The following will be discussed in this chapter: Transmission media, transmission media classification, transmission media characteristics and design specifications, guided and unguided media, wireless transmission frequencies, antennas, wireless propagation. | Transmission Media Lecture 4 Overview Transmission media Transmission media classification Transmission Media characteristics and design specifications Guided and Unguided media Wireless Transmission Frequencies Antennas Wireless Propagation 1 Transmission Media The transmission medium is the physical path by which a message travels from sender to receiver. Computers and telecommunication devices use signals to represent data. These signals are transmitted from a device to another in the form of electromagnetic energy. Examples of Electromagnetic energy include power, radio waves, infrared light, visible light, ultraviolet light, and X and gamma rays. All these electromagnetic signals constitute the electromagnetic spectrum 2 Electromagnetic Spectrum 3 Not all portion of the spectrum are currently usable for telecommunications Each portion of the spectrum requires a particular transmission medium Transmission Media Classification 4 Guided media, which are those that provide a conduit from one device to another. Examples: twisted-pair, coaxial cable, optical fiber. Unguided media (or wireless communication) transport electromagnetic waves without using a physical conductor. Instead, signals are broadcast through air (or, in a few cases, water), and thus are available to anyone who has a device capable of receiving them. Transmission Media Classification 5 Characteristics and quality determined by medium and signal For guided, the medium is more important For unguided, the bandwidth produced by the antenna is more important Key concerns are data rate and distance 5 Transmission Media Classification One key property of signals transmitted by antenna is directionality. In general, signals at lower frequencies are omnidirectional; that is, the signal propagates in all directions from the antenna. At higher frequencies, it is possible to focus the signal into a directional beam 6 6 Transmission Media Classification 7 Signals of low frequency (like voice signals) are . | Transmission Media Lecture 4 Overview Transmission media Transmission media classification Transmission Media characteristics and design specifications Guided and Unguided media Wireless Transmission Frequencies Antennas Wireless Propagation 1 Transmission Media The transmission medium is the physical path by which a message travels from sender to receiver. Computers and telecommunication devices use signals to represent data. These signals are transmitted from a device to another in the form of electromagnetic energy. Examples of Electromagnetic energy include power, radio waves, infrared light, visible light, ultraviolet light, and X and gamma rays. All these electromagnetic signals constitute the electromagnetic spectrum 2 Electromagnetic Spectrum 3 Not all portion of the spectrum are currently usable for telecommunications Each portion of the spectrum requires a particular transmission medium Transmission Media Classification 4 Guided media, which are those that provide a conduit
