Interactive calculators for Earth–Moon–Earth (EME / moonbounce) propagation and link budgets. Enter grid squares and station parameters to estimate path losses, receive power, noise power and SNR.
This tool provides current Moon azimuth and elevation based on grid square, plus elevation over the next 48 hours (hover over the plot). A 30-day Moon elevation and distance plot is also shown, including next perigee and next peak elevation. A simple world clock is provided for planning.
|
Moon elevation vs time (now → +48h)
Moon elevation & distance vs time (next 30 days)
|
Grid:
World Clock
Az: —
El: —
Lat: —
Lon: —
Next Perigee: —
Next Peak El: —
|
The following EME Link Budget tool can be used to estimate the SNR during an EME QSO.
| Parameters | |||
|---|---|---|---|
| Frequency (MHz) [30–60000] |
Noise Bandwidth (Hz) | ||
| M0 Grid | DX Grid | ||
| Elevation at M0 (deg) |
|
Elevation at DX (deg) |
|
| Moon Distance (km) |
|
UTC Time | |
| Lunar Reflection Coefficient (η) | Doppler Spreading Loss (dB) | ||
| Polarisation Mismatch Mode | Polarisation Mismatch Loss (dB) | ||
| Update | Status | ||
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Notes
Faraday rotation is the rotation of the plane of linear polarization as a radio wave propagates through the ionized terrestrial ionosphere in the presence of Earth’s magnetic field. The rotation angle is proportional to the integrated electron density and magnetic field along the path and scales approximately as 1 / f², making it significant at VHF and lower UHF, noticeable at 432 MHz, sometimes present at 1296 MHz under disturbed ionospheric conditions, and generally negligible above a few GHz. Faraday rotation applies only to linearly polarized signals (LP), where it can cause time-varying polarization mismatch between transmitting and receiving antennas; it has no effect on circular polarization (CP), which is why CP is commonly preferred for EME at lower frequencies. In LP–LP antenna scenarios, Faraday rotation can introduce rapid and unpredictable fading as the polarization alignment rotates, while in CP–LP paths it manifests as an average ~3 dB loss. For EME links, Faraday rotation is primarily relevant below ~1–2 GHz, during daytime, at low elevation angles, and near geomagnetic or solar disturbances.
EME uses quiet-sky antenna temperature above 200 MHz; ITU-R P.372 median sky noise (used for the satcom link budget) is not used here, as it would significantly overestimate noise for EME paths. Below 200 MHz, an effective sky + environment noise model is used to predict SNR in typical amateur environments.
Rain/cloud/scintillation are excluded for clear-sky operation; include them above ~1 GHz for availability analyses. An input box for atmospheric loss is included; at 1296 MHz this loss is very small but above about 5 GHz it has an effect.
The following EME Echo Link Budget tool can be used to estimate the SNR during an EME echo test.
| Parameters | |
| Frequency (MHz) [30–60000] | |
| Noise Bandwidth (Hz) | |
| Grid | |
| Elevation (deg) |
|
| Moon Distance (km) |
|
| Echo Delay (ms) | |
| Echo Doppler (Hz) | |
| Lunar Reflection Coefficient (η) | |
| Transmit | |
| TX Power (W) | |
| TX Power (dBm) | |
| TX Cable Loss (dB) | |
| Power at Feed (W) | |
| TX Antenna Gain (dBi) | |
| EIRP (dBm) | |
| Propagation | |
| EME Path Loss (dB) | |
| Atmospheric Loss (dB) | |
| Polarisation Mismatch Loss (dB) | |
| Doppler Spreading Loss (dB) | |
| Receive | |
| RX Antenna Gain (dBi) | |
| Receive Signal (dBm) | |
| Antenna Temperature Ta (K) | |
| Feeder Loss (ant→LNA) (dB) | |
| LNA NF (dB) | |
| LNA Gain (dB) | |
| Loss LNA out→Radio in (dB) | |
| Radio NF (post-LNA) (dB) | |
| Noise Power N/BW (dBm) | |
| SNR (dB) | |
| Update | |