The extension of the operation frequency range of the resonant BWOs by use of the multistage gratings

The problem of the operation frequency range extension in resonant BWO's is discussed. The methods of the multistage grating analysis are presented. The carried out theoretical and experimental investigations show the possibility of the broad band operation with low start currents at the 2
^nd
pass band of the 3-stage grating. The preliminary design of the slow-wave structure for operation at 220 GHz with 7 % frequency tuning range is carried out.