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36-465: BTS is also referred to as the node B (in 3G networks) or, simply, the base station (BS). For discussion of the LTE standard the abbreviation eNB for evolved node B is widely used, and GNodeB for 5G. Though the term BTS can be applicable to any of the wireless communication standards, it is generally associated with mobile communication technologies like GSM and CDMA. In this regard, a BTS forms part of

72-813: A spherical radiation pattern. Omnidirectional antennas oriented vertically are widely used for nondirectional antennas on the surface of the Earth because they radiate equally in all horizontal directions, while the power radiated drops off with elevation angle so little radio energy is aimed into the sky or down toward the earth and wasted. Omnidirectional antennas are widely used for radio broadcasting antennas, and in mobile devices that use radio such as cell phones , FM radios , walkie-talkies , wireless computer networks , cordless phones , GPS , as well as for base stations that communicate with mobile radios, such as police and taxi dispatchers and aircraft communications. The most common omnidirectional antenna designs are

108-435: A 'circular aerial' because of the shape) and the halo antenna . Higher-gain omnidirectional antennas can also be built. "Higher gain" in this case means that the antenna radiates less energy at higher and lower elevation angles and more in the horizontal directions. High-gain omnidirectional antennas are generally realized using collinear dipole arrays . These consist of multiple half-wave dipoles mounted collinearly (in

144-478: A dipole, or a quarter-wave whip with an adequate size ground plane. Whips not mounted on the radio itself are usually fed with coaxial cable feedline of 50 ohm or 75 ohm impedance. In transmitting antennas the impedance of the antenna must be matched to the feedline for maximum power transfer. A half wave whip antenna (length of 1 2 λ {\displaystyle {\tfrac {1}{2}}\lambda } ) has somewhat higher gain than

180-571: A line), fed in phase. The coaxial collinear (COCO) antenna uses transposed coaxial sections to produce in-phase half-wavelength radiators. A Franklin Array uses short U-shaped half-wavelength sections whose radiation cancels in the far-field to bring each half-wavelength dipole section into equal phase. Another type is the Omnidirectional Microstrip Antenna (OMA). Omnidirectional radiation patterns are produced by

216-495: A perfectly conducting ground plane under it maximum field strength is in horizontal directions, falling monotonically to zero on the axis. With a small or imperfectly conducting ground plane or no ground plane under it, the general result is to tilt the main lobe up so maximum power is no longer radiated horizontally but at an angle into the sky. Antennas longer than a half-wavelength have patterns consisting of several conical "lobes"; with radiation maxima at several elevation angles;

252-441: A quarter wave ground plane antenna with horizontal ground wires is around 22 ohms, a poor match to coaxial cable feedline, and the main lobe of the radiation pattern is still tilted up toward the sky. Often (see pictures) the ground plane rods are sloped downward at a 45-degree angle, which has the effect of lowering the main lobe of the radiation pattern so more of the power is radiated in horizontal directions, and increases

288-416: A quarter wave whip, but it has a current node at its feedpoint at the base of the rod so it has very high input impedance. If it was infinitely thin the antenna would have an infinite input impedance, but the finite width gives typical, practical half wave whips an impedance of 800–1,500 ohms. These are usually fed through an impedance matching transformer or a quarter wave stub matching section (e.g.

324-462: A quarter-wavelength long connected to the opposite side of the feedline, extending horizontally from the base of the whip, is often used. This is called a ground plane antenna . These few short wire elements serve to receive the displacement current from the driven element and return it to the ground conductor of the transmission line, making the antenna behave somewhat as if it has a continuous conducting plane under it. The radiation resistance of

360-403: A quarter-wavelength, and still be resonant , by cancelling out the capacitive reactance of the short antenna. This is called an electrically short whip . The coil is added at the base of the whip (called a base-loaded whip) or occasionally in the middle (center-loaded whip). In the most widely used form, the rubber ducky antenna , the loading coil is integrated with the antenna itself by making

396-417: A separate direction of tracking, typically of 120° with respect to the adjacent ones. Other orientations may be used to suit the local conditions. Bisectored cells are also implemented. These are most often oriented with the antennas serving sectors of 180° separation to one another, but again, local variations do exist. Omnidirectional antenna In radio communication , an omnidirectional antenna

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432-414: A whip antenna is determined by the wavelength of the radio waves it is used with. Their length varies from compact electrically short antennas ⁠ 1 / 10  ⁠  wavelength long, up to ⁠ 5  / 8 ⁠   wavelength to improve directivity. The most common type is the quarter-wave whip , which is approximately ⁠ 1  / 4 ⁠ wavelength long. Whips are

468-408: Is a monopole antenna , and like a vertical dipole has an omnidirectional radiation pattern , radiating equal radio power in all azimuthal directions (perpendicular to the antenna's axis), with the radiated power falling off with elevation angle to zero on the antenna's axis. Whip antennas less than one-half wavelength long, including the common quarter wave whip, have a single main lobe , and with

504-440: Is a class of antenna which radiates equal radio power in all directions perpendicular to an axis ( azimuthal directions), with power varying with angle to the axis ( elevation angle ), declining to zero on the axis. When graphed in three dimensions (see graph) this radiation pattern is often described as doughnut-shaped . This is different from an isotropic antenna , which radiates equal power in all directions, having

540-404: Is because they transmit (or receive) equally well in all horizontal directions, while radiating little radio energy up into the sky where it is wasted. Whip antennas are normally designed as resonant antennas; the rod acts as a resonator for radio waves, with standing waves of voltage and current reflected back and forth from its ends. Therefore, the length of the antenna rod is determined by

576-468: Is designed to be flexible so that it does not break easily, and the name is derived from the whip -like motion that it exhibits when disturbed. Whip antennas for portable radios are often made of a series of interlocking telescoping metal tubes, so they can be retracted when not in use. Longer whips, made for mounting on vehicles and structures, are made of a flexible fiberglass rod around a wire core and can be up to 11 m (35 feet) long. The length of

612-404: Is never approached in actual antennas unless the ground plane is many wavelengths in diameter. 2 dBi is more typical for a whip with a ground plane of 1 2 λ   . {\displaystyle {\tfrac {1}{2}}\lambda ~.} Whips mounted on vehicles use the metal skin of the vehicle as a ground plane. In hand-held devices usually no explicit ground plane

648-449: Is possible with coils at about one-half or one-third and two-thirds that do not affect the aerial much at the lowest band, but it creates the effect of stacked dipoles at a higher band (usually ×2 or ×3 frequency). At higher frequencies the feed coax can go up the centre of a tube. The insulated junction of the tube and whip is fed from the coax and the lower tube end where coax cable enters has an insulated mount. This kind of vertical whip

684-426: Is provided, and the ground side of the antenna's feed line is just connected to the ground (common) on the device's circuit board. Therefore, the radio itself serves as a rudimentary ground plane. If the radio chassis is not a good deal larger than the antenna itself, the combination of whip and radio functions more as an asymmetrical dipole antenna than as a monopole antenna . The gain will be somewhat lower than

720-470: Is split into a horizontal lobe and a small second lobe at a 60° angle, so high angle radiation is poor. The input impedance is around 40 ohms. In a whip antenna not mounted on a conductive surface, such as one mounted on a mast, the lack of reflected radio waves from the ground plane causes the lobe of the radiation pattern to be tilted up toward the sky so less power is radiated in horizontal directions, undesirable for terrestrial communication. Also

756-451: The J-pole antenna ). An advantage is that because it acts as a dipole it does not need a ground plane. The maximum horizontal gain of a monopole antenna is achieved at a length of five eighths of a wavelength 5 8 λ {\displaystyle {\tfrac {5}{8}}\lambda } so this is also a popular length for whips. However at this length the radiation pattern

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792-401: The monopole antenna , consisting of a vertical rod conductor mounted over a conducting ground plane , and vertical dipole antenna , consisting of two collinear vertical rods. The quarter-wave monopole and half-wave dipole both have vertical radiation patterns consisting of a single broad lobe with maximum radiation in horizontal directions, so they are popular. The quarter-wave monopole,

828-415: The wavelength ( λ {\displaystyle \lambda } ) of the radio waves used. The most common length is approximately one-quarter of the wavelength ( 1 4 λ {\displaystyle {\tfrac {1}{4}}\lambda } ), called a "quarter-wave whip" (although often shortened by the use of a loading coil ; see Electrically short whips below). For example,

864-458: The BTS remains the same regardless of the wireless technologies. A BTS is usually composed of: Directional antennas reduce LoRa (long-range) interference. If not sectorised, the cell will be served by an omnidirectional antenna , which radiates in all directions. A typical structure is the trisector, also known as clover, in which there are three sectors served by separate antennas. Each sector has

900-431: The assumption of a sin ⁡ ( b θ ) / b θ {\displaystyle \sin(b\theta )/{b\theta }} pattern shape is: Whip antenna A whip antenna is an antenna consisting of a straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter . A whip antenna is a form of monopole antenna . The antenna

936-444: The base station subsystem (BSS) developments for system management. It may also have equipment for encrypting and decrypting communications, spectrum filtering tools (band pass filters) and so on. Antennas may also be considered as components of BTS in general sense as they facilitate the functioning of BTS. Typically a BTS will have several transceivers (TRXs) which allow it to serve several different frequencies and different sectors of

972-491: The cell (in the case of sectorised base stations). A BTS is controlled by a parent base station controller via the base station control function (BCF). The BCF is implemented as a discrete unit or even incorporated in a TRX in compact base stations. The BCF provides an operations and maintenance (O&M) connection to the network management system (NMS), and manages operational states of each TRX, as well as software handling and alarm collection. The basic structure and functions of

1008-631: The common quarter-wave whip antennas used on FM radios in the USA are approximately 75 cm (2.5 feet) long, which is roughly one-quarter the length of radio waves in the FM radio band, which are 2.78 to 3.41 m (9 to 11 feet) long. Half-wave whips ( 1 2 λ {\displaystyle {\tfrac {1}{2}}\lambda } long) which have greater gain , and five-eighth wave whips ( 5 8 λ {\displaystyle {\tfrac {5}{8}}\lambda } long) which have

1044-413: The input impedance for a good match to standard 50-ohm coaxial cable . To match 75-ohm coaxial cable, the ends of the ground plane can be turned downward or a folded monopole driven element can be used. To reduce the length of a whip antenna to make it less cumbersome, an inductor ( loading coil ) is often added in series with it. This allows the antenna to be made much shorter than the normal length of

1080-523: The longer the electrical length of the antenna, the more lobes the pattern has. A vertical whip radiates vertically polarized radio waves, with the electric field vertical and the magnetic field horizontal. Vertical whip antennas are widely used for nondirectional radio communication on the surface of the Earth, where the direction to the transmitter (or the receiver) is unknown or constantly changing, for example in portable FM radio receivers, walkie-talkies , and two-way radios in vehicles. This

1116-462: The maximum horizontal gain achievable by a monopole, are also common lengths. The gain and input impedance of the antenna is dependent on the length of the whip element, compared to a wavelength, but also on the size and shape of the ground plane used (if any). A quarter wave vertical antenna working against a perfectly conducting, infinite ground will have a gain of 5.19  dBi and a radiation resistance of about 36.8  ohms . However this gain

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1152-590: The most common type of monopole antenna , and are used in the higher frequency HF , VHF and UHF radio bands. They are widely used as the antennas for hand-held radios, cordless phones , walkie-talkies , FM radios , boom boxes , and Wi-Fi enabled devices, and are attached to vehicles as the antennas for car radios and two-way radios for wheeled vehicles and for aircraft. Larger versions mounted on roofs, balconies and radio masts are used as base station antennas for amateur radio and police, fire, ambulance, taxi, and other vehicle dispatchers. The whip antenna

1188-591: The most compact resonant antenna, may be the most widely used antenna in the world. The five-eighth wave monopole, with a length of 5 / 8 = 0.625 {\displaystyle 5/8=0.625} of a wavelength, is also popular because at that length a monopole radiates maximum power in horizontal directions. Common types of low-gain omnidirectional antennas are the whip antenna , "Rubber Ducky" antenna , ground plane antenna , vertically oriented dipole antenna , discone antenna , mast radiator , horizontal loop antenna (sometimes known colloquially as

1224-470: The simplest practical antennas, monopole and dipole antennas , consisting of one or two straight rod conductors on a common axis. Antenna gain (G) is defined as antenna efficiency (e) multiplied by antenna directivity (D) which is expressed mathematically as: G = e D {\displaystyle G=eD} . A useful relationship between omnidirectional radiation pattern directivity (D) in decibels and half-power beamwidth (HPBW) based on

1260-405: The unbalanced impedance of the monopole element causes RF currents in the supporting mast and on the outside of the ground shield conductor of the coaxial feedline, causing these structures to radiate radio waves, which usually has a deleterious effect on the radiation pattern. To prevent this, with stationary whips mounted on structures, an artificial "ground plane" consisting of three or four rods

1296-441: The whip out of a narrow helix of springy wire. The helix distributes the inductance along the antenna's length, improving the radiation pattern, and also makes it more flexible. Another alternative occasionally used to shorten the antenna is to add a "capacity hat", a metal screen or radiating wires, at the end. However all these electrically short whips have lower gain than a full-length quarter-wave whip. Multi-band operation

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