Radio waves are part of a larger family of waves on the electromagnetic spectrum. They have the longest wave length in the electromagnetic spectrum and can range from 1 millimetre to hundreds of metres. Radio waves have frequencies varying from as low as 3 kHz up to 300 GHz. They are used for various different forms of communication.
This diagram shows radio waves on the electromagnetic spectrum. It showsthe length of the wavelengths for different devices that use radio waveswith radar, television, FM and AM waves. It shows that radio waves not onlyhave the largest wavelength in the electromagnetic spectrum, they alsohave the biggest range in wave size in the spectrum.Radio waves cannot be seen as they lie outside of the visible light section inthe electromagnetic spectrum.
Radio waves are very important in everyday life. They are used for nearly all non-written communication and most wireless technologies. Radio waves transmit music, conversations, pictures and data invisibly through the air, often over vast distances. Many common household products require radio waves to work. AM and FM radios, wireless networks, telephones and televisions all require radio waves to operate.
AM and FM radio broadcasts Cordless phones Radar Garage door openers Wireless networks Radio-controlled toys Television broadcasts Mobile phones GPS receivers Satellite communications Police radios Wireless clocks
Many people use wireless networking, also known as WiFi, to connect to the internet via their computers, laptops or mobile phones. It makes internet connecting more convenient because it doesn’t require wires or cables and therefore allows for roaming.
WiFi transmits at frequencies of 2.4 GHz or 5 GHz which is considerably higher than many other devices that use radio waves. This allows the signal to carry more data, allowing for a better internet connection. Wireless radio waves can transmit on three different frequency bands or, they can “frequency hop”, switching between all three bandwidths. This helps to reduce interference and allows multiple devices to use the same wireless connection simultaneously.
A radar system emits radio waves, called radar signals, in predetermined directions through a transmitter. When the signals come into contact with an object they are reflected and/or scattered into different directions. The signals that are reflected back towards the transmitter are the desirable ones which make the radar work, making the object visible on the radar.
Radar is used in a variety of ways, for example: to detect a moving object in the distance; to detect the speed of an object; or to map something. Police use it to detect speeding motorists. Planes, both in the air and on land, can be detected via radar and air traffic controllers use it to guide safe landings. The military use radar to detect the enemy and to guide weapons. NASA use radar to map the Earth and other planets as well as tracking satellites. Meteorologists can use radar to track storms, hurricanes and tornadoes.