| 摘要 |
PURPOSE:To efficiently exhaust the air in a waveguide to a vacuum condition without causing leakage of high frequencies and decline in transmission efficiency, by providing numerous openings in the wall of the waveguide to be maintained under a high-vacuum condition. CONSTITUTION:In the wall of a waveguide 9 openings 12 of a dimension smaller than the 1/2 of the inside-waveguide wavelength of transmitting high frequencies are provided and a manifold 10 is installed to the outside of the waveguide 9 so as to cover the waveguide 9. Then an exhaust port 11 is fitted to the manifold 10 and the air in the waveguide 9 is exhausted through the openings 12 by means of a vacuum pump 3 so as to form a vacuum condition in the waveguide 9. If the minimum interval among the openings 12 is set at or larger than the 1/2 of the inside-waveguide wavelength of the transmitting high frequencies, the high-frequency transmitting efficiency in the waveguide does not decline even if numerous openings are provided. On the other hand, the air inside the waveguide 9 can be exhausted efficiently by means of the vacuum pump 3 even if the dimension of the opening is small, since numerous openings are provided. |
