Editing Diode (section)

===Radio demodulation===
[[File:Simple envelope detector.svg|thumb|300x300px|A simple [[envelope detector|envelope demodulator]] circuit.]]
The first use for the diode was the demodulation of [[amplitude modulation|amplitude modulated]] (AM) radio broadcasts. The history of this discovery is treated in depth in the [[crystal detector]] article. In summary, an AM signal consists of alternating positive and negative peaks of a radio carrier wave, whose [[amplitude]] or envelope is proportional to the original audio signal. The diode [[rectifier|rectifies]] the AM radio frequency signal, leaving only the positive peaks of the carrier wave. The audio is then extracted from the rectified carrier wave using a simple [[electronic filter|filter]] and fed into an audio amplifier or [[transducer]], which generates sound waves via [[Loudspeaker|audio speaker]].

In microwave and millimeter wave technology, beginning in the 1930s, researchers improved and miniaturized the crystal detector. [[#Point-contact diodes|Point contact diodes]] (''crystal diodes'') and [[#Junction diodes|Schottky diodes]] are used in radar, microwave and millimeter wave detectors.<ref name="skyworks_01"/>