Correlation-based analysis of mode converters in multimode waveguides

In this work, a novel method for the mode content extrapolation in multimode waveguides with focus on the characterization of mode converters is presented. The proposed method is based on the direct determination of the correlation coefficients between the structural functions of all possible propagating modes and the complex measured near-field pattern. To implement the method, standard near-field equipment is simply required. Test simulations and measurements from 4 to 8 GHz on a 6-in. circular pipe for radar level monitoring are reported in the last section and demonstrate that the proposed technique provides accurate information about the mode content of the structure under test.