Development and Preliminary Results of Small-Size Uav-Borne Fmcw Sar

The small-size unmanned aerial vehicle (UAV) is being used widely in many fields, especially in surveying, mapping and remote sensing. Due to the platform's size and load ability, its payload is strictly limited. Synthetic aperture radar(SAR) is a kind of microwave imaging instrument with high performance under all weather, day and night conditions. Highly miniaturized SAR can satisfy the requirement of observation on small UAV. Frequency modulation continuous wave (FMCW) technology provides a way for small volume, low cost, high reliability and high resolution SAR. FMCW SAR transmits frequency modulated signal continuously. This reduces the peak power, which is the important factor determining the size and cost of SAR. Meanwhile, due to transmitting and receiving signals simultaneously, increasing the isolation between the transmitter and receiver becomes associated problem. Two separated antennas solve the problem partly. There is another problem in processing algorithm. Long duration of signal makes the assumption of stop and go model ineffective. Frequency scaling algorithm has to be chosen to correct the phase variation during one period of frequency sweep. Procedure of development for prototype and practical systems and verification experiments are shown in this paper. The results of experiments with such radars prove the expected performance.