A Compact 24 × 24 Channel MIMO FMCW Radar System Using a Substrate Integrated Waveguide-Based Reference Distribution Backplane

In this article a compact 120-GHz multiple-input-multiple-output (MIMO) imaging radar is presented. With a module size of only 25 cm, an angular resolution of less than 0.9° is obtained in elevation and azimuth direction using 24 transmitters and 24 receivers. The hardware is based on a SiGe:C MMIC technology and integrated into a modular frontend and backend structure. This article presents the overall hardware architecture of the RF-frontend, including a novel reference oscillator distribution concept and a connectorless board-to-board transition based on substrate integrated waveguides. A fully integrated backend is shown, and the entire radar system is evaluated experimentally and the imaging results are presented, demonstrating the large potential of the presented millimeter-wave 3-D imaging radar.