Hybrid modes in a square corrugated waveguide

By using two scalar eigenfunctions, electric and magnetic fields in the rec tangular (or square) corrugated waveguide are analyzed. In a rectangular co rrugated waveguide, the boundary conditions on two corrugated and two smoot h walls can be satisfied to excite the hybrid mode. In a highly oversized w aveguide where the wavelength of dominant mode is close to that in vacuum, two smooth walls can be exchanged with the corrugated walls because the bou ndary condition at those walls is satisfied approximately. The replacement is possible due to almost no penetration of the electromagnetic fields into the gap of the replaced walls when the direction of main electric field is parallel to the gap of replaced walls. This characteristic enables us to r otate the polarization of the hybrid mode in the oversized square waveguide with all four corrugated walls and is applicable to the remote steering an tenna for electron cyclotron heating in the ITER.