Bistatic SAR Imaging Geometry Performance Metric

摘要

Two bistatic SAR image quality metrics are postulated. The combination of the two metrics provide a quick and computationally non-intensive means of predicting bistatic SAR image quality as a function of collection geometry. The metrics are based on local orthogonality criteria. By noting the fact that all SAR imaging techniques essentially map the downrange and Doppler frequency onto the image plane, it is observed that the downrange and crossrange direction vectors can be obtained via the gradients of the isorange and isoDoppler contours respectively. Using the criteria that maximum image information content is obtained if the downrange and crossrange directions are orthogonal, a metric is postulated which relates the isorange and isoDoppler contour grandients in such a way as to be maximum under such orthogonal conditions. A secondary measure of merit is also postulated related to isoDoppler contour density and crossrange resolution for a given CPI. A good qualitative correlation between the image metrics and reconstructed images of a representative collection of point scatterers was shown to exist.