Using Advanced Textiles to Enhance UK-based Technology and Manufacturing Capability in the US Dominated Space Satellite Telecommunication Industry

Communications satellites still use expensive (£615,000/m2) metal mesh reflectors made by warp knitting developed by NASA in the 1960s. These are not suitable for new generations of micro satellites that require lightweight, tightly-packaged, accurately-shaped, unfurlable reflectors that can operate at a higher frequency and higher data-throughput rates.

The impact is an enhanced UK space technology capability which was achieved through the development of a pioneering, lower-cost, lightweight and deployable knitted metal mesh reflector for new generation antennae for Oxford Space Systems (OSS).

The Advanced Textile Research Group (ATRG) at NTU created a new technology to produce a viable alternative to costly US warp-knitted metal fabrics for use in UK/EU space telecommunication satellites. The micro-knitting technology utilised computerised flat-bed knitting with ultra-fine metal wires to create a seamless, 3D parabolic mesh reflector that was capable of being unfurled in space.

Tests showed that these new UK-manufactured reflectors met European Space Agency performance standards and therefore demonstrated the technology’s potential to deliver significant commercial advantage that is aligned to UK government space and security aspirations to establish an internationally-leading national commercial space industry.

In 2006, Professor Tilak Dias researched how stainless-steel wire was processed on Computerised Flat-Bed Knitting Machines (CFBKM) in order to craft cut-resistant gloves. The results were protected with a granted patent. This early research on knitting with stainless-steel provided a knowledge base which has underpinned the work of the Advanced Textiles Research Group on knitted mesh for antennae since 2010. The later work included knitting superfine tungsten wire on CFBKM and led to a collaboration with Oxford Space Systems (OSS).

Dias developed understanding of functional electromagnetic textile structures to operate as antennae and reflectors. Dias produced antennae that were embroidered using twisted multi-strand fine copper wires and silver-plated multi-filament Zylon (pphenylene-2,6-benzobisoxazole) yarn onto fabric for search and rescue purposes.

Dias and Senior Lecturer William Hurley further explored the potential of using CFBKM in a project with the University of Sheffield funded by the Defence Science and Technology Laboratory (DSTL) and then with BAE Systems. The IP related to knitting fabric antennae has been protected with a granted patent. A new approach that used CFBKMs to manufacture conducting textiles, which were able to operate at microwave frequencies, subsequently demonstrated that the technique could be used for the mass production of frequency selective surfaces (FSS).

The approach used 3D knitted spacer structures that were made from silver-plated nylon yarn in combination with a polyester spacer yarn. It confirmed that low-pass, and high-pass, knitted, flexible, frequency-selective surfaces could operate together. Further research through demonstrated the use of a knitted conducting fabric as an electrical ground plane in a single-layer radar absorber and in a microwave patch antenna. This was manufactured by knitting a silver-plated conducting yarn.

Dias and Hurley continued their fabric antennae research through developing an F-antenna grid for BAE by knitting the host and silver-plated Zylon yarns together into a single layer of fabric antennae for VHF and UHF range for portable communication equipment.

In an Innovate UK project with OSS, the work on knitting conductive yarns to create fabric antennae was combined with the earlier knowledge of using stainless-steel wire to produce cutresistant gloves. This led to the crafting of knitted metal mesh reflector surfaces that utilised ultra-fine gold-plated tungsten wire. Dias and Hurley developed a novel, knitted metal mesh surface material that could perform at Super High Frequency band (K and Ka) in the demanding space environment and a novel wire delivery technique. The manufacturing process was low cost, highly efficient and produced a knitted metal mesh of parabolic shape. It used commercial CFBKM to produce an entire structure in one continuous process.

This knitted metal-mesh reflector surface enabled the method of tensioning the reflector structure to be significantly simplified. As a result, a less complex, lighter, cheaper reflector was developed.

A research collaboration between NTU’s Advanced Textiles Research Group (ATRG) and Oxford Space Systems (OSS) has resulted in the development of a proven-in-principle lightweight, unfurlable, knitted antenna that is manufactured from electro-conductive super-fine metal wires. As a consequence, OSS has leveraged £1M European Space Agency (ESA) investment to develop 3 to 5m diameter ‘Wrapped-Rib’ Antenna (WRA) for telecommunications and defence sectors at a new large-scale production facility at Harwell Space Cluster, Oxfordshire. Post Brexit, the UK remains a member of the ESA with UK businesses able to bid for contracts through ESA.

The development of a wrapped-rib antenna will make the UK the first European country with the capability to advance space telecommunications through flight-proven parabolic deployable antenna and to comply with International Traffic in Arms Regulations (ITAR).

Strengthening OSS Capability

The Innovate UK and DeCSA-M (ESA) research projects (TRL 5) have enabled OSS and ATRG to develop the weft-knitted metal mesh for deployable antennae to allow it to be employed on larger reflectors. Evidence collected demonstrates the potential for superior performance over rival technology, but at lower cost.

The research developed a single-piece multi-gore mesh that proved the potential of a scalable, novel manufacturing process. OSS CEO confirmed, ‘NTU’s expertise in high-performance textiles enabled our consortium to overcome many technical challenges and prepared the path for future robust characterisation, qualification and industrialisation of the technology’.

The antenna’s bespoke design meets the requirement for small, lightweight, resilient and reliable engineering, capable of operating at high radio frequencies with low risk of failure in space.  The fine wire mesh seamlessly integrates with the deployable structure. With low mass, the antenna folds compactly when stowed for transport. It adopts the correct geometry and uniform mesh tension when deployed, which is critical for efficient high-frequency radio transmission in space.

OSS have confirmed that baseline capability has been achieved and that the technology was ready for the development of larger antennae and greater manufacturing capability. OSS and NTU are formalising arrangements and an agreement, covering NTU’s support.

OSS R&D Investment

Impact on OSS strategy/competitiveness

The prototype delivers a novel technology aligned to OSS’s commercial objective of developing innovative solutions for creating light-weight, low-cost antenna systems for smaller satellites. NTU’s development directly influenced the OSS business strategy, in particular the decision to invest in advanced manufacturing capability for the production of the next generation of microsatellite antennae. Initial investment of £100,000 has been made through the Innovate UK project. The potential for a satellite wholly manufactured in the UK positions OSS well in terms of the UK government Space and Security Policy to establish an internationally-leading commercial space industry in the UK. As such it offers OSS a significant commercial and competitive advantage.

Historically, UK and European space companies have relied on US-manufactured metal-meshes for reflector antennas. This has made them vulnerable to US export restrictions. OSS characterised the strategic advantage of the new technology for OSS and UK PLC as follows: ‘The fact that OSS can develop a facility so that it can be produced entirely in the UK is a significant commercial advantage. It negates the need to address potential United States export restrictions’.

The CEO at OSS also confirmed NTU’s contribution has created significant competitive advantages in this growing sector: ‘[The] prototype antenna is part of our objective to find innovative solutions to develop deployable antenna systems for a variety of space applications…[which] are targeting low cost and compact satellite buses where stowage volume and mass budgets are at a premium. This stowage efficient deployable antenna offers an attractive commercial product due to the performance, low mass and low volume attributes compared to conventional antenna architectures.’ Furthermore, they will maintain UK military advantage over adversaries: ‘There are security and military elements which contribute to the increasing demand for domestic defence space assets. The technology…allows us to tap into the potential of these markets.

• Dias, T. et al, European patent EP2155942B1 (granted on 10.08.2011, Bulletin 2011/32), US patent US8,322,167B2 (granted on 04.12.2012); Proprietor: BM Polyco Ltd.
• Acti, T., Chauraya, A., Zhang, S., Zhang, S., Whittow, W.G., Seager, R., Vardaxoglou, J.C. and Dias, T., (2015). Embroidered Wire Dipole Antennas Using Novel Copper Yarns IEEE Antennas and Wireless Propagation Letters, 14, pp. 638-641. ISSN 1536-1225. DOI:10.1109/LAWP.2014.2371338.
• Tennant, A., Hurley, W. and Dias, T., 2013. Knitted, textile, high impedance surface with integrated conducting vias. Electronics Letters, 49 (1), pp. 8-10. ISSN 0013-5194. DOI:10.1049/el.2012.3896.
• Tennant, A., Hurley, W. and Dias, T., (2012). Experimental knitted, textile frequency selective surfaces. Electronics Letters, 48 (22), p. 1386. ISSN 0013-5194 DOI:10.1049/el.2012.3005.
• Kitchener, D., Wyllie, C.B., Lewis, R.A., Juraite, I., Dias., T., and Hurley, W. Fabric Antenna. UK Patent GB2539306 (Date of Publication 25.10.2017/Date of Filing 11.03.2016) Assignee: BAE Systems PLC, UK.
• UK patent, Title: Satellite Reflectors, Application Date: 18th February 2020; Application Number: GB 2002196.0.