Experimental Investigation of 95GHz Folded Waveguide Backward Wave Oscillator Fabricated by Two-Step LIGA

Most recently, 95GHz three-dimensional folded waveguide structure including the electron beam-tunnel is completely microfabricated by two-step deep-etch x-ray lithography (x-ray LIGA). The precision and positional tolerance of the circuit elements are respectively 2μ and 2 - 3μm. We experimentally measured its dispersive and attenuative properties through scattering matrices and compare them to analytical and numerical calculations. The MAGIC3D simulation numerically predicted the folded waveguide BWO (FWBWO) has start-oscillation current of 30mA and produces output power of 5Watts at the beam condition of about 12kV and 50mA. Currently, we prepare experiment of the FWBWO equipped with the electron gun.