Fig. 1. Operating principle of TWT

Fig. 2. Operating principle of TWT with feedback circuit

Fig. 3. Operating principle of regenerative feedback oscillator (RFO)

Fig. 4. 0.8 THz folded waveguide module

Fig. 5. Influence of waveguide broadside on dispersion curve

Fig. 6. Influence of straight waveguide length on dispersion curve

Fig. 7. Influence of half period length on dispersion curve

Fig. 8. Influence of waveguide narrow side length on coupled impedance

Fig. 9. Influence of half period length on coupled impedance

Fig. 10. Influence of half edge length of electronic channel on coupled impedance

Fig. 11. Model of regenerative feedback oscillator

Fig. 12. Progress of self-oscillation

Fig. 13. FFT spectrum analysis

Fig. 14. Output signal amplitude

Fig. 15. Output signal power

Fig. 16. Oscillation frequency jumps with the electron voltage