CoachThe first Fresnel zone of a radio path is the ellipsoid around the straight line between the antennas in which paths are at most half a wavelength longer than the direct one; obstacles inside it weaken the received signal, so a link is designed to keep it clear. The earth bulge is the height of the Earth’s surface above the straight line joining two points at ground level, at a given point between them; atmospheric refraction bends radio waves slightly downward, which is modelled by an earth of radius times the real one.
| Hop | Frequency | Earth bulge | Fresnel radius | Tower height |
| (km) | (GHz) | at mid-hop (m) | at mid-hop (m) | (m) |
| 30 | 6 | 13.2 | 19.4 | 42.6 |
| 30 | 11 | 13.2 | 14.3 | 37.5 |
| 50 | 6 | 36.8 | 25.0 | 71.8 |
| 50 | 11 | 36.8 | 18.5 | 65.3 |
| 70 | 6 | 72.1 | 29.6 | 111.7 |
| 70 | 11 | 72.1 | 21.8 | 104.0 |
nw_wireless.geometry_rows().