Greater distance can be covered with multiple-hop transmissions by decreasing the:

In multiple-hop skywave propagation, a radio signal bounces between the ionosphere and the Earth's surface several times. To maximize the distance covered by each individual hop, the signal must leave the antenna at a very shallow, or low, vertical radiation angle. By decreasing the vertical radiation angle, you increase the skip distance of every single bounce. Altering the power, antenna length, or maintaining a specific height does not fundamentally change the geometry of the skip distance as directly as lowering the takeoff angle does.