Absolute radiometric calibration of Kondor-FKA SAR using images of test calibration site in Amazonian forests

Amazonian forests are known to be stable distributed calibrating target being explored in various frequency bands, therefore they are widely used worldwide for spaceborne SAR calibration and intercalibration. Based on the analysis of scattering properties of Amazonian forests acquired in foreign SARs missions in various frequency bands the prediction the signal backscatter for domestic S-band SAR is made in the paper. A list of the operating parameters and description of Kondor-FKA SAR geometry of observations in 6 data takes over the calibration test site is provided. An algorithm of the SAR image synthesis with the stages of radiometric data correction is described. As a result of the radiometric correction the signal power on the image is made regardless of the SAR operating parameters and geometry of observations. An expression for the absolute radiometric calibration coefficient relating the signal power in the image to normalized radar cross section is derived and an experimental estimation of the calibration coefficient is made. A statistical analysis of the echo signal power in images demonstrated high overall temporal stability (~0.25 dB) of both forests scattered signal level and the stability of the Kondor-FKA SAR transmit/receive path. An assessment of radiometric sensitivity and an onboard antenna beam width was made. The results obtained meet the requirements of the technical specifications.