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Amateur Radio HF Propagation
HF communications use the ionosphere for long range skywave propagation. It consists of the D, E, and F layers extending 50 to 600 miles around the earth and is created by radiation from the sun. Each layer either refracts or absorbs signals depending on the level of ionization and wavelength. The outermost F layer supports the majority of long range (skywave) HF propagation while the innermost D layer primarily absorbs 160M, 80M and 40M signals during the day. Ionization (during the day) and dissipation (during the night) is a daily process impacting HF band performance. The level of impact depends on the season and the solar conditions including the 11 year sunspot cycle.

Current HF Band Conditions
HF Band Propagation status displays the current long range (skywave) performance expected over the various HF amateur radio bands based on current solar activity. Parameters such as the Smoothed Sunspot Number (SSN) and Solar Flux Index (SFI) reflect the degree of ionizing radiation available from the sun supporting effective ionospheric propagation.

Solar Flares / Band Outages
Solar Flares can disrupt HF radio communications for minutes to hours. The flares occur near sunspots and are outbursts of x-ray and extreme ultraviolet radiation.

Geomagnetic Activity / HF Impact
Geomagnetic activity can disturb the F-layer of the ionosphere reducing the maximum useable HF frequency.

D-Layer Absorption
D-layer absorption can occur during Solar Flares as ionization takes place during the increased x-ray flux. The impact can be amazing - the HF bands can go dead in an instant making you wonder your radio broke. The plot above shows the highest frequency impacted by a flare and the projected recovery time.

Which Bands are Actually Working
The Weak Signal Propagation Reporting Network (WSPR) is implemented via a computer program and protocol that uses weak-signal radio communication between amateur radio stations to identify potential propagation paths. Thousands of stations worldwide, some receive only, automatically upload their reception reports to a central database called WSPRnet. A live map is provided showing the successful propagation paths established by those stations giving an instant snapshot of band performance. View the current world-wide status of operational HF propagation paths at:

HF Propagation Prediction Online Program
VOACAP Online for Ham Radio is a very easy to use point-to-point HF propagtion prediction tool. You provide your location, the point you want to communicate with, and (optionally) your antenna type, power level, and mode of operation (i.e. SSB) and it does all the work for you!. Based on current solar conditions, it provides you with the best 3 HF amateur bands to use, the expected received signal levels, and the projected reliability of those communications paths. You also get a plot showing the time of day those bands will work best for you. IT IS AS SIMPLE AS THAT!

The Solar Sunspot Cycle Plot
Sunspot Cycle #25 is in progress following Cycle 24, a noticeably weak one, during the latter half of 2020. The last cycle had substantially fewer sunspots, solar flares, and coronal mass ejections than others. Solar Cycle 25 had a slow start but is anticipated to peak with solar maximum occurring between 2023 and 2026, during which we will hopefully enjoy tremendous performance on the HF bands.

The Latest Space Weather Forecast
The Space Weather Woman, Dr. Tamitha Skov brings you the latest updates regarding space weather and the impact on HF amateur radio propagation. Stay up to date on the spectacular events the sun sends our way by watching the weekly videos or reading the daily forecasts provided by Dr. Skov.