High power, pulsed soliton generation at radio and microwave frequencies

It is well known that the nonlinear-dispersive system, described by the Korteweg de Vries equation, will convert a pulse into an array of solitons. Work exploiting this effect is well advanced in the optical field using nonlinear optical materials. In contrast, comparatively little work has been done in the area of high voltage electronics using nonlinear dielectric materials, due mainly to the lack of suitable materials. This paper reviews the theory and experimental techniques required to produce a high power pulse of RF or microwave radiation at MW power levels, using a high voltage soliton generator. To generate the solitons, a pulse is fed on to a transmission line which is periodically loaded with a nonlinear ceramic dielectric in the paraelectric phase. The combination of the nonlinearity and dispersion in the line cause the pulse to break up into an array of solitons. The highest frequency solitons generated so far have been produced using a predominately strontium titanate ceramic and operating the transmission line immersed in liquid nitrogen. The work to be presented includes details of the properties and production of the nonlinear materials used, the construction of the transmission lines, the electrical diagnostics and the numerical modelling used to optimise the experiment.