Radio waves belongs to the unguided media and they are of different frequencies ranging from 3 KHz to 300 KHz. The picture below shows the spectrum of the radio communication band.
- Very Low Frequency (VLF) waves propagate s surface waves, usually through air, but sometimes through water also. They are usually used for long rang radio navigation and submarine communication.
- Low Frequency (LF) waves also propagate as surface waves and these are used for long range radio navigation or navigation locators.
- Middle Frequency (MF) waves reply on line of sight antennas to increase and control absorption problems. These waves are used for Am radio, radio direction finding and emergency frequencies.
- High Frequency (HF) waves are used for amateur radio, international broadcasting, military communication, telephone, telegraph and facsimile communication.
- Very High Frequency (VHF) waves use line of sight propagation and are used for VHF television, FM radio, aircraft AM radio and aircraft navigation.
- Ultra High Frequency (UHF) waves use fine of sight propagation and they are used for television, mobile phone, cellular radio, paging and micro wave links.
- Super High Frequency (SHF) waves are transmitted as either line of sight or into space. They are used foe terrestrial and satellite microwave and radar communication.
- Extremely High Frequency (EHF) waves are transmitted into space, and are used for scientific applications such as radar, satellite and experimental communication.
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