Comment on “Compact envelope dark solitary wave in a discrete nonlinear electrical transmission line” [Phys. Lett. A 373 (2009) 3801–3809]

•RWA method based investigation of modulated waves in an NLTL.•Derived NLS type equation contains more terms than earlier reported.•NLS coefficients strongly depend on NLTL parameters than earlier reported.•Nonlinear dispersive elements are not indispensable to support compact solutions.

We revisit the derivation of the equation modeling envelope waves in a discrete nonlinear electrical transmission line (NLTL) considered a few years back in Physics Letters A 373 (2009) 3801–3809. Using a combination of rotating wave approximation and the Gardner–Morikawa transformation, we show that the modulated waves are described by a new type of extended nonlinear Schrödinger equation. In addition the expressions of several coefficients of this equation are found to be strongly different from those given earlier. As a consequence, key relationships between these coefficients that sustained the previous analysis are broken.