Inverse Omega-K Algorithm for the Electromagnetic Deception of Synthetic Aperture Radar

Abstract

Deceptive jamming against synthetic aperture radar (SAR) receives intensive interests during the past decade. However, it is still a challenging task to design a jamming method that is competent both in focus capability and in computational efficiency, especially in the case where jammer is confronted with SAR with significant squint angle and long synthetic aperture. In this paper, we propose an inverse omega-K algorithm and present an accurate and an approximate implementation scheme of the algorithm. The accurate scheme can achieve full focus with no regard to the squint angle and synthetic aperture of radar. Its computations include fast Fourier transform (FFT), Stolt interpolation, and complex multiply. Advantage of computational efficiency can be achieved under assumption that the support region of radar can be crudely evaluated a priori so that the most time-consuming Stolt interpolation can be done offline. The support region is determined by carrier frequency and bandwidth of radar signal, pointing direction, and azimuth beam width of radar antenna. For the case in which the support region of radar is not available to jammer beforehand, the approximate scheme is a remedy. By substituting the Stolt interpolation with Chirp-Z transform (CZT), the approximate scheme is readily fit for parallel computation and hence appealing for its high efficiency. However, the focus criterion exerts a limitation on range scale of electromagnetic deception when the squint angle of SAR is large. Both implementation schemes are verified by simulation results.