A grid of parallel metal wires is placed in the path of a microwave beam to demonstrate polarization. As the grid is rotated, the intensity of the microwaves detected by a receiver changes. When the grid's wires are aligned with the electric field of the microwaves, the waves are absorbed, and minimal energy reaches the receiver. When the grid is perpendicular to the electric field, the waves pass through with little attenuation. This experiment illustrates how microwaves, like light, can be polarized and how polarization filters work.