|
cond | BAD | Low | Average | Good | Better | Best | |||||
---|---|---|---|---|---|---|---|---|---|---|---|
MUF | < 15 MHz | > 21 MHz | > 24 MHz | > 28 MHz | > 50 MHz | ||||||
SSN | 0 | 25 | 50 | 75 | 100 | 125 | 150 | 175 | 200 | 250 | |
SFI | 67 | 83 | 102 | 124 | 148 | 172 | 196 | 219 | 240 | 273 |
High SSN and SFI values are good for daytime propagation on all HF bands. Best for higher frequency bands (20 meters and up). Provides better long-distance communication opportunities.
Assess HF disturbances using the geomagnetic indices: X, A, Xp, Ap
HF Propagation conditions | Best | Average | Poor | BAD | |||||||
Geomagnetic activity index (log-scale) | K | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
---|---|---|---|---|---|---|---|---|---|---|---|
Geomagnetic activity index (linear) | A | 0 | 4 | 7 | 15 | 27 | 48 | 80 | 132 | 207 | 400 |
Solar Flare Class![]() | A | B | C | M | X | |||
---|---|---|---|---|---|---|---|---|
Radio Blackout Scale![]() | R0 | R1 | R2 | R3 | R4 | R5 |
The above five indices, SSN, SFI, A, K, and X-ray, are known as "propagation indices."
Space Weather Prediction Center (SWPC) provides real-time solar and geomagnetic data, including SFI, A-Index, and K-Index.
DX Cluster Websites: Many DX cluster websites display current propagation conditions and include propagation indices.
Propagation Prediction Software: Use dedicated software like VOACAP (Voice of America Coverage Analysis Program) for detailed HF propagation forecasts based on propagation indices.
HF propagation is a dynamic field, and propagation indices can vary daily. Stay engaged with the amateur radio community and learn from experienced operators to refine your understanding and skills in using propagation indices for HF propagation.
By grasping the basics of propagation indices and their impact on HF propagation, you can enhance your ability to make effective long-distance HF contacts and enjoy the exciting world of amateur radio and shortwave communication.
Read more about propagation indices & Ham Radio Propagation
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