G. Busse et Af. Jacob, COMPLEX POWER AND MODE-COUPLING IN CIRCULAR CHIROWAVEGUIDES, IEEE transactions on microwave theory and techniques, 43(5), 1995, pp. 1182-1186
The total power carried by two (or more) modes of lossless circular ch
irowaveguides is shown to be complex in general, both above and below
cutoff, This is explained by the coupling between modes which, in turn
, proves the lack of orthogonality, at least in the power sense.