What is the Solar Flux Index?
Solar flux index (SFI) represents the level of solar activity.
Higher SFI values correlate with improved HF propagation conditions.
| SFI (sfu) | 67 | 83 | 102 | 124 | 148 | 172 | 196 | 219 | 240 | 273 | |
| SSN | 0 | 25 | 50 | 75 | 100 | 125 | 150 | 175 | 200 | 250 | |
| MUF (MHz) | <12 | <15 | > 21 | > 24 | > 28 | > 50 | |||||
| Conditions | BAD | Low | Average | Good | Better | Best | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
- SFI - Solar flux index refers to the intensity of solar radio emissions at 10.7 cm (2,800 MHz).↗
Higher flux correlates with increased ionization levels of the ionosphere, enhancing HF radio propagation conditions.
The current index is: Loading solar flux data...; data source: NOAA Space Waether Prediction Center
Solar flux unit: 1sfu=10-22 Watts per meter² per Hz. - SSN - Sunspot Number is a count of the number of dark spots seen on the sun.
Higher SSN values correlate with improved conditions on 14 MHz band and above.
Monitoring solar flux as well as other propagation indicators is essential for optimizing communication strategies and maintaining reliable connections. The project Understanding HF Propagation provides a detailed overview and tutorials covering this subject.