In the late 1930s, Al Gross, a teenage ham radio enthusiast in Cleveland, OH, built some handheld devices that allowed his friends and him to communicate on an unused portion of the radio frequency band; he named his creation the “walkie-talkie.” Although Gross’s innovation later played an important part in World War II, neither it nor his other major inventions became commercially successful until many years after his patents expired.
As an electrical engineering student at Cleveland’s Case School of Applied Sciences, Gross discovered a way to cause miniature vacuum tubes to operate at about 300 megahertz, a relatively unexplored high frequency. By 1938, he had built battery-operated models that allowed him to communicate with radio operators more than 45 kilometers away.
Early in World War II, the U.S. Office of Strategic Services learned about Gross’s walkie-talkies and called the young inventor to Washington, DC. The office asked him to develop a system that would allow Allied agents in Germany and occupied countries to communicate with pilots flying overhead. Because the system operated at a virtually unused high frequency, operators could transmit military intelligence without being detected by enemy shortwave-radio operators.
After the war ended, Gross founded Citizens Radio to commercialize the technology. The company’s customers included the U.S. Coast Guard and farmers, but the walkie-talkie wasn’t a commercial hit.
Meanwhile, Gross built other communications devices, including cordless telephones and personal paging systems. Gross had begun developing the pager during World War II, when he designed a device that could be attached to dynamite on the ground and signaled to ignite it from an airplane flying nearby. Gross thought that a modified version could be used to page doctors. He built a prototype device in 1949, but when he demonstrated it at a medical convention, his audience wasn’t interested. “They said it would interfere with the patients, and it would interrupt their leisure time, like golf games, I suppose,” Gross said during a 2000 interview on Canada’s CBC Radio One.
Although Gross’s key inventions didn’t become popular until after his patents expired in the early 1970s, he didn’t become frustrated. At the time of his death in 2000, at age 82, he was working as a senior principal electrical engineer at Orbital Sciences in Chandler, AZ, helping design electrical systems on rockets.
Anti-aging drugs are being tested as a way to treat covid
Drugs that rejuvenate our immune systems and make us biologically younger could help protect us from the disease’s worst effects.
These materials were meant to revolutionize the solar industry. Why hasn’t it happened?
Perovskites are promising, but real-world conditions have held them back.
The baby formula shortage has birthed a shady online marketplace
Desperate parents just want to feed their babies. They’re having to contend with misinformation, price gouging, and scams along the way.
I tried to buy an Olive Garden NFT. All I got was heartburn.
Our newest issue spells out what you need to know about the dizzying world of digital money.
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.