PURPOSE: To obtain a rotary coupler to its rotary shaft of which an antenna on a waveguide is fitted obliquely.

CONSTITUTION: A feeding throughhole 12 is provided to an upper face of a waveguide 11, and a center conductor 4a of a coaxial line is inserted into the throughhole 12 rotatably as a feeding pin. An upper end of an outer conductor 4b of the coaxial line 4 is connected to a metallic circular flat plate 5. An insulator 6 is intervened between the waveguide 11 and the circular flat plate 5. A radial waveguide 1 is provided to an upper part of the circular flat plate 5 freely rotatably and obliquely with respect to a rotary shaft. A coaxial line 13 is loaded to the throughhole 3 provided to a lower part of the radial waveguide 1 and a center conductor 13a is inserted into the radial waveguide 1. A center conductor 4a of the coaxial line 4 and the center conductor 13a of the coaxial line 13 are connected with a flexible coaxial line 16 via plugs 14, 15. As a result, the radial waveguide 1 is rotated while being fitted obliquely.