Additively Manufactured Interdigital Filters for Ultra-Wideband Radar

In this paper, we present the development of two ultra-wideband (UWB) inter-digital cavity filters manufactured with an additive technique. We employed a selective laser melting process with stainless steel via a "flipping and fixturing" approach to achieve dimensional accuracy and frequency selectivity (no post-fabrication tuning) comparable to that of conventional micromachining. Both filters provide 2 GHz of instantaneous bandwidth. Their center operating frequencies are 3.75 GHz and 6 GHz, respectively. This paper presents design and fabrication details, a discussion of the measured characteristics of both filters, and a performance comparison with respect to subtractively manufactured parts.