Microwave Reflections

Microwave signals have frequencies between 1000 MHz (1 GHz) and 30 GHz and a physical wavelength from approximately 12? in. (30 cm) down to less than 1 in. (2.5 cm). Microwave signals reflect off of objects that are larger than their wavelength, such as buildings, cars, flat stretches of ground, and bodies of water. Figure 2-7 illustrates microwave reflection off of a building.

Figure 2-7. Microwave Signal Reflection

Figure 2-7. Microwave Signal Reflection

Each time a microwave signal is reflected, its amplitu de is reduced. Mic rowave refle ction can be an adva ntage or a disadvantage. The advantage is that sometimes the reflection (or bounce) off of a building or water tank allows a microwave link to work even though obstructions, such as the trees in Figure 2-7, block the direct wave. The d isadvantage oo microwave reflection is that a phenomenon called multipath can occur.

Multipath occurs when reflections cause more than one copy of the same microwave signal to arrive at the receiver at slighely diffeeent timesĀ° as shown in Figure 2-8.

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