Orthomode Transducers (OMTs) are critical components in microwave communication systems, tasked with handling cross-polarized microwave energy and separating it into vertical and horizontal channels. Gregory Peter Le Sage, Program Developer / Manager at SLAC National Accelerator Laboratory developed a high-frequency OMT and initially attempted to 3D print it using Stereolithography (SLA) technology. However, the SLA print did not meet performance expectations, prompting Le Sage to seek alternatives that could offer better resolution and mechanical strength.
Initial Challenges
The SLA printing process, with a resolution of 50 microns, resulted in an OMT with significant performance issues. The device exhibited an insertion loss of 11 dB at 71 GHz, far exceeding the acceptable loss threshold of 1.5 dB observed in the CNC machined prototype. The lower resolution of SLA led to dimensional inaccuracies that adversely affected the OMT’s high-frequency performance, as simulations indicated that even minor deviations of 10 microns or more could drastically degrade the component’s effectiveness.
Redesign and Process Improvement
Recognizing the need for improved resolution and mechanical strength, Le Sage undertook a redesign of the OMT specifically for advanced 3D printing. The redesign aimed to enhance the structural integrity of the part, which would be crucial for both performance and durability. He then selected High-Precision DLP 3D printing technology, otherwise known as Projection Micro Stereolithography (PµSL) known for its superior resolution, to fabricate the redesigned OMT.
Advanced Manufacturing
The new OMT was printed using Boston Micro Fabrication’s (BMF) microArch S240 10µm resolution micro-precision 3D printer. This technology offered a significant improvement over SLA, with a resolution that closely matched the tolerances required for high-frequency applications. After 3D printing, the OMT was electroplated with copper by RePliForm Inc., ensuring that the electroplating was effective due to the improved access to internal surfaces.
Performance Evaluation
The newly 3D printed OMT demonstrated markedly improved performance compared to the SLA-printed version. The insertion loss of the DLP-printed OMT was substantially reduced, approaching the performance levels of commercially available equipment designed for high-frequency microwave applications. This result confirmed that the higher resolution DLP process was critical in achieving the necessary precision and functionality for the OMT.
This case study highlights the impact of 3D printing technology on the performance of high-frequency components. The transition from SLA to DLP 3D printing proved essential in overcoming the limitations of resolution and tolerance, resulting in a functional OMT that met the rigorous demands of microwave communication systems. The success of the DLP-printed OMT underscores the importance of selecting the appropriate manufacturing technology to achieve high precision and performance in advanced engineering applications.
