The radio was born in the last years of the nineteenth century, after the theoretical studies of the physicists of the time on electromagnetism. The patent is from the Italian Guglielmo Marconi, a physics student at the University of Bologna. The young Marconi became interested in electromagnetism and proposed his idea to his professor, Augusto Righi. He believed it was possible to transmit a signal over a very long distance without wires, thus surpassing the technology related to the telegraph.
But how is it possible to send an “invisible” signal? How do electronic devices manage to send and receive signals? Answering these questions is not trivial, especially since we cannot touch the mechanisms underlying radio broadcasts firsthand. While it is easy to observe the propagation of the waves of the sea when we throw a stone in it, it is much more difficult to imagine music and sounds that travel who knows where and arrive straight into our homes.
Unfortunately, it often happens that there is interference. This happens because the other fundamental quantity when it comes to radio broadcasts is the wavelength, or the distance after which the periodic signal repeats itself. In the case of radio waves, considering the typical frequencies of FM, the wavelength is of the order of 3 or 4 meters. If an obstacle is placed along the wave’s path, reception will be disturbed.
Radio waves aren’t just used for radio broadcasts, as many think. They are also used to display visual content on our televisions, both thanks to satellites and digital terrestrial. But the now global and widespread use is that linked to telephony. All our calls are handled through radio waves emitted and received by antennas placed on the earth’s surface and by our smartphones.