This is a question I came across in lab. I inserted a reflecter between a microwave transmitter and receptor, with the plane of the reflector parallel the the axis of the beam. The reflector is then moved away. See the setup and data plot in the attachment. I understand that the waves are coming in an out of phase as you move the reflector which is why the plot oscillates. I also know that the further away the reflector, the less the receptor picks up because the waves diverges off the reflector. What I can't explain is why the amplitude of the wave falls to zero when the reflector is in the middle. Any ideas?