Attenuation constant of air

I have an FM Tx that produces power of about 200mW with antenna elevated about 15 meters above the ground.

What is the value of the air attenuation constant (α).?

Thanks very much for your consideration.

realy you need the "free space atenuation"

L=(lamda/(4*pi*R))^2

of course the information of the TX and RX antennas

If you do not consider any propagation effect except the free lost

the equation is:

L[dB]=32.4 + 20 log d[Km] + 20 log F[MHz]

Prx[dBm] = Ptx[dBm] + Gtx[dBi] - L[dB] + Grx[dBi]

I hope it helps you


TaPa