His field of interest was: antenna design, amplification and detection advanced the development of radio telegraphy. In March 1913 he discovered the principle of positive feedback independently of Edwin Armstrong, and by applying positive feedback to vacuum tube amplifiers, Meissner co-invented the electronic oscillator, which became the basis of radio transmission by 1920 and has innumerable uses today. The inductively-coupled oscillator circuit he invented is today known as the Meissner oscillator.