A simple, mobile and robust high power wideband source has been developed. It is comprised of a ring switch, a transmission line, and a conical antenna. The resonance is simulated by a finite difference time domain(FDTD) software. A wideband microwave is obtained with a radiation centered on 272 MHz ,and a percent bandwidth of about 13.5%. The resonance system employs a high power source to obtain a voltage-charging level of 71 kV in the switch. The experiment a results show that the radiation electric field is 8.58 kV/m at 3.3 m range, and the radiation is centered on 197 MHz with a percent bandwidth of about 24%.