I think you mix optical term"field of view" with RF definition of antenna beam width.
Antenna itself does not "see" anything, only a complete system can, and the radiation pattern shows all important features. For direction finding and similar applications, the beam width defined to -3 dB from a maximum directivity is used.
Field of view is used with cameras, and I have not seen any -3dB definition with it.
In attachment you will see an TDRS Single Access antenna which is characterized by FOV. So this attribute can belong to an antenna. The FOV there is 44 degrees x 56 degrees so the 3dB beamwidth is very large.
In attachment you will see an TDRS Single Access antenna which is characterized by FOV. So this attribute can belong to an antenna. The FOV there is 44 degrees x 56 degrees so the 3dB beamwidth is very large.