| 摘要 |
PROBLEM TO BE SOLVED: To provide a high frequency cutoff filter suppressing higher harmonic wave transmitted in a TM11 mode.SOLUTION: A waveguide having a rectangular cross section includes a convex 201A (and convex 201B) on the short-length cross section direction side of the inner wall face of the waveguide. An electric field in the TM11 mode is strongest at the center of the inner wall face on the short-length cross section side. Therefore, with the provision of the convex 201A and the convex 201B on the short-length cross section direction side of the inner wall face, a transmittable frequency in the TM11 mode varies, so that the transmission of a secondary higher harmonic wave in the TM11 mode can be suppressed in the waveguide transmitting a fundamental wave in a TE10 mode. |
