# Near field path loss with attenuation

1. Sep 27, 2012

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1. The problem statement, all variables and given/known data

I have a 2 wireless cards with a power output of 0dBm, two 5dBi gain antennas, and a 30dB attenuator connected to each antenna. I need to figure out what the path loss will be in this scenario, so I can therefore determine the maximum distance possible between the antennas before they can no longer receive each other's signal.

2. Relevant equations

I know path loss in dB:

L = 20 log_10(4 * π *d / λ)

this one I can use to find the max distance once I know L, but I don't know how to find the path loss due to the attenuation in the first place.

3. The attempt at a solution

I know attenuation is:

= 10 * log_10(power out/ power in)

so

30 dB = 10 * log(power out/ odBm)

How can I find power out from here?

And how could I use that in the path loss equation?

Thank you for the help.

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