HAM radio saves lives, even if it can’t contact other dimensions.

In episode four of the Netflix series ‘Stranger Things,’ our heroes sneak into the Hawkins Middle School science lab. There, telepath Elle manages to pick up the voice of the missing boy Will on an old-timey radio thingy. After listening to Will crying out for help, the apparatus catches on fire. But what is the old-timey radio thingy?

It’s a HAM radio, and in the years before most people used the internet, it sort of was an internet. In fact, it’s still used by some two million licensed operators all over the world. It’s a geeky pastime that requires some knowledge of science and technology, a place in your house that you can fill up with strange, boxy equipment and a T-shaped antenna on your roof.

Many people dive deep into the hobby and build their own setups, which are always called “radio shacks” —yep, just like that old-school chain of electronics stores that has long supplied hobbyists with the bits and bobs to build their setups. You probably know someone who is a HAM operator. Maybe even your dad or grandmother.

It all started back in 1901 when Italian inventor Guglielmo Marconi successfully transmitted a wireless signal from Canada to England. Radio was of great interest to amateur technology buffs, much in the way virtual reality is today. Americans were fairly affluent and the gear wasn’t too expensive. Amateur radio stations began popping up all over the country.

Amateur radio operators began sending signals across the Atlantic in 1921. After that, the technology went global. In 1960, two HAMs bounced signals off the moon. HAMs can communicate with satellites, too. These days you can even transmit pictures using television frequencies!

So how did the radios come to be called HAMs? There are a few theories, but RF Cafe’s Kirt Blattenberger believes it began with three members of the Harvard Radio Club — with the last names Hyman, Almy and Murray — who operated a station together under the call sign “HAM” circa 1908. Amateur radio operators sometimes caused interference when they used the same frequencies as commercial operators. When the commercial operators pushed for legislation that would have increased licensing costs for amateur operators, Hyman went before Congress to testify against the bill.

“Little station ‘HAM’ became the symbol for all the little amateur stations in the country crying to be saved from the menace and greed of the big commercial stations who didn’t want them around.”
 — Blattenberger

It must have seemed like magic to many people. You could set a radio up in your house, or in a field, and talk to people as far away as Tasmania. When HAM operators picked up signals from far away, they’d send each other postcards, which HAMs often proudly displayed on the wall behind their radio shacks.

But it’s not all fun and games. HAM radio operators are required to learn radio theory, and have to pass an exam. This generally involves learning Morse code, that signal language of “dits” and dahs” you sometimes hear under the music when the news comes on.

This is because operating a radio requires a degree of professionalism and courtesy — users must talk with the proper protocols and stick to certain bands on the radio spectrum. And there’s a second, more critical reason to have licensed operators. The government needs to know where proficient radio operators are in the event of an emergency or natural disaster. If the cellular network is down, and a power failure shuts down the internet, HAM radio still works. All you need are batteries, a radio and some kind of antenna.

HAMs have saved countless lives when other communication media are unavailable, or when disaster strikes in a remote area, like a cave in the woods or a boat in the middle of the ocean.

The Italian dirigible Italia crashed in Antarctica in 1928. The radio operator saved his radio, and built an antenna out of wreckage. He began tapping out the Morse code signal “SOS-Italia.” A couple days later, it was picked up by a Soviet HAM in Arkhangelsk, Russia. The crew was soon rescued.

When World War II came, HAMs were in hot demand by any branch of the military to serve as radio operators. Those who stayed home were crucial as well, manning radio posts in the event of aerial attack or other emergencies.

Even today, when a hurricane strikes Cuba, you can bet HAM radio operators in the surrounding countries are standing by, listening for calls for help.

It only takes about 200 bucks to get started with HAM. If you’d like to get your geek on, check out the American Radio Relay League (ARRL), the national association for HAM radio operators. There are plenty of “Elmers,” or mentors, around to help you get started.