directional coupler


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directional coupler

[də′rek·shən·əl ′kəp·lər]
(electronics)
A device that couples a secondary system only to a wave traveling in a particular direction in a primary transmission system, while completely ignoring a wave traveling in the opposite direction. Also known as directive feed.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Directional Coupler

 

a device consisting of two sections of radio waveguides. A fraction of the electromagnetic-wave energy propagating through the main waveguide is shunted into an auxiliary waveguide by using coupling links; in the auxiliary waveguide the energy is transmitted only in a specific direction. If the wave-propagation direction in the main waveguide is reversed, then the propagation direction of the shunted wave in the auxiliary waveguide will also be reversed. The unidirectional propagation in the auxiliary waveguide results from the interference of the waves that are excited in it. The superposition of these waves in one direction results in cancellation of the waves; superposition in the other direction results in the formation of the summed shunted wave. Examples of coupling links between two waveguides are (1) apertures in adjacent walls and (2) loops. Directional couplers are widely used in superhigh-frequency apparatus (frequencies from 30 megahertz to 300 gigahertz) for splitting or combining the energies of waves; for determining the wave direction, power, and phase; and for other applications.

REFERENCES

Lebedev, I. V. Tekhnika i pribory sverkhvysokikh chastot, vol. 1. Moscow-Leningrad, 1961.
Altman, J. Ustroistva sverkhvysokikh chastot. Moscow, 1968. (Translated from English.)

L. S. OSIPOV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

directional coupler

(communications)
(tap) A passive device used in cable systems to divide and combine radio frequency signals. A directional coupler has at least three ports: line in, line out, and the tap. The signal passes between line in and line out ports with loss referred to as the insertion loss. A small portion of the signal power applied to the line in port passes to the tap port. A signal applied to the tap port is passed to the line in port less the tap attenuation value. The tap signals are isolated from the line out port to prevent reflections. A signal applied to the line out port passes to the line in port and is isolated from the tap port. Some devices provide more than one tap output line (multi-taps).
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References in periodicals archive ?
Jiang, "Voltage-controlled multiguide directional coupler formed in a planar nematic liquid crystal film," Applied Physics Letters, vol.
To take account of reference phases at all ports of the directional coupler, the scattering matrix of the directional coupler in Figure 2 is a reciprocal four-port network and rewritten as [S.sub.DC] [3]
Although the emphasis of this paper is laid on the realization of the quasi 0-dB coupled-line directional coupler, a 0-dB coupler is not very interesting, except possibly for DC blocks.
Yang, "Design of new hybrid-ring directional coupler using [lambda]/8 or [lambda]/6 sections," IEEE Trans.
Forsberg, "Ultra-compact directional couplers and Mach-Zehnder interferometers employing surface plasmon polaritons," Optics Communications, vol.
A three-branch line directional coupler has been employed as 3 dB/90[degrees] bridge, which has proper performance of power distribution, port isolation, and 90[degrees] phase shift in wider bandwidth.
To achieve a directional coupler with good restraint outside the passband, two wide coupled open-circuited lines are employed instead of two microstrip line branches.
The SIW H-plane cruciform directional coupler topology was selected as it is well adapted for planar realizations [25].
Ideally, a directional coupler would measure only the forward or reverse traveling signals and produce an output for signals traveling in the opposite direction.
Buried homogeneous structures are particularly well suited to directional coupler design, as they support TEM modes with the same phase velocity [1].
AVX Corporation has developed a new wideband directional coupler with high directivity.
A directional coupler has the capability to separate and sample signal components based on the direction of signal flow.

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