Multi-frequency Backward Propagation

I perform image formation by applying the backward propagation technique in two ways. First, I apply the technique across all aperture data points while gradually increasing the bandwidth of the transmitted chirp. Second, I apply the technique using a wide band of frequencies for each individual aperture data point and sequentially combine the reconstructions. In either method, as the sub-image range profiles are gradually added together, the reconstruction of the source region is improved. The technique is applied for a source region consisting of three point sources. The magnitude content of Green’s function is ignored. I find that the image resolution, aperture size, and spectral coverage are closely related.