3-D Printed microwave and tetrahertz passive components

This thesis presents the design of microwave and terahertz filters, fabricated using different types of 3-D printing technology. The work demonstrates the potential of using 3-D printing in the fabrication of microwave and terahertz passive components. The first project introduces a compact coaxial cavity resonator filter which was fabricated using stereolithography 3 D printing process. The size and volume of this filter reduced by almost half, by fitting one resonator inside another resonator. This filter is ideal for fabrication by 3 D printing, as such a complex structure cannot be made easily by other methods. This project demonstrates the advantage of using 3-D printing in fabrication of components with complex structures. The second project introduces three waveguide bandpass filters operating at centre frequency of 90 GHz, which were fabricated using the micro laser sintering process. The filters were the highest frequency metal 3-D printed filters reported at the time of publication. The third project introduces two waveguide filters operating at centre frequency of 180 GHz, which were also fabricated using the micro laser sintering process. These are the world highest frequency waveguide filters fabricated by a metal 3-D printing process. The capability of reproducibility of the micro laser sintering process is also discussed in this thesis. The fourth project introduces a hybrid coaxial bandpass filter with two symmetrical transmission zeros, which was fabricated using stereolithography 3-D printing process. In this project the main-line couplings and input/ output coupling were realized using PCB lines, the idea of using PCB lines instead of coupling irises or probes is to allow different topologies to be designed easily by altering the PCB layout. Finally, the fifth project introduces a terahertz waveguide bandpass filter with embedded H plane waveguide bends. This filter is being fabricated using 3-D screen printing

Structured-Glass Waveguide Technology for High-Performance Millimetre-Wave Components and Systems

This work presents a novel waveguide medium based on laser-induced structured-glass for the design of high-end millimetre-wave components and systems. The material properties, fabrication process and functional attributes of the structured-glass technology are first described and then applied in order to demonstrate a fourth-order bandpass filter prototype operating within the W-band frequency range, centered around 88 GHz with a narrow fractional bandwidth of 2.3%. The basic filter design, dimensional considerations, and assembly process are discussed in order to outline the fabrication process. The prototype filter, along with its associated feed-line transitions and split-block interface are measured and characterized in the laboratory in order to validate the design approach. The measured response is shown to be exceptionally accurate; the insertion loss is found to be approximately 1.43 dB - 1.97 dB throughout the measured passband with a return loss of better than 22 dB and center-frequency offset of approximately 0.117%. A comparison to existing technologies is discussed in order to highlight the advantages of the proposed medium and to contrast the differences in both manufacture and achievable results for high-end components

Advanced Filter Solutions for High-performance Millimetre and Submillimetre-wave Systems

This thesis is devoted to the investigation of advanced filter design solutions for high-performance millimetre and submillimetre-wave systems. Each of the proposed design solutions are enabled using waveguide-based technologies with the aim of advancing future generations of satellite communications, radar, and remote sensing. As trends for frequency allocations move to higher and higher frequency bands, engineers are faced with increasingly complex challenges such as the degradation of component performance, the inability to correctively tune the performance, or scenarios that all together make circuits infeasible. In light of these challenges, this work seeks to advance the current literature on filter design and proposes many unique design solutions for overcoming manufacturing and accuracy limitations, reducing the transmission losses, and reducing the overall design complexity. Each of the proposed filter solutions that are presented in this thesis are based on either a novel structural design or a novel technology. Each of the proposed designs are presented with functional prototypes as a means of verifying the theory. In the majority of cases, prototypes have been manufactured using high-precision computer numerical control (CNC) milling, and in several articles, exploratory activities with the use of alternative technologies such as stereolithography (SLA) 3D-printing and deep-reactive ion etching (DRIE) are presented. Prior to the presentation of the filter designs, an overview on the design and synthesis of millimetre-wave filters and diplexers is provided and serves as a foundation for the coupling matrix descriptions of symmetric and asymmetric resonator designs throughout this work

Advanced Design and Fabrication of Microwave Components Based on Shape Optimization and 3D Ceramic Stereolithography Process

International audienceThe design of advanced components for space and terrestrial telecommunication systems requires both sophisticated design methodologies and manufacturing technologies for improving current component characteristics. In particular, optimizing the shape and the size of a component is a problem of primary importance for microwave engineers. Moreover, for designing RF and microwave components or antennas, the use of ceramic materials is preferable in order to satisfy both electrical and dimensional constraints. The main objective of this chapter is to demonstrate that it is possible to jointly improve the design and fabrication procedures of ceramic based advanced RF components. In this context, a ceramic 3D stereolithography based rapid prototyping technique is applied for fabricating 3D ceramic structures. As presented next, theoretical and experimental approaches are complementary and innovative components with excellent electrical performances have been designed, manufactured and characterized. Then the contribution demonstrates how an original CAD design approach based on shape optimization methods can be applied for improving electrical performance and integration of microwave and millimeter-wave devices

Low cost fabrication processing for microwave and millimetre-wave passive components

Microwave and millimetre-wave technology has enabled many commercial applications to play a key role in the development of wireless communication. When dissipative attenuation is a critical factor, metal-pipe waveguides are essential in the development of microwave and millimetre-wave systems. However, their cost and weight may represent a limitation for their application. In the first part of this work two 3D printing technologies and electroless plating were employed to fabricate metal pipe rectangular waveguides in X and W-band. The performance for the fabricated waveguides was comparable to the one of commercially available equivalents, showing good impedance matching and low attenuation losses. Using these technologies, a high-performance inductive iris filter in W-band and a dielectric flap phase shifter in X-band were fabricated. Eventually the design and fabrication of a phased antenna array is reported. For microwave and millimetre-wave applications, system-on-substrate technology can be considered a very valuable alternative, where bulky coax and waveguide interconnects are replaced by low-loss transmission lines embedded into a multilayer substrate, which can include a wide range of components and subsystems. In the second part of this work the integration of RF MEMS with LTCC fabrication process is investigated. Three approaches to the manufacture of suspended structures were considered, based on laser micromachining, laser bending of aluminium foil and hybrid thick/thin film technology. Although the fabrication process posed many challenges, resulting in very poor yield, two of the solution investigated showed potential for the fabrication of low-cost RF MEMS fully integrated in LTCC technology. With the experience gained with laser machining, the rapid prototyping of high aspect ratio beams for silicon MEMS was also investigated. In the third part of this work, a statistical study based on the Taguchi design of experiment and analysis of variance was undertaken. The results show a performance comparable with standard cleanroom processing, but at a fraction of the processing costs and greater design flexibility, due to the lack of need for masks.Open Acces

Review of 3D Printed Millimeter-Wave and Terahertz Passive Devices

The 3D printing technology is catching attention nowadays. It has certain advantages over the traditional fabrication processes. We give a chronical review of the 3D printing technology from the time it was invented. This technology has also been used to fabricate millimeter-wave (mmWave) and terahertz (THz) passive devices. Though promising results have been demonstrated, the challenge lies in the fabrication tolerance improvement such as dimensional tolerance and surface roughness. We propose the design methodology of high order device to circumvent the dimensional tolerance and suggest specific modelling of the surface roughness of 3D printed devices. It is believed that, with the improvement of the 3D printing technology and related subjects in material science and mechanical engineering, the 3D printing technology will become mainstream for mmWave and THz passive device fabrication