Power dividers and directional couplers
Power dividers and directional couplers are
passive devices used in the field of radio technology. They couple part of the transmission power in a
transmission line by a known amount out through another port, often by using two transmission lines set close enough together such that energy passing through one is coupled to the other. As shown in Figure 1, the device has four ports: input, transmitted, coupled, and isolated. The term "main line" refers to the section between ports 1 and 2. On some directional couplers, the main line is designed for high power operation (large connectors), while the coupled port may use a small
SMA connector. Often the isolated port is terminated with an internal or external
matched load (typically 50 ohms). It should be pointed out that since the directional coupler is a linear device, the notations on Figure 1 are arbitrary. Any port can be the input, (as in Figure 3) which will result in the directly connected port being the transmitted port, the adjacent port being the coupled port, and the diagonal port being the isolated port.
See more at Wikipedia.org...
directional coupler
A
transmission coupling device for separately sampling (through a known
coupling loss) either the forward (incident) or the backward (reflected) wave in a
transmission line. (
188 ) Note: 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.
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).
(1995-12-23)
(c) Copyright 1993 by Denis Howe
directional coupler