HF Propagation: How to See Which Bands Are Open

On the HF bands (3-30MHz), long-distance communication often relies on signals being refracted by the ionosphere. Changes in the ionosphere can affect which bands work best and how far signals are likely to travel.

Two common questions are: how do I know which bands are open? and how can I predict HF propagation? This page gives you a few useful ways to check.

How can I tell which bands are open?

You may come across propagation graphics showing conditions on the various HF bands. One popular example is provided by Paul N0NBH, who makes solar and propagation information available for websites.

You can find out more here: HamQSL Solar-Terrestrial Data.

Another easy-to-use site is solar.w5mmw.net, which also gives an indication of current band conditions.

Check real-time activity

Band-condition indicators are useful, but one of the best ways to see what is actually happening right now is to look at signals being heard around the world.

PSK Reporter collects reception reports from stations using digital modes. This makes it useful for seeing where signals from the UK are currently reaching, and which bands are being used successfully.

On the map, try looking at signals sent from the UK over the last 15 minutes. This can give you a good idea of which bands are currently supporting contacts over particular distances.

PSK Reporter – Live propagation from the UK

Predicting HF propagation

Propagation can also be predicted using information about solar activity, ionospheric conditions and the time of day. Like weather forecasts, propagation predictions are useful guides rather than guarantees.

There are many websites, apps and software packages that can help with propagation prediction. One useful directory is:

DXZone Propagation Prediction Resources

A practical approach

HF propagation is a huge subject, but you do not need to understand every detail to get started. A simple approach is:

• Check a propagation or solar-condition display
• Look at real-time activity on PSK Reporter
• Listen on the band yourself
• Try calling CQ – conditions can sometimes be better than the indicators suggest

The best propagation tool is still your radio. Conditions change constantly, so if a band looks quiet, it can still be worth listening and trying a call.