Three octaves with one TWT

This paper reports on work aimed at developing helix traveling wave tubes having a 9 to 1 instantaneous bandwidth (3.2 octaves) and delivering 100 W CW. By use of an unusual velocity step and other techniques, the output circuit of such a tube can be made to operate at very wide bandwidths. Test results from a prototype tube are reported. Although the prototype did not achieve the full design bandwidth, it did show good performance over a 6.7 to 1 band (2.74 octaves). Additional prototypes are under construction in order to further optimize the bandwidth performance.