For example, the result of doubling 10 milliwatts (mW) is 20 mW. Watts have linear characteristics that follow mathematical relationships we are all very familiar with. Radio waves have amplitudes with units of watts, which represent the amount of power in the signal. As the power increases, so does the range. Similarly, power in terms of electromagnetic signals represents the amount of energy necessary to push the signal over a particular distance. The measure for amplitude is generally power, which is analogous to the amount of effort a person needs to exert to ride a bicycle over a specific distance. The amplitude of a radio wave indicates its strength. These attributes may be varied in time to represent information. As shown in Figure 2-1, a radio wave has amplitude, frequency, and phase elements. In addition, radio waves are the primary means for carrying data over a wireless network. They provide the means for carrying music to FM radios and video to televisions. Radio waves have been in use for many years. These signals oscillate at a very high frequency, which allows the waves to travel through the air similar to waves on an ocean. Sometimes radio waves are referred to as radio frequency (RF) signals.
Radio wave attributesĪ radio wave is a type of electromagnetic signal designed to carry information through the air over relatively long distances. This excerpt explains the fundamentals of radio waves so that you have a good basis for understanding the complexities of deploying WLANs. In addition, regulatory rules govern the use and limitations of radio waves. Along the way, the waves encounter various obstacles or obstructions that can impact range and performance, depending on the characteristics of the radio wave. Every Wi-Fi deployment requires that the systems engineer understand the fundamentals of how radio waves move and react within the environment.įor example, in a WLAN, radio waves carry information over the air from one point to another. Editor's note: This is a chapter excerpt from " Designing and Deploying 802.11 Wireless Networks," by Jim Geier and published by Cisco Press.Īs the basis for understanding the installation, operation, and troubleshooting of wireless LANs (WLANs), it is important that you have a good knowledge of how radio waves propagate through an environment.