In　the　popular　electromagnetic　exploration　technique,　a　bipolar　artificial　pulse　current　is　emitted　from　an　electromagnetic　transmitter　into　the　ground　to　generate　a　transient　secondary　electromagnetic　field　in　the　surface　strata,　and　the　geological　structure　in　obtained　by　analysing　the　distribution　of　the　secondary　magnetic　field.　This　paper　presents　a　cascaded　electromagnetic　transmitter　to　overcome　the　drawbacks　of　the　existing　transmitters.　First,　the　structure　and　composition　of　the　earth　load　are　analysed　when　the　transmitter　is　working　in　the　low　frequency　or　high　frequency　mode,　and　the　relationship　between　the　earth　load　and　the　emission　frequency　is　provided　directly.　Then,　based　on　the　small-signal　model　of　phase-shifted　full-bridge　converter,　the　influencing　factors　on　the　stability　of　the　source　converter　are　analysed　and　summarized　in　details　when　the　transmitter　worked　in　the　whole　frequency　range.　Moreover,　we　have　derived　the　possible　solutions　to　ensure　the　steady-state　and　dynamic　features　of　the　source　converter　output　in　the　whole　frequency　range.　Two　methods　are　developed　through　detailed　analysis:　increase　the　gain　of　the　voltage-loop　transfer　function,　and　increase　the　output　filter　inductance　of　the　source　converter.　Finally,　the　research　findings　have　been　verified　by　a　prototype　through　an　experimental　simulation.　©　2017　AMSE　Press.　All　rights　reserved.