3D Printed Waveguide Transition for 77 GHz Radar Applications

A novel approach of a differential microstrip line to a rectangular waveguide realized by an alternative manu-facturing method, based on additive manufacturing, is presented. In comparison with conventional machining, this approach offers an improved behavior regarding weight, costs and uncomplicated alignment with simultaneous high manufacturing accuracy. The transition is designed for applications in the frequency range of 70 - 90 GHz in particular for automotive radar at 77 GHz but yet can easily be adapted for other frequencies. Measurements are carried out stating a return loss of /S11/2 < -24 dB and an insertion loss /S21/2 better than -1.3 dB at 77 GHz for the transition. To demonstrate excellent suitability for hybrid circuits an analysis of manufacturing tolerances and resulting degradation on the performance of the transition have been conducted. The measurements of this analysis prove a high reproducibility and robustness of the promising technology even for precision demanding mmW applications.