Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!


Satellite communication


Microwaves and radio waves are used to communicate with satellites. Microwaves pass straight through the atmosphere and are suitable for communicating with distant geostationary satellites, while radio waves are suitable for communicating with satellites in low orbit.

Radio waves and microwaves

Radio waves and microwaves are types of electromagnetic radiation [electromagnetic radiation: Energy travelling as waves in the form of changing electrical and magnetic fields.. Both have communication uses. Radio waves are used to transmit television and radio programmes, while microwaves are used for mobile phones and Wi-Fi. However, they have different properties:

  • Radio waves have longer wavelengths [wavelength: The length of a single wave, measured from one wave crest to the next. and are reflected by the ionosphere [ionosphere: Ionised region of the Earth's upper atmosphere. (part of the Earth’s atmosphere).

  • Microwaves have shorter wavelengths and pass through the Earth’s atmosphere.

Diffraction through a narrow gap causing a lot of spread with no sharp shadow

Radio waves are reflected by the ionosphere, but microwaves pass straight through it

Effects of frequency

The way that electromagnetic waves behave in the atmosphere depends on their frequency. The table below summarises this.

Increasing frequency
Frequency Less than 30 MHz 30 MHz – 30 GHz More than 30 GHz
Behaviour Reflected by the ionosphere Waves pass straight through the atmosphere Rain, dust and other atmospheric effects reduce the strength of the signal due to absorption and scattering
Low amounts of energy needed Carbon dioxide is produced as a by-product Less land needed Higher amounts of energy needed
Wavelength More than 10 m 10 m – 10 cm Less than 10 cm
Decreasing wavelength


boy smiling wearing headphones

Science Audio Bites

Put down that pen and listen to some Science audio.

More audio


Mia Cadaver illustration

Mia Cadaver's Tombstone Timeout

Revision topics from beyond the grave!

More games

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.