If a half-wave dipole is converted to a Yagi by adding a slightly shorter parasitic element, in what direction(s) does the radiation strength increase?

In a Yagi antenna, parasitic elements are placed parallel to the main driven element (the dipole) to shape the radiation pattern. A parasitic element that is slightly shorter than the driven element acts as a 'director.' The director works by combining its induced electromagnetic field with the driven element's field, resulting in a stronger signal pointing toward the shorter element. Therefore, the radiation strength increases in the direction moving from the dipole outward through the director. Remembering that the shorter element 'directs' the signal forward is the key to visualizing the antenna's beam.