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Gene, thanks for the reply and I appreciate you taking the time to bat this around with me, however, I beg to differ....

In our example, whatever the antenna choice, EIRP is the same.

From CWNP, Wikipedia et al:

Received Power (dBm) = Transmitted Power (dBm) + Gains (dB) − Losses (dB)


The equation is the same if the EIRP is the same, isn't it ?

100mw EIRP from 50mw into a 3db antenna will fade at the same rate as 100mw EIRP from 25mw into a 6db antenna.

Note I am referrng to someone standing in the line of maximum power direction, I realise the shape of the coverage area will differ with antenna type. However, in the path of strongest signal, I don't see any way that the same EIRP will propogate differently because of different antennas. The reason for this is the antenna gain is accounted for BEFORE we arrive at our final EIRP quantity.

You say we get a better signal if we use a higher gain antenna, and I agree, however, if we reduce the power, then it cancels out in the advantage. 100mwEIRP is 100mw EIRP.... It's the same...

Reduce the power, take away half the dough, flatten it, the dough is not as wide, but it's just as dense at any point on the direct line of maximum power as radiated out from the antenna.

The equation for FSPL factors:

Wavelength
Frequency
Distance from transmitter
Speed of light

I contend that the received signal is going to be the same for different antennas if:

1) The EIRP is the same
2) We are standing the same distance away
3) We are measuring from the direct line of maximum power.

How can it be otherwise ?

-Neil