Howstuffworks "How Ham Radio Works"
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How Ham Radio Works
by Gary Brown
A teen in Florida makes friends over the airwaves with a ham in Germany. An aircraft engineer in
Washington participates in an annual contest and exchanges call signs with hams in 100 countries
during a single weekend. In North Carolina, volunteers pass health and welfare messages in the
aftermath of a hurricane.
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Howstuffworks "How Ham Radio Works"
Norm Lauterette, WA4HYJ, is on the radio reporting a new flare
up during the wildfires that broke out in several counties in
Florida during June and July of 1998.
At the scene of a traffic accident on a rural highway, a ham calls for help using a pocket-sized handheld radio, outside the range of any cell phone tower. An Ohio teenager uses her computer to send a
chess move to an orbiting space satellite, where it's retrieved by a fellow chess enthusiast in Japan.
This mix of fun, public service, friendship and convenience is the main feature of amateur radio. The
"ham" part of ham radio is really a shortcut way of saying just the first syllable of amateur radio.
Hams start out in amateur radio for many reasons, but they all have in common a basic knowledge of
radio technology, regulations and operating principles. They get this knowledge by studying for
licensing exams -- hams have licenses (after passing an exam) from the Federal Communications
Commission (FCC) and use frequency bands assigned by the FCC.
In September 1895, Guglielmo Marconi, a self-taught 21-year-old from Bologna, Italy, performed
simple experiments that showed it was possible to send signals using electromagnetic waves to
connect a transmitting and a receiving antenna. By 1901, he sent a wireless signal across the
Atlantic. For the next seven years, many Americans experimented with wireless. The first radio clubs
appeared in 1909, and the Titanic disaster of 1912 pointed out the need for regulation of wireless.
Today, ham radio operators younger than Guglielmo Marconi regularly make radio contacts around
the world, often using very inexpensive (and sometimes home-made!) equipment.
Ham radio can be very portable and affordable. In this article, we will look at ham radio and show
you how to get started in this wireless world!
Why would I get into ham radio?
Ham radio is for anyone who likes to communicate with others via wireless technology. It is also for
anyone who enjoys experimentation. Licensed amateur radio operators communicate with each other
in nearby places, across the country, around the world or even with astronauts in outer space!
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A young operator enjoys making friends over the radio during
Kid's Day. Kid's Day is an annual event that encourages young
people to get on the air, perhaps with a family member or a
neighbor who is a licensed amateur radio operator.
Amateur radio is a worldwide group of people who communicate with each other over a wide
frequency spectrum using many different types of wireless transmitting modes.
Often, younger hams get a chance to meet other hams of various ages and professions. The
frequent networking often helps teens when they are making career or education choices and wish
to get some advice (from professionals in many technical fields) that maybe mom, dad or the
guidance counselor may not be able to give.
How many licensed ham radio operators are there?
Today, there are approximately 675,000 amateur radio operators in the United States, and more than
2.5 million around the world. To find out how to get started and who to contact in your area, call or
write the non-profit organization:
American Radio Relay League
225 Main Street
Newington, CT 06111
USA
Telephone: 1-800-32-NEW-HAM
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Frequencies and Transmitting Modes
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 very many digital
modes as well, and hams use radio modems to communicate in various networks.
Ham Radio Activities
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, with computer screens replacing the noisy teletype machines of the
past.
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Computer-assisted radioteletype
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.
When deadly floods struck central and southern Texas in midOctober 1998, amateur radio operators from four states
volunteered their time. Susan Manor, NF0T, is shown helping
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with communications at the New Braunfels Red Cross office.
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 the 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.
Amateur radio satellites are a cutting-edge use of technology in amateur radio. Radio amateurs use
their hand-held radios to communicate through an amateur radio satellite when the satellite is
overhead. A current British satellite has a receiver (uplink) at 145.975 MHz and simultaneously
rebroadcasts (downlink) at 435.070 MHz for one station at a time, as a repeater.
Natural disasters like hurricanes or tornadoes disrupt normal telephone and cell phone systems. Ham
radio operators pitch in to help with emergency communications, and you will often hear about them
on news reports.
On Space Shuttle missions, each member of the crew usually has an amateur radio operator's
license. During breaks, astronauts hold their 1- to 5-watt VHF FM hand-held radios up to the shuttle
window and chat with other hams for a few minutes, often at schools while the shuttle is in an orbit
overhead! 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 shuttle is overhead. The
space station MIR used 145.985 MHz for similar conversations. Future ham radio efforts in space will
focus on the use of amateur radio within the International Space Station (ARISS) project.
License Requirements
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.
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Recently, the FCC relaxed the Morse code requirements portion of the rules to make it easier to get
an amateur radio operator's license. The FCC's new licensing plan means you will be able to become
a ham by passing a single 35-question written examination. License study guides are readily
available for the written test.
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.
The ARRL has many useful publications. 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 includes a mixture of written tests for several license classes and a
Morse Code test of five words per minute for some 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.
Equipment
A typical ham radio is a transmitter and a receiver, usually purchased as one unit, called a
transceiver. Newer transceiver models often have semi-complicated controls and menu systems that
may take some reading of the manual. You may be able to find an older transceiver with controls that
are easier to use as a beginner, having the usual analog controls.
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Vintage tube-type short-wave receiver
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.
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Ham radio station in automobile
Power Output
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 (1,500 watts).
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. Right now, during the current sunspot cycle, it is possible to talk around the
world during daylight hours running just a few watts of power. This particular type of radio-wave
propagation is in the 28-MHz band (commonly called the 10-meter band) thanks to short-wave
propagation (300 divided by the frequency in MHz is a quick way to convert to "meters").
Antennas
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Little whip antennas, wire antennas in trees, and antennas atop a tower are all used, depending on
the frequency in use. Lower frequencies have longer wavelengths. Longer wavelengths need larger
antennas. The same antennas (used to transmit and receive) can be small, portable, put in trees or
on the trunk of a car.
Short-wave antenna
The common 146-MHz (2-meter) antenna is a 19-inch quarter-wave whip. A wavelength at 146 MHz
is approximately 2 (300 divided by 146) 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. Some antennas are
made of wire strung between trees. Be sure to use lightning protection for outside antennas!
Hams, including the writer of this article, have communicated with other hams using the following
types of antennas with antenna tuners:
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Metal window screens in upper floors of hotels and motels
Aluminum extension ladders, insulated from the ground, leaning against a house (the lower the
frequency, the longer the ladder)
Soldered-together rain gutters and downspouts
Flat copper "burglar-tape" hidden behind wallpapered walls
Extended "Slinky" toys supported by a rope through the middle, in an attic
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Camera-tripod-supported whip antenna
Disguised flagpoles fed with buried coaxial cable
Fine wires cast with a fishing rod between dormitory buildings
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.
This LCD on a modern transceiver is displaying the spectrum of
nearby stations. The band-scope at the bottom helps ham
operators find signals.
Hams collect confirmations of contacts using QSL cards. Hams collect the QSL cards and receive
awards for contacting so many countries on certain frequency bands. VHF and UHF hand-held radios
typically use channeled communications, using selectable fixed frequencies.
Hamfests
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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. Think of a hamfest as a real-time, in-person ham radio display like that found at eBay -but you don't have to bid against others!
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.
Getting Started
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Listen in on the Amateur Radio Frequency Bands (U.S.) 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.
Read the information in the various links on the next page of this article.
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!
Who knows, maybe someday your next ham radio contact may be music entertainers such as Ronnie
Milsap, Patty Loveless, or Joe Walsh -- they are all FCC-licensed amateur radio operators!
For more information on ham radio and related topics, check out the links on the next page.
Lots More Information
Related HowStuffWorks Articles
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How Radio Works
How Radio Scanners Work
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How the Radio Spectrum Works
How Bluetooth Works
How Satellite Radio Works
How Radar Works
How Radar Detectors Work
How does an EPIRB distress radio work?
Do certain radio wave frequencies pose health risks?
Why do you hear some radio stations better at night than in the day?
Why do all FM radio stations end in an odd number?
Sponsored Links
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1800CheapSeats invites you to "call or click" for the best travel values available!
More Great Links
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QRZ.com: The Ham Radio SuperSite
Raleigh Amateur Radio Society: Club Information
Amateur Radio Newsline
Ham-Links
eHam.net Reviews - ham radio product reviews
American Radio Relay League Resources for New Hams
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Welcome to Amateur Radio!
Affiliated Club Search - over 2000 local clubs!
American Radio Relay League Fact Sheet
ARRL Products Catalog - including licensing study guide
Backgrounder: What is Amateur Radio?
Amateur Restructuring - new FCC regulations
Backgrounder: The American Radio Relay League
Backgrounder: News Gathering and Amateur Radio
Backgrounder: Amateur Radio Emergency Communication
Backgrounder: Using Amateur Radio in an Emergency
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What Hams Do
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faqs.org: Radio
Amateur Radio Repeaters
Getting Your License
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ARRL: License study materials
Gordon West Radio School
Amateur Radio and Morse Code Tutorials
w5yi National Radio Examiners
Frequencies Hams Use
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Amateur Frequencies Outside the USA
US Amateur Radio Frequency Allocations
Where Hams Shop
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Hamfest and Convention Database
Ham Ads - used equipment
Amateur Electronic Supply - dealer
Photographs and assistance provided by the American Radio Relay League, Reed-AB4W, BobK4HA, and Gary-KN4AQ.
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