Aircoupled

Aircoupled, or air-coupled, describes systems and methods that use air as the medium for transmitting energy or coupling signals between components. In practice this means acoustic or mechanical energy travels through air rather than through a liquid or solid, or that a sensor and its target are connected through the air gap without direct contact.

In acoustics and sensing, air-coupled devices include transducers and sensors that operate with a path entirely in air. Air-coupled ultrasound transducers emit ultrasonic waves into air and receive echoes from a material under test without immersion or direct contact. This approach is valued for non-contact inspection, material characterization, and settings where couplants or liquids cannot be used. Air-coupled microphones and related measurement systems also rely on sound transmission through air to capture or analyze acoustic signals.

Principles and limitations are dominated by the physics of air as a coupling medium. The acoustic impedance of air is low compared with most solids, causing strong reflections at interfaces and substantial attenuation with distance. Consequently, air-coupled systems typically require higher transmitter power or very sensitive receivers, careful alignment, and control of the air path (distance, angles, humidity, and temperature). They offer advantages such as non-contact operation, rapid setup, and avoiding surface contamination or damage, but they often trade off with reduced signal strength and penetration depth.

Applications span nondestructive testing, material science, and certain audio and measurement contexts where contactless coupling is essential.