To provide a converter for receiving linearly polarized wave at a reduced manufacturing cost with superior cross polarized wave characteristic.

One end of a circular waveguide 1 is open and the other end is closed by a short plate 5. Providing projections 2 to the inner wall of a circular waveguide 1 configures a 90-degree phase shifter and providing a partition 3 to the inside of the circular waveguide 1 configures a partition polarizer. Then a probe 4 is respectively placed to two semicircular waveguide sections separated by the partition 3.