Ionospheric D Layer absorption attenuates radio signals, mainly below 10 MHz. Here is how it is caused and when. Read more

You have probably heard people talk about ionosphere virtual height. What is it and why is it important for HF propagation? Read more

So, how exactly do oblique radio rays bend as they transit the ionosphere and return to earth? Let’s find out. Read more

Radio wave refraction depends on density of free electrons and frequency. Skip distance is tied to refractive index and height. Read more

Let’s understand radio waves, and how they behave is different media including solid wire, free space and plasma. Read more

Let’s do a level set on basic HF radio propagation through the ionosphere and around the world. Read more

Grey line propagation enhancement is magic on the HF bands, for both ham radio and shortwave listening at long distances. Read more

Here are the basics for reading your ionogram. You can discover real time propagation conditions almost anywhere in the world. Read more