Modes of elliptical waveguides: a correction

It is shown that the fields associated with the TM₀₁ (transverse magnetic) mode of an elliptical waveguide are qualitatively different from those which have appeared in the standard literature for the past 50 years, and that the original fields as plotted were also in qualitative disagreement with the analytic expressions which accompanied them. Nonetheless, the cutoff frequencies given for that mode as well as for five other modes are exceedingly accurate (within roughly 1%) for elliptical eccentricities as large as 0.75; for eccentricities in excess of 0.9, the inaccuracy increases from 5% to nearly 50%, depending on the mode in question