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127-508: Uniden was established on February 7, 1966, by its founder Hidero Fujimoto as "Uni Electronics Corp". Uniden became a well-known brand in the 1970s by manufacturing and marketing millions of citizens band radios (CB), under the Uniden brand as well as other companies such as Midland and Realistic , which rebranded the equipment under their own labels. Uniden also marketed CB Radios in the UK under

254-471: A proof of concept , but the engineering problems proved to be more onerous than conventional systems. Yagi published the first English-language reference on the antenna in a 1928 survey article on short wave research in Japan and it came to be associated with his name. However, Yagi who provided the conception which was originally vague expression to Uda, always acknowledged Uda's principal contribution towards

381-455: A 1974 strike protesting the new speed limit and other trucking regulations. The radios were crucial for independent truckers; many were paid by the mile, and the 55 mph speed limit lowered their productivity. Their use spread further into the general population in the US in the middle of the 1970s. Originally, CB radios required the use of a callsign in addition to a purchased license ($ 20 in

508-618: A CBer to monitor a town's home channel to contact another CBer from that town instead of a making a general call on channel 11. Since the price of CB was dropping and VHF Marine Band was still expensive, many boaters installed CB radios. Business caught on to this market, and introduced marine CBs containing a weather band (WX). There was much controversy over whether the Coast Guard should monitor CB radio, but for safety they did so, using Motorola base stations at their search and rescue stations. The Coast Guard stopped this practice in

635-703: A channel must take turns transmitting. In the US and Canada , and in the EU and the UK , transmitter power is limited to 4  watts when using AM and FM and 12 W PEP when using SSB . Illegal amplifiers to increase range are common. CB radios using an omni-directional vertical antenna typically have a range of about 5 km to 30 km depending on terrain, for line of sight communication; however, various radio propagation conditions may intermittently allow communication over much greater distances. Base stations however may be connected to

762-558: A directional Yagi–Uda antenna commonly called a Beam or a Yagi. Multiple countries have created similar radio services, with varying technical standards and requirements for licensing. While they may be known by other names, such as the General Radio Service in Canada, they often use similar frequencies (26–28 MHz) and have similar uses, and similar technical standards. Although licenses may be required, eligibility

889-427: A feedpoint at the centre with a voltage V j and a current I j flowing into it. Just considering two such elements we can write the voltage at each feedpoint in terms of the currents using the mutual impedances Z ij : Z 11 and Z 22 are simply the ordinary driving point impedances of a dipole, thus 73 + j43 ohms for a half-wave element (or purely resistive for one slightly shorter, as

1016-486: A finite number of frequencies during the mid-to-late 1970s and early 1980s, channels often were noisy and communication difficult, which reduced interest among hobbyists. Business users (such as tow-truck operators, plumbers, and electricians) moved to the VHF and UHF business band frequencies. The business band requires an FCC license, and usually results in an assignment to a single frequency. The advantages of fewer users sharing

1143-484: A frequency, greater authorized output power, clarity of FM transmission, lack of interference by distant stations due to skip propagation , and consistent communications made the VHF ( Very High Frequency ) radio an attractive alternative to the overcrowded CB channels. With these factors in play, CB radio has once again gained popularity in recent years, an uptick not seen since the 90's. Manufacturers report an increase in sales, while social media sites like YouTube show

1270-511: A growing popularity in CB radio content, mainly as a hobby. The technology has also given way to more compact CB radios with far more features afforded in older models. The FCC restricts channel 9 to emergency communications and roadside assistance. Most highway travelers monitor channel 19. Truck drivers still use CB, which is an effective means of obtaining information about road construction, accidents and police speed traps . Before CB

1397-407: A half wave in length. Rarely, the elements are discs rather than rods. Often they are supported on a perpendicular crossbar or "boom" along their centers. Usually there is a single dipole driven element consisting of two collinear rods each connected to one side of the transmission line, and a variable number of parasitic elements , reflectors on one side and optionally one or more directors on

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1524-437: A license and may be used for business or personal communications. Like many other land mobile radio services, multiple radios in a local area share a single frequency channel, but only one can transmit at a time. The radio is normally in receive mode to receive transmissions of other radios on the channel; when users want to communicate they press a " push to talk " button on their radio, which turns on their transmitter. Users on

1651-666: A nationwide craze in the United States over the mid- to late-1970s. The phenomenon also inspired several country and rock music songs in 1975 and 1976. Betty Ford , the former First Lady of the United States , used the CB handle "First Mama". Voice actor Mel Blanc was also an active CB operator, often using " Bugs " or " Daffy " as his handle and talking on the air in the Los Angeles area in one of his many voice characters. He appeared in an interview (with clips having fun talking to children on his home CB radio station) in

1778-641: A power output of 0.5 watt. An unofficial citizens band radio club in Malaysia is the "Malaysia Boleh Citizen Radio Group", known as "Mike Bravo" ( Malaysia Boleh ). In the UK, a small but growing number of people were illegally using American CB radios during the late 1970s and early 1980s. The prominence of CB radio grew in Britain partly due to the success of novelty songs like C.W. McCall's "Convoy" and Laurie Lingo & The Dipsticks’ "Convoy GB" in 1976 (both of which were Top 5 hits). By 1980, CB radio

1905-941: A power output of 500 mW. A CB radio or Personal Radio Service Device under Class Assignment does not need an individual license to operate in Malaysia if it adheres to the rules of the Warta Kerajaan Malaysia On 1 April 2010 the MCMC (Malaysian Communications and Multimedia Commission) released a new regulation and later on 2017. This includes a new UHF PMR 446 MHz allocation: an eight-channel analog Personal Mobile Radio 446 MHz (Analog PMR446) with frequencies from 446.00625 to 446.09375 MHz (12.5 kHz spacing) FM with 0.5 watt power output, and 16 channels for Digital Personal Mobile Radio 446 MHz (Digital PMR 446). Frequencies for Digital PMR 446 are from 446.103125 to 446.196875 MHz with 6.25 kHz channel spacing in 4FSK mode and

2032-442: A reflector, driven element, and a single director as shown here. The driven element is typically a 1 ⁄ 2 λ dipole or folded dipole and is the only member of the structure that is directly excited (electrically connected to the feedline ). All the other elements are considered parasitic . That is, they reradiate power which they receive from the driven element. They also interact with each other, but this mutual coupling

2159-575: A revenue of 77.7 billion yen. Just three years later in 2010, Uniden reported a revenue of just 35.5 billion yen. As of 2018, current products include cordless telephones , radar detectors , radio scanners, CB radios , and security/surveillance products. As of 2023, Uniden no longer produces cordless telephones, as per FAQs at support.uniden.com. At one point Uniden produced over two million wireless products every month and manufactures one cordless phone every 3.2 seconds. This statistic has become part of their company description used by many retailers and

2286-447: A significant part of the primary radiation. A more realistic model of a Yagi–Uda array using just a driven element and a director is illustrated in the accompanying diagram. The wave generated by the driven element (green) propagates in both the forward and reverse directions (as well as other directions, not shown). The director receives that wave slightly delayed in time (amounting to a phase delay of about 45° which will be important for

2413-485: A spacing of 20 kHz instead of the regular 10 kHz step. These intermediate frequencies are reserved for the Radio Control Radio Service (RCRS). The RCRS service is commonly used for remote control of model aircraft and boats. It is an unofficial practice to name these channels by their next lower standard channel number along with a suffix "A" ( after ). For example, channel "11A"

2540-410: A tower, the combination of antennas for three amateur bands in one unit is a practical solution. The use of traps is not without disadvantages, however, as they reduce the bandwidth of the antenna on the individual bands and reduce the antenna's electrical efficiency and subject the antenna to additional mechanical considerations (wind loading, water and insect ingress). Consider a Yagi–Uda consisting of

2667-571: Is 27.095 MHz, spaced 10 kHz after standard channel 11 (at 27.085 MHz) is used to provide for part of European railroad's Eurobalise radio communication with trains. Single-sideband (SSB) operation involves the selection of either the Lower Side Band (LSB) or the Upper Side Band (USB) mode for transmit and receive. SSB radios also have the standard AM mode for communicating with standard CB radio models. With

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2794-492: Is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array ; these elements are most often metal rods (or discs) acting as half-wave dipoles . Yagi–Uda antennas consist of a single driven element connected to a radio transmitter or receiver (or both) through a transmission line , and additional passive radiators with no electrical connection, usually including one so-called reflector and any number of directors . It

2921-531: Is a land mobile radio system , a system allowing short-distance one-to-many bidirectional voice communication among individuals, using two-way radios operating near 27 MHz (or the 11-m wavelength) in the high frequency or shortwave band. Citizens band is distinct from other personal radio service allocations such as FRS , GMRS , MURS , UHF CB and the Amateur Radio Service ( "ham" radio). In many countries, CB operation does not require

3048-435: Is a calling channel. On UHF 477 MHz, citizens band PRS radio devices are allowed 5 watts power output on FM on 39 assigned channels spaced at 12.5 kHz intervals from 477.0125 to 477.4875 MHz. Channel 9 is reserved for emergencies, and channel 11 for calling. A short-range simplex radio communications service for recreational use is from 477.5250 to 477.9875 MHz FM mode with 38 channels and

3175-417: Is also useful in reducing TV interference . MPT 1320 also restricted antennas to a maximum length of 1.5 meters (5'), with base loading being the only type permitted for 27 MHz operation. Over the next several years antenna regulations were relaxed, with antenna length increasing to 1.65 meters (5'5") and centre- or top-loading of the main radiating element permitted. On 1 September 1987

3302-422: Is as rooftop terrestrial television antennas , but it is also used for point-to-point fixed communication links, radar, and long-distance shortwave communication by broadcasting stations and radio amateurs . The antenna was invented by Shintaro Uda of Tohoku Imperial University , Japan , in 1926, with a lesser role played by Hidetsugu Yagi . However, the name Yagi has become more familiar, while

3429-514: Is far different: Attempting an SSB conversation while an AM conversation is in progress results in jammed communications for everyone. In general, each channel can only support one AM conversation and no others; if no AM conversation is in progress, two SSB conversations can share one channel without interference if one is in LSB and the other in USB mode. For a particular conversation, everyone must be tuned to

3556-759: Is generally simple. Some countries also have personal radio services in the UHF band, such as the European PMR446 and the Australian UHF CB. The citizens band radio service originated in the United States as one of several personal radio services regulated by the Federal Communications Commission (FCC). These services began in 1945 to permit citizens a radio band for personal communication (e.g., radio-controlled model airplanes and family and business communications). In 1948,

3683-415: Is neglected in the following simplified explanation, which applies to far-field conditions. One way of thinking about the operation of such an antenna is to consider a parasitic element to be a normal dipole element of finite diameter fed at its centre, with a short circuit across its feed point. The principal part of the current in a loaded receiving antenna is distributed as in a center-driven antenna. It

3810-441: Is not straightforward. The mutual impedances plotted above only apply to λ /2 length elements, so these might need to be recomputed to get good accuracy. The current distribution along a real antenna element is only approximately given by the usual assumption of a classical standing wave, requiring a solution of Hallen's integral equation taking into account the other conductors. Such a complete exact analysis, considering all of

3937-427: Is proportional to the effective length of the antenna and is in phase with the incident electric field if the passive dipole is excited exactly at its resonance frequency. Now we imagine the current as the source of a power wave at the (short-circuited) port of the antenna. As is well known in transmission line theory, a short circuit reflects the incident voltage 180 degrees out of phase. So one could as well model

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4064-401: Is rarely enforced. AM and SSB on the freeband and amplifier use are common among enthusiasts. Packet radio is legal in the UK, although not widely used. Internet gateway stations are also beginning to appear; although illegal on 27 MHz, these units are connected to other CB stations around the world. Although the use of CB radios in the UK is limited they are still in use, especially with

4191-408: Is the current induced in the parasitic element due to the current I 1 in the driven element. We can also solve for the voltage V 1 at the feedpoint of the driven element using the earlier equation: where we have substituted Z 12 = Z 21 . The ratio of voltage to current at this point is the driving point impedance Z dp of the 2-element Yagi: With only the driven element present

4318-424: Is usually desired for the driven element). Due to the differences in the elements' lengths Z 11 and Z 22 have a substantially different reactive component. Due to reciprocity we know that Z 21 = Z 12 . Now the difficult computation is in determining that mutual impedance Z 21 which requires a numerical solution. This has been computed for two exact half-wave dipole elements at various spacings in

4445-429: Is usually mounted for either horizontal or vertical polarization. It is relatively lightweight, inexpensive and simple to construct. The bandwidth of a Yagi antenna, the frequency range over which it maintains its gain and feedpoint impedance , is narrow, just a few percent of the center frequency, decreasing for models with higher gain, making it ideal for fixed-frequency applications. The largest and best-known use

4572-544: The CRTC officially calls the CB band the "General Radio Service," though regulations also note that this service is commonly called "CB". Canada's GRS uses the identical frequencies and modes as the United States citizens band, and no special provisions are required for either Canadians or Americans using CB gear while traveling across the border. The General Radio Service was authorized in 1962. Initially, CB channels 1–3 remained allocated to amateur radio and channel 23

4699-497: The NBC Knowledge television episode about CB radio in 1978. Similar to Internet chat rooms a quarter-century later, CB allowed people to get to know one another in a quasi-anonymous manner. Originally, the U.S. had 23 CB channels; the 40 channel band plan was implemented in 1977. Two more channels between 22 & 23, commonly referred to as 22A & 22B, were available. Several people had 22A, but few had 22B. In

4826-436: The "Notification of Issuance Of Class Assignments" by Communication and Multimedia Malaysia was published on 1 April 2000. Under this class assignment, a CB radio is classified as a "Personal Radio Service device". The frequency band is HF, 26.9650 MHz to 27.4050 MHz (40 channels), power output is 4 watts for AM and FM and 12 watts PEP for SSB. Channel 9 is reserved for emergencies, and channel 11

4953-549: The "mid band" (standard CB band) as "band D" which shifts the letters up one (making 26.515–26.955 MHz "band C" and 27.415–27.855 MHz "band E". For the convenience of users of the grid were marked by letters. Classic is considered the marking when the main range is designated letter "C". The most common description of the channel is considered to be similar to the following: (C9FM or C9EFM or C9EF or 9EF). In it: An example of correct designations: C9EF, C9EA, C9RF, C9RA The 25–30 MHz band (including

5080-503: The "standard" 40 channel 26.965–27.405 MHz frequency plan for a total of 80 HF CB channels. New Zealand has adopted the Australian UHF CB System as well. Japan's CB allocation consists of 8 voice and 2 radio control channels with a maximum power output of 500 mW. AM mode is the only mode permitted and antennas must be non-removable and less than 199 cm (78 inches) long. In Japan,

5207-409: The 18 channel band plan. So channel 1 on an 18 channel was actually channel 5 on a 23 channel radio. These roughly corresponded to the present channels 5–22, except for the two unique frequencies that are known as 11A (Channel 7 on an 18 channel Australian CB) and 19A (Channel 16 on an 18 channel Australian CB) or remote control frequencies but are no longer part of

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5334-522: The 1970s was frequently depicted in film, television, and music. Movies such as Smokey and the Bandit (1977), Breaker! Breaker! (1977), Handle with Care (also released as Citizens Band ; 1977), and Convoy (1978), made heavy reference to the phenomenon, as did television series such as Movin' On (debuted in 1974), The Dukes of Hazzard (debuted in 1979) and the animated series CB Bears (debuted in 1977) helped cement CB radio's status as

5461-425: The 26–28 MHz range is allocated to fishery radio services and these frequencies are heavily used for marine communications. Japan's "double side band fishery radio" or "DSB Fishery Radio Service" covers 26.760 MHz-26.944 MHz, 27.016 MHz, and 27.524-27.988 MHz. However, frequencies such as 27.005 MHz AM are widely pirated in Japan with very high power transmitters. This causes interference to

5588-623: The 460–470 MHz band was reassigned for business and public-safety use; CB Class A is the forerunner of the General Mobile Radio Service (GMRS). CB Class B 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 filed in 1973 to create a CB Class E service at 220 MHz, (part of

5715-806: The American channels and their associated frequencies, which is generally in AM mode except some higher channels which are sometimes in SSB mode. In September 2021 the FCC approved the use of FM on CB radio. The standard channel numbering is harmonized through the FCC ( USA ) and the CEPT ( Europe ). See also channel assignments for CB use in the United States . When looking at the FCC/CEPT channel list there are some channels with

5842-467: The Australian 27 MHz CB band since 40 Channels were introduced. On January 1, 1982, the American 40 channel band plan was adopted. From the outset, the government attempted to regulate CB radio with license fees and call signs, but eventually they abandoned this approach. Enthusiasts rushed for licences when the doors opened at post offices around Australia in mid-1977 and by the end of

5969-479: The CB allocations and frequencies above and below the 26.5–27.860 MHz band) is heavily used for taxi cab and other mobile two-way communications systems in Russia, Ukraine and other former USSR country states. New Zealand and Japan have unique allocations compared to any other country. New Zealand authorizes use of their New Zealand specific 40 channel 26.330–26.770 MHz frequency plan in addition to

6096-488: The Mississippi; channel 19 then became the preferred highway channel in most areas, as it did not have adjacent-channel interference problems with channel 9. Many CBers called channel 19 "the trucker's channel". The FCC originally restricted channel 11 for use as the calling channel. The original FCC output power limitation for CB radios was "5 watts DC input to the final amplifier stage", which

6223-497: The North American channel designation. Some member countries permit additional modes and frequencies; for example, Germany has 40 additional channels at 26 MHz for a total of 80. The United Kingdom has an additional 40 channels between 27.60125 and 27.99125 MHz, also making 80 channels in total. Before CEPT, most member countries used a subset of the 40 U.S. channels. In Russia and Poland ,

6350-487: The UK added the usual 40 frequencies (26.965–27.405 MHz) used worldwide, for a total of 80 channels at 27 MHz; antenna regulations were further relaxed, and the 934 MHz band was withdrawn in 1998. CB radio in the UK was deregulated in December ;2006 by the regulatory body Ofcom , and CB radio in the UK is now license-free. The old MPT 1320 27/81 band will continue to be available for

6477-679: The Uniden and Uniace brands during the early '80s. During the 1980s, Uniden grew to become the world's largest manufacturer of cordless telephones in addition to television satellite equipment, mobile radios, advanced marine electronics and radio scanners (the latter under BearCat brand). In Europe , it became successful in the telecommunications market with its introduction of 900 MHz cordless telephones. As Uniden continued to grow and extend its international operations, Uniden Australia and Uniden New Zealand were established in 1989. Uniden's revenue has plummeted since smartphones and VOIP solutions have become mainstream. In 2007, Uniden had

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6604-424: The accompanying graph. The solution of the system then is as follows. Let the driven element be designated 1 so that V 1 and I 1 are the voltage and current supplied by the transmitter. The parasitic element is designated 2, and since it is shorted at its "feedpoint" we can write that V 2  = 0. Using the above relationships, then, we can solve for I 2 in terms of I 1 : and so This

6731-600: The allocation of channels available for UHF CB Radio from 40 to 80, and doubled the number of repeater channels from 8 to 16. Source: Several channels are allocated for maritime use in Australia. Australia also permits the use of marine VHF radio . 27 MHz radios have the advantage of not requiring a certificate of proficiency to use, however they may not be monitored by rescue organisations or larger vessels. VHF radios are recommended by state agencies, such as Marine Safety Victoria and Marine Rescue NSW . In Canada ,

6858-437: The amateur radio 1.25-meter band at the time) which 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). During the 1960s, the service was used by small businesses (e.g., electricians, plumbers, carpenters), truck drivers and radio hobbyists. By the late 1960s, advances in solid-state electronics allowed

6985-526: The antenna's central support boom. The most common form of the driven element is one fed at its centre so its two halves must be insulated where the boom supports them. The gain increases with the number of parasitic elements used. Only one reflector is normally used since the improvement of gain with additional reflectors is small, but more reflectors may be employed for other reasons such as wider bandwidth. Yagis have been built with 40 directors and more. The bandwidth of an antenna is, by one definition,

7112-603: The authorized low-power 1 Watt DSB (1 Watt AM) fishery radio service. Instead of 26–27 MHz, Japan has authorized several UHF FM CB-type personal radio services in the 348 MHz, 420–422 MHz and 903–904 MHz bands. Indonesia has the usual 40 channels at 27 MHz, plus a unique 60-channel allocation from 142.050 to 143.525 MHz. In Brazil , CB channels were upgraded from 23 to 60 channels starting in 1979 and again in 1980 to 80 channels (from 26.965 MHz to 27.855 MHz). Yagi-Uda A Yagi–Uda antenna , or simply Yagi antenna ,

7239-479: The busy Hume Highway between Melbourne and Sydney. Other regional cities such as Bendigo, Mildura, Mount Gambier and Port Augusta, developed lively, colourful CB radio communities. With the introduction of UHF CB radios in 1977, many operators used both UHF and HF radios and formed groups to own and operate local FM repeaters. Members of the CBTCC formed what became known as Australian Citizens Radio Movement (ACRM) in

7366-508: The ceremonial first legal British CB call from Trafalgar Square in London. The maximum power allowable on the MPT ;1320 27/81 system was 4 watts (in common with the American system), although initially radios were equipped to reduce output power by 10  dB (to 0.4 watts) if the antenna was mounted more than 7 meters (23') above ground level. The power-reduction switch

7493-474: The channels are shifted 5 kHz down; for example, channel 30 is 27.300 MHz. Many operators add a switch to change between the "zeroes" (the Russian/Polish channel assignment) and the "fives" (the international/European assignment). Most contemporary radios built for those markets can do "fives" as well as "zeroes" out of the box. Since roughly 2005–2006, Russia and Poland have adopted use of

7620-680: The cheeks of the P-61 and on the nose cones of many WWII aircraft, notably the Lichtenstein radar -equipped examples of the German Junkers Ju 88 R-1 fighter-bomber , and the British Bristol Beaufighter night-fighter and Short Sunderland flying-boat. Indeed, the latter had so many antenna elements arranged on its back – in addition to its formidable turreted defensive armament in the nose and tail, and atop

7747-428: The confusion created by the false advertising that SSB radios have 120 channels compared to only 40 for AM radios. While a SSB radio has three possible "modes" (AM, LSB, USB) it can operate in, operation is still limited to the same 40 channels. Some manufacturers tried to sell more radios by claiming that with three different modes possible for each channel, it was the equivalent to 120 channels. Reality

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7874-468: The current) and an additional 90 degrees lagging phase offset. Thus, the reradiated field may be thought as having a 90 degrees lagging phase with respect to the incident field. Parasitic elements involved in Yagi–Uda antennas are not exactly resonant but are somewhat shorter (or longer) than 1 ⁄ 2 λ so that the phase of the element's current is modified with respect to its excitation from

8001-775: The date of the statistic is unknown. Despite the cordless phone's falling popularity, this claim still appears on Uniden Australia's website. Uniden operates globally, but the main commercial activities are situated in the United States and Japan . Manufacturing sites have been located in China , Hong Kong , Taiwan , and the Philippines . In 2008, Uniden began to move production from China to Vietnam because of lower wages. Uniden delisted in November 29, 2022. Citizens band radio Citizens band radio ( CB radio )

8128-520: The design until late in the war, partly due to rivalry between the Army and Navy. The Japanese military authorities first became aware of this technology after the Battle of Singapore when they captured the notes of a British radar technician that mentioned "yagi antenna". Japanese intelligence officers did not even recognise that Yagi was a Japanese name in this context. When questioned, the technician said it

8255-409: The design which will currently be recognized as the reduction to practice , and if the novelty is not considered, the proper name for the antenna is, as above, the Yagi–Uda antenna (or array). The Yagi was first widely used during World War II for airborne radar sets, because of its simplicity and directionality. Despite its being invented in Japan, many Japanese radar engineers were unaware of

8382-416: The dipole at the feedpoint (making it a solid element, as it is). However, the current of the backward wave is in phase with the current of the incident wave. This current drives the reradiation of the (passive) dipole element. At some distance, the reradiated electric field is described by the far-field component of the radiation field of a dipole antenna . Its phase includes the propagation delay (relating to

8509-414: The director element is made sufficiently short, the phase delay may be imagined to approach zero and the incident wave and the wave reemitted by the reflector interfere constructively in the forward direction. Interference also occurs in the backward direction. This interference is influenced by the distance between the driven and the passive element, because the propagation delays of the incident wave (from

8636-402: The distance between the adjacent directors it is possible to reduce the back lobe of the radiation pattern. The Yagi–Uda antenna was invented in 1926 by Shintaro Uda of Tohoku Imperial University , Sendai , Japan , with the guidance of Hidetsugu Yagi , also of Tohoku Imperial University. Yagi and Uda published their first report on the wave projector directional antenna. Yagi demonstrated

8763-422: The driven dipole, it interacts with the near field , in which the phase-to-distance relation is not governed by propagation delay, as would be the case in the far field. Thus, the amplitude and phase relation between the driven and the passive element cannot be understood with a model of successive collection and reemission of a wave that has become completely disconnected from the primary radiating element. Instead,

8890-456: The driven element (green), in this particular design. These waves combine to produce the net forward wave (bottom, right) with an amplitude somewhat larger than the individual waves. In the reverse direction, on the other hand, the additional delay of the wave from the director (blue) due to the spacing between the two elements (about 45° of phase delay traversed twice) causes it to be about 160° (70° + 2 × 45°) out of phase with

9017-401: The driven element to the passive element) and of the reradiated wave (from the passive element back to the driven element) have to be taken into account. To illustrate the effect, we assume zero and 180 degrees phase delay for the reemission of director and reflector, respectively, and assume a distance of a quarter wavelength between the driven and the passive element. Under these conditions

9144-427: The driven element. The so-called reflector element, being longer than 1 ⁄ 2 λ , has an inductive reactance , which means the phase of its current lags the phase of the open-circuit voltage that would be induced by the received field. The phase delay is thus larger than 90 degrees and, if the reflector element is made sufficiently long, the phase delay may be imagined to approach 180 degrees, so that

9271-406: The driven elements' radiation in one direction at the expense of the other, the assumption of an additional 90 degrees (leading or lagging) phase shift of the reemitted wave is not valid. Typically, the phase shift in the passive element is much smaller. Moreover, to increase the effect of the passive radiators, they should be placed close to the driven element, so that they can collect and reemit

9398-427: The driving point impedance would have simply been Z 11 , but has now been modified by the presence of the parasitic element. And now knowing the phase (and amplitude) of I 2 in relation to I 1 as computed above allows us to determine the radiation pattern (gain as a function of direction) due to the currents flowing in these two elements. Solution of such an antenna with more than two elements proceeds along

9525-493: The early 1970s Radio Shack sold a "base station" CB radio that contained a crystal for each of the 23 channels, two extra slots existed, and one could order the 22A & 22B crystals for an easy plug-in. Channel 9 was officially reserved for emergency use by the FCC in 1969. Channel 10 was originally often used for highway travel communications east of the Mississippi River , and channel 19 west of

9652-520: The early 1970s, reduced to $ 4 on March 1, 1975, or $ 22.6 in 2023 dollars). However, when the CB craze was at its peak, many people ignored the requirement and invented their own nicknames (known as "handles"). Lax enforcement of the rules on authorized use of CB radio led to further widespread disregard of regulations (such as for antenna height, distance communications, licensing, call signs, and transmitter power). Individual licensing came to an end on April 28, 1983. The growing popularity of CB radios in

9779-499: The early 1970s; this organization became the voice for legalization of CB radio throughout Australia. After peaking in the 1970s and early 1980s, the use of 27 MHz CB in Australia has fallen dramatically due to the introduction of 477 MHz UHF CB (with FM and repeaters) and the proliferation of cheap, compact handheld UHF transceivers. Technology such as mobile telephones and the internet have provided people with other choices for communications. The Australian government has changed

9906-461: The effect of truncating the element at the higher frequency band, making it approximately a half wavelength in length. At the lower frequency, the entire element (including the remaining inductance due to the trap) is close to half-wave resonance, implementing a different Yagi–Uda antenna. Using a second set of traps, a "triband" antenna can be resonant at three different bands. Given the associated costs of erecting an antenna and rotator system above

10033-592: The extreme tips of the Morgenstern's antenna elements protruding from the radome's surface, with an NJG 4 Ju 88 G-6 of the wing's staff flight using it late in the war for its Lichtenstein SN-2 AI radar. After World War II, the advent of television broadcasting motivated extensive adaptation of the Yagi–Uda design for rooftop television reception in the VHF band (and later for UHF television) and also as an FM radio antenna in fringe areas. A major drawback

10160-856: The farming community, truckers, off-roaders and mini-cab services. The widely used channel for the Young Farmers' Club is channel 11. The normal calling and truckers' channel is channel 19, although many truck organisations and groups use other channels to avoid abuse. CB radio is not a worldwide, standardized radio service. Each country decides if it wants to authorize such a radio service from its domestic frequency authorizations, and what its standards will be; however, similar radio services exist in many countries. Frequencies, power levels and modes (such as frequency modulation (FM), amplitude modulation (AM), and single-sideband modulation (SSB), often vary from country to country; use of foreign equipment may be illegal. However, many countries have adopted

10287-456: The first director element just as the crest of the wave is emitted from that element, and so on. The waves in the reverse direction interfere destructively , cancelling out, so the signal strength radiated in the reverse direction is small. Thus the antenna radiates a unidirectional beam of radio waves from the front (director end) of the antenna. While the above qualitative explanation is useful for understanding how parasitic elements can enhance

10414-598: The first quarter of 1978 an estimated 200,000 licences were issued (Australia's Population in 1978 was 14.36 million). The regulations called for one licence per CB radio. The price for a licence in 1977 was AU$ 25 per year (In mid 1977 the Australian Dollar exchange rate was AU$ 0.90 to US$ 1.00), a not insubstantial amount for the average Australian wage-earner. Australian CB radio uses AM, USB, and LSB modes (no FM) on 27 MHz, allowed output power being 4 Watts AM and 12 Watts SSB. When UHF CB

10541-421: The foreseeable future. On 27 June 2014, changes were made by Ofcom to allow the use of AM & SSB modes on CB in the UK legally for the first time. The rules regarding non-approved radios and power levels above 4 Watts on AM/FM and 12 Watts on SSB still apply, despite deregulation. Persons using illegal equipment or accessories still risk prosecution, fines or confiscation of equipment, although this

10668-404: The hull – it was nicknamed the fliegendes Stachelschwein , or "Flying Porcupine" by German airmen. The experimental Morgenstern German AI VHF-band radar antenna of 1943–44 used a "double-Yagi" structure from its 90° angled pairs of Yagi antennas formed from six discrete dipole elements, making it possible to fit the array within a conical, rubber-covered plywood radome on an aircraft's nose, with

10795-400: The incident wave and the wave reemitted by the reflector interfere destructively in the forward direction (i.e. looking from the driven element towards the passive element). The director element, on the other hand, being shorter than 1 ⁄ 2 λ , has a capacitive reactance with the voltage phase lagging that of the current. The phase delay is thus smaller than 90 degrees and, if

10922-410: The intended direction. These parasitic elements are typically off-tuned short-circuited dipole elements, that is, instead of a break at the feedpoint (like the driven element) a solid rod is used. They receive and reradiate the radio waves from the driven element but in a different phase determined by their exact lengths. Their effect is to modify the driven element's radiation pattern . The waves from

11049-410: The interactions mentioned, is rather overwhelming, and approximations are inevitable on the path to finding a usable antenna. Consequently, these antennas are often empirical designs using an element of trial and error , often starting with an existing design modified according to one's hunch. The result might be checked by direct measurement or by computer simulation. A well-known reference employed in

11176-469: The last official registration date for 23 channel sets was January 31, 1978. After this date, use of unregistered 23 channel CB sets was deemed illegal and unlicensed sets were no longer eligible to be licensed. The 18 channel band plan used 16 channels of the 23 channel CB radios plus 2 extra channels at 27.095 and 27.195 MHz, to make up the 18 channels. The original channels 1, 2, 3, 4, 10, 21 and 23 were deleted from

11303-421: The late 1980s and recommends VHF Marine Band radios for boaters. CB has lost much of its original appeal due to development of mobile phones , the internet and the Family Radio Service . Changing radio propagation for long-distance communications due to the 11–year sunspot cycle is a factor at these frequencies. In addition, CB may have become a victim of its own popularity; with millions of users on

11430-565: The latter approach is a report published by the United States National Bureau of Standards (NBS) (now the National Institute of Standards and Technology (NIST)) that provides six basic designs derived from measurements conducted at 400 MHz and procedures for adapting these designs to other frequencies. These designs, and those derived from them, are sometimes referred to as "NBS yagis." By adjusting

11557-583: The multiple elements superpose and interfere to enhance radiation in a single direction, increasing the antenna's gain in that direction. Also called a beam antenna and parasitic array , the Yagi is widely used as a directional antenna on the HF , VHF and UHF bands. It has moderate to high gain of up to 20  dBi , depending on the number of elements used, and a front-to-back ratio of up to 20 dB. It radiates linearly polarized radio waves and

11684-403: The name of Uda, who applied the idea in practice or established the conception through experiment, is often omitted. This appears to have been due to the fact that Yagi based his work on Uda's pre-announcement and developed the principle of the absorption phenomenon Yagi had announced earlier. Yagi filed a patent application in Japan on the new idea, without Uda's name in it, and later transferred

11811-463: The operation of the parasitic element as the superposition of a dipole element receiving power and sending it down a transmission line to a matched load, and a transmitter sending the same amount of power up the transmission line back toward the antenna element. If the transmitted voltage wave were 180 degrees out of phase with the received wave at that point, the superposition of the two voltage waves would give zero voltage, equivalent to shorting out

11938-466: The original 23 CB channels SSB stations commonly used channel 16, to avoid interference to those using AM (SSB stations are authorized to use 12 watts, as opposed to 4 watts for AM stations) and to more easily locate other SSB stations. With the FCC authorization of 40 channels, SSB operation shifted to channels 36–40. Channel 36 (or 38 for LSB) became the unofficial SSB "calling channels" for stations seeking contacts, with

12065-488: The original CB radios were designed for operation on the 460–470 MHz UHF band. There were two classes of CB radio: "A" and "B". Class B radios had simpler technical requirements, and were limited to a smaller frequency range. Al Gross established the Citizens Radio Corporation during the late 1940s to manufacture class B handhelds for the general public. Originally designed for use by

12192-403: The other side. The parasitic elements are not electrically connected to the transmission line and serve as passive radiators , reradiating the radio waves to modify the radiation pattern . Typical spacings between elements vary from about 1 ⁄ 10 to 1 ⁄ 4 of a wavelength, depending on the specific design. The directors are slightly shorter than the driven element, while

12319-525: The passive elements. There are no simple formulas for designing Yagi–Uda antennas due to the complex relationships between physical parameters such as However using the above kinds of iterative analysis, one can calculate the performance of a given a set of parameters and adjust them to optimize the gain (perhaps subject to some constraints). Since with an n element Yagi–Uda antenna, there are 2 n  −  1 parameters to adjust (the element lengths and relative spacings), this iterative analysis method

12446-575: The patent to the Marconi Company in the UK. Incidentally, in the US, the patent was transferred to RCA Corporation . Yagi antennas were first widely used during World War II in radar systems by Japan, Germany, the United Kingdom, and the United States. After the war, they saw extensive development as home television antennas . The Yagi–Uda antenna typically consists of a number of parallel thin rod elements, each approximately

12573-457: The prefix "GL" (for Gippsland ), since "CB" could not be used. After July 1, 1977, the club changed its name to Citizens Band Two Way Communication Club (CBTCC). Other early clubs were "LV" ( Latrobe Valley ) and "WB" (named after Wayne Britain). Members of these clubs are still active, and have also become amateur radio operators . Other Australian cities which became CB radio "hotspots" were Seymour, Benalla, Holbrook and Gundagai, all located on

12700-486: The public sector, the Citizens Radio Corporation sold over 100,000 units, primarily to farmers and the US Coast Guard. Ultra-high frequency (UHF) radios, at the time, were neither practical nor affordable for the average consumer. On September 11, 1958 CB service class D was created on 27 MHz, and this band became what is commonly known today as "Citizens Band". Only 23 channels were available at

12827-401: The radio waves radiated by the driven element and those re-radiated by the parasitic elements all arrive at the front of the antenna in-phase, so they superpose and add, increasing signal strength in the forward direction. In other words, the crest of the forward wave from the reflector element reaches the driven element just as the crest of the wave is emitted from that element. These waves reach

12954-446: The radio", resulting in a far simpler and easier specification. Initially, the FCC intended for CB to be the "poor man's business-band radio", and CB regulations were structured similarly to those regulating the business band radio service. Until 1975, only channels 9–14 and 23 could be used for "interstation" calls (to other licensees). Channels 1–8 and 15–22 were reserved for "intrastation" communications (among units with

13081-500: The reflector(s) are slightly longer. The radiation pattern is unidirectional, with the main lobe along the axis perpendicular to the elements in the plane of the elements, off the end with the directors. Conveniently, the dipole parasitic elements have a node (point of zero RF voltage ) at their centre, so they can be attached to a conductive metal support at that point without need of insulation, without disturbing their electrical operation. They are usually bolted or welded to

13208-414: The relevant portions of the VHF and UHF bands. Wider bandwidth can also be achieved by the use of "traps", as described below. Yagi–Uda antennas used for amateur radio are sometimes designed to operate on multiple bands. These elaborate designs create electrical breaks along each element (both sides) at which point a parallel LC ( inductor and capacitor ) circuit is inserted. This so-called trap has

13335-418: The reverse direction calculations later). Due to the director's shorter length, the current generated in the director is advanced in phase (by about 20°) with respect to the incident field and emits an electromagnetic field, which lags (under far-field conditions) this current by 90°. The net effect is a wave emitted by the director (blue) which is about 70° (20° - 90°) retarded with respect to that from

13462-570: The same channel and same mode in order to talk with each other. Starting in October 2021 the FCC has approved FM for CB in the US. The European Conference of Postal and Telecommunications Administrations (CEPT) adopted the North American channel assignments, except channel 23, frequency 27.235 MHz; channel 24, frequency 27.245 MHz; and channel 25, frequency 27.255 MHz. However, legal CB equipment sold in Europe does follow

13589-512: The same license). After the inter-station/intra-station rule was dropped, channel 11 was reserved as a calling frequency (for the purpose of establishing communications); however, this was withdrawn in 1977. During this early period, many CB radios had "inter-station" channels colored on their dials, while the other channels were clear or normally colored. It was common for a town to adopt an inter-station channel as its "home" channel. This helped prevent overcrowding on channel 11, enabling

13716-425: The same lines, setting each V j  = 0 for all but the driven element, and solving for the currents in each element (and the voltage V 1 at the feedpoint). Generally the mutual coupling tends to lower the impedance of the primary radiator and thus, folded dipole antennas are frequently used because of their large radiation resistance, which is reduced to the typical 50 to 75 Ohm range by coupling with

13843-409: The specification had changed to 4 watts output. The older 23 channel radios built under the old specifications typically had an output of around 3.5 to 3.8 watts output when measured at the antenna connector. The FCC simply rounded up the old "5 watts DC input to the final amplifier stage" specification to the new "4 watts output as measured at the antenna connector on the back of

13970-512: The standard US channel offset as well as the older channel plan, for two overlapping "grids" of channels. Russia uses an alphanumeric designation for their CB channel plans, because several "grids" or "bands" of 40 channels each are used, along with both AM and FM mode. Russian CB allocations follow the CB band 26.965–27.405 MHz (designated as band C), as well as 26.515–26.955 MHz (designated as band B) and 27.415–27.855 MHz (designated as band D). Some radios refer to

14097-405: The subsequent conversation moving to channels 37–40. CBers with AM-only radios are asked to not use channels 36 through 40. In return, SSB stations stay off the remaining 35 channels so they could be used by AM stations. This agreement provides interference-free operation for all operators by separating the far more powerful SSB stations from the AM stations. This solution also resolves

14224-544: The time; the first 22 were taken from the former amateur radio service 11-meter band, and channel 23 was shared with radio-controlled devices. Some hobbyists continue to use the designation "11 meters" to refer to the Citizens Band and adjoining frequencies. Part 95 of the Code of Federal Regulations regulates the class D CB service, on the 27 MHz band, since the 1970s and continuing today. Most of

14351-463: The two antenna elements form a coupled system, in which, for example, the self-impedance (or radiation resistance ) of the driven element is strongly influenced by the passive element. A full analysis of such a system requires computing the mutual impedances between the dipole elements which implicitly takes into account the propagation delay due to the finite spacing between elements and near-field coupling effects. We model element number j as having

14478-402: The wave from the driven element (green). The net effect of these two waves, when added (bottom, left), is partial cancellation. The combination of the director's position and shorter length has thus obtained a unidirectional rather than the bidirectional response of the driven (half-wave dipole) element alone. When a passive radiator is placed close (less than a quarter wavelength distance) to

14605-420: The wave reemitted by the director interferes destructively with the wave emitted by the driven element in the backward direction (away from the passive element), and the wave reemitted by the reflector interferes constructively. In reality, the phase delay of passive dipole elements does not reach the extreme values of zero and 180 degrees. Thus, the elements are given the correct lengths and spacings so that

14732-607: The weight, size, and cost of the radios to fall, giving the public access to a communications medium previously only available to specialists. CB clubs were formed; a CB slang language evolved alongside ten-code , similar to those used in emergency services . After the 1973 oil crisis , the U.S. government imposed a nationwide 55 mph speed limit , and fuel shortages and rationing were widespread. Drivers (especially commercial truckers ) used CB radios to locate service stations with better supplies of fuel, to notify other drivers of speed traps , and to organize blockades and convoys in

14859-501: The width of the band of frequencies having a gain within 3 dB (one-half the power) of its maximum gain. The Yagi–Uda array in its basic form has a narrow bandwidth, 2–3 percent of the centre frequency. There is a tradeoff between gain and bandwidth, with the bandwidth narrowing as more elements are used. For applications that require wider bandwidths, such as terrestrial television , Yagi–Uda antennas commonly feature trigonal reflectors, and larger diameter conductors, in order to cover

14986-514: Was a reference to the earlier radios equipped with tubes. With solid state radios becoming more common in the 1970s, the FCC revised this specification at the same time the authorized channels were increased to 40. The current specification is simply "4 watts output (AM) or 12 watts output (SSB)" as measured at the antenna connector on the back of the radio. The old specification was often used in false advertising by some manufacturers who would claim their CB radios had "5 watts" long after

15113-624: Was adopted; a VHF band was added in 1994, along with allowing use of the Australian UHF CB channel plan at 476-477 MHz On 10 November 1980, the Indonesian Directorate General of Posts and Telecommunications issued another decree establishing RAPI ( Radio Antar Penduduk Indonesia ) as the official citizens band radio organization in Indonesia. In Malaysia, citizens band radios became legal when

15240-628: Was an antenna named after a Japanese professor. A horizontally polarized array can be seen on many different types of WWII aircraft, particularly those types engaged in maritime patrol, or night fighters, commonly installed on the lower surface of each wing. Two types that often carried such equipment are the Grumman TBF Avenger carrier-based US Navy aircraft and the Consolidated PBY Catalina long range patrol seaplane. Vertically polarized arrays can be seen on

15367-399: Was authorized in Australia, hand-held 27-MHz "walkie-talkies" were available, which used several frequencies between the present CB channels, such as 27.240 MHz. By the mid-1970s, hobbyists were experimenting with handheld radios and unauthorized 23 channel American CB radios. At that time in Australia, licensed ham operators and Emergency Services still used the 11 meter band which

15494-592: Was becoming a popular pastime in Britain; as late as the summer of 1981 the British government was still saying that CB would never be legalized on 27 MHz, proposing a UHF service around 860 MHz called "Open Channel" instead. However, in November 1981 (after high-profile public demonstrations) 40 frequencies unique to the UK, known as the 27/81 Bandplan using FM were allocated at 27 MHz plus 20 channels on 934 MHz (934.0125–934.9625 MHz with 50 kHz spacing). CB's inventor, Al Gross , made

15621-706: Was first legalised the 27 MHz CB Band was intended to be closed to Australian CBers in 1982 and only the 477 MHz UHF band was to continue, however this did not eventuate. The first 477 MHz CB radio in 1977 was designed and made in Australia by Philips TMC and was a 40 channel CB called the FM320. The first CB club in Australia was the Charlie Brown Touring Car Club (CBTCC), which formed in Morwell, Victoria in 1967 and consisted mainly of four-wheel drive enthusiasts. The club used

15748-416: Was invented in 1926 by Shintaro Uda of Tohoku Imperial University , Japan , with a lesser role played by his boss Hidetsugu Yagi . Reflector elements (usually only one is used) are slightly longer than the driven dipole and placed behind the driven element, opposite the direction of intended transmission. Directors, on the other hand, are a little shorter and placed in front of the driven element in

15875-605: Was known around large cities such as Jakarta , Bandung , Yogyakarta , Surabaya and Medan . The Indonesian government legalized CB on 6 October 1980 with a decision by the Minister of Communications, the "Ministerial Decree on the Licensing for the Operation of Inter-Citizens Radio Communication". Because many people were already using 40 channel radios prior to legalization, the American band plan (with AM and SSB)

16002-535: Was not yet available for CB use. Multiple CB clubs had formed by this time, which assigned call signs to members, exchanged QSL cards , and lobbied for the legalisation of CB. In late 1977, having legalised Australian CB and allowed the import / sale of American and Japanese 23 channel sets, the Federal Government drafted new interim regulations for Australian 18 channel transceivers. The new RB249 regulations came into effect on January 1, 1978, and

16129-441: Was used by paging services . American CB licensees were initially required to apply for a temporary license to operate in Canada. In April 1977, the service was expanded to the same 40 channels as the American service. In Indonesia , CB radios were first introduced about 1977 when some transceivers were imported illegally from Australia, Japan and the United States. The dates are hard to confirm accurately, but early use

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