For the most part, high power RF generators are large, heavy and usually need large external power supplies to drive them. Many of these generators require large auxiliary power supplies for filament circuits. There has been an increased interest in the use of Hertzian or spark transmitters as a means of generating extreme power levels because of geometric simplicity as well as inherent limitations on electron beam devices. They are usually limited in size and power due to the need for extremely high voltage supplies and a general lack of suitable dielectric materials.
Current vacuum tube transmitters in this frequency range are limited to peak powers in the 100 megawatt range and weigh several tons. Hertzian generators operating in the same frequency range need large high voltage power supplies, have severe insulation difficulties or require complicated multiple switching to satisfactorily perform. These transmitters also have constraints placed upon them which tend to limit energy storage, operating frequency, efficiency and pulse characteristics.