British radar developments in pulsed radar prior to 1938
Care must be taken in writing the milestone citation for the Zenit radar to avoid too broad a claim. Care must also be taken in crediting the work in pulsed radar prior to the Ukrainian work. According to Guerlac, Henry, "Radar in World War II", volume 8, 1987, American Institute of Physics, pp 70-75, "Leo Young...was the first to hit upon the idea of using reflected pulses of radio energy for the detection of aircraft and other targets." Leo Young and Lawrence Hyland discussed the pulse method in 1930. Guerlac goes on the describe Leo Young and Robert Page working on the project as of 1934. On 28 April 1936, the pulse radar was successfully tested at the U.S. Naval Research Lab. Thus establishing the value of the method.
The British tested pulsed radar 15 June 1935 (Guerlac p 136-141) According to Guerlac, the value of the pulsed method was already established from the beginning of the British program (1934); and they did not attempt to develop beat radar.
Buderi, Robert, "The Invention That Changed the World," 1996, Simon and Schuster, also credits Robert Page with building a pulsed radar in March 1934 (p. 63) and notes the British experiments of June 1935.
Brown, Louis, "A Radar History of World War II", 1999, Institute of Physics Publishing, p. 81 describes the Lorenz company in Germany testing a pulsed radar in early 1936, and the Anti-Aircraft training school ordered sets for field evaluation.
Right. I agree fully. This was related to the USSR radar research only. So I will modify the citation to emphasize the regional and national importance.
All of the above is correct. As Guerlac and many others state, the original ionospheric experiments used pulsed signals. These experiments were known by all radio physicists worldwide. Hence, based on the results of these experiments, the possibility of the use of pulses for detecting the distance of targets was picked up by many countries, leading to the development of pulsed radars. (Note also that most countries, including the Soviet Union, developed cw (continues-wave) radars at the same time.) What makes the Zenit development unique, in my opinion, is the simultaneous use of three significant elements: pulses, microwave magnetron transmitters, and parabolic antennas.(Most of the earlier radars used tube transmitters rather than magnetrons, which were better suited to microwave frequencies.) The resulting system, although not without its flaws, was capable of measuring target range (distance),altitude, and azimuth.