I would like to do some reading about how EM waves interact with each other via internet. Upon googling "EM wave interaction," I got some general links about EM radiation and some book titles but I didn't see any websites. Does anyone know one or more good online sources that give an overview of different kinds of EM wave interactions and an explanation of how the interactions work? BTW, I don't even know where to post this question on this forum because none of the physics sub-forums specifically mention EM radiation. Thanks.