Reach map
Where a station can be heard, and how each specific circuit behaves.
Add receivers to draw the paths and read the usable band range for each one.
Real ITU-R P.533 predictions on a 6° grid — 1,620 points per
transmitter, every point evaluated across all nine bands. August, SSN 60,
24 dB required SNR in 3 kHz.
Transmitting from
Station
100 W, isotropic 100 W + dipole
1 kW + dipole 1 kW + 3-el beam
Colour by
Signal margin Best band
Path MUF
Daylight
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Theme
match viewer field-dark
field-light night-ops
Circuits
No receivers yet — search above to add one.
Usable range is the lowest and highest band that meets the
requirement on that circuit — the practical version of LUF and MUF. It is
narrower than the raw MUF, because a frequency can be below the MUF and still be
too weak to work.
The shaded half is night. The bright curve is the terminator, the
“grey line” operators watch: the absorbing D layer decays quickly after
sunset while the reflecting F layer lingers, so paths along it often run long.
Station setting: the grid was computed at 100 W into isotropic
antennas. Transmit power and transmit antenna gain add directly to the signal while
noise at the far end is unchanged, so they shift SNR by a flat number of dB and can be
applied exactly. Receive antenna gain is deliberately excluded — at HF the
receiver is limited by external noise, so a bigger receive antenna lifts signal and
noise together and largely cancels out of SNR.
Receiver positions snap to the nearest 6° grid cell (up to ~330 km), so
circuit figures are representative of the region rather than the exact site.
Engine