The soon-to-be-launched Inmarsat S-band/Hellas Sat 3 satellite* includes Inmarsat’s S-band payload, which will form the space component of the European Aviation Network (EAN). The world’s first hybrid satellite/air-to-ground high-speed passenger connectivity solution, EAN will deliver the fastest inflight broadband service for airlines flying throughout Europe and is currently scheduled to enter commercial service in 2017.

The Inmarsat S-band payload relies on two new Harris fixed-mesh space reflectors (FMRs). The FMR is an innovative hybrid design that combines the high-frequency mesh surface technology of Harris’ legacy unfurlable antennas with a fixed graphite frame. Together, they provide an effective solution for high-throughput satellites, which are increasingly demanding larger apertures and smaller spot beams than currently possible with solid reflectors.

One of the FMR’s key advantages is its lighter weight, facilitated not only by Harris’ patented gold-plated knit wire fabric—one of the most efficient RF reflective surfaces on the planet—and the graphite frame, but also by the use of 3D printed components. More than 60 percent of FMR components, including all of the surface fittings, are produced from titanium using 3D printing, or additive manufacturing processes.

An Alternative to Injection Molded Plastics and Traditional Machining

The FMR began as an internal research and development project. Initially, the team planned to try using injection-molded plastic parts to reduce weight. But because few plastics qualify for the temperatures that the FMR would be subjected to, the team turned their attention to 3D printing as a more viable solution.

“3D printed metal has certain advantages over injection molding and traditional machining,” explains Jeff McGinn, director of Harris’ ISR Space Antennas and Structures business area. “For example, it can yield more complex parts and can accommodate small quantities more cheaply and quickly than injection molded plastic.”

Using powdered titanium and additive manufacturing processes, Harris has created seven discrete parts for the FMR that contain less material than traditionally machined metal or injection-molded plastic parts without sacrificing structural integrity. They also have an ultralow coefficient of thermal expansion. Thermal expansion can be caused by the extreme temperature swings experienced by orbiting satellites and creates undesirable movement that adversely affects antenna performance. While this can be addressed by adding weight to stabilize structures, Harris was looking for ways to lighten the load, not add to it, states McGinn. A rigorous test program conducted over five months has now qualified the parts.

A New Way to Design

Because 3D printing is an additive, rather than subtractive manufacturing process, it can reduce machining time and the resulting waste, saving resources, money, and manufacturing time. Using 3D printing also enables Harris to design antennas with components that are very different from those produced through traditional manufacturing technologies. In many cases, previously complex assemblies of parts can be printed into a single integrated unit. This allows the part to be more mass efficient and optimized for its intended function.  Quality is also significantly improved due to the elimination of workmanship-dependent assembly steps, such as bonding and fastening.

As an example, Harris has been able to use 3D printing for a new reflector to replace a part composed of 25 individual pieces with one single piece of hardware. This eliminated 3.5 hours of production labor and creating a component less susceptible to assembly errors and costing significantly less than the predecessor assembly.

 

*The “Inmarsat S-band/Hellas Sat 3” satellite is a joint Inmarsat/Hellas Sat satellite built by Thales Alenia Space on a Spacebus platform.