directionnelles

Directionnelles is the plural form of directionnel, used in French to describe devices or receptors that are sensitive or radiate signals more in certain directions than others. The term is used across disciplines such as telecommunications, acoustics and sensing. It contrasts with omnidirectionnelles, which respond equally in all directions.

In telecommunications and radar, une antenne directionnelle or des antennes directionnelles are designed to concentrate radiated power along particular axes. This improves gain and range in the selected direction while reducing energy toward unwanted angles. Common types include Yagi-Uda, parabolic, and log-periodic antennas. They are used for point-to-point links, satellite downlinks, radar, and broadcasting where precise bearing is required.

In audio capture, directionnelles refer to microphones with directional pickup patterns, such as cardioid, supercardioid, hypercardioid, bidirectional (figure-eight), or shotgun. Their sensitivity to sound from certain directions reduces background noise and feedback, making them suitable for live sound, studios, or field recording.

Directivity is quantified by a polar response pattern and a directivity index, often expressed in decibels relative to an isotropic source (dBi) for antennas, or by sensitivity patterns in microphones. Beamforming with arrays can create synthetic directionnelles behavior by combining signals from multiple elements.

Directionnelles are central to modern wireless networks, broadcasting, radar, sonar, and audio engineering. Design involves trade-offs between gain, bandwidth, and angular coverage, as well as environmental factors such as multipath and impedance.