The history of radio

How did inventors stumble on the concept of radio in the first place? Adam Murphy found out from the University of Exeter's Richard Noakes...

Richard - The most important aspect of this is Maxwell's proposal that light is a form of vibration involving electricity and magnetism and their interaction. The paper that Maxwell published showed that measurements of electrical and magnetic phenomena produce the right result or a very good result to the speed of light, to the known speed of light. And so this gave good evidence, not conclusive evidence, that light was actually a form of electromagnetic vibration.

Adam - But the thing about Maxwell's work is it's tricky. Students spend years studying Maxwell's equations and then lie about understanding them. So a lot of other bright sparks put time into expanding Maxwell's work, and one of them was British physicist Oliver Lodge.

Richard - And he's really interested in the possibility that Maxwell's claim that light is an electromagnetic vibration - maybe light can be generated experimentally. And what he does is to produce many versions of lightning flashes in the laboratory using effectively the ancestor of today's capacitors, they're called Leyden jars. His work on this effectively leads him to show that the rapid oscillations of a Leyden jar that's sparking produces kind of waves that flow along wires. But independently of Lodge is a German physicist called Heinrich Hertz. And what he finds is something very similar to what Lodge would find in 1887, which is that there's a kind of wave-like phenomenon between wires connected to Leyden jars. But more interestingly, he's able to find waves flowing outside the wires in free space.

Adam - But Lodge and Hertz weren't really interested in the applications of this. They were interested in the pure science of it all. So they didn't really bother pushing the engineering quite so much. However, Lodge was about to provide some much needed inspiration.

Richard - And it's in 1894 that we see him broaching this topic again. And he does it interestingly in a lecture to memorialise the death of Heinrich Hertz. So Heinrich Hertz died in 1894. Lodge is asked to present a series of lectures on Hertz's work. And in these lectures, he produces a demonstration of a kind of wireless, effectively, telegraphy but on a very small scale. What he does is effectively bring together the kit that he and others have produced to generate electrical waves. And some of the kit that's very well known in conventional wired cable telegraphy. So the kind of Morse key. And what he shows his audience who are stunned by this is that you can send through a lecture theatre coded messages.

Adam - One of the people very interested in this and in that lecture was Italian-Irish physicist Guglielmo Marconi, who had the creativity and the cash to really push the boat out.

Richard - And what Marconi does is effectively to synthesise much of what he reads. And uses that to develop apparatus that he thinks will make wireless stronger and sufficiently stronger for use in forms of signalling and communication. So the very thing that Lodge thought was not going to work out practically. And so from about the mid 1890s through to the early 1900s, Marconi develops this wireless telegraphic system. In 1901 he stages his grandest experiment which is between the West coast of Ireland and the East coast of North America in Canada. So in 1901 what he does is effectively to demonstrate that you can send wireless signals across the Atlantic. He sends one letter, the letter S in Morse coded form, and it causes a sensation.