Nowadays electromagnetic waves are widely applied in life, especially in the field of communications. To be able to transmit communications by electromagnetic waves, the transmitter must be used the generators to transmit the signal into space. Regarding generators, there are single-sided generators, amplitude-modulated generators and frequency generators. At the receiving location, a receiver must be used to convert the electrical signal into an acoustic signal as required. The receiver includes: Receiving antenna, audio frequency amplifier, mixer, IF intermediate frequency amplifier block, demodulator.