Radio waves ( Radio Communication )
Radio waves ( Radio Communication )
Electromagnetic wave ranging in frequencies between 3 KHz and 1GHz are normally called radio waves. Radio waves are omni-directional when an antenna transmits radio waves they are propagated in all directions. This means that sending and receiving antenna do not have to be aligned. A sending antenna can send waves that can be received by any receiving antenna. Radio waves particularly those waves that propagate in sky mode, can travel long distances. This makes radio waves a better choice for long-distance broadcasting such as AM radio. Radio waves particularly those of low and medium frequencies can penetrate walls.
• Radio waves are easy to generate, can travel long distances, and can penetrate buildings easily, so they are widely used for communication, both indoors and outdoors.
• Radio waves also are omnidirectional, meaning that they travel in all directions from the source, so the transmitter and receiver do not have to be carefully aligned physically.
• The properties of radio waves are frequency dependent.
• At low frequencies, radio waves pass through obstacles well, but the power falls off sharply with distance from the source, roughly as 1/r2 in air.
• At high frequencies, radio waves tend to travel in straight lines and bounce off obstacles. They are also absorbed by rain.
• At all frequencies, radio waves are subject to interference from motors and other electrical equipment.
• In the VLF, LF, and MF bands, radio waves follow the curvature of the earth.
• In the HF they bounce off the ionosphere