The demand for drone-based synthetic aperture radar (SAR) systems is growing, especially for applications in cases where satellites or airborne systems are not sufficiently flexible. However, the combination of a long operating range and high spatial resolution causes the atmosphere to pose challenges for these systems. In this article, we present our K -band drone system that has a long range sensibility through modification to a commercially available radar. In addition, a moving baseline configuration has been integrated to ensure accurate attitude data, especially the heading. The desired spatial resolution is achieved by our proposed autofocus algorithm based on image sharpness. It is designed to also work in challenging cases of nonlinear flight paths and can be integrated into a processing framework based on back-projection. Several experiments were conducted to demonstrate the drone system's capabilities. These included a comparison with an established airborne radar: MIRANDA35. The obtained results demonstrate the ability of the drone SAR system to map wide areas at high spatial resolution.