I. Introduction
Inverse scattering problems (ISPs) in electromagnetic imaging can be highly nonlinear and ill-posed under strong scattering conditions and have therefore found limited use in fields such as large-scale microwave imaging and indoor radio imaging. The nonlinearity and ill-posedness of ISPs can vary based on factors such as the size and relative permittivity () of objects, the incident wavelength (), and the number and type of measurements available. They also increase significantly when the measurements are phaseless [1], [2], [3]. Thus, phaseless data ISPs (PD-ISPs) are more challenging to solve than full data ISPs (FD-ISPs).