MHzkm

MHzkm is a nonstandard, informal unit representing the product of a frequency expressed in megahertz (MHz) and a distance expressed in kilometers (km). It is not part of the International System of Units (SI) and has no official status from metrology authorities. In practice, some radio engineers and students use MHzkm as a compact shorthand when discussing relationships that involve both frequency and range, such as rough propagation factors or simplifying equations where frequency and distance appear together.

Because MHzkm is not a defined unit, its numerical value depends on how the expression is written. To convert to base units, 1 MHzkm equals 1e6 Hz multiplied by 1000 m, i.e., 1e9 Hz·m. Examples: a link at 1000 MHz over 5 km has a MHzkm value of 5000 MHz·km (or 5e3 MHz·km, which equals 5e12 Hz·m when converted).

Limitations and context: the quantity has no universal physical meaning, and different equations or models may interpret the f·d product in different ways. When performing calculations, it is better to express frequency and distance with SI units (Hz and meters) or to use a dimensionless parameter defined by the specific propagation model. MHzkm thus serves mainly as a shorthand in informal discussions or quick estimates, rather than a standardized physical quantity.

Related concepts include radio propagation models, the Friis transmission equation, free-space path loss, and phase delay, where frequency and distance influence link behavior but are typically treated with explicit SI units in formal work.