The slightly less cool thing about a spherical reflector (as opposed to a
parabolic reflector, for example) is that it focuses to a
line rather than a point.
This can be corrected for either by making your receiving
antenna in the shape of a
line, though this severely limits the range of
frequencies you can be monitoring at any given time (
Arecibo Observatory with its 305-m spherical dish used to have a system of several line feeds that could be swapped in and out for different observing purposes before it switched to the second correcting option...), or by implementing a series of
secondary reflectors that can then
focus the line signal down to a
point.