Wireless signals are electromagnetic
waves, which can travel through the vacuum of outer space and through
media such as air. Therefore, no physical medium is necessary for
wireless signals, making them a very versatile way to build a network.
Figure
represents an electromagnetic
wave.
Figure
illustrates one of the most important charts in all of science and
technology, the Electromagnetic Spectrum chart. You might be amazed
that even tough all of the waves - power waves, radio waves,
microwaves, Infrared light waves, visible light waves, ultraviolet
light waves, x-rays, and gamma rays - look seemingly very different,
they share some very important characteristics:
- All of these waves have an energy
pattern similar to that represented in Figure
.
- All of these waves travel at the
speed of light, c = 299, 792, 458 meters per second, in vacuum.
This speed might more accurately be called the speed of
electromagnetic waves.
- All of these waves obey the equation
(frequency) x (wavelength) = c.
- All of these waves will travel
through vacuum, however, they have very different interactions
with various materials.
The primary difference between the
different electromagnetic waves is their frequency. Low frequency
electromagnetic waves have a long wavelength (the distance from one
peak to the next on the sine wave), while high frequency
electromagnetic waves have a short wavelength.
The interactive calculator in Figure
allows you to experiment. Try the interactive calculator by doing the
following activities:
- Enter a frequency and you will
notice that the calculator displays the wavelength.
- Enter a
wavelength you will notice that the calculator displays the frequency.
In either case, the calculator display
the electromagnetic wave associated with the calculation.
A common application of wireless data
communication is for mobile use. Some examples of mobile use includes:
- people in cars or airplanes
- satellites
- remote space probes
- space shuttles and space stations
- anyone/anything/anywhere/anytime that requires network data
- communications, without having to rely on copper or optical fiber
tethers
Another common application of wireless
data communication is wireless LANs (WLANs), which are built in
accordance with the IEEE 802.11 standards. WLANs typically use radio
waves (for example, 902 MHz), microwaves (for example, 2.4 GHz), and
Infrared waves (for example, 820 nanometers) for communication.
Wireless technologies are a crucial part of the future of networking.
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