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)