TRANSMISSION MEDIA

Guided Transmission media Transmission Media Guided Media Types of Guided Media1. Twisted Pair cable2. Coaxial Cables3. Optical Fiber Unguided Media

Topic Included

What is Transmission Media

Sending of data from one device to another through Medium is called Transmission Media

Transmission Media

Guided Unguided

Guided (Wired)

Guided transmission media means the data signals are guided along the path like cabling system .

Types Of Guided Media

Guided (Wired)

Twisted Pair Coaxial cable Fiber Optics

Guided Media

Twisted Pair Co-Axial Cables Optic fibres

Twisted Pair Wires

Consists of two insulated copper wires arranged in a regular spiral pattern to minimize the electromagnetic interference between adjacent pairs

Often used at customer facilities and also over distances to carry voice as well as data communications

Low frequency transmission medium

Types of Twisted Pair

STP (shielded twisted pair) the pair is wrapped with metallic foil or braid to insulate the pair from

electromagnetic interference UTP (unshielded twisted pair)

each wire is insulated with plastic wrap, but the pair is encased in an outer covering

Twisted Pair Advantages Inexpensive and readily available Flexible and light weight Easy to work with and install

Disadvantages Susceptibility to interference and noise Attenuation problem Relatively low bandwidth (3000Hz)

Coaxial Cable (or Coax)

Used for cable television, LANs, telephony Has an inner conductor surrounded by a braided mesh Both conductors share a common center axial, hence the term “co-

axial”

Coax Advantages Higher bandwidth

400 to 600Mhz up to 10,800 voice conversations

Can be tapped easily (pros and cons) Much less susceptible to interference than twisted pair

Coax Disadvantages High attenuation rate makes it expensive over long

distance Bulky

FIBER OPTIC Cable• Optical fiber consists of a glass

core, surrounded by a glass cladding with slightly lower refractive index.

• In most networks fiber-optic cable is used as the high-speed backbone, and twisted wire and coaxial cable are used to connect the backbone to individual devices.

Fiber Optic Layers

consists of three concentric sections

Fiber Optic Advantages greater capacity (bandwidth of up to 100 Gbps) smaller size and lighter weight lower attenuation immunity to environmental interference highly secure due to tap difficulty and lack of signal radiation

Fiber Optic Disadvantages

Expensive to install requires highly skilled installers adding additional nodes is difficult

Unguided Media

Wireless transmission waves

Radio Waves

Omnidirectional Antenna

Frequencies between 3 KHz and

1 GHz. Are used for multicasts communications, such as radio and television, and paging system.

Microwaves

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frequency between 1 and 300 GHz

Micro waves are unidirectional.

Very high frequency Micro waves can not penetrate walls.

They are used in Cellular phones, satellite networks, wireless LANs.

Infrared

Frequencies between 300 GHz to 400 THz. Can not penetrate walls. Used for short-range communication Typical uses

TV remote control IRD port

Are blocked by walls No licenses required

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