To provide a rotary joint for high-frequency transmission capable of effectively preventing occurrence of discharge in a waveguide, even in the case of transmission of microwaves with a frequency of 10 GHz or higher under a large power of 10 MW or higher, thereby being capable of stable transmission of the microwaves.
A rotary waveguide includes a pair of waveguides 12, 14 including high-frequency transmission hollow waveguide paths 12b, 14b in their inside and connected mutually turnable about a coaxial axis center. A coating film 10 with a substance, whose conductivity is lower than that of a substance configured on the inner circumferential face of a cylindrical part is formed at high electric field positions A, appearing periodically along the inner circumferential face of the cylindrical part of the waveguide 12 in the axis direction.
MATSUO KENICHI
ISHIDA ONORI
TOKUNAGA CHIEKO
