I spent some time writing about radio propagation basics in 2022. Unlike electronic circuits, sending signals through the ionosphere is really complex.
Last summer, I published a series of articles on HF propagation basics. Taken individually, topics like refraction, absorption and most useful frequency are fairly easy to grasp, with or without the math. All hams and shortwave listeners should have a basic understanding of how things work.
Engineers and scientists have been studying radio in the ionosphere for nearly a century. Credit for its first definition goes to Robert Watson-Watt in 1926. Today, we can use software to evaluate radio propagation and get reasonably good results.
But the more we dig into radio propagation basics, the more we realize it is not a simple deterministic process like ohms law. You will discover many probabilistic and chaotic processes at work. At best, evaluating propagation can be done on average and with many simplifying assumptions. At worst, you just need to be lucky at the right time and place.
I have been fascinated by HF ionospheric propagation for nearly 30 years. And, I am still learning. To me, it’s still magic. You will find there are so many ways solar and geomagnetic activity can effect signal paths, you need a lot of humility when you say you understand how it works all the time.
Especially here in the northern latitudes, we are effected a lot by the geomagnetic field. For me, the K index tells me more than the Solar Flux Index.
Radio Propagation Basics – More to Come
Next year, I will post more articles on the basics. For one thing, did you know that signals you receive are neither vertically nor horizontally polarized? All signals traveling through the ionosphere take on elliptical polarization. I will tell you why. Hint: it has to do with the gyrofrequency.
I will also dig into Medium Wave propagation, which relies on the ionosphere but behaves differently than HF.
Hope you enjoyed your Christmas turkey!