Integration of novel mm-wave components on flexible organic substrates for automotive radar applications

This paper reports on novel mm-wave passive components; namely vertical broadband transitions, a high efficiency aperture coupled microstrip antenna array, and their integration on flexible and organic Liquid Crystal Polymer (LCP) to realize a simple, low cost, passive front end module using a system on package (SOP) concept. Coplanar Waveguide-Coplanar Waveguide-Microstrip (CPW-CPW-MSTRIP) and CPW-CPW-CPW 3D transition designs using strategically placed vias and tapering of the CPW ground planes, which suppress radiation loss and optimize the performance over a very broad frequency range are presented. A four-element aperture coupled microstrip antenna array with a high efficiency of 82% and a gain of 12 dBi at 77 GHz is reported. These structures are simple to realize and are compatible with low-cost substrate fabrication guidelines, thereby allowing for the easy feeding of embedded IC´s in 3D modules, especially in compact automotive radar applications and beam-steering wideband antenna arrays. Measurement results are provided for the 3D transitions to show the proof of concept for the front end passive system.