| 摘要 |
PURPOSE:To obtain a desired elliptic polarization rate even with a small sized aperture of an electromagnetic horn, by providing a high pass waveguide apart by a 1/4-wavelength from a coupling hole provided to a main waveguide of a branching filter, and branching and absorbing electromagnetic waves of a low frequency band. CONSTITUTION:A resonator element 12 which is series resonance state to electromagnetic waves fH of a high frequency band is fitted to a coupling hole 11 provided to a main waveguide 3, and a high pass waveguide 4 which cuts off electromagnetic waves fL in a low frequency band is provided apart by a distance, about 1/4 of the waveguide wavelength or its odd number of multiple, from the coupling hole 11. The waves of fL introduced from a square waveguide 1 to the main waveguide 3 are reflected at the waveguide 4, enter a branch waveguide 13 via the coupling hole 11 and are absorbed in an electromagnetic wave absorbing body 14. On the other hand, the waves of fH introduced to the main waveguide 3 are electrically short-circuited at the resonator element 12, reach the waveguide 4 without being affected with the coupling hole 11 and are introduced to a square waveguide 5. |
