How Wireless Signals Propagate

摘要

LOS propagation is a straight line path from TX antenna to RX antenna. If any objects are in the way, the signal will be blocked or at least greatly attenuated. A building may entirely block the transmission. A patch of trees may let some signal through but at a greatly reduced level. In longer distance transmissions, the earth will block the signal due to its curvature. You can actually figure out how far a signal can travel before the earth blocks it (refer to Figure 1):