Empirical Earth · Radio & Long-Distance Signals

Long-path & grey-line — radio that only works on a turning sphere

The claim

“Radio travels straight over a flat plane, so distant contacts prove nothing.”

What is measured

Ham operators routinely receive signals from the “long way” around the planet, a bearing that only exists if Earth is a closed sphere.

Sources

1. HF long-path & grey-line propagation. Skywave signals can arrive from the opposite (long-path) bearing after circling the globe via ionospheric hops, and propagation is enhanced along the su link
2. Round-the-world radio echoes. High-frequency signals can circle the globe and return as an echo about one-seventh of a second later (~138 ms for the ~40,000 km path at light speed); multi-la link

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