Coverage area of the microstrip patch antenna

Hi All,

Good Morning.Can any one help me out to find the coverage area of the patch antenna. I meant "Coverage area" - distance (approximate) - i.e., how far it can radiate ?

depends on link budget https://en.wikipedia.org/wiki/Link_budget
for example, your signal power is 1mW, then

power=1; 'mW
dbm=10*Log10(power)
dbm = 0

so it is 0dBm


Let's say your patch antenna gain is 6dBi
dbi=6;

then
eirp=dbm+dbi
eirp = 6

and _i think_ we can add losses here
some formula for losses exists.
for example some formula gives losses f(distance,frequency,...) = - 40dB
6-40=-36dB

Then convert it back to
mw=10^(some_dB/10)

and see if receiver can use this little power.
Maybe i am wrong somewhere, because i currently was interested only in eirp, so i found those formulas.