A forward-looking 3-D SAR imaging model using unequally spaced array

A forward-looking 3-D SAR imaging model using an unequally spaced array is proposed in this paper. Firstly, based on the problems that a real equally spaced array suffers, like heavy calculation, the couple between antenna elements, an unequally spaced array with optimized element positions, is obtained by Simulated Annealing. Compared with several different types of arrays, the unequally spaced array has obvious advantages: when the lengths of arrays are the same, it successfully avoids the presence of grating lobes in the beam pattern, and needs much less number of array antennas than the real array does; when the number of array antennas is fixed, it has narrower main-lobe than the real array. Furthermore, the signal model of the forward-looking 3-D SAR is analyzed and using BP algorithm the simulation results are presented, validating and verifying the feasibility of this model to reconstruct a 3-D scene.