Poincare's forgotten conferences on wireless telegraphy

摘要

At the beginning of the twentieth century while Henri Poincar\'e (1854-1912)was already deeply involved in the developments of wireless telegraphy, he wasinvited, in 1908, to give a series of lectures at the \'Ecole Sup\'erieure desPostes et T\'el\'egraphes (today Sup'T\'elecom). In the last part of hispresentation he established that the necessary condition for the existence of astable regime of maintained oscillations in a device of radio engineeringcompletely analogous to the triode: the singing arc, is the presence in thephase plane of stable limit cycle. The aim of this work is to prove that thecorrespondence highlighted by Andronov between the periodic solution of anon-linear second order differential equation and Poincar\'e's concept of limitcycle has been carried out by Poincar\'e himself, twenty years before in theseforgotten conferences of 1908.