Electromagnetic　inverse　problems　have　been　traditionally　solved　in　frequency　domain.　The　time-reversal　method　has　been　developed　to　offer　an　alternative　approach　in　time　domain　with　natural　time　stepping　computations.　However,　in　its　applications　to　electromagnetic　source　reconstruction,　much　work　so　far　has　not　considered　possible　different　excitation　times.　In　this　paper,　the　concept　of　entropy　used　in　image　processing　is　incorporated　into　the　time-reversal　process,　which　leads　to　reconstructions　of　not　only　the　spatial　locations　but　also　the　excitation　times　of　the　sources.　Experiments　are　also　set　up　for　verification　purposes　and　the　proposed　work　may　pave　the　way　for　practical　applications　of　the　time-reversal　method.　The　effectiveness　of　the　method　is　proposed　to　solve　realistic　problems　in　future　experimental　test.　©　2020　IEEE.