What does AM Radio Stand for?

Like most people, you’re probably here to learn the AM radio full form. Although the abbreviation “AM radio” is commonly used by radio operators, most people know little about it and that’s totally okay!

To give you a quick answer, the AM in AM radio stands for Amplitude Modulation.

Tracing back to its history, AM radio was one of the earliest broadcasting services; it serves as a talk radio. Most people differentiate FM radio from AM as mostly music, but in reality, there’s much more to the AM band. The key difference between AM and FM is the radio wave modulation technique. To understand the science of the AM band, it’s important to first learn what the abbreviation stands for.

For what does the letter A stand in the radio broadcasting abbreviation AM?

The letter A, in AM radio, stands for amplitude. Literally, amplitude refers to the distance the vibrating particles travel when there’s sound. In simpler terms, each wave has amplitude, which is the overall strength of a signal. Changes to the amplitude can be seen as the change in height of AM radio waves. The signal strength of a carrier wave is critical for the transmission of messages. In the AM band, the amplitude or overall signal strength of the carrier wave varies according to the modulating audio signal. It helps the signal adapt to the incoming audio information, which is broadcasted through wavelengths.

Now that you’ve understood what the letter “A” stands for, let’s look at the complete abbreviation.

What does AM radio stand for?

AM is short for “Amplitude Modulation.” The name comes from its carrier wave modulation method. Radio signals are transmitted over the air, as a part of the electromagnetic waves, which are generated through alternating current. As explained above, in AM broadcasting service, signals adjust their amplitude in accordance with the information being broadcasted.

To understand it better, look at the amplitude modulation as a steady wave being broadcasted at 1,000 kHz. This steady signal is unmodulated and, therefore, has constant height. This means the signal doesn’t carry any important information. The constant signal will only produce sound when it modulates with audio information, such as voice or music. The resulting effect of the modulation is variations to the signal’s strength or amplitude. When the signal adapts to the audio information, the amplitude increases or decreases in accordance with the incoming information. These variations in the wave’s height or amplitude are quite noticeable as they occur as audio static. When you switch stations on the AM band, the static that you hear is actually changes to the amplitude.


AM or Amplitude Modulation radio is one of the earliest and simplest radio broadcast forms. As explained above, it works through quite a fascinating process, which involves carrier waves and their modulations. On the contrary, sound travels through frequencies in FM radio, which stands for “Frequency Modulation”. Therefore, the changes that you hear on AM radio often aren’t noticeable on FM. That is because signals in FM present through variations in frequency, and not amplitude. The difference in process is where AM radio gets its name from!