29-08-2017, 01:18 PM
A transmission medium is a material substance (solid, liquid, gas or plasma) that can propagate energy waves. For example, the means of transmitting sounds is usually a gas, but solids and liquids can also act as a means of sound transmission.
The absence of a material medium in a vacuum may also constitute a transmission medium for electromagnetic waves such as light and radio waves. While the material substance is not required for electromagnetic waves to propagate, such waves are usually affected by the transmission media traversing, for example by absorption or by reflection or refraction at the interfaces between the media.
The term "transmission medium" also refers to a technical device which employs the material substance to transmit or guide waves. Thus, an optical fiber or a copper cable is a transmission medium. Not only this but it is also able to guide the transmission of networks.
A transmission medium can be classified as:
• Linear medium, if different waves can be superimposed on any particular point in the medium;
• Limited medium, if it is of finite extension, otherwise half unlimited;
• Homogeneous medium or homogenous medium, if its physical properties do not change at different points;
• Isotropic medium, if its physical properties are the same in different directions.
Electromagnetic radiation may be transmitted through an optical medium, such as optical fiber, or through twisted pair wires, coaxial cable, or slab dielectric waveguides. It can also pass through any physical material that 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, just like other types of mechanical waves and thermal energy. Historically, science incorporated several theories of ether to explain the medium of transmission. However, it is now known that electromagnetic waves do not require a means of physical transmission, and therefore can travel through the "vacuum" of free space. The regions of the insulating vacuum can become conductive for the electric conduction through the presence of free electrons, holes or ions.
The absence of a material medium in a vacuum may also constitute a transmission medium for electromagnetic waves such as light and radio waves. While the material substance is not required for electromagnetic waves to propagate, such waves are usually affected by the transmission media traversing, for example by absorption or by reflection or refraction at the interfaces between the media.
The term "transmission medium" also refers to a technical device which employs the material substance to transmit or guide waves. Thus, an optical fiber or a copper cable is a transmission medium. Not only this but it is also able to guide the transmission of networks.
A transmission medium can be classified as:
• Linear medium, if different waves can be superimposed on any particular point in the medium;
• Limited medium, if it is of finite extension, otherwise half unlimited;
• Homogeneous medium or homogenous medium, if its physical properties do not change at different points;
• Isotropic medium, if its physical properties are the same in different directions.
Electromagnetic radiation may be transmitted through an optical medium, such as optical fiber, or through twisted pair wires, coaxial cable, or slab dielectric waveguides. It can also pass through any physical material that 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, just like other types of mechanical waves and thermal energy. Historically, science incorporated several theories of ether to explain the medium of transmission. However, it is now known that electromagnetic waves do not require a means of physical transmission, and therefore can travel through the "vacuum" of free space. The regions of the insulating vacuum can become conductive for the electric conduction through the presence of free electrons, holes or ions.