Question

The maximum power efiiciency of an am modulator is

Answer 1

AM power efficiency

The power efficiency of amplitude modulation is very low. To see why this is the case, it is necessary to look at the composition of the radio signal and the relative power levels of its constituents: the carrier and the two sidebands.

When a radio frequency signal is modulated by an audio signal the envelope will vary. The level of modulation can be increased to a level where the envelope rises to twice the un-modulated level and then falls to zero. This is called 100% modulation as it is the maximum amount that can be applied.

If the level of modulation is increased beyond the 100% level, then distortion will arise because the envelope cannot fall below zero.