Free-Space Path Loss

Free-space path loss quantifies how a radio signal weakens simply because it spreads out as it travels through unobstructed space. The formula comes from geometric spreading: the received power falls with the square of distance, and because higher-frequency waves have shorter wavelengths, they also suffer more loss for the same path length. The 32.44 constant converts the idealized Friis transmission equation into convenient engineering units with distance in kilometres and frequency in megahertz.

Use this when estimating the theoretical loss on a clear line-of-sight radio link, such as satellite links, microwave backhaul, or long-range Wi‑Fi/radio planning. It is a baseline model for comparing antenna gains, transmit power, and link budget margins before adding real-world losses like buildings, foliage, rain, or atmospheric effects.

• Using frequency in GHz or Hz without converting to MHz first
• Using distance in metres instead of kilometres, which changes the constant
• Applying free-space path loss to obstructed or indoor environments without accounting for extra attenuation