Consider a received radar signal of the form
s(t) = \frac{p e^{i 2 \pi f ( \frac{2 R(t)}{c} )}}{ [4 \pi R(t)]^2}
where p is the reflectivity value, f is the carrier frequency, and R(t) is the range. In some cases I have seen this written as
s(t) = p e^{ i 2 \pi f ( \frac{2 R(t)}{c} )}...