3D 5G communication Bayesian compressive sensing (BCS) Kolmogorov-Smirnov (K-S) test RCS estimation adjoint inversion methods antenna array antenna testing array diagnosis breast cancer breast imaging compressed sensing contraction integral equation for inversion (CIE-I) contrast source inversion (CSI) contrast-source inversion discontinuous Galerkin method (DGM) electrical-property tomography electromagnetic inverse scattering electromagnetic inverse scattering problems finite-difference methods image-based approach imaging inverse obstacles problem inverse problems inverse scattering inverse source problem joint sparsity linear sampling method magnetic resonance imaging microwave imaging