The capability to image scenes from unmanned aerial vehicles (UAVs) even through bad weather conditions or dust clouds gets more and more important. In addition, modern synthetic aperture radar (SAR) systems giving very high resolution have to be light and small in size to fit in small aircrafts. In this paper we show a newly designed SAR system using a high flexible frequency generation module. The SAR-system was flown using a microlight and the radar raw data was transmitted to the ground and processed in real-time, so in an operational scenario the user can have an online image of the measurement. One crucial part of SAR-processing is the accuracy of the used inertial measurement unit (IMU). In this project we tested different kinds of these systems and determined the minimum requirements.