Communication Media

           The communication media is the matter or substance that carries the voice or data. Many different types of transmission media are currently in use. All these different media types can be grouped into two categories: Guided media and Radiated media.

Guided Media

          The guided media are those in which the data flows through physical media.

• Twisted-pair Wire - A twisted-pair wire consists of two insulated copper wires, twisted around each other and covered in another layer of plastic insulation.

• Coaxial Cable - A coaxial cable consists of insulated copper wire wrapped in a metal shield, which is then wrapped in an outer external cover. Often many coaxial cables are  bundled together.

• Fiber-Optical Cable - Consists of hundreds of thin glass wires that transmit pulsation beams of light.

Radiated Media

             And the radiated media are those in which the data is broadcast through the air.

• Radio Transmission - Radio transmission use the same basic principle as standard radio transmission. When using radio transmission each device/computer on the network should equipped with a radio transmitter/receiver on a specific frequency that does not interfere with commercial radio stations. The transmitters are very low power and are designed typically to transmit a signal to a very short distance, typically up to 500 feet.

• Infrared Transmission - Infrared transmission uses low-frequency light wave, below the visible spectrum, to transmit data through the air. Infrared transmitters are seldom uses to transmit data to and from portable or handheld computers.

• Microwave Transmission - Microwave is a high-frequency beam with short wave length. Microwave can be transmitted over a direct line-of sight path between any two points. This transmission medium is typically used for long-distance data/voice transmission.

• Satellite Transmission - In satellite transmission, singles are transmitted to a satellite 500 to 22,000 miles in space. One disadvantage of satellite transmission is the delay that occurs in transmission, which is known as the propagation delay.

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