Correction of platform motion effects in airborne downward-looking thinned array 3D SAR

General side-looking SAR can not obtain scattering information of the observed scenes which are constrained by lay over and shading effects [1~2]. Downward-looking thinned array 3D SAR can be placed on small and mobile platform, allows for acquisition of full 3D microwave images and overcomes the restrictions of shading and lay over effects in side-looking SAR [3]. Downward-looking thinned array 3D SAR can be developed for various applications, such as city planning, environmental monitoring, DEM generation, disaster relief, surveillance and reconnaissance. In this paper, the thinned array we used is composed of multiple transmitting array elements and multiple receiving array elements placed sparsely along cross-track dimension that work on time-divided mode [4]. As there are dozens of array elements in the thinned array, the whole transmitting-and-receiving procedure is quite long that the conventional stop-and-go approximation used in general side-looking SAR can be not valid anymore, therefore the platform motion during time-divided transmitting-and-receiving procedure needs to be taken into account [4~5]. Analytical development, starting from downward-looking thinned array 3D SAR signal model signal model and take the platform motion during time-divided transmitting-and-receiving procedure, is presented in this paper. The effect of the platform motion during the transmitting-and-receiving procedure, if not compensated for, can become seriously degrading for the 3D SAR image quality. The platform motion correction is then verified by numerical simulations.