1. A wideband synthetic aperture radar (SAR) imaging system, comprising: a probe having an aperture through which a signal is transmitted incident to an object located in a medium of interest remotely from the probe and through which a plurality of nonuniformly sampled reflected signals from the object are received by the probe as the probe moves in a measurement plane located a predetermined distance from the object; a memory for storing measurement data representative of the reflected signals collected by the probe; a processor for executing a plurality of computer-executable instructions for a SAR-based reconstruction algorithm, said instructions comprising: instructions for performing a spectral estimation based on the measurement data; instructions for transforming a frequency component of the spectral estimation as a function of the medium of interest; instructions for obtaining an intermediate three-dimensional SAR image from the transformed spectral estimation data using Fourier transforms; instructions for segmenting the intermediate three-dimensional SAR image into a plurality of segments in an image domain, wherein each segment includes a spatial bandwidth of a plurality of spatial bandwidths of the intermediate three-dimensional SAR image; instructions for transforming each of the plurality of segments from the image domain to a measurement domain, wherein each of the plurality of segments is represented as partial data; instructions for performing an optimization operation on each of the plurality of segments based on a comparison between the partial data thereof and the measurement data; instructions for recombining the plurality of segments to produce a final three-dimensional SAR image; and a display responsive to the processor for presenting the final three-dimensional SAR image to a user.