Beacon Range RNAV

For any radio wave travelling one way (so in Radio Navigation, this is everything except primary radar because that has to travel there and back) range is proportional to the square root of power. This is because the radio wave will "spread out" and lose power as it travels away from the transmitter.

  • If you are given an old range and a power factor increase, then multiply the old range by the square root of the factor the power increases by (the factor is new power/old power).
  • If you are given a new range and an old range, divide the new by the old and square the answer to get the power increase.

Note for primary radar, the range is proportional to the fourth root. So if the question is about primary radar, replace "square root" by "fourth root" and "square" by "to the power 4".

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A radio beacon has an approximate range of 69.7 nm. By what factor should the transmitter power be increased to give it a range of 79.2 nm?
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