RESULTS OF AN ERS-1 C-BAND SAR CALIBRATION EXPERIMENT IN JAPAN

An ERS-1 Synthetic Aperture Radar (SAR) radiometric-calibration experi ment was carried out at the Akita test site in Japan during the ERS-1 commissioning-phase operations on 10-16 November 1991 as a part of the ECISAR activity, an international collaboration for ERS-1 SAR calibra tion. The instruments used were square trihedrals with leg lengths of 0.46, 0.6, 0.85 and 1.1 m, and a receiver for SAR antenna-pattern meas urements. The test site, the disused Akita Airport, was successfully o bserved twice by the ERS-1 SAR and the data were received and processe d by NASDA to produce images. These Level 2.1 products, on which radio metric and geometric corrections were performed, were used for the rad iometric-calibration experiment. From the image-intensity analysis inv olving the radar cross-section and the spatial-resolution analysis usi ng the trihedral image, the proportional constant was determined to re late the image data to the target's microwave backscattering character istics. The SAR antenna pattern in the azimuth direction was measured with a dynamic range of 40 dB. The peak sidelobe level was about 13 dB below the main lobe peak, showing good antenna characteristics.