A comment a lab script for a recent experiment I did noted that the mechanism by which reflection of EM waves occurs is through the induction of Hertzian dipoles in a material. Having read up on Hertzian dipoles, I have found nothing which discusses them in the context of reflection. I read that a Hertzian dipole is essentially two small spherical conductors connected by a wire, with charge flowing periodically between them, or something that can be approximated by this. I find it very hard to understand how, for example, a plank of wood would support or even vaguely resemble such a system. To summarise, can someone explain how Hertzian dipoles are the mechanism by which EM waves are reflected, or point me to resources that explain this? What bit corresponds to the spheres and which bit to the wire?