Abstract:The Frequency Diverse Array(FDA) is a new type of array antenna which can perform beam scanning without phase shifters. The signal propagation feature of spotlight Synthetic Aperture Radar(SAR) is analyzed based on linear FDA. The location of the virtual radiation source is discussed and compared to the real radiation source. It can be used to improve cross-range resolution in spotlight SAR and is of great importance to radar stealth-technology and electronic deception. Simulation results have verified the accuracy of the theoretical derivation.