Propagation Mechanisms

Besides line of sight, signal can reach receiver in three other “indirect” ways.

Reflection

Signal is reflected from a large object.

Diffraction

Signal is scattered by the edge of a large object - “bends”.

Scattering

Signal is scattered by an object that is small relative to the wavelength.

Multipath Effects

Receiver receives multiple copies of the signal, each following a different path.

Copies can either strengthen or weaken each other.

Small changes in location can result in big changes in signal strength.

Difference in path length can cause intersymbol interference (ISI).