Coax Cable

"Dielectric" is a 19th-century term coined by polymath William Whewell in the 1830s at the request of Michael Faraday. It derives from the Greek prefix dia- ("through") and electric, describing insulating materials that allow electric field lines (flux) to pass through them while resisting electrical conduction.

Read more on how the coax signal travels (source to destination). It uses an AC wave (High Frequency RF), as does VDSL2 on telephone cable, recently deployed on the NBN after 2015.

Compare with early Phones, having a single line with ground return, read more re early phone exchanges in Australia.