Unshielded twisted pair (UTP) - consists of two insulated wires arranged in a regular spiral pattern. There are two common types to UTP.
Coaxial A standard copper transmission wire that does have a shield.
Fiber A high speed medium for transmitting data. Made of high-purity glass sealed within an opaque tube. Much faster than convential copper wire.
All soft media use electromagnetic radiation but
RadioAM broadcast radio frequency band is 0.55 -1.6 MHz, the FM broadcast radio frequency band is 88-108 MHz and Mobile phones - 800 - 900 MHz
Spread Spectrum Radios are the most common type of wireless system used in local area networks.- These systems use a type of modulation that scatters data transmissions across the available frequency band. It currently spreads signals over frequencies of 902 MHz to 928 MHz and 2.4 GHz to 2.484 GHz. Future systems may appear in the 5 GHz range. This modulation increases the reliability of the signal but reduces the bandwidth efficiency. This technique was developed by the US military. The alternative, and less common, wireless radio frequency system is called Narrowband Technology and uses only a single radio frequency.
Microwave - The Microwave range is traditionally defined as 1 GHz to about 65 GHz. Most of the devices that operate in this range require a special license from the Federal Communications Commission (FCC). Microwave antennas provide ranges on the order of 30 to 40 miles. Most satellite communication also uses microwave systems.
Infrared (IR) - systems use very high frequencies, just below visible light, corresponding to a frequency of about 350,000 GHz. The advantages of IR include no need for licenses, no safety issues, huge potential capacity and good control of interference. Inexpensive IR systems provide very limited ranges on the order of three or four feet. IR does not penetrate walls, so infrared LANs are normally contained in a room.
The length of the media is a very important factor in network transmissions. A good concept to keep in mind is that less bandwidth will be available over longer distances. This concept is illustrated in the following table.
|Data Rate||10 Mbps||100 Mbps||1 Gbps|
|Category 5 UTP||100 m||100 m||25100 m|
|STP/Coax||500 m||100 m||25 m|
|Multimode Fiber||2 km||412 m (hd)*
2 km (fd)
|Single-Mode Fiber||25 km||20 km||2 km|
*IEEE spec half duplex
** IEEE spec full duplex