- When the radio wave propagates in the air, the electric field direction changes regularly. If the electric field direction of radio wave is vertical to the ground, the radio wave is vertical polarization wave
- If the electric field direction of radio wave is parallel with the ground, the radiowave is horizontal polarization wave
- Propagation of electromagnetic propagation takes on an energy propagation mode. During the propagation, the electric field is vertical to the magnetic field, both vertical to the propagation direction. Through interaction between the electric field and the magnetic field, the energy is propagated to the distance, just like propagation of water waves.