second harmonic reduction of traveling wave tube amplifier using ferrite material

Traveling wave tubes (twts) consist of different elements. the most important element of twt is the rf circuit. rf circuits in helix twts need a dielectric support to hold the helix; this support also has an effect on electromagnetic properties of rf circuits. a novel dielectric support is proposed to reduce the second harmonic of helix twts. the dielectric support in this structure consists of two sections. the first section consists of dielectric material as used in all twt(s) supports, and the second one is a ferrite rod replacing a portion of the dielectric support. this configuration can act as a tunable band stop filter. the center frequency of the filter can be adjusted based on the second harmonic of the input frequency to reduce the second harmonic of twt without any loss on fundamental amplified signal.