How are we going to transmit our signal?

Feeling ambitious, we decided to go wireless. We may not to able to make a mobile phone system but our very own radio station with a transmitter and receiver might just be possible.

What is a transmitter?

Radio can be incredibly simple. All you need to transmit a signal is a spark. Radio waves are composed of electric and magnetic fields. The exact way the two fields are brought together in the radio wave is rather complex, but the physical theory that describes these waves means that a changing electric or magnetic field will create radio waves directly.

The tiny spark produced in a light switch when you turn it on also produces radio waves which is why you hear a click on the radio when you turn nearby electrical items on and off. If we can maintain the spark (rather than just for an instant when the switch is operated) you can convert the 'click' into a 'buzz' and use it to send a Morse code type message.

Why does a spark produce radio waves? 

Major funding for Rough Science was provided by the National Science Foundation. Corporate funding was provided by Subaru.

Copyright © 2002 The Open University and WETA.