Courses: P4, P14, P16, P19
The receiver is connected to an amplified speaker so one can hear the amplitude of the received signal. When one connects to the audio jack it disconnects the meter -- so don't expect the meter to show anything when the speaker is plugged in. The transmitter is roughly in the 3 cm wavelength range.
We have a couple of polarizing wire frames, a metal sheet that acts as a mirror, a foam cube with embedded ball bearings, and a couple of tall narrow "guides," one of which is wide enough to pass the signal, and one of which is slightly narrower and which will block the signal.