Design of a Q-band traveling-wave-tube amplifier

Summary form only given. Design of a Q-band travelling-wave tube amplifier is presented in this paper. Two types of slow wave circuit with folded-waveguide type and helix type are examined in the traveling-wave-tube amplifier. A 3D particle-in-cell code (MAGIC3D), a 3D electromagnetic code (HFSS) and Pierce theory are used in the amplifier design. A highly reproducible, low cost folded-waveguide traveling-wave-tube amplifier is designed to operate at 40-48 GHz with a peak output radiation power of 200 W. Initial circuit parameters are obtained from the Pierce theory and circuit dispersion relations. A non-linear, large-signal performance of the amplifier is predicted from the 3D particle-in-cell simulation. A simulation model of the two stage serpentine circuit is shown. The non-linear numerical simulations predict an electronic efficiency of 5.6%, corresponding to a saturated radiation power 200 W at 44 GHz where the beam voltage is 21 W and the beam current is 0.17 A. The saturated 3-dB bandwidth is found to be 16% (40.5-47.5 GHz). A design of a Q-band helix traveling-wave-tube amplifier is underway.