A Yagi is a directional antenna. I am not sure they make a yagi with that kind of radius but I suppose it's possible.
To answer your question. Repeater. A WAP54G for instance would work. Or if the WRT54G is WDS compatible, and I can't remember if it is or if a firmware upgrade enables this functionality, any WDS compatible device on the remote side would work as a WDS Bridge/Repeater. The question would be distance, obstructions, and so on for the Parent to bridge link.