Use of a simple external nonreciprocal attenuator in coupled-cavity TWT's

It is well known that use of a nonreciprocal sever in traveling-wave tube (TWT) design offers several advantages. Previous attempts to obtain these advantages involved incorporation of ferrite material within the envelope of helix TWT's. These attempts have encountered serious difficulties, and have had no apparent effect on TWT design practice. A different approach to realization of a nonreciprocal sever for a coupled cavity TWT is described. This approach involves readily available wave guide components external to the tube, and does not appear to require the solution of significant research and development problems. A computer simulation performed on the CTS 200 W TWT design indicates that a substantial improvement in efficiency could be obtained through use of this technique.