My radio propagation explorations have driven me to understand more about how this wonderful phenomena actually works.
For years, I have enjoyed a basic understanding of high frequency propagation in the ionosphere. You probably have, too. But, truth told, my understanding of what is really happening at the physical level has been very thin. Maybe the same for you. So, I thought it was about time to get my understanding up to the intermediate level, at least.
Along the way, my radio propagation explorations have led me to understand the basic weakness in how we learn about this subject. Basically, the texts we read are either too shallow or too deep. On the shallow side, we can read tons of articles about propagation that tell has little about what the ionosphere really is, how waves refract and why, or how absorption works.
Mostly, we read about out eleven year solar cycle, how propagation varies over the day, and the importance of the F layer.
On the other hand, propagation textbooks become too mathematical really fast. They assume a great deal of knowledge about physics and chemistry most of us do not have.
So, I am going to write a series of articles that explain the nuggets, or really important things, which will help us raise our level of understanding without getting lost in the math.
My Radio Propagation Explorations at home
I do most of my shortwave listening between 8 – 16 MHz. Most of the signals I listen to are from Europe, Africa and Asia. So, these signals travel to my home over northern polar (great circle) paths.
Over time, my radio propagation explorations have led me to pay close attention to the planetary K index. Kp tells me about the current state of geomagnetic activity caused by solar winds. Increased geomagnetic activity can depress the MUF (and me) and increase absorption.
Above, you can see we have had a lot of higher Kp this summer. With higher Kp, the auroral zone expands, shown above left. Kp pretty much tells me how good signals will be at my location. But, only sometimes. I want to find out why, among other things.