Mode content analysis in circular corrugated waveguide using radiated field

The fields radiated from the waveguide were used to analyze propagating mode content in an oversized circular corrugated waveguide. The radiated fields were calculated by the Kirchhoff Integral in the paraxial approximation. The irradiant waveguide modes of the radiated field are orthogonal within the paraxial approximation. The waveguide mode content was evaluated from the irradiant waveguide modes. The radiated intensity and phase profiles were directly measured with a vector network analyzer system at 84GHz for the analysis. The analyzed waveguide mode content was consistent with that excited in the waveguide, predicted by the coupling theory.