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.

Guest Feb 11, 2022

#1**+1 **

Here is what I think is the answer

p = k / d^4

35 = k / (375^{4})

k = 6.92 x 10 ^11 m^{4} - uW

1.5 km = 1500 m

p = 6.92 x 10 ^11 m^{4} - 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 )

ElectricPavlov Feb 11, 2022

#2**0 **

I was curious about the same thing:

https://web2.0calc.com/questions/please-help_76830#r2

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.

GA

--. .-

GingerAle
Feb 14, 2022