the property of a microphone or antenna of being more sensitive to sounds coming from one direction than from another.

Also referred to as dispersion characteristic, this relates to a loudspeaker’s propagation pattern of sound. Smooth and even dispersion is generally considered an important attribute since room boundaries cause most of the sound to be reflected rather than direct. In the low bass, sound propagation is essentially omni-directional like a circular wave emanating from the impact of a rock. With rising frequencies, sound becomes directional and behaves like a more and more tightly focused spotlight.

Directivity describes the radiation pattern and the ability of an antenna to focus energy in a particular direction when transmitting or to receive energy better from a particular direction. In a static situation, system designers can use antenna directivity to concentrate the radiation beam in the wanted direction. However, in a dynamic system, where the transceiver is not fixed, the antenna should radiate equally in all directions, and this is known as an omni-directional antenna.

The amount of power measured at the secondary input relative to the primary input of a coupler.

Fraction of optical power transferred from one input port to any other input port.

See near-end crosstalk.

The property of transmitting or receiving energy more strongly in some directions than in others.