1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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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*105 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 (εr) 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.
A 1-Way and 2-Way Path Loss Calculator is included in RF Cafe Calculator Workbook for FREE.