Chebyshev expansion for accurate and efficient 2D PSP bistatic point target spectrum

The effectiveness of frequency domain processing algorithms in bistatic SAR depends on the accuracy of approximations used for the derivation of the bistatic point target spectrum. This paper presents a modified bistatic point target spectrum based on the 2 dimensional principle of stationary phase with the accuracy improved by the use of a Chebyshev polynomial approximation. The performance of the new method is compared to the conventional Taylor series approximation approach in the approximation of the range-azimuth frequencies coupling variable. The new approach is shown to provide a more accurate approximation reducing the phase error. The accuracy improvement is shown to yield a more accurate spectrum that can be exploited in bistatic SAR focusing algorithms, improving their accuracy and efficiency.