Quasi-optical waveguide-mode converters using a pair of phase correction mirrors

This paper describes a quasi-optical method for the conversion of modes transmitted through highly oversized circular waveguides. A waveguide-mode is radiated once from a waveguide cut in the form of a radiation beam, which is then properly shaped by two curved mirrors and directed back into the waveguide. The curved mirror shapes are iteratively and automatically determined for given propagation distances using the design technique for phase correction mirrors. The proposed method gives favorable results in designing a waveguide expander/reducer, a TE₀₁-TE₀₂ mode converter, and a TE₀₁-HE₁₁ mode converter.