A reflecting electron tube for producing high-power, high-frequency, monoomatic microwave pulses includes an anode which produces little or no ion flux when struck by electrons emitted from a cathode, and requires no applied, external magnetic field. An anode support holding the anode and a cathode shank which supports the cathode are positioned within a vacuum chamber such that the anode is closely spaced from the cathode. The anode support is connected to a pulsed high-voltage supply located external to the chamber. The anode is formed from a material which does not produce a significant amount of ion flux but does permit electrons emitted from the cathode to oscillate through the anode. Electrons oscillating in phase bunch together within the potential well of the system and emit microwave radiation.