Second order motion compensation for squinted spotlight synthetic aperture radar

This paper presents a 2^nd order motion compensation (MoCom) algorithm for squinted spotlight synthetic aperture radar (SAR). A precise compensation of the range-dependent components of the motion error is indispensable for high-resolution SAR systems. Besides, the MoCom has to be compatible with an accurate focusing technique - the Omega-K algorithm in this case. After a proper bulk MoCom and a range cell migration correction, the proposed MoCom accomplishes a phase error compensation considered for every position in the spot. For pulsed SAR with a squint angle of 20° and a depression angle of 20°, the proposed algorithm compensates residual phase errors greater than [-π, +π] radian and obtains significant image quality enhancement. The distinctive feature of the proposed approach is its capability to compensate residual motion errors in the presence of a large squint angle.