A new differential switched oscillator is designed to generate a differential damped sinusoidal signal with a center frequency of 300 MHz. Besides, a radiation system based on a differential switched oscillator and associated helical antenna is designed and analyzed. Firstly, the differential switched oscillator with the same central frequency is compared with the single-ended switched oscillator, which shows that the withstand voltage and output voltage of the differential switched oscillator are twice that of the single-ended switched oscillator. Secondly, the design of a differential switched oscillator is introduced. The characteristic impedance and the static electric field distribution of the oscillator are analyzed. The transient performance of the oscillator is simulated. Thirdly, a differential helical antenna is designed as the radiation antenna, in order to match the output form of the differential switched oscillator. Finally, the experimental result with different nitrogen pressure at different radiation distances is introduced. The radiation systems based on single-ended switched oscillator and differential switched oscillator are compared. It is shown that the radiation system can generate a high power mesoband EMP with a center frequency of 300 MHz and a percent bandwidth of about 20%. The maximum intensity of electric field is about 18 kV/m and the radiation factor is about 110 kV. The electric field intensity of the differential radiation system is twice that of the single-ended radiation system.