What is the purpose of Friis transmission equation [(LdB) = 20 log(d) + 20 log (f) – 27.55 ]?

A.
Calculate earth bulge to determine minimum antenna height

B.
Calculate receive sensitivity for an 802.11 radio/antenna pair

C.
Calculate RF path loss in free space

D.
Calculate the loss experienced between the intentional radiator and antenna

E.
Calculate the minimum voltage requirements for lightning suppression systems