1 Answer

Radio waves are created by a transmitter,  the transmitter creates the energy to 'push' the wave (RF signal) through a carrier - Within the carrier is modulation. (Music/Voice/data)  Similar to a garden hose.  Water pressure pushes the water through a hose.  Where the hose is the carrier, water is the signal modulation..

An RF signal (Radio Frequency)  wave needs to also have a receiving station.  Your radio.  The receiving station must be tuned to the exact frequency as the transmitter.  

The transmitter has a set 'wattage', watts is the pressure! The more pressure, the further the signal will go.

This brings us to 'wavelength'.  The antenna of the transmitter must match the wavelength of the receiver.  Sometimes the actual wave is very large so the receiving antenna to be perfect  must be the same size, this is impossible in most applications so they cut the antenna to half, quarter or eighth wave.  

Hope this helps.