High Resolution Airborne SAR Calibration Technology Research And Precision Analysis

The known radar cross section(corner reflector, tropical rainforests) of calibration equipment are used to get the calibration parameters and calculate the whole image of the scattering cross-sectional area of each cell, this called radiometric calibration. The SAR system without calibration not only owns unstable system but also has a poor measurement repetition rate. And its image also can’t be accurately reflected the actual feature of scattering properties. These weaknesses will directly affect the successful completion of the quantitative remote sensing work. So the calibration of SAR system calibration is imperative.The article studies the SAR radiometric calibration techniques. Firstly, the based on the uniformly distributed target antenna pattern measurement technology was researched. The method which is worked in IDL uses the adjustment idea to remove non-uniform surface features so that we can quickly find the objects in SAR images. Then, the paper applied the method of least squares fitting antenna pattern. The paper also measures the antenna pattern by Envi software. Compared with true values, the IDL method is more close to the true values than the Envi method.Secondly, the commonly four types of corner reflector’s microwave reflection characteristics were studied. Then to the different manufacturing error, the article analyzes the influence of dihedral angle corner reflector and the triangle angle corner reflector. The simulation results show that: the angle and the not flatness make a bigger influence than the other factors.Finally, the article analyzes the advantages and disadvantages of two kinds of calibration constant calculation methods and evaluates calibration accuracy of the integral method and the peak method using experimental data.For the above-mentioned technology and the related conclusion, the article uses the Terra-SAR data and X-band airborne SAR data to do experiment and get the following conclusions: 1.The calibration results were also influenced by different methods. The integration method was more stable than the peak method. 2.The experiments illustrate that the calibration results were effected by different corner reflectors. Compared with square trihedral corner reflector, fan corner reflector, the triangular trihedral corner reflector was more stable. 3.The results show that although airborne SAR calibration was influenced by flight stability of the platform, it could achieve high calibration accuracy.