| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress resonance of high-order modes entering in a gap between a filter box and a waveguide without employing press-fit attaching of the filter box. Ž<P>SOLUTION: In the transmission device with a built-in filter in which a rectangular filter box 12 having a filter 12F with transmission frequency band attenuation characteristics is attached into a waveguide portion 10, for example, a round through-hole 20 is provided at the center portion in a long side direction in a vertical surface (surface of long side of rectangular opening) of the inner wall side of a waveguide portion 10 of the filter box 12. With this configuration, the high-order mode flowing into a subtle gap between the inner wall of the waveguide 10 and the outer side surface of the filter box 12 is returned back into the filter box 12 from the through-hole 20, the high-order mode reflected at the rear surface of a flange 12b is also returned back into the filter box 12 from the through-hole 20, and resonance of high-order modes is suppressed. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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