Hubbry Logo
Amateur radioAmateur radioMain
Open search
Amateur radio
Community hub
Amateur radio
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Contribute something
Amateur radio
Amateur radio
Amateur radio
View on Wikipedia
from Wikipedia

Amateur radio station with transceivers, amplifiers, and a computer for digital modes. On the wall are awards, certificates, and QSL cards from foreign stations

Amateur radio, also known as ham radio, is the use of the radio spectrum for non-commercial communication, technical experimentation, self-training, recreation, radiosport, contesting, and emergency communications.[1] In 1927 a radio amateur was defined as "a duly authorized person interested in radioelectric practice with a purely personal aim and without pecuniary interest," meaning without monetary or similar reward. The definition distinguished amateur activity from commercial broadcasting, public safety services, and professional two-way radio uses such as maritime, aviation, and taxi communication.[2]

Polish amateur radio station SP1QE with a 1930s vacuum tube transmitter and receiver

The amateur radio service (amateur service and amateur-satellite service) is established by the International Telecommunication Union (ITU) through its Radio Regulations. National governments set technical and operational rules for transmissions and issue individual station licences with unique call signs. Call signs must be used in transmissions, at least every ten minutes and at the end. Amateur radio operators must hold an amateur radio licence, granted after an examination that tests knowledge of radio theory, electronics, and national regulations.

Operators are authorised to transmit on frequency ranges allocated internationally as the amateur radio bands. Within these bands they may use any frequency, though some are restricted to particular modes of voice, text, image, or data communications. This allows communication locally, nationally, worldwide, and even with stations in space. In many countries, operators may also exchange radio communications between computers or transceivers connected through virtual private networks on the Internet.

Amateur radio is represented by the International Amateur Radio Union (IARU), which has three regions and includes national amateur radio societies in most countries. In 2011 the American Radio Relay League (the U.S. national society) estimated that about 2 million people worldwide were active in amateur radio.[3] About 830,000 amateur radio stations are in Region 2 (the Americas), about 750,000 in Region 3 (South and East Asia and the Pacific), and about 400,000 in Region 1 (Europe, the Middle East, the CIS and Africa).

History

[edit]
Main article: History of amateur radio
An amateur radio station in Wales. Multiple transceivers are employed for different bands and modes. Computers are used for control, data modes, SDR, RTTY and logging.

The origins of amateur radio can be traced to the late 19th century, but amateur radio as practised today began in the early 20th century. The First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations.[4] This radio callbook lists wireless telegraph stations in Canada and the United States, including 89 amateur radio stations. As with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, and social services. Research by amateur operators has founded new industries,[5] built economies,[6] empowered nations,[7] and saved lives in times of emergency.[8][9] Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, and computer skills.[10]

Ham radio

[edit]
Main article: Etymology of ham radio

The term "ham" was first a pejorative term used in professional wired telegraphy during the 19th century, to mock operators with poor Morse code-sending skills ("ham-fisted").[11][12][13][14] This term continued to be used after the invention of radio, and the proliferation of amateur experimentation with wireless telegraphy; among land- and sea-based professional radio telegraphers, "ham" amateurs were considered a nuisance. The use of "ham" meaning "amateurish or unskilled" survives today sparsely in other disciplines (e.g. "ham actor").

The amateur radio community subsequently reclaimed the word as a label of pride,[15] and by the mid-20th century it had lost its pejorative meaning. Although not an acronym or initialism, it is occasionally written as "HAM" in capital letters.

Activity and practice

[edit]

Amateur radio combines communication, technical experimentation, and recreation. Operators take part in contests, provide emergency service, build and modify equipment, and use transmission modes ranging from traditional Morse code to modern digital protocols.

Amateur operator with antennas in Åland

Community and social use

[edit]
Backyard amateur radio antenna farm

Operators often join conversational groups and take part in scheduled on-air meetings called nets, coordinated by a net control station.[16] Nets may provide training for emergencies, operate as informal discussions, or focus on specialised topics.[17]

With battery- or generator-powered equipment, operators frequently provide communication during natural disasters when commercial services are unavailable.[18]

Competitive activities include contests to contact as many stations as possible in a set period, and operating awards such as Summits on the Air, Worked All States, and Jamboree on the Air. Operators also contribute to citizen science by collecting propagation data and supporting atmospheric science research.[19]

Voice and Morse code

[edit]

The principal voice modes are frequency modulation (FM), single sideband (SSB), and amplitude modulation (AM). FM offers high audio quality, SSB is efficient for long-distance use,[20] and AM continues among users of vintage amateur radio equipment.

Radiotelegraphy using International Morse code, or continuous wave (CW), is one of the oldest modes in amateur radio. Although largely replaced in professional services, it remains in use on shortwave bands because it functions under weak-signal conditions and employs internationally understood codes such as the Q code. CW is also used by hobbyists who build their own equipment (home construction) and by operators engaged in low-power operation, as CW transmitters are simple to construct and weak signals can often be received by ear.

Until 2003, Morse code proficiency was required under international regulations for access to frequencies below 30 MHz.[21] The requirement was withdrawn in the United States in 2007.[22][23]

Digital and computer-assisted modes

[edit]

Personal computers have enabled new digital transmission modes. Radioteletype (RTTY), once operated by mechanical devices,[24] is now handled in software. Packet radio, developed in the 1970s, uses protocols such as AX.25 and TCP/IP. Later modes including PSK31 and FT8 allow efficient low-signal communication on shortwave bands.

Radio over IP (RoIP) applies Internet-based telephony techniques to radio. EchoLink and the Internet Radio Linking Project link repeaters and operators worldwide.[25]

Other specialised modes support weak-signal communication. Automatic link establishment (ALE) maintains networks on high frequency bands, while the WSJT suite supports meteor scatter and moonbounce.[26]

Television and repeater systems

[edit]

Fast-scan amateur television (ATV) adapts consumer video equipment to transmit images. It typically operates on the 70 cm (420–450 MHz) but may also use the 33 cm and higher frequencies. Because of wide bandwidth requirements, ATV usually covers 30–100 km (20–60 mi). Linked repeater systems extend this range to several hundred kilometres.[27] Repeaters are often located on high ground or towers and may be linked by other amateur bands, landlines, or the Internet.

Space and atmospheric propagation

[edit]
NASA astronaut Doug Wheelock using amateur radio aboard the International Space Station

Operators can use amateur radio satellites, sometimes with only a hand-held transceiver.[28] Natural reflectors such as the Moon, the aurora borealis, and meteor trails are also used.[29] Licensed astronauts have also made contacts from the International Space Station through the ARISS programme.[30][31]

Licensing

[edit]

Because radio signals can propagate across national borders, amateur radio is regulated by governments under international frameworks.[32] National requirements generally follow standards set by the International Telecommunication Union (ITU)[33] and World Radiocommunication Conferences.

Most countries require candidates to pass an examination that tests electronics, radio propagation, operating practices, and regulations.[34] Licensing grants access to a broader portion of the spectrum, additional communication modes, and higher transmitter power than unlicensed personal radio services such as CB, FRS, or PMR446.[35]

The top of a tower supporting a Yagi–Uda antenna and several wire antennas, along with a Canadian flag

Examination systems often include several levels, each granting wider frequency access and higher power limits.[36][37] In the United Kingdom and Australia, entry-level candidates must also complete a practical skills test to obtain the Foundation Licence, the first of three licensing stages.[38]

Each licensee is normally assigned a unique call sign.[39] Some countries issue additional station licences, or recognise club and organisational licences.[40]

A handheld VHF/UHF transceiver

Licences are generally valid only in the issuing country or in states with reciprocal agreements.[41][42] In some jurisdictions, a licence is also required to purchase or possess amateur radio equipment.[43]

In the United States, the Federal Communications Commission (FCC) issues three licence classes: Technician, General, and Amateur Extra.[44] Examinations are administered by accredited Volunteer Examiners through the FCC's Volunteer Examiner Coordinator system. Higher licence classes provide access to more frequency bands and higher transmitter power. The tests cover regulations, operating practices, electronics theory, equipment design, and safety. Morse code is no longer tested. Licences are valid for ten years, and the national question pools are published in advance and updated every four years.[44]

Licensing requirements

[edit]

Prospective amateur radio operators are examined on understanding of the key concepts of electronics, radio equipment, antennas, radio propagation, RF safety, and the radio regulations of the government granting the license.[1] These examinations are sets of questions typically posed in either a short answer or multiple-choice format. Examinations can be administered by bureaucrats, non-paid certified examiners, or previously licensed amateur radio operators.[1]

The ease with which an individual can acquire an amateur radio license varies from country to country. In some countries, examinations may be offered only once or twice a year in the national capital and can be inordinately bureaucratic (for example in India) or challenging because some amateurs must undergo difficult security approval (as in Iran). Currently, only Yemen and North Korea do not issue amateur radio licenses to their citizens.[45][46] Some developing countries, especially those in Africa, Asia, and Latin America, require the payment of annual license fees that can be prohibitively expensive for most of their citizens. A few small countries may not have a national licensing process and may instead require prospective amateur radio operators to take the licensing examinations of a foreign country. In countries with the largest numbers of amateur radio licensees, such as Japan, the United States, Thailand, Canada, and most of the countries in Europe, there are frequent license examinations opportunities in major cities.

Granting a separate license to a club or organization generally requires that an individual with a current and valid amateur radio license who is in good standing with the telecommunications authority assumes responsibility for any operations conducted under the club license or club call sign.[47] A few countries may issue special licenses to novices or beginners that do not assign the individual a call sign but instead require the newly licensed individual to operate from stations licensed to a club or organization for a period of time before a higher class of license can be acquired.[1]

Reciprocal licensing

[edit]
Further information: Amateur radio international operation
World map showing reciprocal licensing agreements for amateur radio
Map of amateur radio reciprocal licensing agreements.   CEPT members   IARP members   CEPT and IARP   USA–Canada treaty, CEPT, and IARP

A reciprocal licensing agreement between two countries allows licensed amateur radio operators from one country to operate stations in the other without obtaining a new licence. In some cases, visiting operators may be issued a temporary local licence and call sign.

Requirements vary by jurisdiction. Some countries have bilateral or multilateral agreements that harmonise conditions, while others have no reciprocal arrangements. Regional organisations, such as the Organization of American States, facilitate reciprocity through treaties, including the Inter-American Amateur Radio Service Convention.[48]

Newcomers

[edit]

Many people start their involvement in amateur radio on social media or by finding a local club. Clubs often provide information about licensing, local operating practices, and technical advice. Newcomers also often study independently by purchasing books or other materials, sometimes with the help of a mentor, teacher, or friend. In North America, established amateurs who help newcomers are often referred to as "Elmers", as coined by Rodney Newkirk (W9BRD),[49] within the ham community.[50][51] In addition, many countries have national amateur radio societies which encourage newcomers and work with government communications regulation authorities for the benefit of all radio amateurs. The oldest of these societies is the Wireless Institute of Australia, formed in 1910; other notable societies are the Radio Society of Great Britain, the American Radio Relay League, Radio Amateurs of Canada, Bangladesh NGOs Network for Radio and Communication, the New Zealand Association of Radio Transmitters and South African Radio League. (See Category:Amateur radio organizations)

Call signs

[edit]
Further information: Amateur radio call signs

An amateur radio operator uses a call sign on the air to legally identify the operator or station.[52] In some countries, the call sign assigned to the station must always be used, whereas in other countries, the call sign of either the operator or the station may be used.[53] In certain jurisdictions, an operator may also select a "vanity" call sign although these must also conform to the issuing government's allocation and structure used for amateur radio call signs.[54] Some jurisdictions require a fee to obtain a vanity call sign; in others, such as the UK, a fee is not required and the vanity call sign may be selected when the license is applied for. The FCC in the U.S. discontinued its fee for vanity call sign applications in September 2015, but reinstated it at $35 in 2022.[55]

Call sign structure as prescribed by the ITU consists of three parts which break down as follows, using the call sign ZS1NAT as an example:

ZS The first part may be one or two letters (or a single digit followed by a single letter); it shows the country from which the call sign originates and may also indicate the license class. (This call sign is licensed in South Africa.)
1 The second part is always a single digit that appears as the second or third character, and always follows a letter; it normally gives the subdivision of the country or territory indicated in the first part (this one refers to the Western Cape).
NAT The third part is a set of one, two, or three letters that immediately follows the digit in the second part (the digit in the second or third character); it uniquely identifies the holder of the license. (In the examples below, the third part is represented by "xxx".)

The combination of the three parts identifies the specific transmitting station, and the station's identification (its call sign) is determined by the license held by its operator. In the case of commercial stations and amateur club stations, the operator is a corporation; in the case of amateur radio operators, the license-holder is a resident of the country identified by the first part of the call sign.

Many countries do not follow the ITU convention for the second-part digit. In the United Kingdom the original calls G0xxx, G2xxx, G3xxx, G4xxx, were Full (A) License holders along with the last M0xxx full call signs issued by the City & Guilds examination authority in December 2003. Additional Full Licenses were originally granted to (B) Licenses with G1xxx, G6xxx, G7xxx, G8xxx and 1991 onward with M1xxx call signs. The newer three-level Intermediate License holders are assigned 2E0xxx and 2E1xxx, and the basic Foundation License holders are granted call signs M3xxx, M6xxx or M7xxx.[56]

Instead of using numbers, in the U.K. the second letter after the initial 'G' or 'M' identifies the station's location; for example, a call sign G7OOE becomes GM7OOE and M0RDM becomes MM0RDM when the license holder is operating their station in Scotland. Prefix GM & MM are Scotland, GW & MW are Wales, GI & MI are Northern Ireland, GD & MD are the Isle of Man, GJ & MJ are Jersey and GU & MU are Guernsey. Intermediate licence call signs are slightly different. They begin 2z0 and 2z1 where the z is replaced with one of the country letters, as above. For example 2M0 and 2M1 are Scotland, 2W0 and 2W1 are Wales and so on. The exception however is for England, whose letter would be 'E'; however, letter 'E' is used, but only in intermediate-level call signs, and perplexingly never by the advanced licenses. For example 2E0 & 2E1 are used whereas the call signs beginning 'G' or 'M' for foundation and full licenses never use the 'E'.[57]

In the United States, for non-vanity licenses, the numeral indicates the geographical district the holder resided in when the license was first issued. Prior to 1978, US hams were required to obtain a new call sign if they moved out of their geographic district.

In Canada, call signs start with VA, VE, VY, VO, and CY. Call signs starting with 'V' end with a number after to indicate the political region; whereas the prefix CY indicates geographic islands. Prefixes VA1 and VE1 are used for Nova Scotia; VA2 & VE2 for Quebec; VA3 & VE3 for Ontario; VA4 & VE4 for Manitoba; VA5 & VE5 for Saskatchewan; VA6 & VE6 for Alberta; VA7 & VE7 for British Columbia; VE8 for the Northwest Territories; VE9 for New Brunswick; VY0 for Nunavut; VY1 for the Yukon; VY2 for Prince Edward Island; VO1 for Newfoundland; and VO2 for Labrador. CY is for amateurs operating from Sable Island (CY0) or St. Paul Island (CY9). Special permission is required to access either of these: from Parks Canada for Sable and Coast Guard for St. Paul. The last two or three letters of the call signs are typically the operator's choice (upon completing the licensing test, the ham writes three most-preferred options). Two-letter call sign suffixes require a ham to have already been licensed for 5 years. Call signs in Canada can be requested with a fee.

Also, for smaller geopolitical entities, the digit at the second or third character might be part of the country identification. For example, VP2xxx is in the British West Indies, which is subdivided into VP2Exx Anguilla, VP2Mxx Montserrat, and VP2Vxx British Virgin Islands. VP5xxx is in the Turks and Caicos Islands, VP6xxx is on Pitcairn Island, VP8xxx is in the Falklands, and VP9xxx is in Bermuda.

Online callbooks or call sign databases can be browsed or searched to find out who holds a specific call sign.[58] An example of an online callbook is QRZ.com. Various partial lists of famous people who hold or held amateur radio call signs have been compiled and published.[59]

Many jurisdictions (but not in the U.K. nor Europe) may issue specialty vehicle registration plates to licensed amateur radio operators.[60][61] The fees for application and renewal are usually less than the standard rate for specialty plates.[60][62]

Privileges

[edit]

In most administrations, unlike other RF spectrum users, radio amateurs may build or modify transmitting equipment for their own use within the amateur spectrum without the need to obtain government certification of the equipment.[63][a][64][b] Licensed amateurs can also use any frequency in their bands (rather than being allocated fixed frequencies or channels) and can operate medium-to-high-powered equipment on a wide range of frequencies[65] so long as they meet certain technical parameters including occupied bandwidth, power, and prevention of spurious emission.

Radio amateurs have access to frequency allocations throughout the RF spectrum, usually allowing choice of an effective frequency for communications across a local, regional, or worldwide path. The shortwave bands, or HF, are suitable for worldwide communication, and the VHF and UHF bands normally provide local or regional communication, while the microwave bands have enough space, or bandwidth, for amateur television transmissions and high-speed computer networks.

The international symbol for amateur radio, is included in the logos of many IARU member societies. The diamond holds a circuit diagram featuring components common to every radio: an antenna, inductor and ground.

In most countries, an amateur radio license grants permission to the license holder to own, modify, and operate equipment that is not certified by a governmental regulatory agency. This encourages amateur radio operators to experiment with home-constructed or modified equipment. The use of such equipment must still satisfy national and international standards on spurious emissions.

Amateur radio operators are encouraged both by regulations and tradition of respectful use of the spectrum to use as little power as possible to accomplish the communication.[66] This is to minimise interference or electromagnetic compatibility (EMC) to any other device. Although allowable power levels are moderate by commercial standards, they are sufficient to enable global communication. Lower license classes usually have lower power limits; for example, the lowest license class in the UK (Foundation licence) has a limit of 25 W.[67]

Power limits vary from country to country and between license classes within a country. For example, the peak envelope power limits for the highest available license classes in a few selected countries are: 2.25 kW in Canada;[68] 1.5 kW in the United States; 1.0 kW in Belgium, Luxembourg, Switzerland, South Africa, the United Kingdom, and New Zealand; 750 W in Germany; 500 W in Italy; 400 W in Australia and India; and 150 W in Oman.

Output power limits may also depend on the mode of transmission. In Australia, for example, 400 W may be used for SSB transmissions, but FM and other modes are limited to 120 W.

The point at which power output is measured may also affect transmissions: The United Kingdom measures at the point the antenna is connected to the signal feed cable, which means the radio system may transmit more than 400 W to overcome signal loss in the cable; conversely, the U.S. and Germany measure power at the output of the final amplification stage, which results in a loss in radiated power with longer cable feeds.[citation needed]

Certain countries permit amateur radio licence holders to hold a Notice of Variation that allows higher power to be used than normally allowed for certain specific purposes. E.g. in the UK some amateur radio licence holders are allowed to transmit using (33 dBw) 2.0 kW for experiments entailing using the moon as a passive radio reflector (known as Earth–Moon–Earth communication) (EME).

Band plans and frequency allocations

[edit]
Main article: Amateur radio frequency allocations

The International Telecommunication Union (ITU) governs the allocation of communications frequencies worldwide, with participation by each nation's communications regulation authority. National communications regulators have some liberty to restrict access to these bandplan frequencies or to award additional allocations as long as radio services in other countries do not suffer interference. In some countries, specific emission types are restricted to certain parts of the radio spectrum, and in most other countries, International Amateur Radio Union (IARU) member societies adopt voluntary plans to ensure the most effective use of spectrum.

In a few cases, a national telecommunication agency may also allow hams to use frequencies outside of the internationally allocated amateur radio bands. In Trinidad and Tobago, hams are allowed to use a repeater which is located on 148.800 MHz. This repeater is used and maintained by the National Emergency Management Agency (NEMA), but may be used by radio amateurs in times of emergency or during normal times to test their capability and conduct emergency drills. This repeater can also be used by non-ham NEMA staff and REACT members. In Australia and New Zealand, ham operators are authorized to use one of the UHF TV channels. In the U.S., amateur radio operators providing essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available may use any frequency including those of other radio services such as police and fire and in cases of disaster in Alaska may use the statewide emergency frequency of 5.1675 MHz with restrictions upon emissions.[69]

Similarly, amateurs in the United States may apply to be registered with the Military Auxiliary Radio System (MARS). Once approved and trained, these amateurs also operate on US government military frequencies to provide contingency communications and morale message traffic support to the military services.

Modes of communication

[edit]
See also: List of amateur radio modes

Amateurs use a variety of voice, text, image, and data communication modes over radio. Generally new modes can be tested in the amateur radio service, although national regulations may require disclosure of a new mode to permit radio licensing authorities to monitor the transmissions. Encryption, for example, is not generally permitted in the Amateur Radio service except for the special purpose of satellite vehicle control uplinks.[citation needed] The following is a partial list of the modes of communication used, where the mode includes both modulation types and operating protocols.

Voice

[edit]

Image

[edit]

Text and data

[edit]

In former times, most amateur digital modes were transmitted by inserting audio into the microphone input of a radio and using an analog scheme, such as amplitude modulation (AM), frequency modulation (FM), or single-sideband modulation (SSB). Beginning in 2017, increased use of several digital modes, particularly FT8, became popular within the amateur radio community.[72]

Text-modes
Digital modes

Modes by activity

[edit]

The following "modes" use no one specific modulation scheme but rather are classified by the activity of the communication.

Footnotes

[edit]

See also

[edit]

References

[edit]

Sources

[edit]
Australia
Canada
India
United Kingdom
United States

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Amateur radio

View on Grokipedia
from Grokipedia
Amateur radio, also known as ham radio, is both a popular hobby and a regulated radiocommunication service that allows licensed individuals of any age to pursue self-training, intercommunication, technical experimentation, and global connections using designated radio frequencies—solely for personal, non-commercial aims. This service, formally defined by the (ITU) as encompassing both the amateur service and the amateur-satellite service, allows operators to experiment with various transmission modes, including voice, , digital signals, and television, across 29 allocated frequency bands worldwide. Participation requires obtaining a license through examination, such as the three-tier system in the United States administered by the (FCC), which tests knowledge of radio theory, regulations, and operating practices to ensure safe and responsible use of the spectrum. Originating in the early with enthusiasts experimenting alongside commercial telegraphers—the term "" arising from operators' frustration with amateur interference— radio has grown into a global community of over three million licensed operators (as of 2025), fostering technical innovation, international goodwill, and educational opportunities in and communication. alone, approximately 737,000 individuals hold FCC-issued licenses (as of 2025), enabling activities like contacting distant stations via satellites or moonbounce, building custom equipment, and participating in contests or nets for message relay. Beyond recreation, amateur radio plays a vital role, providing reliable emergency communications when infrastructure fails, as demonstrated during events like in 2005 and the 9/11 attacks in 2001, where operators supported disaster response and coordinated relief efforts. Organizations such as the (ARRL) and the (IARU) advocate for spectrum allocation and promote ethical standards, ensuring the hobby's continued relevance in an era of digital connectivity.

History

Origins in the Early 20th Century

The origins of amateur radio trace back to the late 19th and early 20th centuries, when Marconi's pioneering work in wireless communication inspired a wave of hobbyist experimentation. In 1897, Marconi established the first wireless factory in , , and by 1901, he achieved the first transatlantic radio transmission from St. John's, Newfoundland, using a kite-lifted antenna to send signals at around 500 kHz. This breakthrough demonstrated the potential for long-distance electromagnetic wave transmission without wires, motivating individuals worldwide to build simple radio sets and conduct personal experiments in the and . Marconi's innovations, including oscillators, receivers, and telegraph keys, provided the foundational technology that early enthusiasts adapted for non-commercial use, fostering a culture of self-taught inventors and tinkerers. As amateur activities proliferated, they began interfering with commercial and maritime communications, prompting the first regulatory measures in the United States. The , enacted in the aftermath of the Titanic disaster where amateur signals had disrupted rescue efforts, required all radio operators—including amateurs—to obtain licenses from the Department of Commerce. The act restricted amateurs to wavelengths shorter than 200 meters (above 1.5 MHz) to minimize interference with naval and commercial bands, while mandating call signs and prohibiting use of primary distress frequencies. These provisions formalized amateur radio as a distinct service, emphasizing experimental rather than commercial purposes, though enforcement was initially lax and hobbyists often operated in a legal gray area. In response to growing interest and the need for organized long-distance communication, the first major amateur radio clubs emerged. The (ARRL) was founded on April 6, 1914, by and Clarence D. Tuska in , to coordinate relay stations that could extend message ranges beyond individual equipment limits. This non-commercial organization quickly became a central hub for amateurs, promoting technical standards and advocacy amid regulatory challenges. World War I profoundly disrupted these early efforts, leading to a complete shutdown of amateur operations in the United States. On April 6, 1917, as the U.S. entered the war against and , the government seized control of all private radio facilities, ordering amateurs to cease transmissions, dismantle equipment, and surrender receivers to prevent . Many operators contributed their skills to the military, such as through the Navy's Class 4 Naval Reserve, which required proficiency and trained recruits at facilities like Ellington Airfield. Operations resumed in November 1919, allowing amateurs to rebuild and expand under the existing 1912 regulations, marking a pivotal recovery phase.

Key Developments and Milestones

The 1927 International Radiotelegraph Conference in , marked a pivotal moment by establishing the first international allocations for amateur radio, including exclusive bands at 80 meters (3.5-4.0 MHz), 40 meters (7.0-7.3 MHz), 20 meters (14.0-14.35 MHz), and 10 meters (28.0-29.7 MHz), along with standardized prefixes to facilitate global operations. These allocations recognized amateur radio's contributions to radio science and ensured interference-free spectrum for experimentation, laying the foundation for international amateur networks. World War II profoundly disrupted amateur radio worldwide, with governments imposing complete bans on operations to repurpose spectrum for military use; in the United States, all amateur transmissions ceased on December 8, 1941, following the , and hams were recruited for wartime duties. Postwar recovery began in 1945 with limited access to bands like the 10-meter (HF) and 2-meter (VHF) bands in the U.S., expanding to full high-frequency privileges by 1947 after international reallocations at the 1947 , which reaffirmed and adjusted amateur allocations amid competing commercial demands. During the Cold War era, technological innovations pushed amateur radio boundaries, exemplified by the first successful amateur moonbounce (Earth-Moon-Earth) contacts in the 1950s, with one-way signals achieved on 144 MHz in January 1953 by Ross Bateman (W4AO) and Bill Smith (W3GKP) in , demonstrating VHF propagation via lunar reflection. This evolved to the first two-way moonbounce QSO on 1296 MHz in July 1960 between stations in and New York, showcasing amateur ingenuity in overcoming line-of-sight limitations. Further milestones included the launch of OSCAR 1 on December 12, 1961, the world's first nongovernmental satellite, built by Project OSCAR amateurs and deployed via a U.S. Thor-Agena rocket, enabling global beacon receptions and telecommand experiments on 144.983 MHz. The digital revolution transformed amateur radio in the 1970s with the advent of , pioneered by Canadian amateurs in 1978 who conducted the first transmissions using protocol precursors on VHF frequencies, enabling error-corrected data exchange and laying groundwork for automated networks. By the 1980s, U.S. FCC authorization of ASCII modes accelerated adoption, leading to widespread systems and digital . In the 1990s, -linked systems emerged, such as IRLP in 1997, which connected VHF/UHF worldwide via VoIP, bridging RF and for enhanced global connectivity; EchoLink, released in 2002, further popularized PC-to-radio linking for licensed operators. Recent developments through 2025 highlight amateur radio's adaptability, with (SDR) gaining rapid adoption since the early 2000s, exemplified by affordable receivers like the RTL-SDR in 2009 and transceivers such as the FlexRadio series, enabling spectrum visualization and for experimentation on multiple bands. The spurred unprecedented licensing surges, with U.S. exam sessions increasing by over 20% in 2020 amid , as remote testing pilots and heightened in resilient communications drove new operator numbers to record highs, exceeding 769,000 licensed amateurs by 2022. As of September 2025, active licenses total approximately 737,000. By 2025, SDR integration in emergency response and satellite operations, coupled with ITU World Radiocommunication Conference adjustments for amateur spectrum, including those from WRC-23 for the 1240-1300 MHz band to support amateur and satellite services, underscores ongoing global expansion and technological resilience.

Evolution of the Term "Ham Radio"

The term "ham" originated in the early 20th century as American telegraph slang for unskilled or clumsy operators, often described as "ham-fisted" due to their heavy-handed Morse code transmission style. This derogatory label, first documented in print around 1909 when Robert A. Morton reported overhearing professionals mock an amateur as a "ham" during a wireless exchange, reflected the frustration of commercial telegraphers with inexperienced hobbyists interfering on shared lines. By the 1910s, as wireless experimentation grew, the slur extended to early radio amateurs, who were seen as disruptive "hams" by professionals guarding the ether from unregulated signals. The term gained widespread traction in the 1920s through the burgeoning amateur radio community and publications like the American Radio Relay League's (ARRL) QST magazine, which began featuring "ham" in articles and personal accounts as early as January 1920. Media portrayals in newspapers and periodicals further popularized it, portraying hams as enthusiastic tinkerers rather than mere nuisances, aligning with the post-World War I revival of amateur licensing under the Radio Act of 1912. This era marked "ham radio" as a shorthand for the hobby's technical and social appeal, emphasizing experimentation and long-distance contacts over commercial utility. By the , "" had shifted from to an affectionate badge of identity within the community, symbolizing camaraderie and ingenuity amid the . Examples appear in literature, such as Clinton Crowell's 1930s ham operator memoirs in QST, which celebrated the term as a mark of dedicated enthusiasts, and in films like Everybody's Hobby (1939), a comedy depicting ham radio as a wholesome family pursuit that fosters global connections. This evolution reflected the hobby's maturation, with vacuum-tube technology enabling reliable operations and ARRL handbooks promoting ethical "" conduct. In modern usage, "ham radio" remains a colloquial term predominantly in the United States, evoking the hobby's informal roots, while internationally it is often replaced by the formal "amateur radio" to align with regulatory bodies like the . This distinction highlights the term's cultural specificity, though global operators occasionally adopt "ham" in English-language contexts for its nostalgic charm.

Licensing and Regulation

Requirements for Obtaining a License

In the United States, the Federal Communications Commission (FCC) oversees amateur radio licensing through a tiered system of written examinations administered by volunteer examiners (VEs). There are three operator classes—Technician, General, and Amateur Extra—with increasing privileges and required knowledge. Applicants for the entry-level Technician Class must pass Element 2, a 35-question multiple-choice examination covering basic radio theory, FCC regulations, operating practices, and safety procedures; a score of at least 26 correct answers (74%) is needed to pass. To obtain a General Class license, candidates must also pass Element 3, another 35-question exam focusing on advanced propagation theory, signal reports, and operating techniques beyond VHF/UHF bands, again requiring 26 correct. The highest Amateur Extra Class demands passing Element 4 in addition, a 50-question test on specialized topics like modulation modes and antenna systems, with a passing threshold of 37 correct answers. Exams can be taken in one session for all elements if pursuing higher classes, and successful completion results in a Certificate of Successful Completion of Examination (CSCE) from the VEs, after which the FCC issues the license and assigns a call sign. Preparation for these exams typically involves self-study or structured courses using resources such as the American Radio Relay League (ARRL) Ham Radio License Manual, which provides comprehensive coverage aligned with the question pools, and online platforms like hamstudy.org for flash cards and practice tests drawn from the official pools updated every four years. Local classes offered by ARRL-affiliated groups or clubs often include hands-on sessions and mock exams to build familiarity with topics. Pass rates for the Technician exam average around 70-80% for first-time takers, rising to over 90% in guided preparatory programs, reflecting the exams' emphasis on memorization and conceptual understanding rather than advanced mathematics. Eligibility requires no prior license or citizenship restriction beyond excluding foreign government representatives, and there is no minimum age—applicants as young as five have successfully licensed—though minors may need adult supervision for station operation in practice. Internationally, licensing requirements vary by country but generally follow exam-based models similar to the , administered by national regulatory bodies to ensure knowledge of technical principles, legal obligations, and ethical operations. For instance, in , , Science and issues Basic, Advanced, and endorsements via multiple-choice exams with no minimum age, while in the , requires the Radio Amateur Examination (Foundation, Intermediate, Full levels) starting from age 8 with parental consent. Some nations, like , impose a minimum age of 16 for full licensing. In regions under the European Conference of Postal and Telecommunications Administrations (CEPT), the Harmonised Amateur Radio Examination Certificate (HAREC) standard promotes equivalence, allowing a single comprehensive exam for advanced privileges across member states. Renewal processes differ; in the , licenses remain valid for 10 years and can be renewed online via the FCC's Universal Licensing System (ULS) up to 90 days before expiration or within a two-year afterward, requiring only an application, updated information, and a fee (introduced in 2022) with no re-examination needed.

Call Signs and Operator Identification

In the United States, are uniquely assigned by the (FCC) to identify stations and operators, following structured formats that incorporate prefixes, numerals, and es. The primary prefixes are the single letters , , and , with the numeral immediately following indicating one of 10 geographic regions (or additional regions 11-13 for , /Pacific, and /). For instance, numeral 1 denotes the Northeast ( to ), numeral 4 the Southeast ( to ), and numeral 6 . es consist of one to three letters, resulting in common formats such as 2x3 (two-letter prefix, numeral, three-letter , e.g., KA1XYZ for a or General class licensee in the Northeast) or 1x2 (one-letter prefix, numeral, two-letter , e.g., W2AB, typically for Extra class). These sequential assignments are processed based on the licensee's class and mailing to ensure availability within designated groups. The FCC's vanity call sign program, initiated on May 31, 1996, enables eligible individual and club station licensees to apply for preferred s from specific groups tied to their license class, rather than receiving sequential assignments. Eligibility requires holding a current license for at least 10 years for most applicants (or shorter periods for former holders or close relatives), with new licensees ineligible until they receive an initial . Applications are submitted online via the FCC's Universal Licensing System, where up to five preferred s can be requested by list, former holder, or close relative criteria, subject to availability after a two-year following cancellation of prior assignments. Extra class licensees have access to premium formats like 1x2 or 2x1 (e.g., K1AB), while General and Technician classes are limited to 2x3 or 1x3; a processing fee is required, though no auctions are involved. Internationally, structures are standardized by the (ITU) through Appendix 42 of the Radio Regulations, which allocates series of prefixes to member states for amateur and experimental stations. Each country's prefix is followed by a numeral (if needed) and a sequential alphanumeric to ensure uniqueness, with the prefix denoting national origin—for example, G for the and F for . In the UK, formats typically follow G (or M for some bands) plus a number and letters (e.g., G3ABC), while French call signs use F plus sequential elements (e.g., F6ABC). These ITU allocations facilitate global recognition and reciprocity, though individual countries may impose additional numbering or rules. Operators must identify their station using the assigned during transmissions to comply with regulations, promoting and interference resolution. In the , FCC rules mandate transmission of the at the end of each communication and at least every 10 minutes during ongoing exchanges longer than that interval. Identification occurs on the transmitting channel using the station's emission mode: verbally in English (with phonetic alphabet recommended) for phone, international for CW (not exceeding 20 words per minute if automatic), digital codes for RTTY/data, or conforming standards for image transmissions. Control operators may append their with a slash (e.g., /W1ABC) if different from the station's, and stations identify every 10 minutes but exclude input channel IDs. Special call signs are issued temporarily for notable occasions, allowing operators to highlight events while maintaining standard identification practices. Under the FCC's special event system, 1x1 formats (e.g., or ) using prefixes , , or , a digit 0-9, and a letter A-W/Y/Z (excluding I, O, Q, X) are available for assignments during events of special significance to the community, such as contests. For example, stations participating in the CQ World Wide (CQ WW) contest may coordinate a 1x1 call to attract contacts, applied for through certified coordinators like Volunteer Examiner Coordinators. These calls are limited in duration to the event period, with the primary assigned required at least once per hour; clubs or groups can also use them for temporary operations.

Operating Privileges and Frequency Restrictions

Amateur radio operating privileges in the United States are stratified by license class, as defined by the under 47 CFR Part 97, granting progressively broader access to frequency bands and modes. The entry-level Technician Class license provides full operational privileges on all amateur frequencies above 30 MHz, including VHF and UHF bands, enabling access to local and regional communications via and direct operations. On HF bands below 30 MHz, Technician licensees are restricted to specific segments for (CW) and limited voice (SSB) operations, such as 28.300–28.500 MHz on the for upper voice at up to 200 watts PEP. The General Class license expands HF privileges significantly, allowing access to additional portions of bands like 80 meters (3.800–4.000 MHz for voice), 40 meters (7.175–7.300 MHz for voice), and full segments (14.000–14.350 MHz), supporting international long-distance communications in voice, CW, and data modes. This class also includes low-frequency bands such as 160 meters (1.800–2.000 MHz) and 60 meters (5.330–5.400 MHz), with all modes permitted within allocated channels. General licensees enjoy the same VHF/UHF access as Technicians but with enhanced HF capabilities for more versatile experimentation and participation. The highest tier, Amateur Extra Class, confers complete access to all amateur frequency allocations, including exclusive segments on HF bands such as 3.500–3.600 MHz on 80 meters and 14.000–14.150 MHz on 20 meters for CW and . This full availability supports advanced activities like and weak-signal work, with no restrictions beyond general rules. As of late 2023, FCC amendments eliminated baud rate limits across all bands, including 60 meters, enabling broader digital mode operations such as within the 2.8 kHz bandwidth cap, thereby expanding flexibility for all classes. Transmitter power is capped at 1.5 kW (PEP) for all classes across most bands, though operators must use the minimum necessary for effective communication; band-specific limits apply, such as 100 watts PEP on the 60-meter channels and 200 watts PEP on portions of 30 meters (10.100–10.150 MHz). Mode allocations within bands are governed by emission standards, permitting voice (e.g., SSB in 14.150–14.350 MHz on 20 meters), CW, and data, but voluntary band plans guide sub-band usage to minimize interference. Prohibited activities ensure the non-commercial, experimental nature of amateur radio: transmissions for hire or compensation are banned, as are encoded messages intended to obscure meaning (prohibiting most except for specific control signals). Obscene or indecent is forbidden, and music transmissions are restricted to incidental retransmissions of communications, preventing broadcasting-like uses. These rules, enforced under §97.113, maintain the service's focus on self-training and public welfare.

International Reciprocity and Agreements

International reciprocity in amateur radio enables licensed operators from one country to operate temporarily in another without obtaining a full local license, provided they meet specific criteria outlined in multilateral agreements. These arrangements promote global intercommunication while respecting national regulations, allowing amateurs to maintain their hobby during travel or international events. The foundational framework for such operations is established by the (ITU), which coordinates worldwide radio regulations to ensure harmonious use of frequencies. Article 25 of the , in effect since the 1947 that established the modern ITU framework, defines the service as a radiocommunication activity for self-training, intercommunication, and technical investigations carried out by duly authorized non-commercial enthusiasts. This article specifies operational rules, including prohibitions on encoded transmissions obscuring meaning (except for control signals), limitations to communications of a technical between stations in different countries, and requirements for identifying transmissions with the licensed . It applies to all ITU member states, providing a standardized basis for reciprocal recognition of qualifications and ensuring that international operations do not interfere with other services. The regulations are periodically updated at World Radiocommunication Conferences, with the 2020 edition maintaining these core provisions to support global activities. In , the European Conference of Postal and Telecommunications Administrations (CEPT) facilitates seamless operations through Recommendation T/R 61-01, adopted in 2005 and revised in 2016, which allows holders of a CEPT radio amateur license or equivalent to operate in participating countries without additional licensing. For operators, this applies to Amateur Extra and Advanced class licensees, granting access to all allocated amateur bands and power limits as in their home country, typically for up to three months, subject to carrying proof of qualification and adhering to local band plans. As of 2023, over 40 CEPT member states, including most nations, participate, making it one of the most extensive reciprocal systems and enabling activities like or support during travel. Outside Europe, the International Amateur Radio Permit (IARP), governed by the 1965 Inter-American Convention administered through the Inter-American Telecommunication Commission (CITEL), permits U.S. operators to function in participating countries across the without a separate permit. Valid for up to six months and renewable, the IARP is issued by the (FCC) to , General, Advanced, and Extra class licensees upon application, allowing use of equivalent privileges in nations such as , , and . This agreement streamlines operations in the , where bilateral ties enhance coverage; for instance, maintains a reciprocal arrangement with the U.S., permitting FCC-licensed operators to use their home prefixed with "VK/" for temporary visits up to three months, though it falls outside the IARP framework. Not all regions offer straightforward reciprocity, presenting challenges for operators in non-participating countries. In , for example, foreign amateurs must apply through the Japan Amateur Radio League () for a guest operating license (Form JARL-96-04), submitted at least 60 days in advance with proof of a valid home license and equipment details; while no examination is required for qualified applicants from reciprocal nations, approval is not guaranteed and limits power to 50 watts for portable operations, reflecting Japan's stringent two-tier licensing system. Such processes highlight the need for pre-travel verification, as non-reciprocal areas may impose exams, fees, or restrictions to protect local , underscoring the value of ITU coordination in bridging these gaps.

Operating Fundamentals

Frequency Allocations and Band Plans

Amateur radio frequency allocations are defined by the International Telecommunication Union (ITU) through its Radio Regulations, which divide the radio spectrum into bands available to the amateur service on a primary or secondary basis. These allocations span from low frequencies up to microwave bands, enabling a wide range of propagation characteristics from local to global communications. The core high-frequency (HF) allocations cover 1.8–30 MHz, supporting long-distance skywave propagation; very high-frequency (VHF) bands from 50–148 MHz for regional line-of-sight and sporadic-E contacts; ultra high-frequency (UHF) segments from 222–450 MHz for local and repeater operations; and microwave frequencies above 902 MHz for experimental, satellite, and high-resolution applications. Regional variations exist due to the ITU's division of the world into three regions, with specific band edges adjusted to accommodate national priorities and avoid interference. In IARU Region 1 (, , , and parts of ), the (3.5–3.8 MHz) is narrower than in Region 2 (the , 3.5–4.0 MHz), reflecting denser spectrum sharing with broadcasting services. Similarly, the in Region 1 spans 7.0–7.2 MHz, while Region 2 extends to 7.3 MHz, allowing more space for voice operations in the . These differences require operators to consult local regulations, as privileges may further limit access based on license class. Band plans provide voluntary guidelines developed by the (IARU) to segment allocated bands and minimize interference among modes. Typically, continuous-wave (CW) operations occupy the lower edges for their narrow bandwidth, single-sideband (SSB) voice is placed in upper portions to leverage wider bandwidths, and digital modes are confined to designated segments. For instance, in the , CW is prioritized from 7.000–7.040 MHz in Region 1 and 7.000–7.047 MHz in Region 2, with SSB typically in upper portions such as 7.060–7.100 MHz in Region 1 and 7.060–7.300 MHz in Region 2, per IARU band plans; digital modes, such as , are commonly used around 7.074 MHz despite overlapping CW areas in some plans. These plans evolve through IARU conferences to accommodate while promoting efficient spectrum use. Reallocations occur periodically through World Radiocommunication Conferences (WRC) to expand amateur access amid competing demands. A notable example is the WRC-15 decision to grant a worldwide secondary allocation of 5.3515–5.3665 MHz (), enhancing medium-distance capabilities in all regions while requiring protection of primary users. Such adjustments underscore the amateur service's role in spectrum sharing and innovation.
BandApproximate Range (MHz)Typical UseExample Regional Note
HF1.8–30Long-distanceRegion 1 80m: 3.5–3.8; Region 2: 3.5–4.0
VHF50–148Regional6m uniform 50–54 MHz
UHF222–450Local70cm: 430–450 MHz worldwide
Microwave>902Experimental23cm: 1240–1300 MHz secondary

Equipment and Technical Standards

Amateur radio equipment primarily consists of transceivers, antennas, and supporting accessories designed to operate within allocated bands while adhering to regulatory standards. Transceivers serve as the core devices for transmitting and receiving signals, with high-frequency (HF) all-mode rigs being popular for long-distance communication. These rigs, such as the Yaesu FT-897, typically output 100 watts and cover multiple HF bands (3-30 MHz) with capabilities for single-sideband (SSB), (CW), and digital modes, often including built-in antenna tuners for . For local and regional operations, handheld ()/ () transceivers, like dual-band models outputting 3-5 watts, are commonly used for (FM) voice on 144-148 MHz and 430-450 MHz bands. Antennas are critical for efficient signal , with designs selected based on , terrain, and desired coverage. antennas, consisting of two conductive elements fed at the center, provide omnidirectional horizontal polarization and are simple to construct for HF bands, supporting multi-band operation through traps or parallel configurations. Vertical antennas, often quarter-wave monopoles with ground radials, generate low-angle radiation suitable for ionospheric skip on HF, enabling long-distance (DX) contacts by reflecting signals off the ionosphere's F-layer. Directional Yagi antennas, featuring a driven element and parasitic reflectors/directors, offer gain and beamwidth control for VHF/UHF, ideal for weak-signal work like communication or . Emission standards ensure signals remain clean and confined to authorized bands, as defined by the (ITU) and national regulators like the U.S. (FCC). Common ITU designations include A1A for CW telegraphy (double-sideband with quantized ), J3E for SSB telephony (single-sideband suppressed carrier with analog telephony), and A3E for (AM) with full carrier telephony. Under FCC Part 97, amateur stations must suppress harmonics and spurious emissions to at least -43 dB below the fundamental carrier for frequencies below 30 MHz, with overall spurious levels attenuated by 60 dB or more in the 30-225 MHz range to prevent interference. Modern trends in amateur radio emphasize software-defined radios (SDRs) and homebrew construction, permitted under FCC Part 97 rules that allow uncertified personal equipment if it meets emission and power standards. SDRs like the , covering 1 MHz to 6 GHz with 20 MSPS sampling, enable experimentation with for modes like or custom protocols, often paired with such as . Homebrew kits, including QRP transceivers for low-power HF operation, foster technical innovation while requiring operators to verify compliance with bandwidth limits (e.g., 2.8 kHz for RTTY/data emissions). Accessories such as power supplies (30+ amps for HF rigs) and tuners complement these systems, ensuring stable operation.

Safety Protocols and Best Practices

Amateur radio operators must adhere to strict radiofrequency (RF) exposure guidelines to protect themselves and the public from potential health risks associated with electromagnetic fields. The (FCC) establishes these limits in OET Bulletin 65, which outlines maximum permissible exposure (MPE) levels based on frequency, environment type (controlled or uncontrolled), and exposure duration. For uncontrolled environments, such as areas accessible to the general public, limits are typically set at 1 mW/cm² for frequencies above 1.5 GHz, with more restrictive values like 0.2 mW/cm² for the 30-300 MHz range to account for higher absorption by the . Operators evaluate compliance through calculations, measurements, or exemptions for low-power stations. If the evaluation indicates that RF fields exceed the limits specified in § 1.1310 in accessible areas, the licensee must take actions to mitigate exposure, such as restricting access to the area, posting warning signs, installing physical barriers, or reducing transmission power. Ensuring antennas and transmission lines are positioned to minimize exposure, particularly near high-gain directional antennas. Electrical safety is paramount in amateur radio setups, where high voltages from power supplies, antennas, and transmission lines pose shock hazards. Proper grounding of equipment to a common earth point prevents electrical shocks by providing a low-impedance path for fault currents, as recommended by the (ARRL) for all station installations. This includes all metal components, such as rigs, antennas, and towers, to a single ground rod system to avoid differences in potential that could lead to arcing or injury. For tower work, the (OSHA) mandates fall protection systems, including full-body harnesses and lanyards, for climbs exceeding 6 feet, along with training in rescue procedures and inspection of climbing gear. These standards apply to amateur radio towers, emphasizing three points of contact during ascent and avoidance of working alone at heights. Safe operating etiquette helps prevent man-made interference (QRM) and ensures efficient spectrum use among operators. A fundamental practice is to listen before transmitting—often summarized as using one's "ears and listen in" (ELI)—to identify ongoing communications and select a clear frequency, thereby avoiding disruption to established contacts. This courtesy extends to monitoring for QRM sources, adjusting power or antenna direction to minimize overlap, and yielding to emergency traffic, fostering a collaborative environment as outlined in ARRL operating ethics. When non-amateur sources cause harmful interference, operators can resolve issues by first attempting direct contact with the source, but persistent problems from unlicensed devices fall under FCC Part 15 rules, which require such devices to cease operation if they interfere with licensed services like amateur radio. Reports of violations are submitted to the FCC's Enforcement Bureau, providing details like , time, and to facilitate investigation and . This process protects amateur allocations without requiring operators to diagnose or fix external equipment themselves.

Communication Modes

Voice Transmission Techniques

Voice transmission in amateur radio primarily relies on analog and digital modulation techniques to encode audio signals onto carriers, enabling clear communication within allocated spectrum. Analog methods, such as single sideband (SSB), , and , have been foundational since the mid-20th century, offering varying trade-offs in bandwidth efficiency, power usage, and noise resilience. These techniques are selected based on frequency band, propagation conditions, and operational needs, with SSB dominating high-frequency (HF) operations for its efficiency, while FM prevails on () and () for local links. Digital voice modes, emerging in the early 2000s, introduce codec-based compression to achieve low-bitrate transmission over narrow channels, often integrated with packet data for enhanced functionality like networking. Single (SSB) modulation suppresses the and one sideband of a double-sideband suppressed-carrier signal, transmitting only the essential audio information to optimize spectrum use and power efficiency. This results in a narrow bandwidth of approximately 2.4 kHz, allowing more signals to share crowded HF bands without interference. SSB is particularly suited for long-distance (DX) communications on HF bands like 20 meters and 40 meters, where ionospheric enables global contacts, as the mode's efficiency conserves transmitter power for weak-signal over thousands of kilometers. Upper sideband (USB) is standard above 10 MHz, while lower sideband (LSB) is used below, aligning with international band plans to minimize confusion. Amplitude modulation (AM), a legacy technique from adapted for amateur use, modulates the carrier's amplitude directly with the , producing both upper and lower sidebands alongside the carrier. It occupies a wider bandwidth of about 6 kHz, which supports higher audio fidelity but consumes more than SSB. AM remains popular on 80-meter and 40-meter bands for nostalgic ragchewing and roundtable discussions among enthusiasts, particularly in segments like 3.885 MHz and 7.290 MHz. However, its susceptibility to and interference—such as static from or man-made sources—degrades signal quality on noisy HF bands, making it less ideal for marginal conditions compared to more robust modes. Frequency modulation (FM) varies the carrier's frequency in proportion to the , providing constant that resists -based like or electrical interference. It requires a wider bandwidth of around 15 kHz, accommodating the full audio range for natural-sounding voice. FM is the preferred mode for local communications via VHF and UHF , such as on 2 meters (144-148 MHz), where limits range to tens of kilometers, and infrastructure like extends coverage in urban areas. A key advantage is the , where a stronger signal suppresses a weaker one on the same frequency, reducing in repeater systems and ensuring clearer reception in crowded environments. Digital voice modes employ advanced to compress audio into low-bitrate streams, typically 2-4 kbps, for transmission over channels using packetized frames, enabling integration with -linked networks and . (DMR) uses the AMBE+2 at a 2.45 kbps voice bitrate (total 3.6 kbps with ), modulated via two-slot (TDMA) on 12.5 kHz channels, popular on VHF/UHF for both and operations among club nets and groups. , developed by the Japan Amateur Radio League, relies on the AMBE for low-bitrate compression, supporting 3.6 kbps voice in a 6.25 kHz channel with simultaneous low-speed , ideal for linking distant via the for global voice chats. Yaesu Fusion employs continuous 4-level (C4FM) modulation with a for digital voice at similar low bitrates, offering dual-mode analog/digital operation on 12.5 kHz channels and Wires-X networking for room-based conferencing on VHF/UHF bands. For HF bands, open-source digital voice modes like FreeDV, using the Codec2 , enable transmission (e.g., 700 Hz for 700D mode at ~700 bps or 1600 Hz for 1600 mode), providing robust voice communication over poor conditions without hardware, as of 2025. These enhance reliability through but can introduce artifacts like robotic audio at low bitrates, though they excel in noisy urban settings and support alongside voice.

Image and Visual Modes

Amateur radio operators transmit still and moving images using specialized modes that balance bandwidth constraints with the need for visual clarity over varying conditions. These visual modes enable the sharing of photographs, charts, and live video, often integrated with voice coordination for setup and confirmation. Common protocols emphasize narrowband efficiency for HF bands while leveraging wider allocations on VHF and UHF for higher fidelity. (SSTV) is a primary method for transmitting still color images, particularly suited to HF where bandwidth is limited to a few kilohertz. SSTV encodes images by scanning lines sequentially, using (FSK) to represent and values, typically with resolutions around 320 × 256 s for standard modes. Transmission times vary by mode; for example, low-resolution formats can achieve frame rates as fast as 8 seconds for 120 × 120 pixel images, while higher detail requires longer durations. The Martin M1 mode, widely used on HF by European operators, delivers 320 × 256 resolution in approximately 114 seconds, employing a green-blue-red color sequence and a line speed of 134 lines per minute, making it effective for propagation-challenged shortwave paths. Amateur television (ATV), also known as fast-scan TV, supports real-time moving images and is predominantly operated on VHF and UHF bands to accommodate its wider bandwidth requirements. Analog ATV uses (AM) or vestigial upper sideband (VUSB) on the 70 cm band (420–450 MHz), occupying about 6 MHz per channel, with common simplex frequencies like 427.25 MHz. For enhanced range, (FM) ATV employs 15–20 MHz bandwidth on the 23 cm band (1240–1300 MHz) and higher, allowing full NTSC-compatible video. Digital variants adapt terrestrial standards like ATSC (8-VSB modulation) for 6 MHz channels, often requiring downconverters for UHF reception, while enables narrower 1–8 MHz transmissions with QPSK or QAM encoding, supporting equipment such as camcorders and low-power modulators. Facsimile transmission in amateur radio focuses on grayscale images like weather charts, broadcast over HF using frequency-shift keying (FSK) modulation with a typical 800 Hz shift around a 1900 Hz subcarrier. Stations encode black and white tones via deviations of ±400 Hz, scanning at speeds such as 120 lines per minute (lpm) with an Index of Cooperation (IOC) of 576, which defines 1810 pixels per line for detailed meteorological maps. This mode, akin to professional radiofax, operates on frequencies like 3855 kHz, enabling amateurs to receive synoptic charts from coastal stations for navigation and forecasting. Integration of image modes with amateur satellites extends visual communications to space, where AMSAT OSCAR series satellites relay SSTV images via linear transponders. Operators uplink commands or images using CW or USB on VHF (e.g., 145.850–145.900 MHz), receiving downlinks in USB or FM on UHF (e.g., 435.800 MHz for FO-29), with SSTV formats like Robot 36 or PD120 decoding views and telemetry visuals. Events on the , designated as an OSCAR, transmit SSTV at 145.800 MHz FM during scheduled passes, fostering global participation in educational image exchanges.

Digital Text and Data Modes

Digital text and data modes in amateur radio enable keyboard-to-keyboard communication and automated data exchange without voice, utilizing signals for efficient spectrum use on HF, VHF, and UHF bands. These modes emerged as alternatives to voice transmission, leveraging early principles and modern to facilitate real-time messaging, position reporting, and under varying conditions. They are particularly valued for their robustness in noisy environments and low power requirements, supporting activities from casual contacts to emergency operations. Continuous Wave (CW), also known as radiotelegraphy, employs to transmit text by keying a on and off, creating short (dots) and long (dashes) pulses. Developed from 19th-century and standardized by the (ITU) in Recommendation ITU-R M.1677, the code encodes letters, numbers, and using a 5-unit timing system where a dot is one unit, a dash three units, and intervals vary accordingly. Operators typically send manually with a straight key or electronic paddle for semi-automatic generation, though automated keying via computer software or built-in features allows precise control at speeds of 5 to 50 (WPM), with 15-25 WPM common for conversational exchanges. CW's narrow bandwidth—around 100-200 Hz—and simplicity make it effective for long-distance (DX) contacts, even at low power levels. Radio Teletype (RTTY) represents an early digital text mode, adapting mechanical teletypewriter technology for radio use with 5-bit Baudot or 7-bit ASCII encoding over (FSK) modulation. The standard amateur implementation operates at 45.45 baud with a Hz shift, producing a distinctive "deedle-deedle" audio tone that PCs decode via interfaces. Popular in for its reliability in exchanges, RTTY requires minimal bandwidth (about 250-300 Hz) and supports error-free transmission through synchronous or asynchronous protocols, though it lacks built-in . Phase Shift Keying 31 (PSK31) and related variants offer modern narrowband alternatives to RTTY, using binary or quaternary phase shifts of a 31.25 carrier to encode ASCII text in approximately 31 Hz of bandwidth—narrower than typical CW signals. Designed for weak-signal performance, PSK31 excels in low-power (QRP) operations below 5 W, enabling contacts during marginal by tolerating signal-to-noise ratios as low as -14 dB through efficient . Free software such as , Digipan, and WinWarbler handles encoding/decoding via PC sound cards, with variants like QPSK31 adding error correction via a secondary carrier and Viterbi decoding for improved reliability over channels. These modes prioritize conversational keyboard use on HF bands, often in the 14.070 MHz subband. Among the most popular digital modes as of 2025 is FT8, part of the WSJT-X suite developed by Joe Taylor, K1JT. FT8 uses 8-tone frequency-shift keying (FSK) with 15-second transmission cycles to exchange structured messages for quick QSOs, achieving signal-to-noise ratios down to -24 dB, making it ideal for weak-signal HF DXing and contesting on bands like 20 meters and 40 meters. Its automation and efficiency have made it the dominant mode for HF digital communications, with millions of QSOs logged annually via tools like Logbook of the World. Other WSJT modes, such as JT65 for EME (moonbounce) and QRA64 for VHF/UHF weak signals, complement FT8 by offering even deeper weak-signal capabilities. The Automatic Packet Reporting System (APRS) facilitates automated data exchange, primarily for real-time position tracking and messaging using GPS-integrated . It transmits short data packets—typically position, speed, altitude, and status—via 1200 audio frequency-shift keying (AFSK) on VHF frequencies, with 144.390 MHz designated as the national frequency in for digipeater relaying. Developed for tactical applications, APRS networks beacons from mobiles or fixed stations to display locations on maps, supporting emergency coordination and bulletins without dedicated infrastructure beyond volunteer iGates connecting to the . These modes, including CW, RTTY, and increasingly , also enhance and by enabling precise logging and confirmation exchanges.

Activities and Applications

Emergency and Public Service Communications

Amateur radio operators play a vital role in and communications by providing resilient, independent networks when conventional fails during disasters such as hurricanes, floods, and earthquakes. These operators, often organized through structured programs, relay critical information including damage assessments, resource requests, and welfare checks to agencies, enhancing coordination and saving lives. Their ability to operate on battery power and multiple frequencies ensures continuity in blacked-out areas where cellular and services are unavailable. The (ARES), coordinated by the (ARRL), mobilizes licensed volunteers who register their skills and equipment for public service duties. ARES participants undergo training in message handling, net operations, and interoperability with official responders, preparing them for events like hurricanes where they support shelters, evacuation routes, and health-and-welfare traffic. Complementing ARES, the Radio Amateur Civil Emergency Service (RACES), established by the (FEMA) and the (FCC), authorizes amateur stations for during declared emergencies under Part 97.407 of FCC rules. RACES groups, often overlapping with ARES at the local level, focus on wartime or national crisis scenarios but are activated for , providing dedicated communications channels to government entities. Winlink, a global radio email system, enables operators to send and receive internet-style messages over radio links during infrastructure outages, bridging isolated areas to external networks. In blackouts, it supports non-real-time data transfer for logistics and reports, using protocols like VARA and ARDOP, with modems optimizing high-frequency (HF) transmissions for long-distance reliability in challenging propagation conditions. For instance, during FEMA's 2025 multi-regional exercise simulating a major , handled over 1,100 situation reports from field operators, demonstrating its scalability for large-scale . Skywarn networks, sponsored by the (NWS), integrate amateur radio spotters to provide ground-truth observations of phenomena. Trained volunteers use (VHF) repeaters to relay real-time data on thunderstorms, tornadoes, and flooding directly to NWS offices, supplementing and information for more accurate warnings. With an estimated 350,000 to 400,000 participants nationwide, these networks activate during high-risk events, relaying spotter reports from mobile stations to enhance public safety alerts. In 2025, amateur radio's emergency role was prominently featured in responses to global flood events, such as the floods, where and RACES volunteers provided vital communications support starting July 4, including relaying search-and-rescue updates to emergency operations centers. These activations underscored ongoing adaptations in protocols, with increased emphasis on digital modes for efficient data relay in post-disaster recovery phases.

Contesting, DXing, and Awards

Amateur radio operators engage in , , and awards programs to challenge their technical skills, explore , and achieve recognition for accomplishments. involves timed competitions where participants maximize contacts (QSOs) within rules, often focusing on high-frequency (HF) bands to test operating efficiency and antenna performance. emphasizes long-distance communications, particularly to rare or distant locations, while awards provide formal verification of these feats through confirmed contacts. These pursuits foster a global community, with tools like forecasts aiding strategic planning. Contesting is a competitive activity where operators aim to complete as many QSOs as possible during specified periods, with scores calculated based on points per contact multiplied by geographical multipliers such as or zones. The ARRL International DX , held in February (CW mode) and March (SSB mode), encourages stations in the and (W/VE) to contact international (DX) stations on HF and MF bands, promoting knowledge of and operating techniques; scoring awards two points per 160- or 80-meter QSO, one point on higher bands, with multipliers for each and zone worked. Similarly, the CQ Wide DX , the largest such event with over 35,000 participants, occurs on the last full weekends of October (SSB) and November (CW), where global operators contact stations in as many CQ zones (15 total) and as possible; QSO points vary by distance (three for intercontinental, two for same but different zone, one for same zone), multiplied by zones and confirmed. Various modes, including CW, SSB, and digital, are employed to optimize contact rates during these events. DXing involves pursuing contacts with stations in rare or distant , often relying on ionospheric forecasts to predict optimal times and bands for signals to travel long distances via reflection. Operators monitor solar activity, such as numbers and geomagnetic indices, using tools like VOACAP models or real-time maps to forecast maximum usable frequencies (MUF) and signal-to-noise ratios for paths to entities like remote islands or polar regions. The ARRL DX Century Club (DXCC) recognizes this pursuit by issuing certificates to those confirming at least 100 current DXCC entities ( or territories) through verified QSOs on any amateur bands from 160 to 6 meters, excluding 60 meters; additional endorsements are available for specific bands, modes, or challenges like 1,000 band-points. Awards programs incentivize comprehensive operating achievements by requiring verified contacts across geographical or technical criteria, with electronic systems streamlining confirmations. The Worked All States (WAS) award, ARRL's most popular, is granted to operators worldwide who confirm QSOs with all 50 US states, plus endorsements for bands (e.g., 5-band WAS), modes, or power levels; confirmations can use physical QSL cards or electronic methods. For VHF/UHF operations, the VHF/UHF Century Club (VUCC) award honors confirmations of 100 or more Maidenhead grid squares, emphasizing grid chasing on bands above 50 MHz where line-of-sight and tropospheric propagation dominate. Verification often occurs via Logbook of the World (LoTW), an ARRL-sponsored free electronic QSL system where operators upload logs for automated matching and award crediting, or eQSL.cc, a similar platform offering authenticatable digital confirmations through licensed user authentication. Supporting these activities, DX cluster networks aggregate real-time "spots"—reports of active stations—from users worldwide via telnet-connected nodes, allowing operators to tune to rare DX signals quickly; popular systems include DX Summit and DXWatch, which filter spots by band, mode, and entity. Contest logs submitted in Cabrillo format often include optional "" comments, where participants share experiences on conditions, equipment, or challenges, providing insights published in official results to enhance community learning.

Experimental and Educational Uses

Amateur radio operators frequently engage in , the of custom equipment such as low-power QRP (typically under 5 watts) transceivers and antennas, to explore radio principles and innovate within non-commercial bounds permitted by FCC regulations. These projects, often documented in resources like ARRL's QRP articles, allow operators to build compact rigs for bands like 40 meters or 20 meters using readily available components, fostering technical experimentation without requiring commercial certification. Similarly, homebrew beacons—unattended transmitters sending identification and data—fall under 47 CFR § 97.203, enabling operators with or higher licenses to test signal conditions across amateur bands like 10 meters or 6 meters. Satellite operations represent a key experimental domain, with organizations like AMSAT developing projects such as the Fox-1 series to advance amateur space communications. The Fox-1A (AO-85), launched in 2015, provided an FM transponder for voice and linear modes, while Fox-1B (AO-91) incorporated effects experiments and VHF/UHF capabilities for global access. Operators contribute by decoding —data on satellite health, temperature, and —using open-source tools like FoxTelem software, which demodulates 1200 bps packets downlinked on 145.960 MHz, supporting ongoing mission analysis and educational outreach. In educational contexts, amateur radio integrates into STEM curricula through programs like the ARRL Teachers Institute on , which offers multi-day workshops for K-12 educators to learn , , and basics via hands-on building of circuits and antennas. These sessions, held at locations like ARRL headquarters, equip teachers with lesson plans aligning to national standards, emphasizing in physics and . Complementing this, school licensing initiatives, supported by ARRL's Youth Licensing Grant Program, waive the $35 FCC exam fee for students under 18, enabling classroom clubs to pursue licenses and operate school stations for projects like meteor scatter or digital modes. Recent experiments highlight amateur radio's role in emerging technologies, such as modulation for IoT applications in allocated bands. In 2025, the RSGB's High-Altitude Balloon Challenge utilized the 433 MHz band for a payload, allowing participants to track and relay low-power sensor data over long distances, demonstrating resilient mesh networks for without reliance. These tests, conducted under national band plans, underscore 's potential for off-grid data transmission while adhering to power limits like 10 mW EIRP in amateur allocations.

Communities and Organizations

Amateur Radio Clubs and Societies

Amateur radio clubs form the foundation of the , bringing together local operators for regular meetings, sessions, and on-air activities. These clubs often host weekly nets—scheduled on-air gatherings where members check in via voice or digital modes to exchange , practice operating skills, and foster camaraderie. For instance, many U.S. clubs participate in the ARRL's nationwide net directory, which lists hundreds of such events daily across HF, VHF, and UHF bands. Local clubs also organize field days, temporary outdoor operating events that simulate emergency conditions and promote portable radio setups, with the annual ARRL Field Day drawing nearly 32,000 participants from over 4,000 groups across in 2025. National societies serve as umbrella organizations that coordinate advocacy, education, and resources for amateur radio enthusiasts on a countrywide scale. In the United States, the (ARRL), founded in 1914, represents over 137,000 members and affiliates with local clubs to advance the hobby's interests before regulators and the public. Similarly, the Radio Society of Great Britain (RSGB) supports around 20,400 members through technical publications, exam administration, and spectrum advocacy, while the Deutscher Amateur-Radio-Club (DARC) in aids approximately 33,000 members with similar services tailored to European regulations. These societies collaborate internationally but focus primarily on domestic operator support, distinct from global regulatory bodies like the . Clubs and societies host major events such as hamfests—large conventions featuring vendor exhibits, forums, and equipment swaps—that strengthen community ties and drive innovation. The Dayton Hamvention, organized by the Dayton Amateur Radio Association, is the world's largest annual gathering, attracting 36,814 attendees in 2025 for demonstrations, awards ceremonies, and networking. Many clubs maintain networks, which are automated stations extending VHF/UHF communication range for local voice and data traffic; for example, ARRL-affiliated groups operate thousands of these systems across the U.S., enhancing emergency preparedness and everyday use. Membership in these organizations provides practical benefits, including access to QSL services for confirming international contacts—ARRL's bureau handles hundreds of thousands of cards annually—and coverage for club activities, such as events or operations, up to specified limits for affiliates. Post-2020, societies like the ARRL have emphasized diversity initiatives, launching programs to engage underrepresented groups, including scholarships, women-in-radio workshops, and to minority communities to broaden participation in the hobby.

International Regulatory Bodies

The (ITU), a specialized agency of the , plays a central role in coordinating global use through its Radiocommunication Sector (). The ITU's Radio Regulations, particularly Article 5, outline the international Table of Frequency Allocations, which designates specific frequency bands for the amateur radio service on a primary or secondary basis worldwide or by region. These allocations ensure that amateur radio operations do not interfere with critical services while providing dedicated spectrum for non-commercial experimentation and communication. World Radiocommunication Conferences (WRCs), convened by the ITU every three to four years, revise these regulations based on technological advancements and spectrum needs. For instance, WRC-23 in addressed amateur service allocations in bands such as 1240-1300 MHz, maintaining protections for amateur and amateur-satellite operations. Preparations for WRC-27, ongoing as of , involve study groups examining potential updates to spectrum sharing conditions, including reviews of high-frequency bands that could impact amateur radio. The (IARU), established in 1925, serves as the representative body for amateur radio at the international level, advocating for spectrum access during ITU proceedings. Organized into three regional unions aligned with ITU regions—Region 1 (, Africa, and the ), Region 2 (the ), and Region 3 ()—the IARU coordinates voluntary band plans to guide efficient spectrum use among amateurs. These plans subdivide allocated bands for modes like voice, digital data, and satellite operations, promoting harmony across borders without regulatory enforcement. At the national level, regulatory authorities implement ITU allocations and enforce compliance. In the United States, the (FCC) administers amateur radio licensing under Part 97 of its rules, monitors operations, and issues enforcement actions for violations such as unauthorized transmissions or interference. The United Kingdom's Office of Communications (Ofcom) issues amateur radio licenses, sets technical parameters, and handles enforcement, including investigations into interference complaints and license revocations for misuse. In France, the Autorité de Régulation des Communications Électroniques et des Postes (ARCEP) oversees frequency assignments for amateur radio, conducting public consultations to align national rules with ITU standards and ensuring non-interfering use. Reciprocity in licensing, often referenced in national regulations, allows qualified foreign operators to transmit temporarily under ITU-coordinated agreements. As of , preparations for WRC-27 include regional discussions on potential spectrum expansions, such as studies adjacent to existing VHF bands that could benefit amateur radio experiments.

Educational Resources and

Amateur radio relies on a variety of online platforms that offer accessible tools for self-study and skill-building. HamStudy.org provides free flashcards, practice tests, and detailed explanations drawn from current FCC question pools for , General, and Extra class exams, enabling users to prepare interactively on computers or mobile devices. Similarly, the (ARRL) maintains comprehensive online resources, including randomly generated practice exams and chapter-based review modules aligned with their manuals, which support structured learning for all levels. In-person and structured courses form a core of amateur radio , often delivered through local clubs and organizations. -level classes, which introduce foundational operating practices and regulations, are frequently hosted by amateur radio clubs nationwide, with ARRL's database facilitating searches for sessions in specific areas to connect newcomers with instructors. For more advanced learners, courses on topics like modeling delve into behavior, solar influences, and tools; ARRL's Learning Center offers video-based modules on principles, while software like ACE-HF provides practical modeling for HF forecasting used by enthusiasts and professionals alike. Many clubs complement these with hands-on sessions, fostering practical experience in antenna setup and signal analysis. Specialized certifications extend beyond initial licensing to build expertise in key applications. The ARRL's EC-001 course, Introduction to Emergency Communication, equips volunteers with skills for integrating amateur radio into , covering coordination protocols and message handling; completion yields a certificate recognized by groups. This self-guided or mentored program emphasizes real-world readiness without requiring prior advanced licensing. Outreach initiatives target underrepresented groups to broaden participation in amateur radio. Youth programs like Radio Scouting merge the hobby with Scouting activities, offering merit badge support, on-air events such as Jamboree on the Air, and club formations to engage young learners in radio fundamentals and global connections. For women, organizations such as the Young Ladies Radio League (YLRL) promote inclusion through scholarships for radio-related studies, mentorship networks, and awards programs that recognize achievements, addressing historical underrepresentation and building supportive communities. These efforts, often in partnership with clubs, highlight amateur radio's role in fostering diversity and lifelong technical interest.

References

  1. https://www.fcc.gov/wireless/bureau-divisions/mobility-division/amateur-radio-service
  2. https://www.iaru.org/amateur-radio/
  3. https://hamradioprepper.com/celebrating-100-years-world-amateur-radio-day-2025/
  4. https://www.arrl.org/fcc-license-counts
  5. http://www.arrl.org/what-is-ham-radio
  6. https://nationalmaglab.org/magnet-academy/history-of-electricity-magnetism/museum/marconi-radio-1897
  7. http://www.arrl.org/ham-radio-history
  8. https://firstamendment.mtsu.edu/article/radio-act-of-1912/
  9. http://www.arrl.org/about-arrl
  10. https://www.arrl.org/news/centennial-of-amateur-radio-blackout-for-world-war-i-occurs-on-april-6
  11. https://www.arrl.org/arrlletter?issue=2021-04-01
  12. https://www.arrl.org/ham-radio-history
  13. https://www.arrl.org/files/file/About%20ARRL/Ham_Radio_100_Years.pdf
  14. https://www.arrl.org/files/file/Technology/tis/info/pdf/0210028.pdf
  15. https://www.arrl.org/files/file/Technology/Bilsing.pdf
  16. https://www.arrl.org/files/file/Technology/tis/info/pdf/0210033.pdf
  17. https://www.arrl.org/news/remotely-administered-amateur-exam-systems-showing-promise
  18. http://www.arrl.org/fcc-license-counts
  19. https://www.arrl.org/news/wrc-23-reaches-acceptable-conclusion-on-23-centimeter-issue
  20. https://old.rigexpert.com/news/why-are-radioamateurs-called-hams/
  21. https://thereader.mitpress.mit.edu/the-rich-history-of-ham-radio-culture/
  22. https://www.fcc.gov/wireless/bureau-divisions/mobility-division/amateur-radio-service/examinations
  23. https://www.arrl.org/getting-licensed
  24. https://hamstudy.org/
  25. https://www.coastsidecert.com/radio/ham
  26. https://www.cept.org/ecc/topics/radio-amateurs/
  27. https://www.fcc.gov/wireless/support/knowledge-base/common-amateur-filing-tasks/common-amateur-filing-task-renewing
  28. https://www.midlandeurope.com/en_150/news/how-to-become-a-radio-amateur-license-authorizations-regulations
  29. https://www.fcc.gov/wireless/bureau-divisions/mobility-division/amateur-radio-service/amateur-call-sign-systems
  30. http://www.w2zq.com/wp-content/uploads/2020/05/Finding-your-ham-roots.pdf
  31. https://www.arrl.org/vanity-call-signs
  32. https://www.itu.int/en/ITU-R/terrestrial/fmd/Pages/call_sign_series.aspx
  33. https://www.law.cornell.edu/cfr/text/47/97.119
  34. https://www.fcc.gov/wireless/bureau-divisions/mobility-division/amateur-radio-service/special-event-call-signs
  35. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-97/subpart-B/section-97.301
  36. https://www.federalregister.gov/documents/2023/12/07/2023-26770/amateur-radio-service-rules-to-permit-greater-flexibility-in-data-communications
  37. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-97/subpart-D/section-97.313
  38. https://life.itu.int/radioclub/rr/art25.pdf
  39. https://docdb.cept.org/download/2ae38a89-e58a/TR6101.pdf
  40. https://www.oas.org/en/sla/dil/inter_american_treaties_A-62_international_radio_permit.asp
  41. https://www.arrl.org/iarp
  42. https://www.jarl.org/English/3_Application/A-3.htm
  43. https://www.arrl.org/frequency-allocations
  44. https://www.iaru-r1.org/wp-content/uploads/2019/08/hf_r1_bandplan.pdf
  45. https://www.iaru.org/wp-content/uploads/2020/01/R2-Band-Plan-2016.pdf
  46. https://www.arrl.org/files/file/On%20the%20Air/Choosing.pdf
  47. https://www.arrl.org/files/file/Technology/tis/info/pdf/9106023.pdf
  48. https://www.arrl.org/verticals
  49. https://www.arrl.org/files/file/antplnr.pdf
  50. https://www.itu.int/en/ITU-R/terrestrial/workshops/wrs12/Miscellaneous/Appendix1.pdf
  51. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-97/subpart-D/section-97.307
  52. https://www.arrl.org/part-97-text
  53. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet65/oet65.pdf
  54. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet65/oet65b.pdf
  55. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-1/subpart-I/section-1.1310
  56. https://www.arrl.org/grounding
  57. https://www.osha.gov/sites/default/files/publications/OSHA3877.pdf
  58. https://www.osha.gov/communication-towers
  59. https://www.arrl.org/files/file/DXCC/Eth-operating-EN-ARRL-CORR-JAN-2011.pdf
  60. https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-15
  61. https://www.arrl.org/part-15-radio-frequency-devices
  62. https://www.hamradioschool.com/post/ssb-transmit-power-audio-required
  63. http://www.arrl.org/60m-channel-allocation
  64. https://www.dxengineering.com/parts/arr-8826
  65. https://hamradioacademy.com/the-invention-of-single-sideband-modulation/
  66. https://www.hamradioschool.com/post/understanding-single-sideband-ssb
  67. https://www.kb6nu.com/2015-general-class-study-guide-section-g8a-carriers-and-modulation-am-fm-single-and-double-sideband-modulation-envelope-overmodulation/
  68. http://forums.radioreference.com/threads/modes-for-ham-bands-question-please.449267/
  69. https://newhams.info/category/am-amplitude-modulation/
  70. https://hambook.org/tech2022/pt2/chpt7/section-71-fm-operation/
  71. https://utahvhfs.org/bandplan1.html
  72. http://www.arrl.org/band-plan-1
  73. https://qradiolink.org/open-source-DMR-transceiver-implementation.html
  74. https://www.cnx-software.com/2017/10/24/ambe2-vocoder-promises-high-voice-quality-at-low-2-0-to-9-6-kbps-data-rates/
  75. https://utahvhfs.org/dstar_codec_behavior.html
  76. https://files.tapr.org/meetings/DCC_2019/2019-2-SV9OAN.pdf
  77. https://systemfusion.yaesu.com/what-is-system-fusion/
  78. https://freedv.org/
  79. https://www.dvsinc.com/
  80. https://www.sstv-handbook.com/download/sstv_04.pdf
  81. http://arrl.org/files/file/Technology/pdf/an-55a-atv-handbook-1.pdf
  82. https://www.sstv-handbook.com/download/sstv_11.pdf
  83. https://www.amsat.org/image-transmitting-satellites/
  84. https://www.arrl.org/cw-mode
  85. https://www.arrl.org/digital-data-modes
  86. https://www.arrl.org/psk31-an-introduction-to-narrowband-digital
  87. http://www.arrl.org/weak-signal-modes
  88. https://wsjt.sourceforge.io/
  89. https://www.aprs.org/
  90. https://www.weather.gov/skywarn/
  91. https://winlink.org/
  92. https://www.usraces.org/
  93. https://www.arrl.org/ares-races-faq
  94. https://winlink.org/WinlinkExpress
  95. https://www.arrl.org/news/amateur-radio-volunteers-serving-during-texas-floods
  96. http://www.arrl.org/arrl-dx
  97. https://cqww.com/
  98. https://cqww.com/rules.htm
  99. http://www.arrl.org/contests
  100. https://www.voacap.com/hf/
  101. https://dx.qsl.net/propagation/
  102. http://www.arrl.org/dxcc
  103. http://www.arrl.org/dxcc-rules
  104. http://www.arrl.org/was
  105. https://www.arrl.org/files/file/Awards/WAS_Rules_December_2021.pdf
  106. http://www.arrl.org/AWARDS
  107. https://lotw.arrl.org/lotwuser/default
  108. http://www.arrl.org/logbook-of-the-world
  109. https://www.dxcluster.info/
  110. http://www.dxsummit.fi/
  111. https://cqww.com/soapbox.htm?mode=ph
  112. https://n1mmwp.hamdocs.com/setup/contest-setup/
  113. http://www.arrl.org/qrp-projects
  114. https://www.law.cornell.edu/cfr/text/47/97.203
  115. https://www.amsat.org/two-way-satellites/ao-91/
  116. https://www.amsat.org/foxtelem-software-for-windows-mac-linux/
  117. http://www.arrl.org/teachers-institute-on-wireless-technology
  118. https://www.arrl.org/youth-licensing-grant-program
  119. https://rsgb.org/main/coding-and-amateur-radio/lora-balloon-project/
  120. https://contests.arrl.org/ContestResults/2025/Field-Day-2025-FinalQSTResults.pdf
  121. https://rsgb.org/main/blog/news/rsgb-notices/2025/02/20/rsgb-board-january-2025-key-messages/
  122. https://www.darc.de/mitgliedschaft/mitglied-werden/
  123. https://www.daytondailynews.com/local/hamvention-2025-breaks-attendance-record-draws-36000-to-xenia-organizers-say/B2MDDARQXVBFBEXGPXONRKYUCE/
  124. https://www.arrl.org/affiliated-club-benefits
  125. https://www.itu.int/pub/R-REG-RR
  126. https://life.itu.int/radioclub/rr/art05.htm
  127. https://www.itu.int/en/ITU-R/study-groups/rcpm/Pages/wrc-27-studies.aspx
  128. https://www.iaru.org/about-us/organisation-and-history/history-of-iaru/
  129. https://www.iaru.org/about-us/organisation-and-history/
  130. https://www.iaru.org/on-the-air/band-plans/
  131. https://www.ofcom.org.uk/spectrum/radio-equipment/amateur-radio-info
  132. https://en.arcep.fr/news/press-releases/view/n/arcep-launches-a-public-consultation-on-the-use-of-frequencies-by-amateur-radio-service-stations-and-by-the-amateur-satellite-service.html
  133. https://www.iaru-r2.org/en/wrc-23-ra-23-and-cpm27-1-outcomes/
  134. https://www.arrl.org/exam-practice
  135. https://www.arrl.org/find-an-amateur-radio-license-class
  136. https://learn.arrl.org/courses/35902/video_presentations/212623
  137. https://hfradio.org/ace-hf/
  138. https://www.arrl.org/ceps/ec-001-321
  139. https://www.arrl.org/radio-scouting
Add your contribution
Related Hubs
Contribute something
User Avatar
No comments yet.