Troposcatter

Troposcatter, short for tropospheric scatter, is a method of radio propagation that relies on the scattering of radio waves by irregularities in the troposphere. This phenomenon allows for beyond-line-of-sight communication, typically over distances ranging from 50 to 500 kilometers. Unlike line-of-sight communication, which is limited by the curvature of the Earth and obstructions, troposcatter utilizes the atmospheric layer where weather occurs.

The principle behind troposcatter involves transmitting a powerful, focused radio beam into the troposphere at a relatively low angle. Small variations in the atmospheric density, caused by turbulence and temperature gradients, scatter a portion of this energy in all directions, including back towards the Earth's surface at the receiving location. Highly sensitive receivers are required to detect these weak scattered signals.

Troposcatter communication systems typically operate in the UHF and microwave frequency bands. These systems are characterized by high-gain antennas and powerful transmitters to overcome the significant signal loss inherent in the scattering process. The reliability of troposcatter links can be affected by atmospheric conditions, such as rain, fog, and temperature inversions, which can alter the scattering properties of the troposphere. Despite these limitations, troposcatter has been employed for long-distance voice and data transmission, particularly in military and specialized applications where satellite or cable infrastructure is unavailable or impractical.