Industry Days - Additive Manufacturing for RF/Microwave hardware

22 Nov 2016, 08:00 → 23 Nov 2016, 18:50 UTC

NA052 -Erasmus Conference Room (ESA/ESTEC)

Additive Manufacturing (AM) can suppose a breakthrough technology for the development of RF/microwave hardware such as waveguide harness, filters and antennas. The use of this manufacturing process allows the design of RF/microwave hardware to achieve enhanced performance. RF, thermal and mechanical performance can be improved by using the additional freedom provided by AM.

The assessment of different AM approaches has already started and it considers the whole process chain, including design, material supply, processing, post processing, qualification and verification, and standardisation. This assessment exercise is helping to identify already those AM approaches (materials, designs, processing, etc.) best suited for the manufacturing of part for space applications. It is performed focusing mainly on first mechanical and second thermal requirements.

Considering the already good maturity point and the positive inertia of AM (materials and processes) for other fields, it is deemed very relevant to perform an assessment of the AM for RF/microwave hardware where all the possible parameters are considered (RF performances, required tolerance, surface requirements, materials, thermal constrains, size of the part, etc.).

In these Industrial Days, we would like to create a multi-disciplinary environment in order to discuss about the specific needs for the AM of RF/microwave hardware and possible solutions (existing or to be developed).

The event will be divided in two parts.

• The first part will be dedicated to plenary invited presentations related to RF design, manufacturing processes, materials, qualifications, etc.

• During the second part, two topical working groups (antennas and RF hardware) will be created in order to discuss about AM for RF from different perspectives. The conclusions will be shared at the end of the second day in a plenary session.

Tuesday, 22 November

08:40 → 09:15 WELCOME

Speaker: Franco Ongaro (Franco Ongaro, Director of Technical and Quality Management (D/TEC), and Head of ESTEC)

09:15 → 09:40 ESA PRESENTATION : ESAS RECENT DEVELOPMENTS IN THE FIELD OF 3D-PRINTED RFMICROWAVE HARDWARE (ESA)

Speakers: Mr Maarten Van der Vorst (ESA), Mr Petronilo Martin-Iglesias (ESA / TEC-ETE)

09:40 → 10:05 3D Printing of RF Components (Tesat-Spacecom GmbH)

Additive Layer Manufacturing (ALM) provides a new freedom to design to RF components with the goal to increase performance, to reduce mass and to decrease schedule and cost by a higher level of integration directly manufactured. The whole process chain of ALM including post processing for RF components was investigated and especially the electrical effect of the surface roughness including steps for its reduction was demonstrated. From these results short term and long term application fields of ALM for RF components are derived and first results of wide band components (waveguides) in electrical performance and schedule and cost compared to conventional manufacturing techniques are presented.

Speaker: Dr Ralf Boelter (Tesat-Spacecom GmbH & Co. KG)

10:05 → 10:30 RF performances evaluations on microwave devices made in additive manufacturing (THALES COMMUNICATIONS & SECURITY)

Radiofrequencies parts have been identified by TCS as one of the most interesting applications for additive manufacturing. Indeed, these technologies could allow to: • Decrease dramatically delivery time : from several months with traditional processes to few days • Make one-piece part instead of assembly of several parts, allowing remove of interfaces which could cause dB losses. Nevertheless, the additive manufacturing technologies lead to defaults like high roughness and dimensional imperfections. TCS designed several RF elements (waveguides, filters, etc) in several radiofrequency band (X, Ku, Ka). These one have been additive manufactured in aluminum and titanium materials then analyzed. Moreover, different surface treatments have been applied to see their influence on performances. These tests highlight that : • To date, RF metallic additive manufactured parts are not able to reach performances get with parts made by traditional process in high frequencies bands (Ka band and more). • Adapted surface treatments have to be developed for complex internal designs, in order to improve surface electrical conductivity on the one hand, and to decrease surface roughness on the other hand. Please see attached file for more details.

Speakers: Dr FRIEDMAN TCHOFFO TALOM (THALES COMMUNICATIONS & SECURITY), Mr SIMON TURPAULT (THALES COMMUNICATIONS & SECURITY)

10:30 → 10:55 Additive Manufacturing of Waveguide Microwave Filters (CNR-IEIIT)

This presentation will focus on the development of waveguide microwave filters through two different additive manufacturing (AM) techniques: selective laser melting (SLM) and stereo-lithography (SLA). A robust architecture of Ku/K-band passband filters compatible with AM mechanical tolerances will be described. This architecture has been implemented into two different electromagnetic/mechanical designs: - A fifth-order layout with vertical stubs. - A sixth-order layout with stubs tilted so as to enable the alignment of the filter along the laser direction during the manufacturing process. Several prototypes have been built in aluminum, titanium and steel through SLM. The impact and the need of further metalization (silver-plating) has been investigated. The same architectures have been built through a SLA process combined with a copper coating. A trade-off-analysis among the two AM processes and the different materials will be reported.

Speaker: Dr Oscar Antonio Peverini (CNR-IEIIT)

10:55 → 11:20 COFFEE BREAK

11:20 → 11:45 Using Additive Manufacturing to Enhance Waveguide Filter Performance (Airbus Defence and Space Ltd)

The presentation will describe the development of resonator and coupling architectures that enhance the insertion loss and far out of band rejection of single mode waveguide filters. The inherent geometrical freedom of 3D additive manufacturing techniques is exploited to realize complex geometries monolithically. It also has the added benefit of reduced manufacturing lead time. Resonator and coupling structures using complex geometries are introduced and examples of manufactured direct-coupled-cavity filters are given. Analysis and measurements show excellent agreement.

Speaker: Paul Booth (Airbus Defence and Space Ltd)

11:45 → 12:10 Electrical Tests for Ka band Input Filters for Space Applications (Thales Alenia Space Spain)

The results of the fabrication and testing of Ka band input filters by means of additive manufacturing technology for space applications will be presented. Measurements of manufactured prototypes against recurrent filters designed with specifications used in real satellite communication systems were performed, and conclusions about the potential of the additive manufacturing technology for space applications will be stated.

Speaker: Dr Monica Martinez Mendoza (Thales Alenia Space Spain)

12:10 → 12:35 3D printed passive circuits from 3-100 GHz (The University of Birmingham)

The University of Birmingham have been working with collaborators on 3D printed passive circuits for some time. This cluster of work will be reviewed, picking our important aspects for space and other industries. Filters based on coaxial cavities, spherical resonators and rectangular waveguide cavitiesat 3GHz, 10GHz and 100GHz respectively, have been designed, manufactured and tested. The metal coated polymer components show excellent microwave performance. Measurements of the temperature dependence of the ceramic based spherical resonator filter will be discussed. In addition, an OMT and filtering Butler matrix used for a multiport amplifier will be discussed. The Butler matrix was at 12 GHz and printed from metal. The advantages and disadvantages of the additive manufacturing technique will be highlighted throughout.

Speaker: Prof. Michael Lancaster (The University of Birmingham)

12:35 → 13:00 Assesment of Additive Manufacturing for RF/Microwave components (Public University of Navarra)

Additive Manufacturing (AM) is gaining a lot of popularity in the space industry due to the lightweight of the 3D printed components and its versatility when producing complex monolithic 3D geometries. Even though it is not a new technology, the technological improvements in 3D printers are making them more accurate, reliable and affordable than ever. This is why many companies, universities, and research institutes are starting to use the AM as a fast and cheap technique for prototyping, or even a reliable technology for production. In this work an overview of the different additive manufacturing techniques will be presented. Each technique will be compared in terms of dimensional accuracy, surface roughness and quality taking into account the most suitable applications for each one. Then, two applications will be studied: (a) fast prototyping of waveguide component design using professional grade 3D printers for electromagnetic validation purposes, and (b) 3D printing of waveguide hardware products as a production technology using production grade 3D printers. The first application will be studied with a university approach, where many different designs are manufactured in order to validate a design technique or a model. The second application will be studied with a company approach, where the best quality at a lower price is pursued. This study has been carried out by the Microwave Components and the Antenna Groups at the Public University of Navarra with the collaboration of different international-scope companies working in the Additive Manufacturing industry and the Space industry.

Speaker: Mr Adrian Gomez-Torrent (Public University of Navarra)

13:00 → 14:00 LUNCH

14:00 → 14:25 Additive Manufacturing for RF Spacecraft Payloads (Imperial College London)

Over the past three years, a collaboration between Imperial College London and the National Physical Laboratory (NPL) has investigated the RF performance limits of 3D printed X-band and W-band metal-pipe rectangular waveguides (MPRWGs). The metal coated FDM and SLA parts have a measured performance comparable with commercial MPRWGs [1]; demonstrating measured dissipative attenuation levels of ~0.3 dB/m at 10 GHz and 12 dB/m at 110 GHz [2]. Moreover, we have demonstrated the first completely 3D printed X-band MPRWG variable phase shifter [3] and W-band MPRWG 6th-order Chebyshev band pass filter [2] having an unloaded Q-factor of 152 at 107 GHz. These passive components have demonstrated weight savings of 66% at X-band, fast design turnaround times, ultra-low manufacturing costs and complex 3D features. This research has led to a good understanding of the tolerances in fabrication, the frequency each 3D printing technology is limited to (based on surface roughness and print resolution) and the RF material properties. However, further research is required to bring them to flight model readiness. For launch and flight verification, many tests need to be undertaken (vibration analysis, temperature cycling, effects of radiation and atomic oxygen resilience). Cobham Aerospace Communications provides space qualified solutions; for example, compatible coatings to protect against atomic oxygen. Moreover, they have experience in the development of additive manufacturing for space-based applications.

Speaker: Prof. Stepan Lucyszyn (Imperial College London)

14:25 → 14:50 Practical Considerations In The Development Of Ceramic-Based Filters With Additive Manufacturing (Technische Universität Graz)

Dielectric materials can be found in RF/microwave filters for a wide range of industrial applications. Compared with other technologies, dielectric resonator (DR) filters offer a perfect balance between performance and miniaturization. These structures are capable of handling high-power levels while providing a quality factor (Q) comparable to that of pure waveguide implementations. In addition, the overall volume of the component is significantly reduced thanks to the use of dielectric materials. For that reason, these filters are emerging as the baseline design for many RF filters used in wireless and satellite applications. Due to the difficulty in machining ceramic blocks, the shapes of the dielectric objects included in RF/microwave filters are usually simple: rods, pucks, rectangular blocks, etc. However, the successful development of additive manufacturing (AM) processes for ceramic materials has opened up new geometrical configurations for filter designers to explore. Consequently, we can expect significant advances in key fields for the space industry due to the additional geometrical flexibility provided by AM. Additive manufacturing of ceramic materials differs significantly from processes for metals and plastics. Having a clear understanding of the chemical and mechanical processes that are involved in the creation of a given structure is key to successfully develop ceramic filters for RF/microwave applications. The proposed presentation in these Industry Days will focus on the different steps of the lithography process for monoblock filters like the one shown in Fig. 1 (see attached files). These filters are completely built out of ceramic materials. After manufacturing, a layer of metallic coating is applied on the exterior faces of the filter to create the metallic enclosure. Coaxial flanges are finally glued to the structure in order to provide input and output couplings. The lithography-based ceramic manufacturing (LCM) process developed by Lithoz and applied to these filters involves three steps. First, a green body is manufactured by layer-wise curing of a photoreactive ceramic suspension, building up a 3D object directly from the CAD model. Then, this green body is cleaned in order to eliminate the excess of material that has not been hardened. Finally, the green body is thermally treated to remove the organic binder (up to 600 °C) and sintered at a materials specific sintering temperature to give the dense ceramics filter (> 1000 °C). The successful application of these three steps requires the filtering structure to fulfill certain geometrical specifications. Therefore, filter designers should take into account new geometrical constraints during their design process, not typically present when employing more traditional ways of manufacturing filters. The main constraints of each step that will be discussed in the presentation are: • In the manufacture of the green body: the LCM process requires all the layers parallel to the building platform to be properly supported. This means that hollow monoblock ceramic filters like the one shown in Fig. 1 cannot be built with its bottom wall attached to the base plate, since that would required the top wall (where the connector openings are placed) to be supported from the inside of the filter (which is not readily accessible after manufacturing). Instead, the structure is tilted as shown in Fig. 1 and supports are only placed in the exterior or the filter, where they can be removed once the 3D block is created. At the same time, the use of these supports degrades the surface roughness of the walls where they are attached. This impacts the performance of the final filter, slightly increasing the insertion losses. Consequently, it is important to minimize their usage, and structures that completely avoid these supports are preferred (when available). • Slurry removal: this procedure applies a cleaning solvent to remove the excess of slurry material attached to the ceramic parts. The proper removal of the slurry is key to ensure that the manufacture is done with high geometrical accuracy. In order to do this, all the surfaces of the geometry have to be easily accessible for the solvent to reach them, but also for the suction probe to extract the remaining solvent. As a consequence, the input/output coupling apertures have to be strategically placed to allow this probe to reach the inner part of the filter. • Debinding and sintering: in order for the photopolymeric binder to be completely removed from the ceramic material, the filter cannot have excessively thick walls. Otherwise, traces of the binder may be locked in the ceramic material leading to potential cracks after sintering. This contribution will give a review on design rules for manufacturing ceramic filters using the LCM approach and the corresponding constraints on filter designs. As a result, RF/microwave designers will gain knowledge on how to adapt their designs to improve their performance and increase the chances of a successful manufacture using ceramic-based lithography.

Speaker: Dr Fabrizio Gentili (Technische Universität Graz, Graz, Austria)

14:50 → 15:15 Material customization and performance optimisation of bandpass filters made by ceramic additive manufacturing (Xlim CNRS/University of Limoges)

This presentation will be focused on the application of ceramic additive manufacturing for compact surface mountable bandpass filters and tunable cavity filters. We will specifically target here three sub-topics: - Applied examples from compact to constant absolute bandwidth tunable cavity filters using low loss ceramics. - Topological optimization tools applied to the enhancement of dielectric resonators (unloaded Q factor, spurious free range) - Customization of ceramic permittivity, loss tangent and temperature stability up to 73 GHz.

Speaker: Dr Nicolas Delhote (Xlim CNRS/University of Limoges)

15:15 → 15:40 3D printing by FDM of composites of tunable dielectric constant for high frequency devices (Heriot-Watt University)

Abstract: 3D printing is delivering step changes in fields such as rapid prototyping and additive manufacturing, and it has plenty of potential for a continuous growth in different applications. Fused deposition modelling (FDM), or fused filament fabrication, has recently become readily available. High frequency and microwave technologies could benefit from it. However, the plastic materials available for FDM offer a limited palette of low dielectric constants, which limit its potential for RF applications. In this work, we show the modification of the dielectric constant of an ABS-based composite, which is the commonest thermoplastic for FDM, by the use of additives. Small amounts of TiO2 (anatase phase) have been introduced in the polymeric host, increasing its dielectric constant. Small T-shaped figures have been printed with a resolution of 0.1 mm (Fig.a). Moreover, FDM provides the ability to infill with air (Fig.b), which can decrease the dielectric constant. The T-shaped solid samples have been mounted in a resonant filter (Fig.c) and the transmission has been measured in the 26-40 GHz range. The dielectric constant has been retrieved by fitting the measured response of the perturbed filter to full-wave simulations (Fig.d). The obtained dielectric constant has been found to be 2.46 – 2.61 with a filling factor as small as 16% (Fig.e).

Speakers: Prof. George Goussetis (Heriot-Watt University), Dr Jose Marques Hueso (Heriot-Watt University, Edinburgh, U.K.), Prof. Marc Desmulliez (Heriot-Watt University, Edinburgh, U.K.)

15:40 → 16:00 COFFEE BREAK

16:00 → 16:25 3D Printed Microwave Components with Locally Controlled Dielectric Permittivity (University of Perugia)

In this presentation, the possibility of locally modifying the effective dielectric permittivity by changing the infill factor of the printing process is exploited and demonstrated by using the fused deposition modeling (FDM) technology. This allows adopting a single filament material to obtain different permittivity values in the various portions of a microwave component. Moreover, the variation of the infill factor allows reducing the dielectric loss tangent of the material: this permits decreasing losses even by using the same material. These features are illustrated through the design and experimental verification of two SIW filters, with identical frequency response but fabricated with different infill factor of the printing process, via FDM.

Speaker: Dr Cristiano Tomassoni (University of Perugia)

16:25 → 16:50 Compact Evanescent Rectangular Waveguide Dual-Channel Bandpass Filters for Additive 3-D Manufacturing (Universidad Politecnica de Cartagena)

In this contribution a novel evanescent waveguide dual-channel bandpass filter is proposed. The structure is suitable for additive manufacturing as the inner evanescent structure containing elliptical posts attached to a metallic wall is placed in the middle of a standard waveguide. Since the whole filter should be manufactured as a single piece, only additive manufacturing is able to reproduce the complex geometry required for the practical realization of this structure. From the electrical point of view, the proposed structure has a number of advantages as compared to the state of the art technology. One of the main advantages is the flexibility in the type of transfer functions that can be achieved. This ranges from standard Chebyshev responses to dual-band responses implementing transmission zeros for maximum isolation between channels. This type of structure has never been used before due to manufacturing limitations, that can now be overcome by using emerging additive manufacturing techniques.

Speaker: Mr Alejandro Pons Abenza (Universidad Politecnica de Cartagena)

16:50 → 17:15 Additive Micro-Fabrication of High Q Millimeter-Wave Cavities and Filters (University of Limoges - CNRS - XLIM - UMR 7252)

This paper deals with a novel additive micro-fabrication process for millimeter-wave components. This fabrication process is based on successive lithography, metal electroplating with micron scale accuracy, well suited for millimeter-wave filter fabrication. As an additive fabrication process, the millimeter-wave components can be fabrication on many types of substrates, like PCB or ceramics. First prototypes of air-filled copper cavities and filters have been realized with this process and the prototypes can reach an unloaded quality factor between 450 and 1000 for frequencies between 35 GHz and 140 GHz.

Speaker: Dr Pierre Blondy (University of Limoges - CNRS - XLIM - UMR 7252)

17:15 → 17:40 Additive Manufacturing for Particle Accelerator RF structures– An introduction to Metal Additive Manufacturing at CERN (CERN)

Accelerator components are traditionally fabricated using a wide range and combination of techniques: sheet metal forming, machining, vacuum brazing and welding. As an alternative to tackle ever-increasing performance, cost and lead time requirements of such structures, additive manufacturing (AM) has the potential to metamorphose the manufacturing approach, opening the door to functional design. However, currently the most popular AM materials are limited to steels, aluminium alloys, nickel alloys, and titanium alloys. RF components require the use of oxygen-free electrolytic (OFE) copper or pure niobium, neither of which is common within the AM industry. In this presentation, CERN and its accelerators will be briefly introduced. The relevance of AM for accelerator components is described together with the first AM RF components, in titanium alloy, and the first results of EBM in pure copper, both obtained in collaboration with Industry.

Speaker: Mr Romain Gerard (CERN)

Wednesday, 23 November

09:00 → 09:25 Design and Manufacturing of RF-Feed Chain Components using ALM (Airbus DS GmbH)

Caused by the upcoming interest in very high throuput satellites (VHTS), the market for satellites is requesting satellite systems with high transmissions capacities and a high number of beams. To realize high data rates and an increase spectral efficiency, antenna systems with large bandwidth as well as higher power capabilities are necessary. To allow these requirements, multiple beam antennas are used. These antenna systems can re-use allocated frequency bands, so that the spectral efficiency will increase significantly. A typical multiple spot scenario consists of a single offset reflector fed by a horn cluster. Single feed per beam feed chains are used to generate one beam with ohne horn. Especially multiple feed per beam scenarios results in a high number of horns per antenna, hence new demands concerning accommodation, thermal concept, mass, costs and lead time are raised. Additive manufacturing has potential to fulfill the upcoming demands. Because of more degrees of freedom and new manufacturing boundaries, other possibilities for accommodation as well as mass and volume reduction could be investigated. Airbus DS, ASL, Fotec and AAC research analyzed the use of additive layer manufacturing of RF components and for that, detailed investigations to improve RF relevant parameters were performed and C- and Ku-band RF components as well as non RF samples were manufactured and evaluated. Previous and current results and activities will be presented and discussed.

Speaker: Mr Michael Szymkiewicz (Airbus DS GmbH)

09:25 → 09:50 Polymer-based additive manufacturing of feed-chain components and antennas (SWISSto12)

During the past couple of years, SWISSto12 has developed a proprietary additive manufacturing (AM) technique for the production of RF components. The technique combines high mechanical precision (+/-25 um locally) and low surface roughness (a few hundred nanometers). In essence, it consists of two main steps: first a polymer-based body of a piece is fabricated by stereolithographic (SLA) AM process, and then the body is metal coated using an electroless plating technique developed by the company. The SWISSto12 AM technique is believed to be particularly appropriate for feed-chain components and antennas operating at Ku band, Ka band, and above. It enables low-loss, light and monolithic components in contrast to classical subtractive-machined split-block components that demand careful assembly and often exhibit relatively large weight due to extra metal and flanges needed for the assembly. In addition, the SWISSto12 AM technique, as most AM techniques, enables relatively inexpensive and fast fabrication with inherent design flexibility (geometrical freedom). A number of products fabricated by SWISSto12 will be presented. The first demonstrator is a Ku-band diplexer, developed in collaboration with Laboratory of Electromagnetics and Antennas (LEMA-EPFL), based on two rectangular waveguide filters with inductive irises. The measured RL and IL are in the order of 20 dB and 0.4 dB, respectively. To demonstrate the extended design flexibility, a Ku-bandpass filter based on super-ellipsoid cavities, as designed by Airbus Defence and Space (UK), is also presented. The measurement results reveal RL and IL better than 20 dB and 0.2 dB, respectively. Recently, SWISSto12 has fabricated for ESA a monolithic dual reflector antenna in Ku-band. The antenna exhibits gain of 24 dBi and 27 dBi in the RX- and TX-band, respectively, and overall excellent agreement with theoretical predictions. One of the latest fabricated antennas is a dual-polarized leaky-wave antenna operating at 30 GHz developed in collaboration with IETR. This antenna, also made of a single piece, contains a leaky waveguide section, an OMT, and a waveguide bend and twist. The measurement results are in good agreement with theoretical predictions.

Speakers: Dr Maria Garcia Vigueras (INSA/IETR), Dr Tomislav Debogovic (SWISSto12)

09:50 → 10:15 Electromagnetic Properties of 3D printed Horn Antennas and Microwave Components (Norwegian Defence Research Establishment (FFI))

Our field of work is radar electronic warfare (EW). Our research aim for the work presented here is to study the electromagnetic properties of 3D printed antennas and microwave components, with EW applications in mind. 3D printing is a very attractive technology not only due to low cost and ease of manufacturing, but also the ability to manufacture complicated 3D geometries quickly and easily. Throughout the last decade many researches have shown that metallization of plastic, so that the plastic gains some metal characteristics, is possible. However, none of the studies we have seen did an evaluation on how different materials, 3D printing technologies and metallization methods influence the electromagnetic performance of broadband structures. Therefore, our first step was to investigate how different plastics materials, metallization processes, and thickness of the metal impacted the performance of a broadband horn antenna and waveguide structures. In our study we have investigated different 3D-printing techniques, different types of plastics and several metal thicknesses. To provide confidence in the results, all measurements were compared to measurements on standard metal antennas and waveguides. The electrical performance of the 3D-printed antennas and waveguides was found to be comparable to standard antennas and waveguides manufactured using machining techniques. However, not all metallization methods provided equal performance and a major question to answer for our application is how would these 3D printed antennas with different metallization methods perform with high power signals. So, the next step was to test the same antennas as transmitters and the results show that the antenna with highest conductive loss does not survive high power signals. Another area of interest to us is easy integration of these antennas and microwave structures into systems. One attractive application is to print (parts of) UAVs with (parts of) the payload integrated. One application for this could be using the UAV as a passive sensor to detect emitters of radio frequency signals – normally referred to as Electronic Surveillance Measures (ESM). ESM requires a wide band antenna, and in our case the required frequency coverage was 7.5-18GHz. Waveguides and horns have a number of desirable features for a design like this. Firstly, the structure can be considered as part of the wing structure itself – adding to the structural integrity of the aircraft. Secondly, the waveguide itself is basically an air-filled corridor, adding little weight to the wing (when the waveguide walls can be considered as part of the actual wing structure). Thirdly, waveguides and horns have low losses, making it possible to move all microwave circuitry to the main body of the aircraft. No amplifiers, filters etc. should be required close to the antenna. Finally and most importantly in this context, waveguides and horns can be fully manufactured using 3D printing. This setup showed that the wing structure is transparent to the performance of the antenna and waveguide components. To conclude and look ahead we will briefly look at some new possibilities that 3D printing provides, specifically in terms of allowing more complex electromagnetic structures to be manufactured, providing new or unusual electromagnetic properties. This is recent and ongoing work at our establishment. Currently we are working on a 3D printed dielectric microwave lens with graded refraction index.

Speaker: Mrs Karina Hoel (Norwegian Defence Research Establishment (FFI))

10:15 → 10:40 3D screen printing – additive manufacturing for antenna components at mass production scale (Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM)

3D screen printing is an additive manufacturing technique based on the combination of screen printing and sintering. It is well suited for the manufacture of parts with fine details, complex structures, cavities and material combinations. Ceramic and metal powders are processed into suspensions which are deposited using a screen printing screen. Repetition of this process allows for a layer by layer build-up of parts with a resolution of ~10 µm. Walls as thin as 100 µm can be prepared as well as openings and channels with openings as narrow as 80 µm. Thin structures with an width/high aspect ratio of 1/30 can be printed as well as overhangs and cavities. Since this technique does not use any support structures intricate cavities with narrow openings or even sealed off cavities can be obtained. 3D screen printing is economically suitable for a wide range of lot sizes. It is possible to apply 3D screen printing for small lots having only a few parts as well as mass production scale manufacture of 100,000 parts/yr. and more, depending on the part dimensions and respective machine parameters. A wide range of materials can be processed (ceramics e.g. Al2O3, ZrO2, metals like e.g. iron, stainless steel, copper, refractories, rare earth metals). Even ceramic/metal material combinations are possible. The presentation will outline the 3D screen printing process steps like preparation of screen printing suspensions and debindering/sintering of screen printed green parts. Application examples will give an overview of possible 3D screen printed designs, examples of which can be seen in Figure 1.

Speaker: Dr Martin Dressler (Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM)

10:40 → 11:05 COFFEE

11:05 → 11:30 3D-Printed Quasi-Optical Antenna-Systems for Mm-wave Communications (University Nice Sophia Antipolis)

For telecommunication purpose, new wireless technologies are constantly investigated. One particularly interesting field to explore is about transmissions in mm-wave bands. High performance and cost-effective antennas are strongly needed: fast and low-cost prototyping solutions available for volume production are necessary to establish a real breakthrough. Also, the need is strong for a manufacturing technology able to handle complicated 3D shapes. This presentation demonstrates how 3D printing technology is about to become a mature solution to fabricate cost effective and innovative antennas in V/E, F and G bands. Especially, we present a 3D-printed plastic horn at 60 GHz and 240 GHz and several 3D-printed V/E and F bands plastic lenses with measured promising performance.

Speaker: Prof. Cyril Luxey (University Nice Sophia Antipolis)

11:30 → 11:55 SYMETA - Synthesising 3D metamaterials for RF, microwave & THz applications (Loughborough University)

This presentation will outline the vision, scope and objectives of the UK’s Engineering and Physical Sciences Research Council funded Grand Challenge project *Synthesising 3D metamaterials for RF, microwave & THz applications*. With a total investment of five million pounds over five years, SYMETA aims to develop additive manufacturing (AM) techniques to produce a palette of 3D metamaterials. When combined, these metamaterials will influence and control the electromagnetic (EM) performance of devices such as substrates, filters, transmission lines, antennas and lens. The multidisciplinary research consortium includes materials and material processing expertise at Sheffield and Loughborough Universities, manufacturing capability at Loughborough, EM design, modelling, test and characterisation at Loughborough, Exeter, Oxford and Queen Mary London universities. The academic consortitium is working closely with a number of cross sector industrial partners. Over the next five years, the consortium will investigate a range of AM processes, such as fused deposition modelling and material jetting, and materials that provide a variety of dielectric and conductive properties coupled with optimised feature resolution. Starting with the development of an RF demonstrator at low GHz frequencies, the designs and processes will then be adapted for the production of demonstrators at X-band through to THz. Structures and circuit designs will be created using a palette of novel unit cell designs (meta-atoms) that in certain arrangements will provide either enhanced EM properties or the desired frequency response. The project is in its early stages and is keen to communicate its vision and encourage further engagement from industry. SYMETA has the potential to change how we approach manufacturing to reduce costs, timescales and environmental impact whilst increasing functionality.

Speakers: Dr Darren Cadman (Loughborough University), Prof. Yiannis Vardaxoglou (Loughborough University)

11:55 → 12:20 Micro laser sintering as a tool to manufacture tiny solid structures for RF hardware (3D MicroPrint GmbH)

We will introduce Micro Laser Sintering (MLS) and company 3D MicroPrint GmbH and their capabilities of printing solid high-resolutionally metal parts. We will demonstrate how we develop new applications and demonstrate the possibilities of collaboration. We will show examples of applications and show real parts to touch. We will manufacture a demonstrator part related to RF/microwave to show the functions.

Speaker: Mr Daniel Weber (3D MicroPrint GmbH)

12:20 → 12:45 Automatic design methods for thermo-mechanical components (Adimant ApS)

The design freedom of Additive Manufacturing (AM) is both an advantage and a challenge. More than ever, we need assistance from the computer in exploiting the manufacturing capabilities. Even though Computer-Aided Design (CAD) has been around for 40 years, it is still not ready to fully support design for AM. Meanwhile, the fields of structural optimisation and generative design have developed tremendously and are now at a stage where they can semi-automatically explore the full design space together with the design engineer. The presentation will touch upon several topics: First, a high resolution topology optimisation method capable of designing parts at the manufacturing resolution will be presented. This significantly lowers the component design time and is an opportunity for structural integration between RF components and the full assembly. Secondly, I'll show how this traditionally mechanical optimisation paradigm can be extended to thermal problems on both the micro and macro scale, for instance minimising mechanical deformation while securing parts with isothermal surfaces. Finally, I'll touch upon the generation and manufacturing of huge complex lattice structures with millions of rods, which are used for controlling thermal properties of AM parts.

Speaker: Dr Klaus Loft Højbjerre (Adimant ApS)

12:45 → 13:10 ESA PRESENTATION MATERIALS / PROCESSES (Roadmaps, GSTP, Harmo...)

Speaker: Dr Johannes Gumpinger (ESA)

13:10 → 14:10 LUNCH

14:10 → 15:00 ADDITIVE MANUFACTURING ORIENTED RF/MICROWAVE DESIGN

15:00 → 15:45 ADDITIVE MANUFACTURING ORIENTED ANTENNA COMPONENTS

15:45 → 16:05 COFFEE BREAK

16:05 → 17:05 PLENARY SESSION - GATHERING CONCLUSIONS OF EACH GROUP

17:05 → 17:35 CONCLUSIONS AND CLOSING