How it began
In 1932 Guglielmo Marconi set up a special antenna in the Vatican gardens while Pope Pius XI looked on. The antenna was part of a new radio link connecting the Vatican to the papal summer residence at Castel Gandolfo, about 30 kilometers away. The work came one year after the inauguration of Vatican Radio, a project Marconi had also led. A published history of his microwave work describes the 1932 installation as the first permanent microwave relay link for telephony.
Before it existed
Radio at the time relied on lower frequencies. Marconi had shared the 1909 Nobel Prize in Physics for wireless telegraphy, and his 1901 transatlantic transmission used a non-microwave frequency. Microwave equipment had been demonstrated in the 1890s by the Indian scientist Jagadish Chandra Bose, but in the early 1900s there were few useful applications for microwaves that were not already feasible with lower frequency radio waves.
How it works
The link carried telephone speech on microwaves, which are radio waves with extra-high frequencies, sent between an antenna in the Vatican gardens and the residence at Castel Gandolfo. Marconi also set up a portable microwave communications system attached to a car, which connected the traveling pope to the Vatican. Researchers who studied the Marconi Archive described that apparatus as a portable antenna, a microwave generator and a radio transmitter.
What changed first
The link kept a line open between the Vatican and the pope while he was away at his summer residence. It was one of two communications projects that Marconi carried out for Pius XI in consecutive years, after Vatican Radio in 1931. Pius XI was the first pope to use radio for pastoral purposes.
What lasted
Microwaves went on to become a major carrier of communications because they can carry vast quantities of information. The car-mounted system that Marconi built for the pope has led some writers to call it the first mobile phone, although a very large one, a title otherwise claimed for Bell Laboratories.
Where it stands today
Microwaves are now used for any international call that is connected by satellite, and Wi-Fi routers operate at microwave frequencies. The Nobel Prize organization presents the 1932 Vatican link as an early step toward that use, a long way from the car-mounted equipment installed for the pope in the 1930s.
