Stereolithography Additive Manufacturing of Overmoded Spherical Filters

In this paper, we provide an overview of the stereolithography (SLA) manufacturing process applied to the design of microwave filters. For that purpose, a spherical cavity that operates with the higher order mode TE 101 has been used in order to design filters oriented for additive manufacturing. The characteristics of such mode (high Q-factor and size) make it an interesting choice for filters manufactured with 3-D printers. For validation purposes, two doublet prototypes with different configurations and mechanical structures have been manufactured with an SLA 3-D printer, metalized, and measured. Results show various discrepancies between the two prototypes: with measurements matching fairly well with the simulations for one prototype, while a certain frequency shift is present for the other one.