[lcedp]

Ok, point taken. It is vaguely a logarithm function. But what's the base of this logarithm? How much is it curved?

Just try light up a big room which has no windows with a candle - you can see pretty well at the distance of your hand, but in a few meters from you - it's plain darkness. I expect wi-fi waves to be like this.

Using the grath "Perceived Brightness" at [1] we have roughly the following table:

    Distance/Actual/Perceived Brightness
    1/100/100
    2/25/~55
    4/6.25/~30

[1] http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.htm...

[sp332]

Luminous efficacy depends on wavelength, with the eye being most sensitive to 555nm (green) light at 683 lumens/Watt. Most wifi setups max out at 1W (I think?), so if the eye were as sensitive to wifi signals as to green light, we could get 683 lumens which is about the same as a 60W incandescent bulb.

[lcedp]

And?

[sp332]

Oh, so if we're trying to imagine how bright a wifi router's "light output" would look if we could see it, we can just imagine a 60W (monchromatic, say green) lightbulb. Of course the light would pass through walls more easily which is a bit unusual :) But for attenuation over free space, I think the analogy to a 60W light bulb is very useful.