In telecommunications, a directional coupler is a transmissioncoupling device for separately sampling (through a known coupling loss) either the forward (incident) or the backward (reflected) wave in a transmission line. BlackBerry 7100t Telecommunication refers to the communication of information at a distance. ... In communications, transmission is the act of transmitting electrical messages (and the associated phenonomena of radiant energy that pass through media). ... In electronics and telecommunication, coupling is the desirable or undesirable transfer of energy from one medium, such as a metallic wire or an optical fiber, to another medium, including fortuitous transfer. ... This article needs to be cleaned up to conform to a higher standard of quality. ... 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, such as electromagnetic waves or acoustic waves, as well as electric power transmission. ...
A directional coupler may be used to sample either a forward or backward wave in a transmission line. A unidirectional coupler has available terminals or connections for sampling only one direction of transmission; a bidirectional coupler has available terminals for sampling both directions.
A simple example of a directional coupler is the Bethe coupler between two similar rectangular waveguides, one carrying a TE-10 wave: The waveguides are set long side against long side and a hole is opened to the common wall. Typically either a round hole is placed in the middle and one of the guides is turned about the axis of the hole to control directivity, or the guides are rigidly attached and the distance of the hole from the short wall determines the directivity. The amount of coupled power is determined by the radius of the hole. Hans Bethe in 1945. ... To meet Wikipedias quality standards and appeal to a wider international audience, this article may require cleanup. ... In electromagnetics, directivity is a property of the radation pattern produced by an antenna. ...
For lower frequencies a compact broadband implementation by means of unidirectional couplers (transformers) is possible. This article is about electrical and electronic transformers. ...
Image File history File links Directional_coupler. ...
Directionalcouplers are four-port circuits where one port is isolated from the input port.
A directionalcoupler has four ports, where one is regarded as the input, one is regarded as the "through" port (where most of the incident signal exits), one is regarded as the coupled port (where a fixed fraction of the input signal appears, usually expressed in dB), and an isolated port, which is usually terminated.
The coupled port on a microstrip or stripline directionalcoupler is closest to the input port because it is a backward wave coupler.
Directionalcouplers, or Taps as they are sometimes called, are used to extract a small portion of the signal from the distribution cable to feed subscribers taps, while maintaining the proper characteristic impedance of the ditribution cable.
Directionalcouplers are placed at various locations throughout a distribution system based upon the required tap loss and signal level needed.
Isolation in a directionalcoupler is measured with a known signal applied to the output terminal with the input terminated, as shown in Figure 54.
Feeds |
Contact