This tutorial is also still under construction.
Please do use the resources that ARE here though.
Clipbank video learning resources.
Extracted from educational programmes for secondary schools aired on Channel 4.
Source: https://youtu.be/xkTmv5yBp50
Bill uses a bucket of propylene glycol to show how a fiber optic cable works and how engineers send signal across oceans.
This is A LOT more info than you need - it's fascinating, but at this point you only need the first 2 minutes about an optical fibre using total internal reflection to transmit an EM signal.
Source: https://youtu.be/0MwMkBET_5I
An introduction to Microwave Communications, describing microwave radio links and how they are used.
Again, more information than you need, but covers the basics and is interesting nonetheless.
Source: https://youtu.be/0FnLfVPNZ2E