You should note his comment about using it as the driven element in a Yagi. When one adds parasitic elements (i.e. yagi), the feed-point impedance will change in accordance with said parasitic elements and spacing. As another responder posted, this can be seen in antenna simulations.
Case in point, the proverbial direct fed yagi found all over the internet. The driven element, while basically a dipole (75 ohm impedance), by adding a director and reflector with the correct spacing, the feed-point impedance drops to ~50 ohms.
Somewhat related to this topic, you might want to look into twelfth-wave matching using sections of feedline of different impedances to convert from one Z to another.
As yet another responded mentioned, SimSmith (highly recommended & free), lets you examine many scenarios and will perhaps, provide some deeper insight into impedance.
:)
