C-Band Hybrid 3-D-Printed Microwave Isolator

Abstract

This article presents the design and fabrication of a microstrip $C$ -band microwave isolator using additive technology. Such fabrication requires multimaterial 3-D printing (dielectric and absorber) and the embedding of ferrite ceramic inside the substrate. First, our design demonstrated that an efficient microstrip load can be made by 3-D printing in a single process: not only the dielectric but also the absorber, which takes the form of steps in the substrate. Then, a circulator with a composite dielectric/ferrite resonator was designed. Finally, circulator and load were integrated in a single component to optimize the isolator. The device was then 3-D-printed with a pause during the fabrication to allow the ferrite disk to be embedded. Microwave measurements demonstrated that minimum insertion losses of 0.76 dB were achieved, together with a −15 dB bandwidth of 11.9%. To our knowledge, this is the first demonstration of the feasibility of fabricating a non-reciprocal microwave component by additive technology.