Transmission medium

Transmission medium

A transmission medium"' (plural "transmission media") is a material substance (solid, liquid or gas) which can propagate energy waves. For example, the transmission medium for sound received by the ears is usually air, but solids and liquids may also act as transmission media for sound.

The absence of a material medium (the vacuum of empty space) can also be thought of as a transmission medium for electromagnetic waves such as light and radio waves. While material substance is not required for electromagnetic waves to propagate, such waves are usually affected by the transmission media through which they pass, for instance by absorption or by reflection or refraction at the interfaces between media.

The term transmission medium can also refer to the technical device which employs the material substance to transmit or guide the waves. Thus an optical fiber or a copper cable can be referred to as a transmission medium.

A transmission medium can be classified as a:
*"Linear medium", if different waves at any particular point in the medium can be superposed;
*"Bounded medium", if it is finite in extent, otherwise "unbounded medium";
*"Uniform medium", if its physical properties are unchanged at different points;
*"Isotropic medium", if its physical properties are the same in different directions.

Electromagnetic radiation can be transmitted through an optical media, such as optical fiber, or through twisted pair wires, coaxial cable, or dielectric-slab waveguides. It may also pass through any physical material which is transparent to the specific wavelength, such as water, air, glass, or concrete. Sound is, by definition, the vibration of matter, so it requires a physical medium for transmission, as does other kinds of mechanical waves and heat energy. Historically, various aether theories were used in science and thought to be necessary to explain the transmission medium. However, it is now known that electromagnetic waves do not require a physical transmission medium, and so can travel through the "vacuum" of free space. Regions of the insulative vacuum can become conductive for electrical conduction through the presence of free electrons, holes, or ions.


ee also

*Vacuum permittivity
*Transmission (telecommunications)
*Excitable medium
*Optical medium

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • transmission medium — noun any material substance which can propagate waves or energy …   Wiktionary

  • transmission medium —    The physical cabling used to carry network information, such as fiber optic, coaxial, shielded twisted pair (STP), and unshielded twistedpair (UTP) cabling …   Dictionary of networking

  • Medium — may refer to: Contents 1 Communication 2 Natural science 3 Entertainment …   Wikipedia

  • Transmission Technologies Corporation — is a manufacturer of automobile transmissions, best known for their TREMEC line of manual transmissions. The company has a sales and marketing office in Farmington Hills, Michigan, and production facilities in Querétaro, Querétaro, and Knoxville …   Wikipedia

  • Transmission line — This article is about the radio frequency transmission line. For the power transmission line, see electric power transmission. In communications and electronic engineering, a transmission line is a specialized cable designed to carry alternating… …   Wikipedia

  • Transmission (telecommunications) — In telecommunications, transmission is the process of sending, propagating and receiving an analogue or digital information signal over a physical point to point or point to multipoint transmission medium, either wired or wireless. Tranmission… …   Wikipedia

  • Medium Attachment Unit — ou MAU (unité de raccordement au support) est un moyen matériel utilisé pour connecter un répéteur, un terminal ou un ordinateur (station) à un réseau de transmission de données (support). Celui ci (préconisé par le standard Ethernet 10 Mbits/s d …   Wikipédia en Français

  • Medium Mark C — Medium Tank Mark C Medium Mark C Production history Designer Rigby …   Wikipedia

  • Medium Mark A Whippet — Medium Mk A Whippet Whippet Firefly of F Battalion in The Museum of the Army in Brussels (original colours) Type Medium tank Place of origin …   Wikipedia

  • Medium frequency — Frequency range 0.3 to 3 MHz ITU Radio Band Numbers 1 2 3 4 5 6 7 8 9 10 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”