10 
- 151 ,, 1 ,, 
-3000 -2000 -1000 0 1 000 2000 
rel. ground range [m] 
Figure 7: Comparison of E-SAR and AIRSAR cr° profiles. 
6 - CONCLUSIONS 
This paper shows that great progress has been made in calibrating SAR data, especially in 
recent years. Successful experiments using airborne sensors showed that the calibration goals are 
achievable. We learned a lot from these experiments not only about the techniques and algorithms 
but also about the logistics of ground measurement campaigns. Our comer reflectors showed a 
good performance and have been very useful for external calibration and checks of the overall 
system stability. In summary we feel well prepared for experiments and the project support for the 
SIR-C/X-SAR mission. 
REFERENCES 
[1] Zink M., F. Heel and H. Kietzmann, 1991. The Oberpfaffenhofen SAR Calibration Experiment 
of 1989. Journal of Electromagnetic Waves and Applications, Vol. 5, No. 9, pp. 935-951. 
[2] Seifert P., H. Lentz, M. Zink and F. Heel, 1992. Ground-Based Measurements of Inflight An 
tenna Patterns for Imaging Radar Systems. IEEE Trans. Geosci. Remote Sensing, Vol. 30, No. 
6, pp. 1131-1136. 
[3] Zink M., 1993. X-SAR Calibration Plan, Part 1 and 2. Can be ordered directly from the author. 
[4] Jordan R. L., B. L. Huneycutt and M. Werner, 1991. The SIR-C/X-SAR Synthetic Aperture 
Radar. Proc. IEEE, Vol. 79, No. 6, pp. 827-838. 
[5] Zink M., H. Ottl and A. Freeman, 1993. Design of a Monopulse SAR System for the Determi 
nation of Elevation Angles. Submitted to IEEE Trans. Geosci. Remote Sensing. 
[6] Zink M., Ph. Olivier and A. Freeman, 1993. Cross-Calibration between Airborne SAR Sensors. 
IEEE Trans. Geosci. Remote Sensing, Vol. 31, No. 1, pp. 237-245.