Mode nomenclature for helix waveguide

The possibility of a unique system of mode nomenclature for waveguides is discussed, and tests are described which can be used to ascertain that a proposed system is the unique correct one. The importance of arriving at a correct interpretation of the mode spectrum is pointed out, and an example is given of the way in which different interpretations can lead to different practical expectations. Results of computations by Morgan and Young, and by Bowe and Waldron, of the phase constants of helix waveguide, for various modes, are examined against the above background. It is shown that the interpretation of the mode spectrum made by Morgan and Young does not satisfy the tests, while that made by Bowe and Waldron does. The accompanying note by Morgan and Young is commented on in the light of the foregoing discussion.