TWT metal line
Microwave electron tubes - Traveling Wave Tubes

This term covers several families of traveling-wave tubes, in which the helix gives way to a "massive" periodic metal structure, enabling higher peak and average power to be achieved, at the expense of bandwidth. Initiated by Stanford University physicist Marvin Chodorow, the development of these tubes dates back to the early 1950s, when they were applied to air defense and then airborne radars. Today, metal line TWTs offer attractive solutions in millimeter bands, in particular for missile homing beams and satellite uplinks, and perhaps tomorrow for microwave beams for 5G networks.