Hello, I have a question about dBi antenna gains. From what I gather,
dBi is a unit that specifies the directivity of an antenna and the
focus of the transmission power between a transmitter T and receiver
R1. A 25 dBi antenna gain then, for example, is referenced to a perfect
isotropic antenna.

For an isotropic antenna, received interference power at a receiver,
say R2, is simply the transmit power of T, P_T, multipled by the path
loss in watts between T and R2 that is computed in dB as follows:

0 dBi + 0 dBi - 32.45 - 20*log10(frequency) - 20*log10(distance)

My question is, how do I compute the received interference power at R2
for the same scenario where T, R1 and R2 all use 25 dBi antennas? I
know the positions and path losses between T, R1 and R2, and the
antenna gains of 25 dBi. Do I take a percentage of the transmit power
P_T because these antennas use directivity? How does this work?

Thanks,
Omar