How do you account for receiver sensitivity in tranceiver half wave dipoles?
The "traditional" way of estimating the attenuation between antennas is by using the free-space equations derived by Harold Friis. Then make some adjustments to account for antenna gain and fade-margin (real earth scenarios).


  Link Loss (dB) = 32.4 + 20\$log_{10}\$(F) + 20\$log_{10}\$(d)


where F is MHz and d is distance between the two antennas (in kilometres).

If you are using 2.45 GHz and require 0.8 km to be covered, the link loss is: -

32.4 dB + 67.8 dB + (-1.9 dB) = 98.3 dB


If you transmit 3 watts (34.8 dBm) you will receive -63.5 dBm

But, this is for isotropic antennas and of course these transmit power in all directions. For a quarter wave monopole at each end the link loss lowers by about 4 dB hence you will receive about 60 dBm.

Fade margin is a bit of a hand waving estimate but a simple approach is to assume that you might expect the power received to be down by 20 dB is a reasonable first guess. This leaves you at -80dBm.



The 32.4 dB part comes from mopping up this formula: -



Pr is received power, Pt is transmitted power. Gt and Gr are antenna gains and for isotropic antennas are assumed to be unity. Convertion of \$\lambda\$ to MHz and R to kilometres is part of the mopping up as is the 4\$\pi\$.

Basically 32.4 = 20log\$_{10}(\dfrac{40\pi}{3})\$