The Fresnel Zone Calculator can be used to determine the size of the elliptically-shaped area of RF propagation between a transmit antenna and receive antenna, which is known as the Fresnel zone.

Objects within the area of the Fresnel zone can reflect radio waves and induce multi-path propagation issues between the transmitter and receiver, where direct path line-of-sight radio waves and the reflected path radio waves are received out of phase from one another.