For your conceptual purposes, your question would be similar to this?:

In a deep focal point of parabolic dish two antenns are mounted...

Which of them it does pick up more energy?

An antenna with 180 degree beamwidht or an highly directional antenna
with 0,1 degree beamwidth (both pointed to dish, of course)?

(In focal point of dish there are convergent frontwaves also). (We
could think in a sperical dish, also).

73's

Miguel Ghezzi (LU 6ETJ)