Toward Autonomous Navigation of UAVs in 3-D Space: An 8×8 FMCW MIMO Radar With 90$^{\circ }$ Biaxial FOV at 120 GHz

Abstract

As drones and unmanned aerial vehicles (UAVs) continue to proliferate across diverse application domains, the demand for higher levels of onboard automation steadily increases. Autonomous operation requires sensing technologies capable of handling fast-changing three-dimensional airspace while meeting strict size, weight, and power (SWaP) constraints. This paper presents a novel UAV-intended 8×8 MIMO radar frontend operating from 115–125 GHz, developed to maximize environmental coverage while minimizing the number of sensing modules needed. The system architecture is derived from use case driven design considerations that balance wide field-of-view (FOV) requirements with range performance and SWaP limitations. A scalable hardware demonstrator is realized featuring a compact frontend comprising signal generation, a specialized SiGe chipset, and a PCB-based patch-antenna array integrated on an RF board, paired with a laboratory-intended backend for characterization. SISO measurements confirm horizontal and vertical FOVs of approximately 90$^\circ$ and detection ranges beyond 80 m. MIMO operation yields increased signal-to-noise ratio (SNR), enabling extended range and demonstrating the capability to localize obstacles in three-dimensional space. The results indicate that four such frontends could provide full 360$^\circ$ environmental coverage for UAV-intended applications, supporting reliable autonomous navigation in complex three-dimensional airspace.