Electromagnetic waves are propagated through the following modes:
(i) ground wave propagation
(ii) sky wave propagation, and
(iii) space wave propagation.
For transmission of signal having frequency range from a few MHz up to 40 MHz, sky wave propagation mode is used.
Sky wave propagation:
The mode of wave propagation in which the radiowaves emitted from the transmitter antenna reach the receiving antenna after reflection by the ionosphere.
Filter
Rectifier
FET
Oscillator
transmission
modulation
detection