Experimental investigations of folded-waveguide TWT oscillators

Summary form only given. There have been many efforts to generate THz radiation, among them, the folded waveguide traveling-wave tube (FW-TWT), due to its simple structure, has advantages because it has a high power-handling capacity at higher frequencies and is compatible with planar fabrication using MEMS technologies. A scaled-up experiment as a proof of principle was carried out at Ka-band to investigate the performance of the FW-TWT oscillators. We designed and fabricated the folded waveguide circuits for a backward wave oscillator using the second space harmonic and a delayed feedback oscillator adopting the fundamental forward space harmonic. Relatively low values of the electron beam voltage (12 kV) and current (150 mA) were adopted in order to verify the feasibility of compact and inexpensive high power source comparable to solid-state devices.