Complex waves in a slot-waveguide line and a new approach to estimating the correctness of solving electrodynamic problems formulated in an unclosed form

The spectrum of waves in a slot-waveguide line, including complex waves, is calculated. The transformation of the spectrum under the variation of the parameters of the structure is studied. A new criterion is proposed for estimating the correctness of solving electrodynamic problems, which is based on calculating the power flux of complex waves (averaged over the period) through the cross section of the structure.