Last Updated on May 11, 2026 by John Berry
Radio amateurs need a model summarising ionospheric propagation effects so that we can talk about HF, VHF, and UHF propagation meaningfully.
Here’s my proposal for such a model summarising propagation mechanisms. It covers the range 1.8MHz to 1300MHz and focusses only on ionospheric effects.
To read this model, consider each arrow as a direction of influence, like ‘a’ influences ‘b’. Float over each arrow to see the nature of that influence (verb).
Start at any of the coloured boxes or balloon at the top and work in any direction. Aim for the goal: the blue box, “useful propagation”. Try all the routes possible and you will discover all the propagation mechanisms.
Of course, some influences are positive with useful outcomes, and some are not and degrade. In several cases, negative influences have the arrowhead at the start.
Float over the various nodes (nouns) and click for links to other pages if you want more information. Use your browser back arrow to return to the model.
The diagram gives a reasonably comprehensive model summarising ionospheric propagation.
To view and use on a mobile, turn the device to landscape.
Interactive ionospheric propagation dashboard
generates
has
enable
feeds
feeds1
shapes
focuses
feeds
feeds3
feeds
feeds2
create
shape
degrades
degrades
degrades2
causes
degrades
degrades3
causes
causes2
causes
causes3
causes
causes4
create
create2
shapes
shapes3
cause
causes5
drives
cause
cause6
shapes
shapes4
disturbs
disturbs2
disturbs
distgurbs2
degrades
degrades3
disturbs
disturbs3
enables
enables2
reduces
enables
enables3
raises
raises
raises2
raises
raises3
drives
sets
sets
sets2
cause
cause7
generates
sets
sets3
drives
drives2
enables
enables4
causes
causes8
degrades
degrades4
I’ve left a few mechanisms out because they don’t add anything. To be technically complete, we should perhaps include Faraday rotation, and separation of X-ray and EUV radiation. And jetstream and thunderstorms are unlinked. I’ll add more on those later.