How Ham Radio Works

Ham radio is for anyone who likes to communicate with others and engage in tinkering and experimentation. Licensed amateur radio operators talk to other radio operators in nearby places, across the country, around the world and even with astronauts in outer space! They rely on a wide frequency spectrum using many different types of wireless transmitting modes.

Today, there are approximately 765,000 licensed amateur radio operators in the United States, and approximately 1.75 million around the world.

Hams use a variety of frequencies for communications. Non-hams can "listen in" via their own receivers or radio scanners. Hams are able to use many frequency bands across the radio spectrum — these frequencies are allocated by the FCC for amateur use. Hams may operate from just above the AM broadcast band to the microwave region, in the gigahertz range. Many ham bands are found in the frequency range that goes from above the AM radio band (1.6 MHz) to just above the citizens band (27 MHz). During daylight, 15 to 27 MHz is a good band for long-distance communications. At night, the band from 1.6 to 15 MHz is good for long-distance communications. These bands are often referred to historically as short-wave bands (as in "short-wave radio"). Unlike frequencies used by FM radio stations and TV stations, which are line-of-sight and therefore limited to 40 or 50 miles, short-waves "bounce" off the ionosphere from the transmitter to the receiver's antenna. The higher the frequency is, the "shorter" the wavelength is.

Some ham radio operators use the very reliable Morse code, while others use voice. Morse code signals (beeps) often get through when voice transmissions cannot. There are also many digital modes as well, and hams use radio modems to communicate in various networks.

Although a ham radio does broadcast in all directions, hams generally do not use their radios in a broadcast kind of way as a disk jockey would at a radio station. In normal AM or FM radio, one disk jockey transmits and thousands of people listen. Hams, on the other hand, conduct two-way conversations, often with another ham or with a group of hams in an informal roundtable. The roundtable of hams may be in the same town, county, state, country or continent or may consist of a mix of countries, depending on the frequency and the time of the day. Hams also participate in networks, often called nets, at predetermined times and frequencies to exchange third-party messages. In the case of disasters, hams exchange health and welfare information with other hams. Some hams use radioteletype (RTTY) with computer screens replacing the noisy teletype machines of the past.

Many hams get their start on VHF FM, using battery-operated hand-held transceivers set to transmit on one frequency and receive on another frequency. They use FM repeaters set up and supported by local radio clubs. These repeaters borrow antenna space from TV-station-tower owners on top of mountains and high buildings to receive and re-broadcast signals to extend the range.

The FM repeater receives one signal at a time and simultaneously rebroadcasts it on another frequency using many more watts of power than available from a small hand-held radio. This extends the range of the hand-held radio from a few miles to tens or hundreds of miles! The whole country has these repeaters. (Listen to one with a radio scanner to learn a lot about ham radio.) When a ham is traveling, he or she can find a repeater to use (great for tips on local restaurants), and carry on a nice, static-free, FM-radio-quality conversation via a radio that fits in a shirt pocket or purse. Linked repeaters allow fun wireless communications across an entire state with a hand-held radio.

Repeaters use common transmit and receive frequency pairs. The frequency pairs in use are informally assigned by groups of hams so that any frequency pair in use is far enough from another repeater so as not to cause unwanted interference. Anamateur radio satelliteallows radio amateurs use their hand-held radios to communicate through the satellite when it is overhead.

Natural disasters like hurricanesandtornadoes disrupt normal telephone and cell phone systems, and ham radio operators can pitch in to help with emergency communications.

On the International Space Station, a member of the crew usually has an amateur radio operator's license and sometimes chats with other hams on earth for a few minutes! VHF transmissions have a limit to line-of-sight communications and normally do not travel over the horizon, so a conversation is limited to the time when the ISS is overhead.

You need an easy-to-earn license to transmit on an amateur radio frequency. License tests cover electronics theory and amateur radio rules and regulations. Study guides are readily available. There is no age restriction. Each country has its own licensing arrangements. Many countries share many of the same frequency bands with hams in the United States. Each license class allows operation in certain bands, using certain modes. The higher the class of license, the more allowable frequency bands that are available for use.

The American Radio Relay League (ARRL) helps many get into amateur radio. The ARRL was organized in 1914 by H.P. Maxim to help relay radio messages. Most radio messages had a 25-mile range at that time and were transmitted around 1.5 MHz, at the high end of the AM broadcast band. Now, local volunteers around the country administer amateur radio tests. These volunteers are usually members of an amateur radio club.

What Are the Amateur Radio Operator Exams Like?

The FCC licensing requirements include a mixture of written tests for several license classes. The written tests consist of multiple choice exams. You can access online study guides or you can buy them. Each type of license has specific operating privileges on each ham band.

A typical ham radio is a transmitter and a receiver, usually purchased as one unit, called a transceiver. Hand-held transceivers have their own antennas. Many hams choose to do most of their operating from their automobile during commute times, using a magnetic mount antenna connected to an under-dash transceiver or a hand-held radio.

Depending on the size (hand-held or desktop), power can be from a few milliwatts to 1,500 watts. Many new hams are graduates from citizens band (CB) radio. Unlike the 5-watt limit on CB, hams can use quite a bit more power.

The ham radio can fit in your shirt pocket, take up half of an attic or garage, sit on a desk next to the computer or go into a car.

Little whip antennas, wire antennas in trees, and antennas atop a tower are all used, depending on the frequency in use. Some antennas are made of wire strung between trees. Be sure to use lightning protection for outside antennas! Lower frequencies have longer wavelengths. Longer wavelengths need larger antennas. A single antennas can be used to transmit and receive.

The common 146-MHz (2-meter) antenna is a 19-inch quarter-wave whip. A wavelength at 146 MHz is approximately 2 meters, and a quarter wave of 2 meters is about 19 inches (50 cm). Hams enjoy the fun of experimenting with various types of antennas.

Hams, including the writer of this article, have communicated with other hams using the following types of antennas with antenna tuners:

What Keeps Ham Operators From Transmitting on the Same Frequency?

Many hams can be on the same frequency, but it depends on the propagation factors. VHF and UHF are line-of-sight, so many hams can be on the same frequency in one state. On short-wave bands, radios have variable frequency tuning to allow moving your transmitted signal (in very small increments) in between two other transmitting stations. Hams often do a lot more listening than transmitting. Often, they listen for another ham that identifies the station as being in a sought-after county, state, or country.

Hams may collect confirmations of contacts using QSL cards—postcard-like notes confirming two-way communication that the two radio operators send to each other in the mail. VHF and UHF hand-held radios typically use channeled communications, using selectable fixed frequencies.

There are frequent hamfests, or ham radio flea markets, in many areas. Hamfests are the best place to meet hams, buy equipment, and take your license test. It's a great way to find some terrific deals on used equipment. You will also find computer parts at hamfests. It is relatively inexpensive to get into amateur radio if you learn how to shop for used equipment with the aid of someone at a local radio club.

Look for a transceiver with a built-in general coverage receiver. That way, you get the versatility of two hobbies: ham radio and short-wave listening.

Each May, the world's largest ham radio convention is held in Dayton, Ohio.

Begin by listening in on the amateur radio frequency bands via a radio scanner or a short-wave receiver. Be sure any short-wave receiver you buy is capable of receiving single sideband (SSB), used for voice communications on the short-wave bands. On any scanner, you will hear local ham operators using repeaters in the frequency range of 144 to 148 MHz.

Most important: Talk to a ham! We love to talk about experiences in amateur radio and are known for being "Elmers" (teachers) for those new to amateur radio. When you hear a ham's call sign on your receiver or scanner, look up the ham's call sign to find a way to contact that ham!

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