Consider two different antennas with equal gain. Let's say one of them is a vivaldi antenna
and the other is a horn antenna
I want to learn how much of the incident power these antenna will be able to receive. As I have specified, their gain (in terms of dBi) are equal. But it makes no sense to me that an antenna like the vivaldi antenna would be able to receive the same amount of power as a horn antenna since it is so very thin.
However, Friis Transmission Formula does only cares about the antenna gains. Am I missing something, would the cross sectional area make no difference?