It all starts with the conversion of sound waves in the air into the electrical energy with the help of a transducer, which is generally a microphone. The carrier waves are generated in an oscillator which produces un-modulated sine waves into the radio frequency range. Usually, a tuned oscillator circuit is used which creates carrier wave of a specific frequency. Then the signal from carrier wave generator and transducer is fed into the modulator that encodes carrier wave with the information.
There are two types of modulation methods used – amplitude modulation (AM) and frequency modulation (FM).
It is connected to an antenna that converts the energy from incoming radio waves into small radio frequency alternating current voltage. The oscillating electric and magnetic fields of the radio wave pushes the electrons in antenna back and forth, thus creating an oscillating voltage.
Working of a receiver-