As early as 1897, British physicist Rayleigh established the theory of electromagnetic wave propagation in metal waveguide. However, in the following 20 years, no significant progress has been made in waveguide theory and experiment. It was not until 1924 that the situation began to change. Both Haban and Chachke found that magnetron can automatically generate high-frequency electromagnetic oscillation. 1929, Cravey began the experiment of microwave communication. The next year, he used a parabolic antenna with a diameter of 3 meters to communicate with two radio stations in New Jersey, USA. 1930, some people began to use microwaves for radio broadcasting and communication. 1933, under the auspices of Clavi, the first commercial microwave communication line was opened, which ran from Le Piniel, England to Saint Inglewitt, France.

1936, Southworth put forward the UHF waveguide theory and invented the microwave waveguide. Great progress has been made in the theory, experiment and application of waveguide, which has promoted the progress of microwave technology. In addition, the rise of TV technology in the 1920s and 1930s also stimulated the development of microwave technology.

1937, American physicist Varian brothers made a double-cavity klystron oscillator. 1939, British physicists Randall and Bout made a multi-cavity magnetron. These achievements laid the foundation for the formation and development of microwave technology.