Abstract :
Helix-type traveling-wave tubes are known for their potential multi-octave bandwidth capability. However, at bandwidths of the order of 2:1 or greater, the power output spectrum of typical amplifiers consists of the input frequency and its harmonics. If the input signal is located near the low frequency edge of the amplification band, the second and third harmonic powers become appreciable and may exceed that of the fundamental. Hence, the fundamental efficiency is seriously degraded and the multi-frequency output spectrum seriously deteriorates broadband systems performance.
