Its easier than this.
divide the additional EIRP (due to more tx power, or more antenna
gain) by the path loss exponent (which is never '2.0', even for LOS,
but most people hope it is). The quotent is the additional range,
expressed in dB.
So, if you end up with '3', you'll have about 2X the range.
Example:
add 6dBi of gain (say, from a 2.2dBi 'rubber duck' to a
theoretic 8.2dBi antenna of some description).
6.0/2.0 = 3.0
Jim
Rob Genovesi writes:
> There is a calculation for "free-space path loss" that calculates signal
> fade over distance :
>
> Loss = 96.6 + 10log(d-squared) + 10log(f-squared) dB
>
> d = distance in miles
> f = frequency in gigahertz
>
> So if you know your EIRP (transmit power + antenna gain) you can estimate
> the signal strength at "d" distance.
>
>
> -Rob
>
>
>
>
> PS: I got the equation from the cisco press book "deploying license-free
> wireless wide-area networks" - a good generic resource (not cisco specific)
>
>
>
> At 12:36 PM 1/5/2004 -0800, you wrote:
> >I know this question is very vague, but still I wonder if there is an answer
> >to it.
> >
> >Is there a theoretical formula that links antenna dB gain with increase in
> >maximum range of the wireless signal. I understand that in theory RF signal
> >range is infinity, but I can not figure out if there is a correlation
> >between antenna dB gain and signal range at certain frequency. Following the
> >common logic it is obvious that range will increase as antenna has better dB
> >gain, but how much?
> >
> >A formula for electric field goes something like: E=9500*power/distance (I
> >might be wrong about this), but this does not take in account the frequency
> >of our signal.
> >
> >P.S. I am not concerned with terrain configuration, weather condition, and
> >other factors at this time.
> >
> >--
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>
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