How Antennae Work

There are different behaviors that are exhibited by any substances that can interact with electromagnetic waves, depending on whether you're looking at the near field or the far-field limit. This is important when we're designing electromagnetic, electromagnetically sensitive devices like wires and transistors. The variations in how that works in the pushing of charge one way or the other can be picked up by whatever circuit the antenna is connected to  and used to generate a sound. It's essentially how radios work: You've just got the antennae which is driving a current in the circuit that is connected to, which varies in frequency and amplitude.