Accurate Range Migration for Fast Quantitative Fourier-based Image Reconstruction with Monostatic Radar

This article has been submitted to the IEEE Transactions on Microwave Theory and Techniques and is currently under review.

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Range migration (or range focusing) techniques are widely used in optical, acoustic, and microwave real-time image reconstruction methods. They have been successfully applied to far-field three-dimensional imaging where they rely on plane-wave assumptions, which ignore the data amplitude variation over the acquisition aperture. Their accuracy, however, quickly degrades when applied to close-range imaging, where amplitude variations are significant and where the range distance to the target is on the order of the range sampling step. Here, we present a range-focusing method of improved accuracy, which is applicable to both far-zone and close-range monostatic radar. It refocuses a measured point-spread function (PSF) to any range location, taking into account both magnitude and phase changes. The approach can be applied with any Fourier-based imaging algorithm utilizing the Lippmann-Schwinger equation as the underlying scattering model. Here, it is validated through examples based on simulated and measured data where the images are reconstructed with quantitative microwave holography.