The objective of the Next Generation Antenna (NGA) programme is to generate a range of advanced antenna solutions which meet the evolving Ku and Ka Band market requirements for increased flexibility and performance whilst also increasing value for money.
Key issues with the DMLS process for Ka band applications are:
- Surface roughness (although this is less of an issue at Ka band),
- Voids in the surface of the component (due to the density of the finish material),
- Thermal conductivity of Nickel-Bronze material,
- Electro-less plating of complex internal geometries (where electro plating is impractical due to the small apertures / cavities).
Utilising new rapid production technologies will enable faster and more efficient bespoke or modified designs to meet evolving requirements. It will enable significant reductions in recurring costs and schedule by reducing the number of piece-parts (and hence production / test costs) whilst also opening the way to manufacturing from CAD models (removing the need for detailed drawings).
The typical turn-around time for manufacturing a DMLS recurring part direct from CAD models is far smaller than traditional spark erosion technology thereby consolidating the schedule/cost advantages still further, whilst the rapid turn-around time of breadboard components will greatly speed up the non-recurring design process.
The NGA SFB program has considered many manufacturing technologies to target the above objective and has determined that a significant reduction in piece-part count and cost can be achieved by utilising Rapid Production methods. Specifically NGA is utilising Direct Metal Laser Sintering (DMLS) to create microwave components with complicated internal and external geometries.
Development of the DMLS process and its associated materials to arrive at a robust technology for implementing microwave components.
An EQM Multi-feed assembly (based upon the Hylas requirements) will be the vehicle for demonstrating the suitability/qualification for space applications.
Direct Metal Laser Sintering has been used to manufacture a single piece orthomode transducer (OMT - traditionally spark eroded in four or five pieces), which will be assembled with more conventionally produced components, such as a polariser and horn, to create an array of Ka band feedchains.
In order to reduce the poor insertion loss of a component made in a nickel/bronze material, silver plating of has been successfully carried out using an electroless plating process over a base of electroless nickel. Surface finish is critical to perfect plating.
A Mid term Review has been held and has shown good progress towards the qualification of the DMLS OMT with electroless silver plating. Manufacturing, testing and qualification activities are scheduled to start in the next few months.