Near-Field Focusing of a Fast Electromagnetic Pulse

A new domain of pulsed electric field interactions with cell structures has been opened by using subnanosecond pulses, which are much less than the membrane charging time, allowing a direct electrical field-inner cell molecule interaction. This ultrashort pulse (rising 100 or so ps) also provides a possibility of guiding the energy into the deeper layers of biological targets nonintrusively. We are developing a wideband pulse system for focusing in the near field. This system has a spheroidal reflector with two focal points. A spherical TEM wave is launched in a rotationally symmetric structure towards the reflector from the first focal point by using a biconical radiator. Design issues like optimization of the reflector, biconical structure, feeding impedance and possible measurements will be presented.