DC arcing faults pose an extreme safety risk for microgrids because they may cause fire without protection. This paper focuses on the measurement method of electromagnetic signals which can be used for arcing fault detection. A test platform is established at first, which includes a DC arc generator, a well-designed antenna and a spectrum analyzer. Secondly, electromagnetic signals are recorded and analyzed under different arcing currents, voltages, air gaps. Especially, the distances from the arcing source to the antenna are taken into consideration. Finally, the characteristics of electromagnetic signals analyzed in the frequency domain. Test results show that the electromagnetic signals of dc arcing is broad band signals which covers from high frequency to ultra high frequency bandwidth. The very high frequency and ultra high frequency bandwidth can be useful for arcing fault detection due to lower background noises and smaller antenna.