11.2.1 Ground Waves
As illustrated in Figure 11.3, ground waves include several components. The direct wave travels in a straight line from the transmitting to the receiving antenna, while the ground-reflected wave is reflected from the Earth’s surface before reaching the receiver. At long wavelengths, part of the radiated energy can be guided by interaction between the ground and the lower atmosphere, forming a surface wave that follows the curvature of the Earth. The combination of the direct and ground-reflected waves is known collectively as the space wave. The space wave is therefore limited to line-of-sight distances. Figure 11.4 shows the various components that make up the ground-wave field.
