Demonstration Description: A microwave transmitter emits a 10 GHz polarized signal modulated by a 1000 Hz square wave. A receiver, connected to an audio speaker to make the received signal audible, faces the transmitter. A metallic grid, consisting of thin and closely spaced parallel bars, is held between them at various orientations. When the bars are held parallel to the E-field, the signal is blocked. When the bars are rotated 90o , however, the signal is uninterrupted. A solid metallic sheet attenuates the waves. The output can also be displayed on an oscilloscope
A microwave transmitter and a microwave face each other on a lens bench. A grid inserted between them shows polarization of the microwaves. A solid Al sheet demonstrates attenuation. The receiver is hooked up to an audio speaker which makes the received signal audible. The output of the receiver can also be shown on an oscilloscope.
The frequency of the modulating square wave can be readily set to 1000 Hz (T=1 ms on scope) by adjusting the frequency dial on the generator.
The frequency of the microwave is calculated by measuring the distance the transmitter has to be moved relative to the receiver so that the square waves go from max to alternate max amplitude (one max in between). Typically, this distance is 3 cm.