A mobile base station (BS) in an urban environment has a power measurement of 35 µW at 375 m. If the propagation follows an inverse fourth power law (Section 3.2.2), what is a reasonable power value, in µW, to assume 1.5 km from the BS?


Give your answer in scientific notation to 2 decimal places.

 Feb 11, 2022

Here is what I think is the answer


p = k / d^4

35 = k / (3754)

k = 6.92 x 10 ^11 m4 - uW


1.5 km = 1500 m


p = 6.92 x 10 ^11 m4 - uW  / (1500 m)4  = 1.37 x 10-1 uW


(This applies to radar waves returning to the reciever/transmitter.....I believe wave power diminishes inversely to the SQUARE of the distance.....so this may not be the answer you are looking for.....it may be   p = k / d^2

     in this case the answer would be 2.187 uW )

 Feb 11, 2022
edited by ElectricPavlov  Feb 11, 2022

I was curious about the same thing: W T F



Aside from different power and distance measurements, this question uses a parenthetical (BS) along with base station. However, I think the (BS) is (now) included by the author as a cryptic indication that the physics in the question assumes facts not in evidence: That is, the question is Bull Shit, even though the equation is correct as a baseline for EM waves reflected back to a transmitter, or as a baseline to correct errors in time-domain reflectometry measurements. 



--. .-

GingerAle  Feb 14, 2022
edited by GingerAle  Feb 14, 2022

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