Hollow waveguide-based devices represent one of the most demanding classes of millimeter-wave components from a manufacturing perspective. Their performance depends critically on maintaining precise cross-sectional dimensions, tight straightness tolerances over extended lengths, and exceptionally smooth internal surfaces to minimize RF loss. These requirements become increasingly difficult to meet as operating frequencies rise and waveguide dimensions shrink into the sub-millimeter regime.
The hollow waveguide components shown in this work were manufactured by Horizon Microtechnologies using micro-precision additive manufacturing based on Boston Micro Fabrication’s (BMF) 3D printing technology, followed by Horizon’s proprietary internal metallization process. BMF’s micro-AM platform enables the fabrication of long, narrow, and internally complex waveguide geometries with micron-level dimensional control — geometries that are extremely challenging or impractical to produce using conventional CNC machining, split-block construction, or electroforming.
Using micro-precision 3D printing, waveguide bodies can be produced as monolithic polymer structures with fully enclosed internal channels, eliminating the need for split-block assemblies and the associated risks of misalignment, seam leakage, and assembly-induced RF loss. This approach is particularly advantageous for devices such as waveguide twists, orthomode transducers, and other branched or multi-port devices – think couplers or multiplexers, where internal features must remain precisely registered along the full length of the structure.
Following printing on BMF’s platform, Horizon applies a conformal internal metallization that fully coats the waveguide interior, including tight corners, junctions, and extended internal surfaces. The underlying printed surfaces already exhibit very low roughness, allowing the metallized waveguides to achieve smooth, electrically continuous internal walls with conductivity comparable to the highest conductivity bulk metals such as copper. This combination is essential for maintaining low insertion loss and stable mode propagation at mm-wave frequencies.
The WR3 orthomode transducer shown here exemplifies this capability. The waveguide body was 3D printed using BMF’s micro-precision additive manufacturing technology, enabling accurate realization of the compact internal geometry required at this frequency range. Horizon’s subsequent metallization process ensures uniform coating thickness and consistent RF performance throughout the structure. Compared to traditionally manufactured waveguides, this approach enables lighter components, reduced part count with no or limited assembly tolerances, and significantly greater design freedom without compromising electromagnetic performance.
By combining BMF’s micro-scale additive manufacturing accuracy with Horizon’s metallization and application engineering expertise, hollow waveguide-based devices can be produced with shorter lead times, lower mass, and higher geometric complexity than is achievable with conventional manufacturing methods. This makes precision AM a compelling and production-ready solution for next-generation mm-wave waveguide systems in aerospace, communications, and scientific instrumentation.
