Fig. 1. Sketches of (a) folded rectangular waveguide, and (b) FRCW-SWS

Fig. 2. (a) The model, and (b) the top view of the conducting shield and the dielectric poles in one period

Fig. 3. (a) The model and (b) the top view of the inner conductor and the dielectric poles in one period

Fig. 4. Scalar diagram and vector diagram of electric field intensity distribution of (a,c) the fundamental mode, and (b,d) the second order mode

Fig. 5. (a) Dispersion curves of the FRCW-SWS, (b,c) The normalized phase velocities, and (d,e) the interaction impedances of wave in the FRCW-SWS in various w and t of the second order mode

Fig. 6. (a) The position of electron beam in the SWS, (b) the distribution of sampling points in the cross section of the electron beam, and (c) average pierce interaction impedance in the cross section of the electron beam

Fig. 7. (a) The model, (b) the front cross section view, and (c) the side cross section view of the rectangular coaxial waveguide to rectangular waveguide converter

Fig. 8. (a) Return loss, and (b) insertion loss of the converter

Fig. 9. The transmission characteristics of the FRCW slow wave system with the converters

Fig. 10. (a) The sketch and (b) the transmission characteristics of the truncated FRCW-SWS without the converters

Fig. 11. The diagram of (a) ideal rectangular source face of electrons, (b) presupposed longitudinal uniform magnetic field

Fig. 12. (a) The amplitudes of input and output, (b) the frequency spectrum of output signal, (c) the distribution of the kinetic energy of electrons along with different longitudinal position

Fig. 13. Output power and gain of the FRCW-TWT with 45 mW sinusoidal signal as input signal