- Radio waves are a type of electromagnetic (EM) radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
- They have have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers.
- Like all other electromagnetic waves, radio waves travel at the speed of light i.e., 3x10^8 m/s.
- A radio wave is an electromagnetic wave propagated by an antenna. Radio waves have different frequencies, and by tuning a radio receiver to a specific frequency you can pick up a specific signal.
- In the United States, the FCC (Federal Communications Commission) decides who is able to use which frequencies for which purposes, and it issues licenses to stations for specific frequencies.
- Thus, the spectrum is divided into different frequency bands, and each band has been allocated for a specific application ranging from aeronautical and maritime communication to AM and FM radio stations.
Radio Wave Spectrum:
| NAME | FREQUENCY RANGE | APPLICATIONS |
|---|---|---|
| Very Low Frequency(VLF) | 3 to 30 kHz | Under water communication |
| Low frequency(LF) | 30 to 300kHz | Navigation, time standards |
| Medium frequency (MF) | 300kHz to 3MHz | Marine/aircraft navigation, AM broadcast |
| High frequency (HF) | 3 to 30MHz | AM broadcasting, mobile radio, Mteur radio, shortwave broadcasting |
| Very high frequency (VHF) | 30 to 300MHz | Land mobile, FM/TV broadcast,amateur radio |
| Ultra high frequency (UHF) | 300MHz to 3GHz | Cellular phones, mobile radio, wireless LAN, PAN |
| Super high frequency (SHF) | 3 to 30GHz | Satellite, radar, backhaul, TV, WLAN, 5G cellular |
| Extremely high frequency (EHF) | 30 to 300GHz | Satellite, radar, backhaul, experimental, WLAN, 5G cellular |