Propagation

Everything I like to check before switching the radio on: the state of the Sun, the ionosphere and the magnetic field, updated live.

Now

Kp–

SFI–

X-ray–

Loading NOAA data…

Kp index, last 72 h (red bars = geomagnetic storm)

Solar X-rays, last 6 h (log scale, classes A–X)

Data source: NOAA SWPC

Estimate per band, day and night, for Europe (N0NBH / hamqsl.com):

SFI (10.7 cm solar flux): the higher it is, the more ionised the ionosphere gets by day. Below ~80 only the low bands work well; above ~120 15 m and 20 m open nicely; above ~150 10 m does too.
Kp (0–9): measures how disturbed the Earth’s magnetic field is. Up to 2 is quiet; from 5 (G1) there is a geomagnetic storm, with noise and fading at high latitudes and a lower MUF.
Solar X-rays (classes A, B, C, M, X): an M or X flare ionises the D layer on the sunlit side and absorbs HF, causing a radio blackout that can last minutes to hours, stronger on the low bands.
MUF: the highest frequency the ionosphere reflects on a given path. Above it the signal escapes to space; below it, it is reflected. It pays to operate a little below the path’s MUF.
D-RAP: where and how much the D layer is absorbing HF, by frequency. Handy to understand why a band “dies” during the day.

The values in this panel are read in your browser from public services; if one fails, the links below lead to the source.