Jonathan Adolf Wilhelm Zenneck (April 15, 1871 – April 8, 1959) was a physicist and electrical engineer. Zenneck was born in Ruppertshofen, Württemberg. Zenneck contributed to researches in radio circuit performance and to the scientific and educational contributions to the literature of the pioneer radio art. Zenneck improved the Braun cathode ray tube, by adding a second deflection structure at right angles to the first, which allowed two-dimensional viewing of a waveform.