Additively manufactured antennas based on slotted ridged waveguides for 77 GHz MIMO radar applications

In this work an additively manufactured waveguide antenna array for automotive radar applications is presented. The antenna is based on a slotted single ridged waveguide design with four radiating elements in the elevation plane. This allows for a λ
0
/2 spacing at 76 to 77 GHz, which is desirable to minimise azimutal angular ambiguities in automotive radar applications. The influence of adjacent surfaces close to the radiating slots in the azimutal field of view (FoV) is evaluated based on simulations and measured prototypes, especially demonstrating its role when extending the FoV towards ±70°. Furthermore, the impact on mutual coupling with neighboring antenna elements and the interaction of several channels with the arrays’ cover are evaluated based on a 4x4 channel array prototype, which is also manufactured and measured. The entire antenna arrays are manufactured monolithically with a photopolymer based 3D-printing process and subsequently electroplated in cooperation with Golden Devices GmbH.