A GSTP activity has been investigating whether or not advanced manufacturing techniques are suitable for fabricating antenna feed chains for Earth Observation and other science applications.
Science missions are pushing more and more towards using electromagnetic frequencies in the mm-wave frequency range so a significant number of components need to be designed and manufactured for these frequencies. But most traditional manufacturing technologies (e.g. circuit printing, molding, electroforming, milling, laser cutting etc.) are reaching their limits in terms of mechanical precision.
Swissto12, who are conducting the activity, developed an Advanced Manufacturing (AM) technique based on a method called Stereolithography (SLA). The first step is to create skeletons of the components based on polymer materials. The surfaces of the skeletons are then chemically treated to make them receptive to a metal coating, while simultaneously ensuring good adhesion. The metal plating procedure is based on a chemical copper bath, ensuring high conductivity and low surface roughness. The main advantages of this approach over SLS are its higher mechanical precision, increased design flexibility, and low surface roughness.
The activity wanted to explore using this process to develop antenna feed chains composed of a monolithic mm-wave orthomode transducer (OMT) and an integrated antenna.
Today most remote sensing and radar applications systems employed in satellite and ground-based science missions or civil applications are formed by a primary feeding antenna (the feeder, typically a horn or a planar antenna) feeding a larger secondary antenna (typically a reflector or a lens).
Though lenses and reflectors are frequently the most visible part of the antenna system, the performance of the system depends critically on the feeder. In this activity, these two parts are designed separately to meet realistic RF specifications for applications in V- and Ka-band, then combined in one single component to be manufactured. This optimizes the design performance and reduces the mass by eliminating unnecessary parts and the need for additional assembly.
The team were able to optimise the selected 3D-printing technology (SLA) to produce complex feed-chain components at high frequencies. They were also able to improve the surface preparation and metal plating procedure for polymer parts and the flow of liquids in the chemical baths, since these steps are critical for the adherence of the metal plating on the polymer and for the final surface roughness of the RF parts, with a direct impact on the measured losses due to the high frequencies.
The technology developed by SWISSto12 is a strong contender for the fabrication of RF feed-chains with orthomode transducers (OMTs).
Specifically, this technology can reduce costs by 10 to 30% compared to conventional manufacturing, reduce lead times by up to 6 weeks, reduce weight by up to 50% compared to full metal parts, increase te design flexibility of components and opens the possibility for monolithic fabrication of complex parts.
This documentation for this activity (G627-040EE) was received this month.