Radio L.L. Engels

Lucien Lévy (1892-1965) was a very important French radio pioneer. Just before the First World War he received his engineering degree at l’Ecole Supérieure de Physique et Chimie in Paris. In 1916 he became head of the laboratory of the military radio station on the Eiffeltower. That year the first transmitter (1,5 kW) was completed and Lévy started experiments that lead to the invention of the superheterodyne principle*. In August 1917 the principle was patented in brevet n°493660. In 1918 an upgraded version of the principle followed, described in a second patent. The Americans did not recognise his patents and attributed the invention to Edwin H. Armstrong.

The first experiments of the use of radio tubes in means of transport, like aeroplanes and automobiles were carried out by Lucien Lévy.

In March 1926 he formally founded Établissements Radio LL (although radios were made under that name in the years before 1926). Also in 1926, in order to stimulate the sale of radios, a 1 kW radio transmitter, called Radio LL, started broadcasting in the rue de Javel in Paris. Many radios were made in his factory, among them the famous Syncrodyne.

*)The superheterodyne principle: If an oscillator signal is added to an incoming radio signal, a beat signal will result, that has a frequency of the difference between the two. A fixed filter can be built to narrowly select this beat frequency, and pass it on to a low-frequency amplifier. As the oscillator frequency is varied, different radio frequencies will be moved down to the beat frequency and so selected. In other words, a variable oscillator and a fixed, narrow filter can do the work of a variable narrow filter. This technique is used in practically every radio to this day.