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 Originally Posted by a500lbgorilla
How do antenna work?
There are active and passive antennae. Active antennae are transmitters, passive antennae are receivers.
They are mostly the same thing, a long conductive wire attached to a circuit.
The circuit in a transmitter takes some input signal and amplifies it into a high-voltage AC signal. It outputs that signal to the long wire (usually in a vertical position, going up a tower). This signal pushes the electrons up and down the wire. Moving charges are electric currents. Changing currents create changing electromagnetic fields. The transmitter emits photons in the frequency that the AC signal is driving the wire. These are, unsurprisingly, called radio waves.
The range of the electromagnetic spectrum which is lower than visible photons is the radio wave band.
Play this backward in time and you get the receiver.
There is a long wire sticking up vertically, just waiting for a radio wave to be incident on it. Those waves are the changing electromagnetic fields, and those changing fields create changing currents in a conductor. The charges in the antenna are then moved up and down the wire, which the connecting circuit then inputs.
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