International Scientific Radio Union

The International Union of Radio Science (abbreviated URSI, after its French name, French: Union Radio-Scientifique Internationale) is one of 26 international scientific unions affiliated to the International Council for Science (ICSU).

URSI was officially created in 1919, during the Constitutive Assembly of the International Research Council (now ICSU), based on the earlier French: Commission Internationale de Telegraphie sans Fil (1913–1914) when the only radio communication system was radiotelegraphy. It has held a general assembly every three years from 1922. Fifty years ago URSI was one of the most important promoters of the International Geophysical Year. It co-sponsors the Radio Science journal (co-sponsored by the American Geophysical Union) as well as the Journal of Atmospheric and Solar-Terrestrial Physics.

URSI's original objective (to encourage "scientific studies of radiotelegraphy, especially those which require international cooperation") has been broadened to include all radio science, from telecommunications to radio astronomy, acquisition of radar information about distant passive objects, studies of the radiation stimulated or spontaneously emitted by these objects, biological effects of electromagnetic radiation and active modification of objects by radio waves, within the spectrum from extremely low frequency to the optical domain.

A few Commissions are engaged with international projects in cooperation with other international bodies, for example with the Committee on Space Research in the project International Reference Ionosphere.