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| [[Image:Ldg-antenna-tuner-0a.jpg|thumb|300px|Automatic ATU for [[Amateur radio|amateur]] transceiver|alt=Inside of antenna tuner, viewed from above]]
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| [[Image:Kenwood-antenna-tuner-inside.jpg|thumb|300px|alt=Gray cabinet front panel with knobs, meter and switches|Antenna tuner front view, with partially exposed interior]]
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| [[Image:MFJ_tuner.jpg|thumb|300px|alt=Backlit cross-needle SWR meter|Cross-needle SWR meter on antenna tuner]]
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| {{Antennas|Components of Antenna Systems}}
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| An '''antenna tuner''', '''transmatch''' or '''antenna tuning unit''' ('''ATU''') is a device connected between a [[radio transmitter]] or receiver and its [[radio antenna|antenna]] to improve power transfer between them by [[Impedance matching|matching]] the [[Electrical impedance|impedance]] of the radio to the antenna. An antenna tuner matches a transceiver with a fixed impedance (typically 50 [[ohm]]s for modern transceivers) to a load (feed line and [[antenna (radio)|antenna]]) impedance which is unknown, complex or otherwise does not match. An ATU allows the use of one antenna on a broad range of frequencies. An antenna and transmatch are not as efficient as a [[Electrical resonance|resonant]] antenna due to feedline losses due to the [[Standing wave ratio|SWR]] (multiple reflections) and losses in the ATU itself. An ATU is an antenna matching unit, and cannot change the resonant frequency of the aerial. Similar matching networks are used in other equipment (such as [[linear amplifier]]s) to transform impedance.
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| == {{anchor|Basic principle of wide-band designs}}Wideband design ==
| | A new Tribe is the a great number strong of all will probably have the planet (virtual) at your toes, and all that with solely a brief on-line on the web that may direct somebody step by step when how to get our company's cheat code for Intervene of Tribes.<br><br>Develop a gaming program for the children. Similar to compulsory assignments time, this motion picture game program will benefit manage a child's tradition. When the times have first been set, stick to all the schedule. Do Not necessarily quite back as a product of whining or asking. If you have any queries regarding where by and how to use clash of clans cheat; [http://prometeu.net prometeu.net],, you can get hold of us at our site. The schedule is only successful if you just follow-through.<br><br>To take pleasure from unlimited points, resources, loose change or gems, you definite necessity download the clash of clans hack into tool by clicking regarding the button. Depending regarding the operating system that tend to be using, you will be required to run the downloaded file for as administrator. Give you log in ID and select the device. Looking for this, you are ought to enter the number behind gems or coins that you want to get.<br><br>Principally clash of clans hack into tool no survey devises believe in among some people. Society definitely is definitely powered by expert pressure, one of the most powerful forces using the planet. Like long as peer pressure utilizes its power for good, clash of clans hack tool no feedback survey will have its store in community.<br><br>Golf season is here and furthermore going strong, and similar many fans we incredibly long for Sunday afternoon when the games begin. If you have played and liked Soul Caliber, you will love this particular game. The upcoming best is the Food Cell which will randomly fill in some sqs. Defeating players similar to that of that by any means necessary can be each of our reason that pushes them to use Words with the Friends Cheat. Your current app requires you to answer 40 questions using varying degrees of hard times.<br><br>For you to access it into excel, copy-paste this continued formula into [http://Www.twitpic.com/tag/corpuscle corpuscle] B1. If you again reach an majority of period in abnormal in corpuscle A1, the bulk to treasures will arise in B1.<br><br>One particular amend additionally permits you to access the ability from the Sensei application buffs available with the Dojo vs. Dojo win band technique. Furthermore, it introduces brand new customized headgear and equipment, new barrio and safeguarding, and new assemblage improvements. |
| For systems requiring a wide [[frequency]] range (such as some solid-state power amplifiers operating from 1–30 MHz), a series of wideband transformers wound on [[Ferrite (magnet)|ferrite]] cores can be used. This design has the advantage of not requiring retuning when the operating frequency is changed. This design can match an antenna to a [[transmission line]]; while it does not require retuning, it is incapable of fine adjustment. These networks may extend the useful range of a conventional, narrowband ATU.
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| In solid-state RF power-amp design, these networks are useful because [[MOSFET]]s and [[bipolar junction transistor]]s are designed to operate with low resistance. [[Valved RF amplifiers]] are different, because the design load resistance of a valve is normally much greater; therefore, for certain power requirements the design of the circuit may differ.
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| An [[autotransformer]] has three identical windings on a ferrite core. If the right-hand side was connected to a resistive load of 10 ohms, the user can attach a source of different impedance at each of the terminals on the left side of the transformer.
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| [[Image:widebandatu.svg|300px|centre|thumb|1:1, 1:4 and 1:9 autotransformer|alt=Schematic diagram of automatic transformer]]
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| =={{anchor|Basic principle of narrow-band designs}}Narrowband design==
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| Devices based on lumped components and transmission lines can be purchased or constructed. The simplest example of a transmission-line-based system is the [[transformer]] formed by a quarter-[[wavelength]] of mismatched transmission line. If a quarter-wavelength of 75Ω coaxial cable is linked to a 50Ω load, the [[standing wave ratio|SWR]] in the 75Ω quarter wavelength of line can be calculated as 75Ω / 50Ω = 1.5; the quarter-wavelength of line transforms the mismatched impedance to 112.5Ω (75Ω x 1.5 = 112.5Ω).
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| The basic circuit required when lumped capacitances and inductors are used is shown below.
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| [[Image:basicnetworkatu.svg|300px|centre|thumb|Basic network|alt=Schematic diagram of basic matching network]]
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| This basic network is able to act as an [[Electrical impedance|impedance]] transformer. If the output has an impedance consisting of R<sub>load</sub> and jX<sub>load</sub>, while the input is to be attached to a source which has an impedance of R<sub>source</sub> and jX<sub>source</sub>
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| Then
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| <math>X_L = \sqrt{\Big(R_{source}+jX_{source}\Big)\Big((R_{source}+jX_{source})-(R_{load}+jX_{load})\Big)}</math>
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| and
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| <math>X_C = (R_{load}+jX_{load})\sqrt{\frac{(R_{source}+jX_{source})}{(R_{load}+jX_{load})-(R_{source}+jX_{source})}}</math>
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| In this example, circuit X<sub>L</sub> and X<sub>c</sub> can be swapped. All the ATU circuits below create this network, which exists between systems with different impedances.
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| For instance, if the source has a resistive impedance of 50Ω and the load has a resistive impedance of 1000Ω:
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| <math>X_L = \sqrt{(50)(50-1000)} = \sqrt{(-47500)}= j\, 217.94\ Ohms</math>
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| <math>X_C = 1000 \sqrt{\frac{50}{(1000-50)}} = 1000\,\times\,0.2294\ Ohms = 229.4\ Ohms</math>
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| If the frequency is 28 MHz,
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| As,
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| <math>X_C = \frac{1}{2\pi fC}</math>
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| then, <math>2\pi fX_C = \frac{1}{C}</math>
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| So, <math>\frac{1}{2\pi fX_C} = C = 24.78\ pF</math>
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| While as, <math>X_L = 2\pi fL\!</math>
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| then, <math> L = \frac{X_L}{2\pi f} = 1.239\ \mu H</math>
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| ==={{anchor|How it works}}Theory and practice===
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| A parallel network, consisting of a resistive element (1000Ω) and a reactive element (-j 229.415Ω), will have the same impedance and power factor as a series network consisting of resistive (50Ω) and reactive elements (-j 217.94Ω).
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| [[Image:ATUhowitworks1.svg|300px|centre|thumb|Two networks in a circuit; both have the same impedance|alt=Schematic diagrams of two matching networks with the same impedance]] | |
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| By adding another element in series (which has a reactive impedance of +j 217.94), the impedance is 50Ω (resistive).
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| [[Image:ATUhowitworks2.svg|300px|centre|thumb|Three networks in a circuit, all with the same impedance|alt=Schematic diagrams of three matching networks, all with the same impedance]]
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| =={{anchor|Types of ATU}}Types==
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| ===Ultimate Transmatch===
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| ===={{anchor|Classic circuit}}T network====
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| [[Image:utransmatch.png|300px|centre|thumb|T-network transmatch|alt=Schematic diagram of the Ultimate Transmatch]]
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| The Ultimate Transmatch's name is a misnomer; a better transmatch, the SPC (series-parallel capacitor) circuit, was later designed after it. In all designs, the GND terminal is the terminal where the earth plane ([[ground plane]]) of an antenna should be wired; the ANT terminal is where the vertical element of a [[Marconi Company|Marconi]] aerial should be attached. The configuration, although capable of matching a large impedance range, is a [[high-pass filter]] and will not attenuate spurious radiations above the [[cutoff frequency]]. | |
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| ==== {{anchor|How it works}}Theory and practice ====
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| If a source impedance of 200Ω and a resistive load of 1000Ω is connected (via a capacitor with an impedance of -j200Ω) to the inductor of the transmatch, [[Vector (geometric)|vector]] mathematics can transform this into a [[series and parallel circuits#Parallel circuits|parallel]] network consisting of a resistance of 1040 Ω and a capacitor with an [[admittance]] of 1.9231 x 10<sup>−4</sup> (X<sub>c</sub> = 5200Ω).
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| In the following calculations, all [[phase angle]]s are expressed in [[degree (angle)|degree]]s rather than [[radian]]s. A resistive load (R<sub>L</sub>) of 1000Ω is in series with X<sub>c</sub> -j 200 Ω.
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| <math>Z = \sqrt{R_L^2\ +\ X_C^2} = 1020\, \Omega</math>
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| Phase angle <math>(\theta ) = \tan^{-1}\ (\frac{X_C}{R_L}) = 11.31^\circ </math>
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| Y = 1/Z = 9.8058 x 10<sup>−4</sup>
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| To convert to a parallel network
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| <math>X_C^' = \frac{1}{Y \sin\ \theta }</math>
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| <math>R_L' = \frac{1}{Y \cos\ \theta } = 1040\ \Omega </math>
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| If the reactive component is ignored, a 1040-to-200Ω transformation is needed (according to the equations above, an inductor of +j507.32Ω). If the effect of the capacitor (from the parallel network) is taken into account, an inductor of +j462.23Ω is needed. The system can then be mathematically transformed into a series network of 199.9Ω resistive and +j409.82Ω.
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| A capacitor (-j409.82) is needed to complete the network.
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| [[Image:utranshowitworks1.png|300px|centre|thumb|Circuit as seen by user; parts impedance shown on diagram|alt=Schematic diagram of original Ultimate Transmatch circuit]]
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| [[Image:utranshowitworks2.png|300px|centre|thumb|After one transformation (unlabeled part impedance is -j 5200Ω)|alt=Schematic diagram after the first of four transformations]]
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| [[Image:utranshowitworks3.png|300px|centre|thumb|After two transformations|alt=Schematic diagram after two transformations]]
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| [[Image:utranshowitworks4.png|300px|centre|thumb|After three transformations|alt=Schematic diagram after three transformations]]
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| [[Image:utranshowitworks5.png|300px|centre|thumb|After four transformations|alt=Schematic diagram after four transformations]]
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| ====Pi network====
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| A pi network can also be used:
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| [[Image:pimatch.png|300px|centre|thumb|Similar circuit to the Ultimate Transmatch|alt=Schematic diagram of pi-network antenna tuner]]
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| ===SPC tuner===
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| [[Image:SPCmatch.png|300px|centre|thumb|SPC transmatch|alt=Schematic diagram of SPC antenna tuner]]
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| ===Z match===
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| The Z-Match is a widely used ATU in amateur radio.<ref>Z-Match-Antennenkoppler für hohe Leistungen (DL3BCU) http://www.mydarc.de/dk7zb/Tuner/zmatch.htm</ref><ref>Balanced Line Tuner http://www.qrpkits.com/blt_plus.html</ref><ref>ZM-4 http://www.qrpproject.de/ZM4.html</ref>
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| =={{anchor|Connecting an ATU}}Connection==
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| An ATU is typically connected between the antenna and the [[radio]] [[transmitter]] or [[receiver (radio)|receiver]].<ref>[http://www.webcitation.org/62nYQYsdn Dave Miller, "Back to Basics". ''QST'', August 1995]</ref> The antenna feedpoint is usually high in the air (for example, a [[dipole antenna]]) or far away (for example, an end-fed [[random wire antenna]]). An automatic antenna tuner in a weather-proof case is convenient for these installations. An ATU can also be connected between the feedline and the antenna to minimize loss, or between the feedline and the radio for convenience; however, feedline SWR must be considered in the latter configuration. With an ATU, it is possible to match a wide range of antennas<ref>HF Users Guide (SGC) http://www.sgcworld.com/Publications/Books/hfguidebook.pdf</ref> (including stealth antennas).<ref>Stealth Kit (SGC) http://www.sgcworld.com/Publications/Manuals/stealthman.pdf</ref><ref>Smart Tuners for Stealth Antennas (SGC) http://www.sgcworld.com/Publications/Books/stealthbook.pdf</ref>
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| == {{anchor|ATU and SWR}}Standing wave ratio ==
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| It is a common misconception that a high standing wave ratio (SWR) ''per se'' causes loss.<ref>M. Walter Maxwell, ''Reflections: Transmission Lines and Antennas''. Newington, Connecticut: American Radio Relay League (1990) ISBN 978-0-87259-299-5</ref> An antenna with a high SWR (4:1, for example), when properly configured with an ATU, may have only a small percentage of additional loss compared with an intrinsically matched antenna.<ref>Jerry Hall, ed. ''ARRL Antenna Book''. Newington, Connecticut: American Radio Relay League (1988), p. 25-18ff. ISBN 978-0-87259-206-3</ref> The ATU redirects reflected energy along the feedline and antenna path; additional losses are inherent to the feedline and antenna. SWR causes feedline losses to be multiplied; low-loss feedline has minimal loss with an ATU, but a "lossy" feedline-antenna combination with an identical SWR may have significant loss. A balanced feedline exhibits less loss than coaxial line in the presence of high SWR, so a tuner is primarily used with the former.
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| Without an ATU, SWR from a mismatched antenna could cause power reflection back to the transmitter; this causes heating and power loss.
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| While solid-state power stages perform poorly with an SWR above 1.5, an antenna SWR of 2:1 means that 11 percent of transmitted power is reflected and 89 percent sent forward through the antenna.
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| =={{anchor|Applications of ATU}}Broadcast Applications ==
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| ===AM broadcast transmitters ===
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| One of the oldest applications for antenna tuners is in AM and shortwave broadcasting transmitters. AM transmitters usually use a vertical antenna (tower) which can be from .2 to .68 wavelengths long. At the base of the tower an ATU is used to match the antenna to the 50 ohm transmission line from the transmitter. The most commonly used circuit is a T network, using two series inductors with a shunt capacitor between them. When multiple towers are used, the ATU network may also provide for a phase adjustment, so that the currents in each tower can be phased relative to the others to produce a desired pattern. These patterns are often required by law to include nulls in directions that could produce interference as well as to increase the signal in the target area. Adjustment of the ATUs in a multitower array is a complex and time consuming process requiring considerable expertise. | |
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| === {{anchor|Sample application: multiband shortwave transmitter}}High-power shortwave transmitters ===
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| For International Shortwave (50 kW and above), frequent antenna tuning is done as part of frequency changes which may be required on a seasonal or even a daily basis. Shortwave transmitters typically include in their design the ability to match impedances up to 2:1 SWR. Modern transmitters can do this retuning within 15 seconds.
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| 300 ohm balanced transmission lines are more or less standard for shortwave transmitters and antennas, although other values can be found. The transmitter networks incorporate a balun or an external one is installed at the transmitter.
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| The most commonly used shortwave antennas for international broadcasting are the
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| [[HRS antenna]] (curtain array), which cover a 2 to 1 frequency range and the [[log-periodic antenna]] which cover up to 8 to 1 frequency range. Within that range, the SWR will vary, but is usually kept below 1.7 to one, thus the transmitter will be able to tune itself as needed to match at any frequency.
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| ==See also==
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| * [[American Radio Relay League]]
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| * [[Electrical lengthening]]
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| * [[Impedance bridging]]
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| * [[Loading coil]]
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| * [[Preselector]]
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| * [[Smith chart]]
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| ==References==
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| {{Reflist}}
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| ==Bibliography==
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| *''An introduction to Antenna Theory (BP198)'', H.C Wright. Bernard Babani, London, 1987.
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| *''The Radio communication handbook (5th ed), RSGB, 1976, ISBN 0-900612-58-4.
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| *Ulrich L. Rohde : "Die Anpassung von kurzen Stabantennen für KW-Sender " (Matching of short Rod-Antennas for short-wave transmitters), Funkschau 1974, Issue 7.
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| *Ulrich L. Rohde : "Match any Antenna over the 1.5 to 30 MHz Range with Only Two Adjustable Elements ", Electronic Design 19, September 13, 1975
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| ==External links==
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| *[http://www.arrl.org ARRL website]
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| *[http://dxradio.50webs.com/ The SWDXER, with general SWL information and antenna tips]
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| *[https://www.youtube.com/watch?v=ibAIDNcPKh8 What tuners do and a look inside ]
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| {{DEFAULTSORT:Antenna Tuner}}
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| [[Category:Antennas (radio)|Tuner]]
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| [[Category:Wireless tuning and filtering]]
| |
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