The project "Passive and active SAR 21-24" has been conducted 2021-2024. The goal has been to increase knowledge of passive and active synthetic aperture radar (SAR), and in particular to investigate airborne passive SAR as a possibility to increase persistence of future radar systems. The project has developed new signal processing and performed experiments with FOI's airborne SAR system. Unique results from passive imaging of air and ground targets are shown using signals from digital-TV broadcasting transmitters. The results point to a good capability of detecting military relevant targets with passive SAR. The technique has potential for future developments but has also limitations.