A focal point may mean the same as focus.

Elements of an antenna:

1. driven element
2. parasitic element.

The driven element is directly connected to the transmission line or source.

In mathematics, focal point has a meaning of a critical point of a distance function.

In terms of light and optics, the focal point is the point in which all the rays of light meet after passing through a convex lens, or reflecting off of a concave mirror.