A　dc　arc　fault　can　be　a　serious　threat　to　the　safe　operation　of　a　low-voltage　dc　system.　Typically,　a　fair　amount　of　electromagnetic　radiation　(EMR)　accompanies　the　arcing　process.　To　investigate　the　characteristics　of　EMR　of　the　series　dc　arc　fault,　a　fourth-order　Hilbert　fractal　antenna　is　used　to　detect　the　EMR　signals　generated　by　the　dc　arc.　The　factors　influencing　the　characteristics　of　EMR　including　electrode　material,　diameter,　current,　and　pressure　are　considered.　The　amplitudes　of　the　EMR　pulses　at　the　arc　initiation　moment　are　measured,　and　fast　Fourier　transform　is　used　to　analyze　the　characteristics　of　the　frequency　spectrums.　The　test　results　indicate　that　the　amplitudes　of　the　EMR　pulses　generated　by　stainless　steel　electrodes　are　higher　than　those　generated　by　brass,　copper,　and　aluminum　electrodes.　Furthermore,　the　trends　of　the　amplitudes　of　the　EMR　pulses　with　increasing　current　are　different　for　electrodes　with　different　diameters.　Finally,　it　is　observed　that　the　influence　of　the　pressure　is　different　for　different　electrode　materials.　The　characteristic　frequency　band　of　the　EMR　pulses　of　the　dc　arcs　generated　under　various　test　conditions　is　in　a　certain　range　(36-41　MHz),　which　can　be　used　as　a　detecting　characteristic　parameter　for　the　series　dc　arc.　IEEE