally, future systems will move into the millimeter wave (mm-wave) range (30 300 GHz). While current systems are operating in the Ka-band (20 30 GHz), systems planned for the coming decades will initiate operations in the Q-Band (33 50 GHz), V-Band (50 75 GHz) and W Band (75 110 GHz) of the spectrum. These bands offer extremely broadband capabilities (contiguous allocations of 500 MHz to 1GHz or more) and an uncluttered spectrum for a wide range of applications. NASA, DoD and commercial missions that can benefit from moving into the mm-wave bands include data relay and near-Earth data communications, unmanned aircraft communications, NASA science missions, and commercial broadcast/internet services, all able to be implemented via very small terminals. NASA Glenn Research Center has a long history of performing the inherently governmental function of opening new frequency spectrum by characterizing atmospheric effects on electromagnetic propagation and collaborating with the satellite communication industry to develop specific communications technologies for use by NASA and the nation. Along these lines, there are critical issues related to W/V-band propagation that need to be thoroughly understood before design of any operational system can commence. These issues arise primarily due to the limitations imposed on W/V-band signal propagation by the Earth s atmosphere, and to the fundamental lack of understanding of these effects with regards to proper system design and fade mitigation. In this paper, The GRC RF propagation team recommends measurements that are required to assure that the risk associated with the use of mm-wave is minimized. We develop first order beacon and transponder system payload requirements and beacon terminal requirements. We will suggest and discuss a possible hardware implementation for the space segment, as well for the ground segment. A discussion on a propagation measurement campaign for taking relevant statistical data is also included.

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Michael Zemba

Papers

Multi-layer archimedean spiral antenna fabricated using polymer extrusion 3D printing

Digital Manufacturing of Pathologically-Complex 3D Printed Antennas

3D printing multi-functionality: Embedded RF antennas and components

Printing Multi-Functionality: Additive Manufacturing for CubeSats

W/V-Band RF Propagation Experiment Design