Bijoy / David,
Ok, in Bijoy’s complete formula, that’s the Tx antenna gain on one side, and then the Rx antenna gain on the other side, from the receiving device.
The formula you wrote is :
RxLev = EIRP – Path loss
with the path loss = 32.4 + 20.LOG(…) + etc.
there will always be path loss : how do you measure the RxLev ? With a measuring device ? How far is it from the Tx Antenna ?
If you measure the output from the antenna directly, being physically connected to the dipoles, then the RXLEV = EIRP.
Path loss : it is the loss due to waves “blowing” the energy all over space. The energy is not concentrated in one point anymore : it goes everywhere. Since you are measuring the remaining energy from one point only, the RxLev is way less than the initial EIRP.