Foundations of Amateur Radio

A recurring topic of conversation is propagation. There is learned discussion about sun-spots, A and K indices, forecasts, ionospheric probing, not to mention half-baked guess work from less scientific perspectives.

It's been my experience that all these tools are wonderful, but none of them beat turning on your radio and having a listen, or better still putting out a call.

So when do you listen and where do you listen?

The trivial response would be everywhere, all the time, but none of us has enough time for that.

In general, 20m, 14 MHz works most of the time. At night, frequencies lower than 20m, that is 40m, 7 MHz and 80m 3.5 MHz work better. During the day, higher frequencies, 15m, 21 MHz and 10m, 28 MHz work better.

Of course this is not a hard and fast rule. As I said previously, there is no such thing as a perfect antenna, in fact we can prove that it cannot actually exist. Similarly, there is no such thing as perfect propagation.

We tend to think of propagation in terms of layers in the ionosphere, the D, E and F layers. We might think of them as specific, distinct things, but the reality is that they're more like clouds.

Clouds are not uniform in cover, sometimes fluffy, other times dense thunderclouds and an infinite variety in between. Coverage is variable and forecasting is a real challenge. And that's for something we can see.

The ionosphere is no different. It's not uniform, it's not predictable and forecasting is hard.

Back to the clouds for a moment; you might have a forecast for rain, but it's perfectly dry where you are. Similarly, you might have a forecast of poor propagation, but it's perfectly fine where you are.

So, best tip is to use the forecasts you have access to, but stick your head out of the window to see if it's raining right now. If that was too obscure, turn on your radio and make some noise, even if the sunspot count is rubbish and the Ionospheric Prediction Service tells you that nothing is going to work.

I'm Onno VK6FLAB