3-D pyramidal and collective Ku band pass filters made in Alumina by ceramic stereolithography

An original 3D pyramidal geometry for a low loss and compact (10.5 mm by 10.2 mm by 2 mm) filter is described in this paper. Nine low footprint Alumina filters are manufactured in one single fabrication by a 3D ceramic stereolithography process. Thank to this technology, high unloaded quality factor resonators (above 1000) have been fabricated and associated to create a low footprint 4-pole Chebyshev filter. Its shielding has been created with a Copper and Gold sputtering technique and its input and output coplanar accesses have been etched by a laser ablation technique. The association of these 3D technologies for the collective manufacturing of many filters in one ceramic part, has led to a low insertion loss filter working around 17.5 GHz. This paper goes into details on the theoretical synthesis, design, fabrication and measurements of a Ku band pass filter dedicated to space applications.