Make: Volume 78

space), often multiple times, and reach around

the world. Very high-frequency (VHF) and above

waves (30MHz and up) rely on direct, or line-of-

sight, transmission. These waves are obstructed

by the curvature of the Earth or other obstacles

and tend to have limited range compared to lower

frequencies. Of course, that depends on where

you point them. Aim them at a satellite and even a

handheld radio can contact low Earth orbit!

The higher an antenna is mounted, the

farther its line-of-sight radius is. Tall antenna

towers provide broad coverage for antennas

relying on direct propagation. Cellphone towers,

commercial radio, amateur radio repeater ...