PURPOSE: To absorb a polarized wave component not in use by providing 1st and 2nd circular waveguides, a square branch waveguide including a filter reflecting a high frequency signal and a conversion waveguide leading one of 2 linearly polarized wave signals to the square waveguide and absorbing and attenuating the other signal.

CONSTITUTION: A horizontal polarized wave signal in 4GHz is coupled with a branched waveguide 23 with a slit 26, sent to a 4Ghz output terminal 28 through a band pass filter 27 and not coupled with a selective absorbing load 24. The 4GHz band vertical polarized wave signal is not coupled with the slit 26, coupled with a coupling loop 29 and absorbed to a resistive terminator 31 through a low pass filter 30. A 6GHz band vertical polarized wave fed to a 6GHz input terminal 32 is sent to a circularly waveguide 22 without being affected by a horizontal resistance plate 33 in a conversion waveguide 25 and not coupled with the coupling loop 29. Moreover, the wave is sent as it is to the circular waveguide terminal 34 without being affected by the slit 26. The 6GHz band horizontal polarized wave from the terminal 34 is not coupled with the branch waveguide 23 and the load 24 but enters the waveguide 22 and is absorbed by the resistance plate 33.