Directional antennas come in different forms each with slightly different characteristics sonit's very hard to say. Your also talking about a lot less mass in a

Directional antennas come in different forms each with slightly different characteristics sonit's very hard to say. Your also talking about a lot less mass in a mouse than in a human head. With the wave guide at close enough range, you can assume a much higher percentage of the energy is hitting the mouse than say a yagi, but the specifics depend a lot on the design of the system. To answer the other part of the question, you can think of a wave guide like a tuned pipe for rf to travel down. In alot of cases they are literally just empty tubes that are correctly tuned for the frequency fed into them.