A transmission medium (plural transmission media) is a material substance (solid, liquid or gas) which can propagate energy waves. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of This page is about the physical properties of gas as a state of matter Wave propagation is any of the ways in which waves travel through a Waveguide. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. 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. Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies

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. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Radio waves are electromagnetic waves occurring on the Radio frequency portion of the Electromagnetic spectrum. 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. In Physics, absorption of electromagnetic radiation is the process by which the Energy of a Photon is taken up by matter typically the electrons of an Refraction is the change in direction of a Wave due to a change in its Speed. An interface is a surface forming a common boundary among two different phases, such as an insoluble Solid and a Liquid, two immiscible liquids or a liquid

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. In Physics and Systems theory, the superposition principle, also known as superposition property, states that for all Linear systems

Coaxial Cable, one example of a transmission medium

Electromagnetic radiation can be transmitted through an optical media, such as optical fiber, or through twisted pair wires, coaxial cable, or dielectric-slab waveguides. Coaxial cable is a cable consisting of an inner conductor surrounded by a tubular insulating layer typically made from a flexible material with a high Dielectric constant, all Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. An optical medium is material through which Electromagnetic waves propagate An optical fiber (or fibre) is a Glass or Plastic fiber that carries Light along its length Twisted pair Cabling is a form of wiring in which two conductors (two halves of a single circuit) are wound together for the purposes of canceling out Coaxial cable is a cable consisting of an inner conductor surrounded by a tubular insulating layer typically made from a flexible material with a high Dielectric constant, all A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. A waveguide is a structure which guides waves such as Electromagnetic waves Light, or Sound waves It may also pass through any physical material which is transparent to the specific wavelength, such as water, air, glass, or concrete. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag 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. Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Historically, various aether theories were used in science and thought to be necessary to explain the transmission medium. See also the disambiguation page for Aether. Alchemy, Natural philosophy, and early modern Physics proposed the existence 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. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. In Classical physics, free space is a concept of Electromagnetic theory, corresponding to a theoretically "perfect" Vacuum, and sometimes Regions of the insulative vacuum can become conductive for electrical conduction through the presence of free electrons, holes, or ions. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. In Science and engineering, a conductor is a material which contains movable Electric charges. Electrical conduction is the movement of electrically charged particles through a Transmission medium ( Electrical conductor) In Solid-state physics, the free electron model is a simple model for the behaviour of Valence electrons in a Crystal structure of a Metallic An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge

Telecommunications

Many transmission media are used as a communications channel. Channel, in communications (sometimes called communications channel) refers to the medium used to convey Information from a

For telecommunications purposes in the United States, Federal Standard 1037C, transmission media are classified as one of the following:

• Guided (or bounded) - Waves are guided along a solid medium such as a transmission line. The United States of America —commonly referred to as the Federal Standard 1037C, entitled Telecommunications Glossary of Telecommunication Terms is a United States Federal Standard issued by the General Services Administration A transmission line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy
• Wireless (or unguided) - Transmission and reception are achieved by means of an antenna. For biologic transmitters see Transmitter substance. A transmitter is an electronic device which usually with the aid of an antenna This article is about a radio receiver for other uses see Radio (disambiguation. An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into

Wireless media may carry surface waves or skywaves, either longitudinally or transversely, and are so classified. In Physics, surface wave can refer to a Mechanical wave that propagates along the interface between differing media usually two fluids with different densities Skywave is the propagation of electromagnetic waves bent (refracted back to the Earth's surface by the Ionosphere. Longitudinal waves are waves that have vibrations along or parallel to their direction of travel that is waves in which the motion of the medium is in the same direction as the motion A transverse wave is a moving Wave that consists of oscillations occurring perpendicular to the direction of energy transfer

See also

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