How does the maximum range of ground-wave propagation change when the signal frequency is increased?
It stays the same
It increases
It decreases✓Правильный ответ
It peaks at roughly 8 MHz
Объяснение
The ground wave loses energy to currents induced in the imperfectly conducting earth beneath it, and that loss climbs steadily with frequency, so raising the frequency shortens the useful range. This is why medium-wave broadcast stations cover whole regions by ground wave while at VHF the ground wave barely exceeds line of sight.