A third choice is the phased array. There are two dimensions to focus, and they don't have to be done the same way. For example, the trough antenna is paraboli

A third choice is the phased array. There are two dimensions to focus, and they don't have to be done the same way. For example, the trough antenna is parabolic in one direction but uses something else in the other direction. Viewed from along the resulting beam, it is a rectangle. Manufacture the reflector involves a simple 1-dimensional bend of the metal.