Radar-based microwave imaging (MWI) systems have shown encouraging results in early detection of breast cancer; however, there exist remaining challenges. Resolution is one of the most important issues not being addressed with clear theoretical relations in medical MWI systems. In this analytical study, we thoroughly clarify the relation of resolution to the most fundamental aspects of an MWI system, namely, limited-view versus full-view array geometry, monostatic versus multistatic configuration, single-frequency versus wideband operation, and near-field versus far-field imaging. This goal is achieved by expressing the inverse scattering problem in the spatial frequency domain and utilizing K-space representation. Besides, to analyze the MWI system more accurately, the sidelobe level (SLL) of its point-spread function (PSF) is taken into account. We show that generally, the resolution limits of a multistatic configuration are the same as its monostatic counterpart and, hence, have no superiority in terms of resolution. In addition, in imaging with a full-view array, the signal bandwidth has no effect on the resolution. Thus, the single-frequency operation provides the same resolution as the wideband operation. We also demonstrate that the effect of using multistatic configuration or wideband operation is to reduce the SLL of the PSF and, hence, improve the image quality.

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