From One Hundred Parts Down to One

Antennas are critical for conveying information – voice, video and/or data – across long distances. They are widely employed in commercial and military aircraft, spacecraft, satellite communications, unmanned aerial vehicles (UAVs), and by ground terminals and land-based troops. Yet the complex radio frequency (RF) components that make up an antenna system can be large and heavy, characteristics that can impact mobility and performance. “Companies in the commercial and military space are pressured for shorter lead times, lighter weight and smaller antennas,” says Clinton Cathey, the chief executive officer of Optisys LLC (West Jordan, UT), a provider of sophisticated 3D-printed metal micro-antenna products for high performance aerospace and defense applications. Their team has a combined 60 years of aerospace experience in SATCOM (satellite communications), RF design, LOS (Line-of-Sight) communications and mechanical design.

“We’ve spent years on parameter and process development of our antenna-system optimization technology package,” explains Cathey. “We validate our designs through simulation, test to all aerospace frequencies, and manufacture military-ruggedized production parts.” They have a number of patents pending and are in discussions with leading aerospace companies and academic institutions about expanding their portfolio of product lines. “By combining RF design simulation, mechanical engineering, and system optimization focused on additive manufacturing, we can greatly reduce the size, weight, lead times, part count and cost, with as-good or better RF performance than conventionally manufactured systems. We’re creating structures that simply were not possible to produce in the past,” he adds.

Optisys recently completed a project that documents the significant advantages of employing additive manufacturing to produce such systems. Their test-piece demonstrator project involved a complete redesign of a high-bandwidth, directional tracking antenna array for aircraft (known as a Ka-band 4×4 Monopulse Array). They performed every aspect of the design work in-house and printed the component in a single piece on their powder-bed fusion machine from Concept Laser Inc. (Grapevine, TX). “Powder-bed fusion in particular is perfect for this application because of the fine resolution it provides for antennas functioning in the one GHz to one hundred GHz range of RF in which most of our potential customers operate,” notes Cathey.

“Manufacturing antenna systems via conventional methods, such as brazing and plunge EDM, is a complex multi-stage process that can take an average of eight months of development time and three to six more months of build time,” states Robert Smith, ME, the chief operating officer of Optisys. “Our unique offering is that we redesign everything from an additive manufacturing perspective. We take into account the entire system functionality, combine many parts into one, and reduce both development and manufacturing lead times to just a few weeks. The result is radically improved size and weight at lower costs.” They conducted a profitability analysis on how their redesigned microwave antennae test piece compared to a legacy design that is traditionally manufactured. By optimizing their design for additive manufacturing, they realized the following benefits:

• Part count reduction from 100 discrete pieces to a one-piece integrated assembly.
• Weight savings of over 95 percent.
• Lead time reduced from 11 months to two months.
• Production costs reduced by 20 percent to 25 percent.
• Non-recurring costs reduced by 75 percent.

There are other advantages in 3D printing. “In addition to what our test-piece project revealed, 3D printing offers a number of other advantages,” says Smith. “When we design multiple antenna components into a single part, we reduce the overall insertion loss of the combined parts. And because our antennas are so much smaller, this also lowers insertion loss dramatically despite the higher surface roughness of AM build, for similar or even better RF performance than conventional assemblies.”

Optisys can print in a variety of metals using their powder-bed fusion machine, though for antenna products they prefer aluminum because of its surface conductivity, light weight, corrosion resistance and strength under shock and vibration. “3D-printed metal will have virtually the same properties as a solid piece of the same material for RF performance,” explains Smith. “Structurally the products have been tested in rigorous vibration environments and they also have the same coefficient of thermal expansion (CTE) as wrought metals. This also gives them better stability over temperature than plastic RF components. Part consolidation through AM provides a number of downstream benefits as well. Reducing part count also reduces assembly and rework. It’s easy to add features to an existing AM design, easier to assemble the finished components and, long-term, you have less testing, maintenance and service when you have fewer parts.”