Transmission Bandwidth of FM Wave

The transmission bandwidth of a frequency modulated (FM) wave depends on the maximum frequency deviation and the maximum frequency of the modulating signal.

The maximum frequency deviation, denoted as Δf, is the maximum amount by which the carrier frequency is varied during modulation. The maximum frequency of the modulating signal, denoted as fmax, is the highest frequency component of the modulating signal.

The transmission bandwidth of an FM wave can be calculated using the Carson's rule, which states that the bandwidth of an FM wave is approximately equal to two times the sum of the maximum frequency deviation and the maximum frequency of the modulating signal, i.e.,

BW = 2(Δf + fmax)

For example, if the maximum frequency deviation is 10 kHz and the maximum frequency of the modulating signal is 5 kHz, then the transmission bandwidth of the FM wave would be:

BW = 2(10 kHz + 5 kHz) = 30 kHz

This means that the FM wave would occupy a frequency range of 30 kHz centered around the carrier frequency.

It is important to note that the bandwidth of an FM wave increases as the maximum frequency deviation and the maximum frequency of the modulating signal increase. This can limit the number of FM channels that can be accommodated within a given frequency spectrum, particularly in applications where bandwidth is limited, such as in mobile communication systems.