free-space channel

The free-space channel in telecommunications refers to a communication path where signals, typically light or radio waves, travel through the atmosphere without a physical conductor. This is in contrast to guided channels like optical fibers.

In optical communication, a free-space channel uses a laser beam to transmit information. While this allows for high-rate broadband communication, signals are susceptible to degradation from beam divergence, atmospheric absorption, and scattering caused by factors like fog or dust.1

Radio waves also utilize free-space channels, enabling mobile, satellite, and broadcast communications where physical connections are impractical. However, radio wave propagation is affected by atmospheric conditions and geometric spreading, which reduces signal strength over distance. Examples of free-space optical systems include TV remote controls and LIDAR technology.21