SCTE 03 2022

Test Method for Coaxial Cable Structural Return Loss

Executive Summary

The purpose of this document is to provide instructions to measure the structural return loss characteristics of a coaxial cable from 5 MHz to 3000 MHz.

The purpose of this procedure is to provide instructions to measure coaxial cable structural return loss (SRL).

The cable impedance as a function of frequency is calculated from a vector (magnitude and phase) return loss. The average of this impedance across the desired frequency range is the “cable reference impedance.” The structural return loss is calculated from the cable impedance as a function of frequency and the cable reference impedance. This may be automated, but requires a vector network analyzer, and may be subject to errors due to the cable connection.


Passive devices which have a poor structural return loss and/or voltage standing wave ration (VSWR) result in loss of signal power or degradation of signal information Return loss is a way to characterize impedance mismatches. There are two major causes of return loss degradation in a network: discontinuities and impedance mismatches. Discontinuities occur at connections where cable is terminated to plugs or jacks and within the plug/jack connection itself. A discontinuity can also occur if a cable is bent too much, kinked or otherwise damaged. Components need to have acceptable return loss in order to assure proper network operation.

Intended Audience

The intended audience for this document is for development/design engineers, lab technicians, technical operations, and installers.