A radio frequency (RF) modulating signal splitter used by a multi-beam electron beam RF amplification system includes an RF input port and a plurality of RF output ports. A body frame distributes the RF modulating signal from the input port to the of output ports. The body frame and each one of the RF output ports have dimensions so that each one of the plurality of RF output ports is impedance matched with each other. In a method of modulating a RF input signal onto a plurality of electron beams, the RF input signal is split into a plurality of different paths directed to a plurality of output ports that are impedance matched to each other. RF energy is directed from each output port to a different input cavity of electronic beam RF amplification devices of a multi-beam electronic beam RF amplification system.