An electromagnetic energy source for emitting pulses of electromagnetic energy includes a sonde assembly having a first section axially aligned with, and spaced from, a second section. An energy storage capacitor includes an electrode mounted in each of the first section and the second section of the sonde assembly and operable to generate an electric field. A capacitive charge storage medium is mounted in each of the first section and the second section of the sonde assembly and surrounds each electrode, where the capacitive charge storage medium is a giant dielectrics and giant permeability ferrite. A fast-closing switch is located between the first and second sections of the sonde assembly.