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3D printing additive manufacturing of W-band vacuum tube parts
3D printing technologies (3DP) leverage the benefits of additive manufacturing across many areas including electronics, food, medicine and optics. These technologies allow varying materials to be precision deposited, forming structures ranging from simple to complex composites such as organs and satellites. One important application for 3DP is printed electronics which is expected to exceed USD10 billion in market value by 2030. However, while considerable work has been reported in areas including inter alia: mechanical, thermal and multiple aspects, there has been less emphasis on the critical electromagnetic (EM) domain. In the EM domain, related work for 3DP encompasses interrelated EM studies of materials, processes and built structures and examines material characteristics including permittivity, permeability, electrical conductivity, which are foundational to 3D printed electronics design and fabrication. This paper presents a comprehensive report of 3DP technologies as applied to EM research & development (R&D) and end applications in order to inspire exploratory work in related areas by providing sufficient breadth for newcomers and depth for experts. The paper contributions include: summarization of the major R&D and applications areas for 3DP, thereby quantifying the prevalence of EM related work; examination of mainstream 3DP technologies applied to EM related R&D and end applications based on their materials, technology highlights and known issues; examination of relevant research which incorporates traditional printing, proprietary methods and composite 3DP methods; and classification of 3DP built EM structures as reported by research teams. Finally, the key challenges and opportunities for future research are identified and discussed.
Microfabrication techniques are commonly used to build circuits for millimeter-wave and THz vacuum electron devices. A cost effective solution is becoming available, at least for building prototype circuits intended for cold-testing. Rapid prototyping machines such as 3D printers have advanced to the point that their resolution is below the wavelength of many microwave circuits. This paper reviews the application of this quickly-advancing technology towards waveguide components of vacuum electron devices. The authors use a rapid prototype technique called Direct Metal Laser Sintering (DMLS) to 'print' sample 35 GHz circuits in metal. Circuits in two different materials (aluminum and chromium cobalt) are printed and cold-tested. The test data shows good agreement with simulation.
In this paper, an original solution for dielectric wide bandpass filters is introduced. A 4-pole filter based on the TM01δ mode has been designed in a single piece including resonators and coupling elements. The dielectric part is based on a high permittivity material (Zirconia) and has been manufactured using additive manufacturing technology (stereolithography). The breadboard shows a Q-factor around 1100, 5% bandwidth at 4GHz with insertion losses of 0.25dB and an in-band return loss of -9dB. The introduction of dielectric material for wide bandpass filters provides a reduction size which a key drivers for space applications.
A new approach to millimeter-wave power amplifiers offers significant advantages for military systems. The results of semiconductor manufacturing techniques are applied to Ka-band vacuum devices. ith the need for more band width and security, military communications systems are Wmo ving higher up on the spec-trum scale. These systems are driving the need for higher-frequency amplifiers, espe-cially in the Ka-band. Many Ka-band applica-tions require more power than current solid-state power amplifiers (SSPAs) can provide. While conventional traveling wave tube (TWT) amplifiers (TWT-As) provide the fre-quency, power and reliability needed in such applications, they do not have the mass pro-duction advantages of today's solid-state de-vices. Novel microfabrication techniques blend the virtues of vacuum tubes with solid-state technologies to deliver higher perfor-mance from a compact package at cost-effective prices with much shorter lead times. The new fabrication method has affected the Ka-band power amplifier, and military appli-cations can benefit from new power amplifier techniques.
W-band high power amplifiers offer important and enabling opportunities in radar, directed energy and communications including SATCOM applications. In this study, W-band microwave power modules (MPMs) combining low power monolithic microwave integrated circuit (MMIC) driver amplifiers and Solid State Vacuum Device (SSVD™) traveling wave tube (TWT) high power amplifiers are employed to provide high power density at low cost and small size and weight. In this work, we have also included the development of the necessary integrated power conditioner, modulator, and supply to enable a complete W-band SSVD™ microwave power module.
Quasi-Optical Spatial Power Combining Traveling Wave Tubes
- R J Hwu
A new improved slow wave structure for broadband millimeter wave traveling wave tubes
- L P Sadwick