RADIO How Stations Share The Same Air and How We Listen To Only One Station

Stations Divided By Frequency KISSWBCNWBUR kHz MHz Do Stations Interfere? Yes! Is This Interference Reversible? Fortunately Yes!

Combination of Transmitters KISS 108FM WBUR 90.8FM Your Car, iPod, etc. Transmitter Receiver Transmitter

Listening to One Station Receiver gets combination of two frequencies (stations) We want to recover one frequency (station) Resonators! Small inputs at correct frequency give big outputs Inputs at other frequencies give small outputs Output Input Swing Set Mass-Spring (Slinky) Input Output

Changing Stations Input Output Input Output WBURN 90.8FM KISS 108FM Change something about resonator to “Tune” it to a frequency (station) of choice Knob on radio changes an electrical resonator M1 M2

Big Picture WBURN 90.8FM Multiple StationsCombined Waves ResonatorSingle Station