KUSHIRO, Hokkaido--It may no longer be the "king of hobbies" that it once was, but amateur radio is now a calling to kids in a generation that grew up on smartphones.

Well, at least one of them.

And 16-year-old Yuki Fukumitsu is sending out the call to others to try their hand at ham radio themselves.

The number of local radio hams has rapidly decreased since the hobby's heyday in the 1970s, with many of them now in their 70s.

However, the first-year Hokkaido Kushiro Meiki Senior High School student has taken a deep interest in such technology, as it is "uncertain" unlike the ubiquitous smartphone.

On a typical day off, Fukumitsu can be seen speaking into the microphone in his home, asking other operators to open communications: "CQ, CQ, CQ, this is JM8JPN."

CQ is a code used to invite anyone listening on specific frequencies to respond.

Set up inside Fukumitsu's room with a sign that reads "Radio Communication Room" is a radio receiver and a transmitter. He mounts an antenna about 2 meters long outside the window and adjusts frequencies using a tuner.

Fukumitsu enjoys using the radio on holidays and other occasions when he is free from after-school volleyball club practice.

The student loved playing with walkie-talkies when he was in elementary school, and after searching online about transceivers to expand his interest, he came across amateur radio. He then taught himself to operate a ham radio and attended lectures during summer vacation to acquire an amateur radio license when in the second year of junior high school.

Fukumitsu wasted no time and opened his station, calling out "CQ ..." to invite responses from other operators.

At first, he received no responses and almost gave up on his new hobby. But then about two and a half months later, in November that year, a voice came through, saying, "This is JA8IBU."

It was a transmission from Akira Hosoya, 71, chairman of the Kushiro amateur radio club.

Fukumitsu said his voice trembled with excitement at having finally established a connection.

Regardless of region, age and gender, ham radio operators strike up a conversation by introducing themselves. Fukumitsu replaced his radio receiver and transmitter with a higher-performing one and has communicated with about 500 people.

In addition to hams across Japan, he has established communications with enthusiasts in Indonesia, South Korea, Taiwan, Russia and Hawaii.

"You never know how far your signal will travel, because it varies depending on the season, location, solar activities and other conditions," Fukumitsu said. "You also never know who will respond to your call. And even if you're connected, sometimes all you hear is noise. That is why it is thrilling when you can just talk to someone."

According to the Japan Amateur Radio League, ham radio became popular in Japan during the high economic growth period in and after the 1950s among people who enjoyed it as a means of communicating with people in remote areas.

However, its popularity subsided owing to the spread of cellphones and more recently, online social networking services. It is rare to see high school students or those younger take up the hobby.

The Kushiro amateur radio club, which was founded in 1958, marked its 60th anniversary last year. The club boasted 200-plus members in the late 1970s and currently has 39 members, including Fukumitsu, who recently joined. Many of the members are around 70 years old.

To expand the membership, the radio club has been making promotional efforts including hosting workshops on how to make radio equipment and operate ham radios, in addition to demonstrating radio communications at annual public events.

“The radio club will come to a natural end if we go on like this,” Hosoya said. “We want Fukumitsu to spread its appeal.”

The young hopeful said: “My friends don’t quite understand the fun of amateur radio. I want to recruit like-minded people through Twitter and a blog.”