How do radio waves propagate?

Chapter 6.  Radio Wave Propagation shows us that whenever a current flows in a conductor, it generates an Electro-Magnetic wave (a signal) that escapes from the vicinity of the wire and then travels through space.  If that wave then impinges on another wire, it creates a current in the wire and this is the signal our radio receivers detect.  The distance the signal travels depends on a number of variables including the frequency of the signal.  For the right range of frequencies a magical thing can happen.  It can propagate out into space and "bounce" or "reflect" (it's actually more complicated) off layers of ionized gases back to earth.  This give us our treasured "skip propagation" that allows ham radio contacts around the world. 

A number of variables affect how well this works but the most important is the sun spot activity of the sun.  This chapter shows us how to monitor these conditions to help determine where in the world we can reach with our signals.

Fred Cady,
Nov 19, 2018, 4:42 PM