Three-dimensional ISAR image reconstruction technique with multiple receivers

In this work a new three-dimensional (3-D) model of deterministic components of ISAR trajectory signals with linear frequency modulation is suggested. 3-D ISAR geometry is described based on the analytical geometrical approach. The geometry and kinematics of the object and ISAR observation system are described in separate 3-D Cartesian coordinate system. The object space, moving rectilinearly, is presented as a 3-D regular grid of isotropic point scatterers. The analytical expressions for computing the range distance to point scatterers of the object space are derived. The complex ISAR signal, reflected from the 3-D target is obtained by four receivers, placed on the axes and origin of the coordinate system of observation. Four 2-D ISAR signals, registered by receivers appear to be four 2-D projections of the 3-D ISAR signal. The 3-D image is considered as a set of 2-D images retrieved from the 2-D ISAR signal projections. The image reconstruction procedure includes both range and azimuth compression. Fast Fourier transforms are applied to each 2-D ISAR signal projection to realize range compression and azimuth compression. A synchronized range alignment and an autofocusing technique are applied to each received ISAR signal projection. To illustrate the capability of the 3-D ISAR signal model numerical experiment is accomplished.