Additive Manufacturing of Metal Bandpass Filters for Future Radar Receivers

Selective laser melting (SLM) is a powder-bed fusion (PBF) process that bonds successive layers of powder with a laser to create components directly from computer-aided design (CAD) files. The additive nature of the SLM process in addition to the use of fine powders facilitates the construction of complex geometries, which has captured the attention of those involved in the design of bandpass filters for radar applications. However, a significant drawback of SLM is its difficulty in fabricating parts with overhangs necessitating the use of support structures, which, if not removed, can greatly impact the performance of bandpass filters. Therefore, in this study bandpass filters are manufactured in two stages with 304L stainless steel where each builds only a portion of the part to improve the reliability in manufacturing the overhangs present. The results show that the versatility of SLM can produce difficult-to-manufacture bandpass filters with high dimensional accuracy.