Propagation Frequency Planner
Estimate which amateur-radio HF bands are likely open between two locations. This is a simplified model assuming moderate solar activity (SSN ≈ 100); real-world conditions vary with the solar cycle, geomagnetic activity, and local ionospheric weather. Band ratings assume a 100 W station with dipole antennas at both ends.
Path summary
Daily overview
Best band quality by hour for this QSO. Click an hour to load its full prediction.
Band-by-band prediction
| Band | Freq | Quality | Min. TX | Propagation mode | Notes |
|---|
About this planner
This tool provides rough estimates based on a simplified ionospheric model. Key assumptions and design choices:
- Solar activity
- By default, the model assumes a moderate smoothed sunspot number (SSN ≈ 100). Enable live space weather data to use an effective sunspot number derived from the three-month mean 10.7 cm solar flux reported by NOAA/SWPC instead; the official smoothed SSN is only published about six months in arrears. During solar minimum, the higher bands (10–17 m) will open far less often; during solar maximum, they may open even more than predicted.
- Day/night band behaviour
- Lower bands (160 m, 80 m, 40 m) favour nighttime propagation: the D layer disappears after sunset, dramatically reducing absorption on these frequencies. Higher bands (20 m and above) favour daytime propagation when the F2 layer is strongly ionised. The 30 m band sits at the transition and can work in both conditions. The F2 layer also lags the sun by a few hours: it peaks in the early afternoon and decays slowly after sunset, so the higher bands often stay open well into the evening and are at their worst just before dawn. The map shows the solar terminator so you can see which parts of the path are in darkness.
- Propagation modes
- The planner evaluates ground wave, NVIS (Near Vertical Incidence Skywave for paths under ~500 km), single- and multi-hop F2-layer skywave, E-layer skywave, sporadic E (summer), and gray-line enhancement. Each mode is rated separately, with D-layer absorption scaled for the angle at which its rays cross the D region, and the best mode is shown. It does not model tropospheric ducting, meteor scatter, EME, or other VHF/UHF modes.
- Power estimates
- Minimum TX power assumes half-wave dipole antennas at both ends and a 10 dB SNR in a 2.4 kHz SSB bandwidth. The noise floor is the dominant of atmospheric, galactic and man-made noise from ITU-R P.372; choose the Noise setting that matches the receiving site, as it moves the required power by 10–20 dB. Antenna inefficiency, fading and QRM push real requirements higher still.
- Band quality
- Ratings compare a 100 W station against that requirement. Best clears it by more than 10 dB and Good by 0–10 dB; Fair falls short by up to 6 dB and Poor by up to 12 dB; Very poor means CW or digital modes only; Closed means the band is above the MUF or below the LUF. Frequencies between the FOT and the MUF are capped at Fair because the band is then open on only 50–90% of days.
- Geomagnetic conditions
- By default, the model assumes quiet geomagnetic conditions (K index ≈ 0–2). With live space weather data enabled, the planner uses the NOAA/SWPC Kp index forecast for predictions within the next three days, reducing foF2 estimates during disturbed or storm conditions. Effects scale with geomagnetic latitude and are strongest on high-latitude and polar paths. During geomagnetic storms, HF propagation can be severely disrupted.