Notes on lossy transmission lines

The purpose of this article is to explain common errors that arise when widely accepted, simplified formulas describing lossy transmission lines are used. These formulas describing lossy transmission lines are expanded in series with respect to the inverse of frequency, under the assumption that the resistance-per-unit-length and conductance-per-unit-length are frequency independent. The source of errors is identified. Commonly used simplifications are Taylor series of various orders. Consequently, the order of the result is a minimal order of simplified formulas used. Correctness of the methodology is illustrated by measurements of coaxial-cable losses.