Serpentine waveguide TWT

Amplification over an instantaneous frequency band of 40 to 54 GHz has been achieved in a traveling-wave tube using a rectangular serpentine waveguide as a slow-wave interaction circuit. Such a circuit is much more rugged and is easier to fabricate than a helix circuit in the millimeter wavelength range. In a low-gain Periodic Permanent Magnet (PPM) focused model, more than 300 W with a basic efficiency of over 7 percent was measured at mid-band. Initial beam transmission of more than 94 percent under DC conditions was achieved, with magnetic flux intentionally threading the emitter.