Citizens' Band radio (CB) is, in the
United States, a system of short distance radio communication
between individuals on a selection of 40 channels within the
single 27 MHz (11 meter) band. The CB radio service should not
be confused with FRS, GMRS, MURS or amateur radio. Similar
personal radio services exist in other countries, with varying
requirements for licensing and differing technical standards. In
many countries, CB does not require a license and unlike amateur
radio, it may be used for commercial communication.
The Citizens' Band radio service in the United States is one
of several personal radio services regulated by the FCC. These
services began in 1945 to permit citizens a short-distance radio
band for personal communication (e.g. radio controlled models,
family communications, individual businesses). Originally CB was
located in the 460-470 MHz UHF band. There were two classes of
CB, A and B. Class B radios had simpler technical requirements
but were limited to a smaller range of frequencies.
At the time, the technology wasn't advanced enough to make a
UHF radio practical for the average consumer. So, in 1958 the
Class D CB service was opened at 27 MHz and this is what is
popularly known as CB. Previously, this was a government band
(primary allocation to US Forest service, military, etc.) with a
secondary allocation for the amateur radio service.
Most of the 460-470 MHz band was reassigned for business and
public safety uses, but Class A CB is the ancestor of the
present General Mobile Radio Service GMRS. Class B, in the same
vein, is a more distant ancestor of the Family Radio Service.
The Multi-Use Radio Service is another two-way radio service, in
the VHF high band. An unsuccessful petition was made in 1973 to
create a Class E CB service at 220 MHz, but this was opposed by
amateur radio organizations and others. There are several other
classes of personal radio services for specialized purposes such
as remote control devices.
While parts of this article are specific to the United
States, several countries have similar radio services. While
they may be known by other names, they often use similar
frequencies (26 to 28 MHz), and have similar uses. Licenses may
or may not be required but eligibility is generally simple.
On the other hand, some foreign personal radio services, such
as the European PMR446 and the Australian UHF CB are more
similar to the American FRS or GMRS services than the CB
service, and so are not covered in this article.
the 1960s the service was popular for small trade businesses
(e.g. electricians, plumbers, carpenters) and transportation
services (e.g. taxi and trucking firms). "10 codes" originally
used in the public service (e.g. police, fire, ambulance) and
land mobile service were used for short acknowledgements. With
the advancement of solid state technology (transistors replacing
tubes) in the 1970s, the weight, size and cost of the radios
decreased. US truckers were at the head of the boom. Many CB
clubs were formed and a special CB slang language evolved. The
prominent use of CB radios in mid- and late-1970s films (see
list below), television shows such as The Dukes of Hazzard
(debuted 1979), and in popular novelty songs such as C.W.
McCall's "Convoy" (1976) helped to establish the radios as a
nationwide craze in America from the mid-1970s to the early
Originally CB did require a license and the use of a call
sign but when the CB craze was at its peak, many people ignored
this requirement and used made up nicknames or "handles". The
use of handles instead of call signs is related to the common
practice of using the radios to warn other drivers of speed
traps during the time when the United States dropped the
national speed limit to 55 mph (90 km/h) beginning in 1974 in
response to the 1973 hike in oil prices. The FCC recommended the
use of ten-codes and these were used, often in a shortened form,
but also many slang terms were developed.
The low cost and simple operation of CB equipment gave access
to a communications medium that was previously only available to
specialists. The "boom" in CB usage in the 1970s and in Britain
in the early 1980s bears several similarities to the advent of
the Internet in the 1990s. The many restrictions on the
authorized use of CB radio led to widespread disregard of the
regulations, most notably in antenna height, distance
restriction for communications, licensing and the use of call
signs, and allowable transmitter power. Eventually the license
requirement was dropped entirely.
Originally, there were only 23 CB channels in the U.S.;
40-channel radios did not come along until 1977. In the 1960s,
channels 1-8 and 15-22 were reserved for "intrastation"
communications among units under the same license, while the
other channels (9-14 and 23) could be used for "interstation"
calls to other licenses.
In the early 1970s, channel 9 became reserved for emergency
use. Channel 10 was used for highway communications, and channel
11 was used as a general calling channel. Later, channel 19
became the preferred highway channel in most areas, as it did
not have the adjacent-channel interference problems with channel
Until the late 1970s when synthesized radios appeared, CB
radios were controlled by plug-in quartz crystals. Almost all
were AM only, though there were a few single sideband sets in
the early days.
In 1973, various groups petitioned the FCC for an allocation
of frequencies near 220 MHz for a new "Class E" Citizen's Band
service. This was opposed by amateur radio organizations as well
as other government agencies and commercial users who desired
this allocation for their own usage. While the "Class E"
initiative was not successful early on, the Reagan
Administration’s sponsored some of these requirements for the
development of the Family Radio Service, General Mobile Radio
Service and Multi-Use Radio Service. These services fulfilled a
majority of the requirements (e.g. eliminate some of the
interference and skip that existed on the shortwave frequencies)
proposed by the petitioners in 1973. Today these radios are
quiet, affordable and readily accessible.
Throughout the 1970s and early 1980s a phenomenon was
developing over the CB radio. Similar to the Internet chat rooms
a quarter century later, the CB allowed people to get to know
one another in a quasi-anonymous manner. Many movies and stories
about CBers and the culture on-the-air developed.
In Britain, some people were using CB radio illegally in the
1970s, a craze which suddenly peaked in 1980, leading to
legalisation on 2 November 1981. However, in the summer of 1981
the British government were still saying that CB would never be
legalised on 27 MHz. The government wanted a uhf frequency
around 860 MHz named 'Open Channel' instead. Eventually 40
channels at 27 MHz, plus 20 channels on 934 MHz were legalised.
Both allocations used frequencies unique to the UK; the 934 MHz
allocation was later withdrawn in 1998. CB's inventor Al Gross
made the first legal British CB call, from Trafalgar Square,
London. CB was so popular in the UK by 1982 that it was featured
in a Coronation Street storyline - fame indeed!
In more recent years CB has lost much of its original appeal
due to the advancement of technologies and changing values. Some
of this rapid development includes: mobile phones, the Internet,
and Family Radio Service. The changing radio wave propagation
for long-distance communications, due to the 11 year Sunspot
cycle is always a factor for these frequencies.
In Australia, Citizens Band radio had its beginnings in the
1960s when small numbers of American branded 1-watt
“walkie-talkies” started to become available from a handful of
outlets. In those days, households were required to hold
licenses to operate a TV set, but no such licenses were
available to the general public for the use of 27 MHz band
By the early 1970s CB radio began to gather pace as bigger
and better transceivers appeared on the market. Designed for
in-car installation, these units began to be sold from well
recognized and specialist retail outlets. As the popularity of
CB radio grew in cities such as Melbourne and Sydney, the 27.240
MHz calling frequency became congested at times and users were
forced to find other less popular channels to have conversations
and to organize an ‘eyeball’ (meeting).
By 1974, the transceiver of choice was the American designed
Midland 23-channel, 5-watt transceiver with upper and lower
single sideband (SSB). The Lafayette and Tandy/Realistic brands
were also popular. These higher-powered units, when coupled with
high-gain antennas and linear amplifiers, often sent out
spurious RF emissions which attracted unwanted attentions. The
Federal Postmaster-General (PMG Department) was solely
responsible for Australian radio spectrum management and radio
licensing since the end of World War 2. For the 27 MHz/11-metre
band however, the only persons who could legally operate
transceivers were licensed radio amateurs who had passed a
technical examination, and most had nothing but contempt for the
persons operating illegally on the 11-metre band. A small team
of radio inspectors began covert surveillance of the “radio
pirates” (as they were known) using the 27 MHz band in major
Australian cities. They built a database of regular, or nuisance
users, particularly those using the higher-powered transceivers,
or those boasting of the use of home made linear amplifiers.
Radio inspectors, most of who were licensed radio amateurs, had
extraordinary powers in those days and it was not uncommon to
hear of or meet CB operators who had been on the receiving end
of a visit from overly zealous inspectors with a search warrant.
Such visits often resulted in the forced entry of houses and
rooms, a confiscation of all equipment, (illegal or otherwise),
and a summons to appear in court for various breaches of the
‘wireless telegraphy’ laws and regulations in force at the time.
Running battles and cat and mouse-like games developed as radio
pirates tried to keep one step ahead of inspectors. Some pirates
developed elaborate hiding places in their homes or cars for
their equipment. Various State polices forces were mainly
ignorant of the illegality of the use of CB radios since it was
a Federal jurisdiction issue. CB radios or giveaway antennas
were however viewed suspiciously by some individual police who
saw them as a means to warn other drivers of speed traps
established by the police. Unsure of the legal position, they
usually took no further action if they found a CB radio fitted
in a car.
By the mid-seventies, a number of CB clubs had developed
around Australia including the KT (Kangaroo Territory) Club, the
GL Club and Delta Whisky Club, all of whom assigned call-sign
numbers to radio pirates interested in ‘joining’ the club. The
exchange of QSL cards become popular (like with the licensed
radio amateurs), and if atmospheric and sunspot activity was
suitable, long-distance ‘skip’ communications could be achieved
between pirates thousands of kilometres apart. As the popularity
of CB continued to grow, pressure began to be applied to the
Federal Government to permit the legal use of the 27 MHz band
The GL Club in the Gippsland region in the State of Victoria
was particularly active with representations being made to
locally based Federal politicians. In February 1975 an informal
but widely CB-advertised convention was held in a hall on the
outskirts of the town of Morwell, and a newly formed lobby group
known as the Australian Citizens Radio Movement began life. Its
primary aim was to get CB radio legalized.
On 1 July 1977, after more than two years of relentless
pressure from public lobby groups, interstate truck drivers,
rural fire brigades and volunteer emergency service units, the
Federal Government finally legalized CB radio on 27 MHz with an
initial allocation of 18 channels. Not surprisingly, the radio
inspectors who had so zealously attempted to protect the airways
prior to this time imposed industrial bans because they opposed
the new laws. Hence the initial flood of license applications
were slow in being processed. In 1980 a total of 40 channels was
approved for 27 MHz band and it was aligned with the 40 channels
used in the USA. From the outset, the Government attempted to
regulate CB radio with license fees and call-signs etc, but some
years later abandoned this approach.
After peaking in the 1970s and early 1980s, the use of 27 MHz
CB in Australia has fallen dramatically in the last decade. The
later introduction of UHF CB Radio and the proliferation of
cheap, compact handheld and portable transceivers have been a
part of the reason. But other emerging technologies such as
e-mail, IRC chat, mobile phones/SMS, and the Internet have
played a role by providing people with many choices of
Over the years there have been repeated attempts by the
Federal Department of Communications to close down the 27 MHz
band. To date, these attempts have failed in the face of
CB Radio today
CB is still a popular hobby in many countries though its
utility as a method of communication among the general public
has diminished, due to developments such as mobile phones and
Internet chat rooms and IM. CB radio is still a near-universal
method of communication among semi truck drivers in America and
also remains very popular in rural areas with farmers and
hunters, plus sometimes even acting as a sort of "party line"
phone system in deep-rural areas too far in the boonies to have
Commercial drivers use CB to communicate to other truck
drivers directions, traffic problems, and other things of
importance. Channel 19 is the most commonly used for this
purpose, to the point that some radios even have a dedicated
button to bring up channel 19. In some areas of the U.S.,
different channels are customarily used on highways running
North-South versus East-West, and sometimes even for specific
roads. Other channels regionally used for this purpose include
10, 17, and 21.
Legitimate, short-range use of CB radio is sometimes made
difficult by uncooperative users or illegal high-power
transmitters, which are capable of being heard hundreds of miles
away. In the United States, the vast number of users and the low
financing of the regulatory body mean that the regulations are
only actively enforced against the most severe interfering
stations, which makes legitimate operations on the Citizen's
band unreliable. Other services, such as Multi-Use Radio Service
in the VHF band or FRS and GMRS in the UHF band, exist now to
provide the reliable short-range communication service
originally envisioned for the Citizen's Band.
The maximum legal CB power output level is four watts for AM
and 12 watts (peak envelope power or "PEP") for single side
band, as measured at the antenna connection on the back of the
radio. More powerful external linear amplifiers are commonly and
Citizens' Band radios in the United States use frequencies
near 27 MHz. During periods of peak sunspot activity, even
low-powered transmitters can sometimes be heard for hundreds or
even thousands of miles. This "skip" activity, in which signals
which bounce off the ionosphere, contributes to interference on
CB frequencies. Working "skip" is illegal in the United States,
since it contradicts the short-range intended use of the
service, though the regulation is widely ignored.
Many radio hobbyists operate illegitimately in the so-called
"free band", (which is often referred to as 11 meters, similar
to how hams refer to their bands by the approximate wavelengths)
using either Citizens' Band equipment that has been modified for
extended frequency range and higher power, or else amateur radio
equipment operated outside the assigned amateur 10 meter band.
Such operations are not part of the legally authorized Citizen's
Band service and should not be called "CB". Out-of-band
operations may interfere with licensed, public safety,
commercial, or military users of these frequencies. Illegal
transmitters may not meet good engineering practice for harmonic
distortion or "splatter", and resulting interference to
radio spectrum users will often attract the attention of
In its heyday in the 1970s, you were likely to find CB
Channel 9 monitored by parties who could relay messages to the
authorities, or even directly monitored by the authorities
themselves. However, with the popularity of cellular phones,
support for Channel 9 as an emergency channel has largely
vanished. If you are in dire need of help on the road and your
only communications tool is a CB radio, you are much more likely
to find help on Channel 19.
CB Usage in the United States
In the United States Citizens' Band (CB) radio service is
intended to be a private two-way voice communication service for
use in personal and business activities of the general public.
Its communications range is from one to five miles. The
Citizens' Band radio services are described in part 95 of the
Federal Communications Commission's (FCC) and is defined as a
personal radio service.
There are no age, citizenship or license requirements to
operate a CB radio in the United States. You may operate on any
of the authorized 40 CB channels, however channel 9 is used only
for emergency communications or for traveler assistance. Usage
of all channels is on a shared basis. Foreign governments and
their representatives are not eligible to operate a citizens'
band radio station within the United States.
You may operate your station anywhere within the United
States, its territories and possessions. You may also operate
your US station anywhere in the world except within the
territorial limits of areas where radio services are regulated
by another agency; such as the United States Department of
Defense or of any foreign government.
You must use an FCC certified transmitter. No modifications
are allowed to your equipment. Equipment output power is limited
to 4 watts for AM transmitters and 12 watts PEP (peak envelope
power) for single sideband (SSB) transmitters. There are no
restrictions on size or type of antennas, except the antenna
must not be more than 20 feet above the highest point of the
structure it is mounted to and may not be more than 60 feet
above the ground.
To simplify selection of an operating frequency, the
Citizens' Band radio spectrum is divided into 40 numbered radio
frequency channels from 26.965 to 27.405 MHz, with channels
generally spaced 10 kHz apart. Channel numbers are not strictly
sequential with frequency; there are gaps for frequencies used
by radio-controlled devices.
Furthermore, there is a gap between Channel 22 and Channel 23
(which was later filled by Channels 24 and 25) for historical
reasons. Before CB was in existence, there was an Amateur
11-meter band from 26.96 to 27.23 MHz, and a frequency for
radio-controlled devices at 27.255 MHz. The 11-meter band became
CB Channels 1 to 22, and the radio control frequency was shared
with Channel 23.
The frequencies for the 40 North American/CEPT channels are
Channel 01 26.965 MHz
Channel 02 26.975 MHz
Channel 03 26.985 MHz
Channel 04 27.005 MHz
Channel 05 27.015 MHz
Channel 06 27.025 MHz
Channel 07 27.035 MHz
Channel 08 27.055 MHz
Channel 09 27.065 MHz (emergency channel)
Channel 10 27.075 MHz
Channel 11 27.085 MHz
Channel 12 27.105 MHz
Channel 13 27.115 MHz
Channel 14 27.125 MHz
Channel 15 27.135 MHz
Channel 16 27.155 MHz
Channel 17 27.165 MHz
Channel 18 27.175 MHz
Channel 19 27.185 MHz (unofficial highway channel)
Channel 20 27.205 MHz
Channel 21 27.215 MHz
Channel 22 27.225 MHz
Channel 23 27.255 MHz (Note frequencies not in ascending order}
Channel 24 27.235 MHz
Channel 25 27.245 MHz
Channel 26 27.265 MHz
Channel 27 27.275 MHz
Channel 28 27.285 MHz
Channel 29 27.295 MHz
Channel 30 27.305 MHz
Channel 31 27.315 MHz
Channel 32 27.325 MHz
Channel 33 27.335 MHz
Channel 34 27.345 MHz
Channel 35 27.355 MHz
Channel 36 27.365 MHz
Channel 37 27.375 MHz
Channel 38 27.385 MHz (lsb, national calling frequency)
Channel 39 27.395 MHz
Channel 40 27.405 MHz
The frequency allocation list is supplied by the FCC (Federal
Communications Commission) from Part 95 - Subpart D - Rules for
CB Service Citizens Band (CB) Radio Service.
Remote control channels
There is also a Class C Citizens Band service for
radio-controlled devices; no voice transmissions are permitted.
It has six channels in the 27 MHz band. Five are unused 10 kHz
assignments between channels 3/4, 7/8, 11/12, 15/16 and 19/20,
and the sixth is shared with Channel 23. Radio control
transmitters may use up to 4 watts on the first five channels
and 25 watts on the last, 27.255 MHz. Some in-house paging
systems, and car alarms with a paging feature, also use these
frequencies, especially 27.255 where more power is permitted.
The 27 MHz Class C channels are not officially numbered. R/C
enthusiasts usually designate them by color, and fly
different-colored flags from the antenna to show who is on which
channel. On the other hand, some CB operators illegally use
these channels for voice communications, and usually refer to
them by the closest voice channel below them, ex. "3A", "7A",
Because of interference from CB radios, legal or otherwise,
the noise level, and the limited number of channels, most
"serious" hobby radio-controlled models operate on other bands.
Interference is especially important for model aircraft where it
presents a safety issue.
The Class C service has 50 channels just for model aircraft
in the 72.0-73.0 MHz range, and 30 more channels for surface
models such as cars and boats in the 75.4-76.0 MHz range. 0.75
watts is allowed on these numbered channels. Licensed amateur
radio operators also have their own R/C channels around 50 and
Part 15 and ISM Devices
Most toy R/C cars and most wireless keyboards and mice
operate on the 27 MHz R/C channels, especially 27.145 MHz. But
most of these devices run far less than 4 watts and do not
operate under the Class C CB service. Instead, they operate
under the FCC's Part 15 rules, which allow a wide variety of low
powered devices to use the frequencies from 26.96 to 27.28 MHz,
which covers CB Channels 1 through 27.
Some other of these toys operate on the 49 MHz Part 15
channels, and often a pair of cars will be sold with one on
27.145 and one on 49.860 to avoid interference. This allows less
selective, and therefore less expensive, receivers to be used
than if they were using channels in the same band.
In the days when CB required a license, some low-powered or
toy walkie-talkies were exempt because they operated within Part
15. More recently in the 1990's, low-powered handhelds using FM
voice on the radio-control channels were also sold to operate
legally under Part 15.
Broadband over Power Lines (BPL) technology uses a wide range of
HF frequencies to transmit data, including the CB frequencies.
There is some potential for interference, as power lines were
never specifically designed to shield radio frequencies. RF
leakage from BPL is regulated under Part 15.
Another class of devices operating in the 27 MHz band are ISM
( Industial, Scientific and Medical ) devices regulated by the
FCC's Part 18 rules. Induction welding of plastics, and some
types of diathermy machines commonly operate in this range.
These devices are centered around 27.12 MHz with a tolerance of
±163 kHz, that is, 26.957 to 27.283 MHz.
Although CB radio was only intended to be a short range
communications service, the frequencies on which it operates
have some very interesting propagation characteristics. All
frequencies in the HF spectrum (3–30 MHz) are able to be
refracted by the existence of highly charged particles in the
ionosphere. This bouncing of a signal off the ionosphere is
called skywave propagation or "shooting skip". With the ability
to shoot skip, CBers have been able to communicate thousands of
miles, sometimes around the world. The ability of the ionosphere
to refract signals back to work is caused by the sun and the
amount of ionization possible is related to the 11-year sunspot
cycle. In times of high sunspot activity the band can remain
"open" to much of the world for long periods of time. In years
of low sunspot activity it may not be possible to shoot skip at
It is recorded that, before CB radio arose, the Afrika Korps
in North Africa in WWII used 27 MHz for battlefield
communications, thinking that it could only be heard locally;
but skip was strong at the time, and the messages were routinely
monitored in the United Kingdom.
Finally, it should be noted that under Part 95, Subpart D of
the FCC rules it is illegal to engage in, or attempt to engage
in communications with any station more than 250 kilometers
(155.3 miles) from your location, thereby making it practically
impossible for CB operators who wish to shoot skip to remain in
compliance with FCC regulations. The intent behind this
restriction is typically regarded as an effort to keep CB as an
inherently local service.
Skywave is the propagation of radio waves bent (refracted)
back to the Earth's surface by the ionosphere. As a result of
skywave propagation, a nighttime broadcast signal from a distant
AM broadcasting or shortwave radio station (or rarely, a TV
station) can sometimes be heard as clearly as local stations.
Most long-distance HF radio communication (between 3 and 30 MHz)
is a result of skywave propagation. For decades Amateur radio
operators, limited to lower transmit power than commercial
radio, have taken advantage of skywave for distance or DX
Role of the ionosphere
The ionosphere is a region of the upper atmosphere, where
neutral air is ionized by solar photons and cosmic rays. When
radio waves reach the ionosphere at a shallow angle, they are
partly reflected by the surface. The ionosphere can also be
similar to a prism refracting light; different frequencies are
"bent" by different amounts.
Much as the surface of the ocean interacts with the wind, the
condition of the ionosphere is constantly changing due to
interaction with incoming radiation. When signals have "bounced"
off this irregular surface, they may fade in and out and have
the "phasing", "flanging" or "fluttery" character familiar to
listeners of shortwave music broadcasts.
Depending on the transmitting antenna, the signals may reach the
ionosphere at a steep angle (vertical incidence) and be
reflected almost straight down. Alternately the antenna may
"aim" the signal at the horizon; the signal reaches the
ionosphere at a shallow angle and returns to earth at a great
Under some conditions, the Earth's surface (ground or water) may
reflect the incoming wave back toward the ionosphere again. As a
result, like a rock "skipping" across water, the wave may
actually "bounce" or "skip" between the earth and ionosphere
several times. This phenomenon is known as "skip" or multihop
propagation. Signals of only a few watts can sometimes be
received thousands of miles away as a result.
Signals with frequencies above about 30 MHz (VHF and UHF for
example) are progressively not returned to the Earth's surface,
because they penetrate the ionosphere. (This includes most
communications with spacecraft and satellites.) Exceptions
include rare occasions of E-skip, when FM and TV signals are
reflected. Skywave may be disrupted during geomagnetic storms.
Low to mid frequencies below approximately 10 MHz (longer than
30 meters), including broadcasts in the mediumwave and shortwave
bands (and to some extent longwave), travel most efficiently by
skywave at night. Frequencies above 10 MHz (shorter than 30
meters) travel better during the day. Frequencies lower than 3
kHz have a wavelength longer than the distance between the Earth
and the ionosphere. The Maximum usable frequency for skywave
propagation is strongly influenced by sunspot number.
Because the lower-altitude layers (the E-layer in particular) of
the ionosphere largely disappear at night, the refractive layer
of the ionosphere is much higher above the surface at night.
This leads to an increase in the "skip" or "hop" distance of the
skywave at night.
Freebanding and Export Radios
Operation on frequencies above ("uppers") or below ("lowers")
the established citizens band is referred to as "freebanding" or
"outbanding". Many perceive these frequencies just below the CB
band, or between the CB band and the amateur radio 10-meter band
to be quiet and under-utilized.
This is done with modified CB equipment, modified 10-meter
ham radios, foreign CB radios that may offer different channels,
or with radios which are purportedly sold for export.
Unlike modified amateur radios which are frequency-agile,
export CB's are channelized. Frequency selection on these
"export radios", however, resembles that of modified American
CB's more than any foreign frequency plan. They typically have a
knob and display that reads up to channel 40, but include an
extra "band" selector that shifts all 40 channels above or below
the band, plus a "+10 kHz" button to reach the model control 'A'
channels. These radios may have 6 or even 12 bands, establishing
a set of quasi-CB channels on all sorts of unauthorized
frequencies. The bands are typically lettered 'A' through 'F',
with the normal CB band as 'D'.
For example, a freebander with an export radio who wants to
use 27.635 MHz would choose Channel 19 ( 27.185 ) and then shift
the radio up one band ( + 0.450 ). The operator may have to do
quite a bit of arithmetic to know which frequency he is actually
operating on, though more expensive radios include a frequency
Even well-meaning ( but illegal ) operations can end up on
frequencies which are very much in use. For instance, Channel
19, 2 bands up, becomes 28.085 MHz, which is in a Morse
code-only part of the 10-meter ham band. Licensed amateurs
typically regard this activity as an intrusion, and have been
known to record, locate, and report such transmissions.
Freeband operators have been known to use modified amateur
radios that are capable of transmitting on the 11 meter CB band
after modification. In newer amateur radios this modification is
usually as simple as removing a single part, while in older
amateur radios it is often more difficult. Some examples of
amateur radios that popularly used on "freeband" are the Kenwood
440, Kenwood 520, and the Yaesu FT-101. However, these are
classic examples and today one can hear many different types of
amateur radios on 11 meter freeband. It is illegal in the United
States to transmit on the 11 meter band with an amateur radio
under normal, non-life threatening instances.
Adjacent Radio Services
The Business Radio Service has several channels just above
the Citizen's Band, at 27.430, 27.450, 27.470, 27.490, 27.510,
and 27.530 MHz.
The federal government has the frequencies from 27.540 up to
28.000. Many civilian agencies use, or used to use, the
frequencies 27.575 and 27.585 for low-power use.
The 10 meter ham band runs from 28.000 to 29.700 MHz.
Below the Citizen's Band, the U.S. military has the frequencies
from 26.480 to 26.960.
The Civil Air Patrol has 26.620, though it now uses mostly VHF
frequencies. Years ago, CAP volunteers with crystal-controlled
CBs would put this frequency in their radios. Now, this
frequency is all but abandoned as VHF radios are now easier to
come by than crystal-controlled CBs.
Regulation and Enforcement
Actions against violations of FCC regulations have been
minimal in the past. This has often been cited as the reason for
many of the problems that have plagued the Citizens' band radio
service in the past.
In recent years, the FCC has had a renewed interest in taking
enforcement actions against freebanding, the sale and use of
illegally modified radios and linear amplifiers. Usually, the
FCC will issue a request for information explaining actions
found to be in violation of the commissions rules and
regulations. Responding in a timely manner to such a request
usually results in a "quick and painless" resolution which in
most cases does not result in a fine, but merely a cease and
desist order. Failure to respond to the commission's letters of
inquiry will commonly result in the issuing of a $10,000 fine
and in rem seizure of the equipment used, and suspension
of licenses in other FCC regulated services.
Today's actions of illegal CBer's are usually not cared about
by the FCC. They will only go after people who disrupt important
radiocommunications, or are reported by people who are having
trouble with neighbors who have over-powered CB's. It usually
interferes with broadcast television.
Many actions have been taken in recent years against the
so-called freebanders operating illegally between 26 and 30 MHz.
This segment includes military, government allocations (26 MHz -
28 MHz) not assigned to the Citizens Band service as well as the
Amateur radio 10-meter band (28 - 30 MHz). Actions have also
been taken against retailers in the United States for selling
linear amplifiers and non-type approved equipment in violation
of the commission's rules.
CB Usage Worldwide
Similar radio services exist in other countries around the
world. Frequencies, power levels, and modes ( such as FM, AM and
SSB ) may vary from country to country, and usage of foreign
equipment may be illegal.
In Canada, the "General Radio Service" has the identical
frequencies and modes as the United States "Citizen's band", and
no special provisions are required for either Canadians or
Americans using CB gear while travelling across the border.
In Europe, the CEPT adopted the North American channel
assignments, except that FM is used instead of AM. Some member
countries permit additional modes and frequencies.
Before CEPT, most of the member countries used some subset of
the 40 USA channels. The United Kingdom, on the other hand,
originally had 40 unique 27 MHz channels, known as the 27/81
Bandplan. See CB radio in the United Kingdom. With the CEPT
channels added, the UK now has 80 channels. Germany also has 40
unique channels at 26 MHz for a total of 80.
In the United Kingdom though CB is virtually devoid of activity,
a licence is still required, though may soon be withdrawn, but
the UK-only frequencies may themselves be withdrawn in 2010 and
reassigned to the Community Audio Distribution System service.
Australia now has the 40 North American channels, though
previously it had only approved the use of the first 22
channels. On the other hand, New Zealand and Japan have unique
allocations that don't correspond to any other country's.
A gray market trade in imported CB gear does exist in many
countries. In many instances, sale or ownership of
foreign-specification CB gear is not illegal, but the actual use
of it is. With the FCC's minimal enforcement of its rules
regarding CB radio, enthusiasts in the USA often use "export"
radios, or possibly European FM CB gear to get away from the
overcrowded AM channels. American AM gear has also been exported
Using radios outside their intended market can be dangerous as
well as illegal. For example, the British frequencies clash with
a radio system used by ambulance services in Ukraine.
As 27 MHz is a relatively long wavelength for mobile
communications, the choice of antenna has a considerable impact
on the performance of a CB radio.
One common mobile antenna is a quarter-wave vertical whip.
This is roughly nine feet tall and mounted low on the vehicle
body, and often has a spring and ball mount.
Where a nine-foot whip would be impractical, shorter antennas
include loading coils to make the antenna electrically longer
than it actually is. The loading coil may be on the bottom,
middle, or top of the antenna, while some antennas are wound in
a continuously loaded helix.
Many truckers use two co-phased antennas mounted on their
mirrors. This arrangement provides some directivity toward the
front and back of the truck, that is, up and down the highway.
Another specialty mobile antenna is the continuously-loaded
half-wave antenna. These do not require a ground plane, and are
often used on fiberglass vehicles such as snowmobiles or boats.
Handheld CB's often use either a telescoping center-loaded
whip, or a continuously-loaded "rubber ducky" antenna.
Base CB antennas may be vertical for omnidirectional
coverage, or directional "beam" antennas may be used to direct
communications to a particular region.