A finite amount of time is required for a signal to travel from one place to another. In a vacuum, electromagnetic
energy travels at 2.9979*10^{5} km/s (186,282 mi/s). The following equation holds for signal propagation time in a vacuum
(and in the air),
where the relative dielectric constant (ε_{r}) is 1. In keeping with a radar theme, 'R' is used for
range rather than the more common 'd' for distance. Be sure to keep dimensional units consistent across all values.

If a radar system is being evaluated where a round trip out and back needs to be accounted for, then double the range figure. A "radar mile," which is a nautical mile out and a nautical mile back, is 12.36 μs.

Note: Only enter values in the yellow cells or risk overwriting formulas! |

Two charts of propagation time vs. distance are provided below - one for units of km and one for units of miles.

Here is information on Doppler, radar equation and path loss.

A 1-Way and 2-Way Path Loss Calculator is included in RF Cafe Calculator Workbook for FREE.

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