title: Comment on "Dynamics and properties of waves in a modified Noguchi electrical transmission line".
abstract: A recent paper [Phys. Rev. E 91, 022925 (2015)PRESCM1539-375510.1103/PhysRevE.91.022925] presents the derivation of the nonlinear equation modeling envelope waves in a specific case of band passed filter discrete nonlinear electrical transmission line (NLTL), called "A modified Noguchi electrical transmission line" according to the authors. Using the reductive perturbation approach in the semidiscrete approximation, they showed that the modulated waves propagating in this NLTL are described by the ordinary nonlinear Schrödinger (NLS) equation. On the basis of their results, the authors claimed that all previous works on the band passed filter NLTL, which considered the vanishing of the dc component of the signal voltage, are incorrect, and this dc term is nonzero. As a consequence, the dispersion and nonlinearity coefficients of the NLS equation are strongly different from those usually obtained, and they found, according to the sign of the product PQ, the existence of one more region (compared to the work of Marquié et al. [Phys. Rev. E 49, 828 (1994)]PLEEE81063-651X10.1103/PhysRevE.49.828) in the dispersion curve that allows the motion of envelope solitons of higher frequency in the system. In this Comment we provide sufficient theoretical and numerical evidence showing that the evidence obtained by the authors otherwise is due to certain terms missed in their mathematical developments when they derived the NLS equation. Our results also suggest that the previous work of Marquié and co-workers correctly predict the fact that the dc term of the signal voltage does not exist and there exist only two regions in the dispersion curve according to the sign of the product PQ.
authors.affiliation: Laboratoire de Mécanique et de Modélisation des Systèmes Physiques, Faculté des Sciences, Université de Dschang, Boîte Postale 067, Dschang, Cameroon.
authors.forename: Fabien
authors.initials: F
authors.lastname: Kenmogne
authors.affiliation: Laboratoire de Mécanique et de Modélisation des Systèmes Physiques, Faculté des Sciences, Université de Dschang, Boîte Postale 067, Dschang, Cameroon.
authors.forename: David
authors.initials: D
authors.lastname: Yemélé
authors.affiliation: Laboratoire d'Electronique, Informatique et Image (LE2I) UMR 6306, CNRS, Arts et Métiers, Université de Bourgogne Franche Comté Aile des Sciences de l'Ingénieur, Boîte Postale 47870, 21078 Dijon Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Marquié