...
(Eq. 211220)
with:
X is the normalized radio path between transmitter and receiver 
...
Y2 is the normalized antenna height of the receiver
where:
is a parameter derived from the earth admittance factor K :
=1 for > 20 MHz.
...
(Eq. 212221)
The antenna height gain G(Y) is given by the formula set:
for Y>2 (Eq. 213222)
for 10K < Y < 2
...
for Y < K/10
...
where K is the normalized earth surface admittance factor (see ITU-R Rec. P.526), default value 10e-5:
...