RF: radio frequencies transmitions. They are made of electric and magnetic waves, electromagnetic waves. They can be horizontal or vertical.
It all began with morse code, that were followed by radio and then television broadcast. Then cordless telephones, remote controls, cellular controls, cable and satellite TV nd now data (WiFi, bluetooth).
Wavelenght = speed of light / frequency. The signal is affected by the wave lenght.
Radio waves can be emitted or absorbed by antennas, they can also amplificate signals.
