What exactly is a sideband physically in an A.M wave and how is it generated when only carrier is modulated?

Question

and why does carrier does not contain any information even though its amplitude is modulated in accordance of that of the modulating signal.

Answer 1

First the name side band was given to it because it was a vernier capacitor that dialed the band width.and the dead center was the band and on either side of center was the sideband...now the side band is actually the clipped upper and lower apogee of the amplitude of the frequency modulation. if you have a scope it will appear as a sine wave and will be very similar to the PEP cut off line. It has in the AM unit a devise called a discriminator that rejects this and all you get is a clean RF right in the middle . Sometimes though through faulty output or over modulation a bleed over will occur and since your only hearing about 2-3 % of the transmission it sounds a little like Donald Duck...There ya go Side band it is not ...............unless you want to call it that (note: i still call it that too....:)..from the E...

Answer 2

You're confusing time-domain with frequency-domain. When a 'carrier' is modulated by (multiplied by) another sine wave, there will be four terms in the resultant expression. The 2 original frequencies, their sum, and their difference. It's the sum and difference terms that contain all of the modulation information.

Doug