Effects of structure parameters on output characteristics of folded waveguide traveling wave tube

Effects of the structure parameters, including the ratio of b/a, the height of the folded waveguide, the width of the beam tunnel, on the output characteristics of the terahertz band folded waveguide traveling wave tube are analyzed. Calculation results show that there exists an optimal value of b/a for the maximum small signal gain and the coupling impedance. With the increasing of the width of the beam tunnel, the attenuation constant will increase markedly. Thus the small signal gain and the coupling impedance will decreased markedly. Both the attenuation constant and the small signal gain are relatively insensitive to the height of the folded waveguide. The results are useful to the design of the folded waveguide tube in practical applications.