Propagation of radio waves is a huge subject. Just when you think you’ve understood one type, it’s all challenged when some of the many boundaries are broken. A good example is with VHF space waves. All is well, for example, until the waves go sky-ward, refract in the ionosphere and return to Earth many hundreds or thousands of kilometres distant. And again, all is well with those sky-bound VHF waves until the angle of incidence at the ionosphere is too great and they pass straight through and are lost to space.

There are so many of these boundary conditions which, when breached, demand that we think differently and use different calculations. Everything about propagation calculations and predictions is conditional. There is no one law.

To provide an emerging clarity, I’ve placed here several of what I term propagation primitives –propagation building blocks which must be learned and understood before attempting to stitch a group together to form an algorithm for one band or mode or other.

Once I have enough of these propagation primitives documented, I’ll do just that – I’ll stitch groups together with associated conditions to enable understanding of propagation mechanisms.