The precursor to the radio, the Tesla coil, was invented by Nikola Tesla in 1884, and Tesla's device to send a radio signal, which was ready to go, was burned up in a lab fire in 1895. Instead, Guglielmo Marconi tested his wireless signal device in 1896; many say he relied on Tesla's technology to create it.
In fact, the United States Patent Office gave Tesla the patent for the coil and other radio parts in 1900. However, the office took it away from Tesla and gave it to Marconi in 1904. Some scholars think the patent office did so because Marconi had powerful people with money backing him, including Thomas Edison and Andrew Carnegie, according to PBS. However, the patent was reverted back to Tesla in 1943 by the U.S. Supreme Court, mere months after Tesla had died.