Empirical Earth · Radio & Long-Distance Signals

Radio distance records — every band, and the curve each one measures

The claim

“Radio reaches the whole world, so there’s no curve to get over.”

What is measured

The records do not escape the globe. They measure it. Read the longest contact on each band backwards and it hands you the curvature, the circumference, or the distance to the Moon.

What would show this is wrong

a low-power line-of-sight contact that keeps going past the altitude-set radio horizon, an HF single hop well beyond ~4,000 km, or any terrestrial contact past ~20,000 km, none of which is on record.

Sources

  1. Hop length is set by the curve. The maximum single-hop skywave distance is fixed by the height of the ionospheric layer and the curvature of the Earth — about 2,000 km off the E region and 4 link
  2. Documented VHF records. A well-documented long 2 m terrestrial path is ~6,500 km (Italy–Namibia, trans-equatorial, 2024); the 2 m tropospheric-ducting record is 4,754 km (Hawaii to a ship so link
  3. ARRL distance records. The ARRL maintains the official VHF/UHF distance records by propagation mode (tropo, Sporadic-E, meteor scatter, trans-equatorial, aurora). The first direct 70 cm tran link
  4. LoRaWAN distance records. A 25 mW LoRaWAN packet from a balloon at ~38 km altitude was received 832 km away on a Czech mountaintop; the overall record is 1,336 km, set at sea level over an o link
  5. Microwave DX records. A 902 MHz contact spanned 4,095 km California–Hawaii through a transpacific tropospheric duct; the North American 47 GHz record is 344.8 km. ARRL: new microwave/UHF dis link
  6. First LoRa message bounced off the Moon. On 5 October 2021 a four-person team bounced a LoRa message off the Moon and back over a 730,360 km path, the furthest a LoRa signal has traveled: Ja link
  7. LoRa propagation limits and mesh records. Semtech’s LoRaWAN Academy gives a European maximum near 800 km at 25 mW in the 868 MHz band, so the 1,336 km over-sea result depends on tropospheric link
  8. Knife-edge diffraction physics. How far a radio wave bends around an obstacle edge is set by the Fresnel–Kirchhoff parameter ν ; at a grazing edge ( ν = 0) the diffraction loss is about 6 dB link
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