Aperture is the same as capture area. Both are the same thing as gain
(although numerically different), just looking in the problem in the
reverse direction. Once you know the gain, you know the aperture and
capture area or vice-versa.

Roy Lewallen, W7EL

Caveat Lector wrote:
Ok I screwed up by referring to the Sommer antenna site for Capture Area

But I was taught that antenna gain is a function of Aperture - part of the
classic radar range equation
https://ewhdbks.mugu.navy.mil/2waymon.htm

For Aperture discussion see URL:
https://ewhdbks.mugu.navy.mil/ANTENNAS.HTM

So would be interested in your comments on Antenna aperture and antenna gain
and capture area