Henrik Forstén built a homemade polarimetric synthetic aperture radar drone for about 800 EUR that can image targets at least 1.5 km away. The lightweight system uses a custom 6 GHz FMCW radar, a Zynq 7020 FPGA for signal processing, and a cheap FPV drone platform, achieving four polarization modes and video SAR imaging capabilities. He also released the image formation and autofocus code as torchbp, an MIT-licensed PyTorch extension that runs SAR backprojection on Nvidia GPUs. Drone-borne SAR on a budget is an active research topic: researchers at the University of Birmingham showed in 2021 that a low-cost drone carrying a 77 GHz vehicular FMCW radar can produce imagery with under 2 cm cross-range resolution without a dedicated INS or GPS. This project demonstrates how advanced radar imaging technology previously limited to military and research applications can now be developed at low cost using commercial off-the-shelf components.
