Sideband
（重定向自Double sideband）
![The power of an AM signal plotted against frequency.Key: fc is the carrier frequency, fm is the maximum modulation frequency](/Images/godic/202501/09/Am-sidebands2457.png")
![Sidebands are evident in this spectrogram of an AM broadcast (The carrier is highlighted in red, the two mirrored audio spectra (green) are the lower and upper sideband).](/Images/godic/202501/09/AM_signal2457.jpg")
In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier. All forms of modulation produce sidebands.