High power microwave switch employing electron beam triggering with application to active rf pulse compressors

Abstract

Switch for modulation of the Q factor of a multimode rf energy storage resonator is described. The rf energy is stored in a cylindrical resonator in the TE_{02} mode, and switched out from it in the TE_{01} mode. The operating principle of the switch is based on effecting a fast increase in the TE_{02}→TE_{01} mode coupling coefficient when an electron beam is injected into the switch cavity. This paper focuses on use of the switch in an active rf pulse compressor. Use of the electron beam allows one to separate the switching element from the compressor itself, and therefore to eliminate limitations to the level of switched power that exists for other switches. The pulse compressor was tested at low power at a frequency of 11.424 GHz. The level of peak power gain achieved in these experiments was 19–21, with compressed pulse widths of 30–40 ns. Good stability and repeatability of the shape of compressed pulses was observed. High power versions of this switch appear promising for use in active GW-level microwave compressors.