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A wire antenna kit, with a coil of wire, strain insulators and a balun. When installed the wire is supported by buildings or trees using the insulators to prevent a short circuit to ground.

A random wire antenna is a radio antenna consisting of a long wire suspended above the ground, whose length does not bear a particular relation to the wavelength of the radio waves used, but is typically chosen more for convenient fit between the available supports, or the length of wire at hand, rather than selecting length to be resonant on any particular frequency. The wire may be straight or it may be strung back and forth between trees or walls just to get as much wire into the air as feasible. Due to the great variability of the (unplanned) antenna structure, the random wire’s effectiveness can vary erratically from one installation to another, and a single random wire antenna can have wildly different reception / transmission strength in one direction than it achieves in another azimuth direction about 70°~140° different, and finally reception / transmission strengths and directions can be wildly different on only moderately different frequencies. Random wire antennas are typically fed at one end against a suitable counterpoise (such as earth ground or a parallel wire hidden under the grass below the elevated antenna wire).

They are widely used as receiving antennas on the long wave, medium wave, and short wave bands, as well as transmitting antennas on these bands for small outdoor, temporary or emergency transmitting stations, as well as in situations where more permanent antennas cannot be installed.

Random wire and long wire

Often random wire antennas are also (inaccurately) referred to as long-wire antennas. There is no accepted minimum size, but actual long-wire antennas must be greater than at least a quarter-wavelength (⁠ 1 / 4 ⁠ $λ$ ) or perhaps greater than a half (⁠ 1 / 2 ⁠ $λ$ ) at the frequency the long wire antenna is used for, and even a half-wave may only be considered "long-ish" rather than "truly" long; the required lower size limit depends on the book consulted. Most sources consider a "true" long wire to be at least one wavelength,^[1] whereas random wire antennas involve no such confusion.^[2] Further confusing the issue, if an antenna is used over a wide range of frequencies, some writers may technically qualify it as a long wire at the shorter wavelengths but not at the longer. The term random wire raises no such quibbles: Its only requirement is that the antenna length was not planned for resonance at a particular interesting frequency.

Although antennas an odd numbers of quarter-wavelengths long are easy to feed, when the length of the wire is near an even multiple of a ⁠ 1 / 4 ⁠ wave, its feedpoint impedance may take on thousands of Ohms of both reactance and resistance due to antiresonance – extreme values which can exceed the ranges where conventional impedance matching schemes are adequate. The radiation efficiency of the antenna is not changed, despite high resistance; if the antenna had been fed transmit power against a resistive counterpoise (such as a poor ground) and an appropriate matching system is used, the efficiency of the antenna system may actually increase significantly. Based on these considerations, operator W0IPL developed a table of usable odd multiple lengths and un usable even multiple lengths for HF frequencies assigned to amateurs, and then selected a compromise among all of them as an ideal work-any-band length of 74 feet (22.56 m) for the amateur radio HF bands.^[3] Hence ~74 feet (22.6 m) is a carefully selected non-random length preferred for an HF "random" length antenna. Another favored length is 100 feet (30.5 m).^[1]

Radiation pattern

The radiation pattern of a thin wire antenna is easily predictable using antenna modeling. For a straight wire, the radiation pattern can be described by axially symmetric multipole moments with no component along the wire direction; as the length of the wire is increased, higher multipole contributions become more prominent and multiple lobes (maxima) at angles to the antenna axis develop.^[4] Under about 0.6 $λ$ a wire antenna will have a single lobe with a maximum at right angles to the axis. Above this the lobe will split into two conical lobes with their maximum directed at equal angles to the wire, and a null between them. This results in four azimuth angles at which the gain is maximum. As the length of wire in wavelengths increases, the number of lobes increases and the maxima become increasingly sharp.

Any unpredictability of the radiation pattern is caused by uncontrolled interaction with nearby matter (such as soil or structures). For example, a long wire antenna close to the ground will form a leaky two-conductor transmission line and therefore also act somewhat as a traveling wave antenna, with reception off the end of the wire (the system is no longer axially symmetric). A folded or zig-zag antenna may exhibit a more complex pattern as there are even fewer symmetry constraints on the dipole moments that may contribute.

Long wire antennas are reported to be more effective for reception than multi-element antennas such as Yagi or quad antennas with the same length of wire.

Construction

A random wire antenna usually consists of a long (at least one quarter wavelength) wire with one end connected to the radio and the other in free space, arranged in any way most convenient for the space available. Ideally, it is strung as high as possible between trees or buildings, with any bends as obtuse as possible, and with the ends insulated from supports.^[a]^[b]

If used for transmitting, a random wire antenna usually will also require an antenna tuner, as it has an unpredictable impedance that varies with frequency.^[1] One side of the output of the tuner is connected directly to the antenna, without a transmission line, the other to a good earth ground. A wire near an odd number of a quarter-waves in length works best; in contrast, a wire near an even number of quarter-wavelengths long, although fine for receiving, on transmit will exceed the matching ability of most small tuners, unless first fed through an unun with a large transform ratio.^[5]^[6] Even without a good earth, the antenna will still radiate, although poorly; it will do so by capacitively coupling to any nearby conducting material; this is not recommended.^[7]

The ground for a random wire antenna may be chosen by experimentation. The antenna tuner ground could be connected to a nearby cold water pipe (if the pipe used reaches the soil via an all-steel or all-copper segment) or one or several wires laid on the floor or ground, one of which is approximately one-quarter wavelength long, or the ground can be connected to one or several randomly laid-out counterpoise wires under the antenna, at least one of which is a quarter-wavelength.^[1]

Footnotes

^ Any available wire will do for as long as it happens to stay up, and for lengths strung up indoors there are essentially no wire-quality requirements, other than it must conduct electricity only to the radio. The best possible outdoor wire is copper-clad steel wire covered with UV-safe insulation, sized AWG 12 or 14 – diameter 1.6 to 2.0 mm (0.063 to 0.079 in). But the extra expense may not be warranted: If put up outdoors, even the best-made wire will eventually be blown down and have to be restrung. To alleviate stress that wind gusts put on any kind of wire erected outdoors, it is usual to attach the wire at its supports with some kind of strain relief, such as spring-loaded strain insulators, or weight and pulley systems to hold the wire in tension, but yield to unexpected loads added to the wire, such as ice.
^ Folding the wire into a zigzag pattern, with acute angles, to fit in a limited space such as an apartment or attic will reduce effectiveness and make theoretical analysis extremely difficult – however the added length typically helps more than the acute folding hurts, and zig-zagging in the last third or quarter of the wire near the antenna's far end is not much trouble at frequencies where the antenna is between about a quarter to a half-wave long.

References

^ ^a ^b ^c ^d Straw, R. Dean; et al., eds. (2003). The ARRL Antenna Book (20th ed.). Newington, CT: The American Radio Relay League. p. 944. ISBN 0-87259-904-3.
^ Carr, J. Practical Antenna Handbook. McGraw Hill. Chapter 9.
^ ""Random" length". w0ipl.net. Wire antennas.
^ Silver, Ward; et al., eds. (2007). The ARRL General Class License Manual (6th ed.). Newington, CT: The American Radio Relay League. p. 6.6. ISBN 978-087259996-3 – via Google Books.
^ "The "almost random" wire antenna". kb6nu.com. 12 March 2007.
^ "Random length wire". w0ipl.net. NVIS.
^ Yates, Steve (AA5TB). "End-fed half wave antenna". aa5tb.com.{{cite web}}: CS1 maint: numeric names: authors list (link)

[5] Any available wire will do for as long as it happens to stay up, and for lengths strung up indoors there are essentially no wire-quality requirements, other than it must conduct electricity only to the radio. The best possible outdoor wire is copper-clad steel wire covered with UV-safe insulation, sized AWG 12 or 14 – diameter 1.6 to 2.0 mm (0.063 to 0.079 in). But the extra expense may not be warranted: If put up outdoors, even the best-made wire will eventually be blown down and have to be restrung. To alleviate stress that wind gusts put on any kind of wire erected outdoors, it is usual to attach the wire at its supports with some kind of strain relief, such as spring-loaded strain insulators, or weight and pulley systems to hold the wire in tension, but yield to unexpected loads added to the wire, such as ice.

[6] Folding the wire into a zigzag pattern, with acute angles, to fit in a limited space such as an apartment or attic will reduce effectiveness and make theoretical analysis extremely difficult – however the added length typically helps more than the acute folding hurts, and zig-zagging in the last third or quarter of the wire near the antenna's far end is not much trouble at frequencies where the antenna is between about a quarter to a half-wave long.

[ARRL-Antenna-Book-1] Straw, R. Dean; et al., eds. (2003). The ARRL Antenna Book (20th ed.). Newington, CT: The American Radio Relay League. p. 944. ISBN 0-87259-904-3.

[2] Carr, J. Practical Antenna Handbook. McGraw Hill. Chapter 9.

[3] ""Random" length". w0ipl.net. Wire antennas.

[Silver-4] Silver, Ward; et al., eds. (2007). The ARRL General Class License Manual (6th ed.). Newington, CT: The American Radio Relay League. p. 6.6. ISBN 978-087259996-3 – via Google Books.

[7] "The "almost random" wire antenna". kb6nu.com. 12 March 2007.

[8] "Random length wire". w0ipl.net. NVIS.

[9] Yates, Steve (AA5TB). "End-fed half wave antenna". aa5tb.com.{{cite web}}: CS1 maint: numeric names: authors list (link)

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@@ Line 1: / Line 1: @@
-[[File:Long-wire-and-balun-0a.jpg|thumb|right|A wire antenna kit, with a coil of wire,  [[strain insulator]]s and a [[balun]].  When installed the wire is supported by buildings or trees using the insulators to prevent a short circuit to ground.]]
+{{Short description|A radio antenna consisting of a long wire suspended above the ground}}
+[[File:Long-wire-and-balun-0a.jpg|thumb|right|A wire antenna kit, with a coil of wire,  [[strain insulator]]s and a [[balun]]. When installed the wire is supported by buildings or trees using the insulators to prevent a short circuit to ground.]]
-A '''random wire antenna''' is a [[antenna (radio)|radio antenna]] consisting of a long wire suspended above the ground, whose length does not bear a particular relation to the [[wavelength]] of the radio waves used, but is typically chosen more for convenience. The wire may be straight or it may be strung back and forth between trees or walls just to get enough wire into the air. Due to the great variability of the (unplanned) antenna structure, effectiveness can vary wildly from one installation to another.  Random wire antennas are typically fed at one end against a suitable counterpoise (such as earth [[ground (electricity)|ground]]).
+A '''random wire antenna''' is a [[antenna (radio)|radio antenna]] consisting of a long wire suspended above the ground, whose length does not bear a particular relation to the [[wavelength]] of the radio waves used, but is typically chosen more for convenient fit between the available supports, or the length of wire at hand, rather than selecting length to be resonant on any particular frequency. The wire may be straight or it may be strung back and forth between trees or walls just to get as much wire into the air as feasible. Due to the great variability of the (unplanned) antenna structure, the random wire’s effectiveness can vary erratically from one installation to another, and a single random wire antenna can have wildly different reception / transmission strength in one direction than it achieves in another [[azimuth]] direction about 70°~140°&nbsp;different, and finally reception / transmission strengths and directions can be wildly different on only moderately different frequencies. Random wire antennas are typically fed at one end against a suitable counterpoise (such as earth [[ground (electricity)|ground]] or a parallel wire hidden under the grass below the elevated antenna wire).
 They are widely used as receiving antennas on the [[long wave]], [[medium wave]], and [[short wave]] bands, as well as transmitting antennas on these bands for small outdoor, temporary or emergency transmitting stations, as well as in situations where more permanent antennas cannot be installed.
 == Random wire and long wire ==
-Often '''random wire antennas''' are also (inaccurately) referred to as '''long-wire antenna'''. Actual long-wire antennas require a length greater than a quarter-wavelength (λ/4) or half (λ/2) of the radio waves (most consider a true long wire to be least one wavelength<ref name="ARRLntenna Book" />), whereas random wire antennas have no such constraint.<ref>Practical Antenna Handbook (Carr, Mc Graw Hill) - Chapter 9</ref>
+Often '''random wire antennas''' are also (inaccurately) referred to as ''long-wire antennas''. There is no accepted minimum size, but actual ''long-wire'' antennas must be greater than ''at least'' a quarter-[[wavelength]] ({{small|{{sfrac| 1 | 4 }}}}[[wavelength|{{mvar|λ}}]]) or perhaps greater than a half ({{small|{{sfrac| 1 | 2 }}}}[[wavelength|{{mvar|λ}}]]) at the frequency the long wire antenna is used for, and even a half-wave may only be considered "long-''ish''" rather than "truly" long; the required lower size limit depends on the book consulted. Most sources consider a "true" long wire to be at least one wavelength,<ref name=ARRL-Antenna-Book/> whereas ''random wire antennas'' involve no such confusion.<ref>{{cite book |author=Carr, J. |title=Practical Antenna Handbook |publisher=McGraw Hill |at=Chapter&nbsp;9}}</ref> Further confusing the issue, if an antenna is used over a wide range of frequencies, some writers may technically qualify it as a ''long wire'' at the shorter wavelengths but not at the longer. The term ''random wire'' raises no such quibbles: Its only requirement is that the antenna length was not ''planned'' for [[electrical resonance|resonance]] at a particular interesting frequency.
-When the length of the wire is near an even multiple of quarter-wavelengths, its feedpoint [[Electrical impedance|impedance]] may take on extreme values (thousands of [[ohm]]s) due to [[resonance]], which can cause low efficiency with popular [[impedance matching]] schemes. The radiation efficiency of the wire is not affected; if the antenna is worked against a resistive counterpoise (such as a poor ground) and a suitable matching scheme is used, the efficiency of the antenna system may actually increase significantly. For the [[amateur radio]] HF bands, operator W0IPL developed a table of usable odd multiple lengths, and then down-selected these to pick an ideal work-any-band length of {{convert|74|feet|sigfig=4}}.<ref>{{Cite web|url=http://www.w0ipl.net/ECom/NVIS/random-l.htm|title="Random" Length - Wire Antennas WØIPL}}</ref>
+Although antennas an odd numbers of quarter-wavelengths long are easy to feed, when the length of the wire is near an ''even'' multiple of a {{nobr|{{small|{{sfrac| 1 | 4 }}}} wave,}} its feedpoint [[electrical impedance|impedance]] may take on thousands of [[Ohm (unit)|Ohms]] of both [[electrical reactance|reactance]] and [[electrical resistance|resistance]] due to [[antiresonance]] – extreme values which can exceed the ranges where conventional [[impedance matching]] schemes are adequate. The [[antenna efficiency|radiation efficiency]] of the antenna is not changed, despite high resistance; if the antenna had been fed transmit power against a resistive counterpoise (such as a poor ground) and an appropriate [[antenna tuner|matching system]] is used, the efficiency of the antenna system may actually increase significantly. Based on these considerations, [[radio amateur|operator]] {{sc|W0IPL}} developed a table of usable [[odd number|odd]] multiple lengths and {{nobr|''un''&thinsp;usable}} [[even number|even]] multiple lengths for [[amateur radio frequency allocations#high_frequency_anchor|HF frequencies assigned to amateurs]], and then selected a compromise among all of them as an ideal work-any-band length of {{convert|74|feet|sigfig=4}} for the [[amateur radio]] [[high frequency|HF bands]].<ref>{{cite web |title="Random" length |series=Wire antennas |website=w0ipl.net |url=http://www.w0ipl.net/ECom/NVIS/random-l.htm}}</ref> Hence ~{{convert|74|feet|sigfig=3}} is a carefully selected ''non''-random length preferred for an [[high frequency|HF]] "random" length antenna. Another favored length is {{convert|100|feet|sigfig=3}}.<ref name=ARRL-Antenna-Book/>
 ==Radiation pattern==
-The [[radiation pattern]] of a thin wire antenna is easily predictable using [[computational electromagnetics|antenna modeling]]. For a straight wire, the radiation pattern can be described by [[axially symmetric]] [[multipole moments]] with no component along the along the wire direction; as the length of the wire is increased, higher multipole contributions become more prominent and multiple lobes (maxima) at angles to the antenna axis develop.<ref name="Silver">{{cite book|last=Silver|first=Ward|url=https://books.google.com/books?id=2rvTFmCCshsC&pg=SA6-PA6|title=The ARRL General Class License Manual, 6th Ed.|date=2007|publisher=American Radio Relay League|isbn=978-0872599963|location=USA|pages=6.6}}</ref>    Under about 0.6λ a wire antenna will have a single lobe with a maximum at right angles to the axis.  Above this the lobe will split into two conical lobes with their maximum directed at equal angles to the wire, and a [[null (radio)|null]] between them.  This results in four azimuth angles at which the gain is maximum.  As the length of wire in wavelengths increases, the number of lobes increases and the maxima become increasingly sharp.
+The [[radiation pattern]] of a thin wire antenna is easily predictable using [[computational electromagnetics|antenna modeling]]. For a straight wire, the radiation pattern can be described by [[axially symmetric]] [[multipole moments]] with no component along the wire direction; as the length of the wire is increased, higher multipole contributions become more prominent and multiple lobes (maxima) at angles to the antenna axis develop.<ref name=Silver>
+{{cite book
+ |editor-last=Silver |editor-first=Ward |display-editors=etal
+ |year=2007
+ |title=The ARRL General Class License Manual |edition=6th
+ |place=Newington, CT
+ |publisher=[[The American Radio Relay League]]
+ |isbn=978-087259996-3
+ |page=6.6
+ |url=https://books.google.com/books?id=2rvTFmCCshsC&pg=SA6-PA6
+ |via=Google Books
+}}
+</ref>
+Under about  0.6&nbsp;[[wavelength|{{mvar|λ}}]]  a wire antenna will have a single lobe with a maximum at right angles to the axis. Above this the lobe will split into two conical lobes with their maximum directed at equal angles to the wire, and a [[null (radio)|null]] between them. This results in four azimuth angles at which the gain is maximum. As the length of wire in wavelengths increases, the number of lobes increases and the maxima become increasingly sharp.
-Any unpredictability of the radiation pattern is caused by uncontrolled interaction with nearby matter (such as soil or structures). For example, a long wire antenna close to the ground will form a leaky two-conductor [[transmission line]] and therefore also act somewhat as a [[traveling wave antenna]], with reception off the end of the wire (the system is no longer axially symmetric).   A folded or zig-zag antenna may exhibit a more complex pattern as there are even fewer symmetry constraints on the dipole moments that may contribute.
+Any unpredictability of the radiation pattern is caused by uncontrolled interaction with nearby matter (such as soil or structures). For example, a long wire antenna close to the ground will form a leaky two-conductor [[transmission line]] and therefore also act somewhat as a [[traveling wave antenna]], with reception off the end of the wire (the system is no longer axially symmetric). A folded or zig-zag antenna may exhibit a more complex pattern as there are even fewer symmetry constraints on the dipole moments that may contribute.
-Long wire antennas are reported to be more effective for reception than multielement antennas such as Yagi or quad antennas with the same length of wire.
+Long wire antennas are reported to be more effective for reception than multi-element antennas such as [[Yagi-Uda antenna|Yagi]] or [[quad antenna]]s with the same length of wire.
 ==Construction==
-[[File:Wire inverted L antenna construction.png|thumb|upright=1.5|A typical permanent wire antenna strung between two buildings. This example has a ''lightning switch'' to ground the antenna for safety during electrical storms.]]
+[[File:Random_wire_antenna_example_picture.png|thumb|upright=1.5|A typical permanent wire antenna strung between two buildings and then extended off to a remote post. This example shows a ''lightning switch'' on the window frame, to disconnect the radio and ground the antenna for safety during electrical storms.]]
-A random wire antenna usually consists of a long (at least one quarter wavelength) wire with one end connected to the radio and the other in free space, arranged in any way most convenient for the space available.   Ideally, it is a straight wire strung as high as possible between trees or buildings, the ends insulated from supports with [[strain insulator]]s. Typically it is made from number 12 or 14 [[American wire gauge|AWG]] ({{convert|1.6|to|2.0|mm|in|abbr=on}} diameter) copperclad wire.   Folding the wire into a zigzag pattern to fit in a limited space such as an apartment or attic will reduce effectiveness and make theoretical analysis extremely difficult. (The added length helps more than the folding typically hurts.)
+A random wire antenna usually consists of a long (at least one quarter wavelength) wire with one end connected to the radio and the other in free space, arranged in any way most convenient for the space available. Ideally, it is  strung as high as possible between trees or buildings, with any bends as [[obtuse angle|obtuse]] as possible, and with the ends insulated from supports.{{efn|
+''Any'' available wire will do for as long as it happens to stay up, and for lengths strung up indoors there are essentially no wire-quality requirements, other than it must conduct electricity only to the radio. The best possible outdoor wire is [[copper-clad steel]] wire covered with [[ultraviolet|UV]]-safe insulation, sized [[American wire gauge|AWG]]&nbsp;12 or 14 – diameter {{convert|1.6|to|2.0|mm|in|abbr=on}}. But the extra expense may not be warranted: If put up outdoors, even the best-made wire will eventually be blown down and have to be restrung. To alleviate stress that wind gusts put on any kind of wire erected outdoors, it is usual to attach the wire at its supports with some kind of strain relief, such as spring-loaded [[strain insulator]]s, or weight and pulley systems to hold the wire in tension, but yield to unexpected loads added to the wire, such as ice.
+}}{{efn|
+Folding the wire into a zigzag pattern, with [[acute angle]]s, to fit in a limited space such as an apartment or attic will reduce effectiveness and make theoretical analysis extremely difficult – however the added length typically helps more than the [[acute angle|acute folding]] hurts, and zig-zagging in the ''last'' third or quarter of the wire near the antenna's far end is not much trouble at frequencies where the antenna is between about a quarter to a half-wave long.
+}}
-If used for transmitting, a random wire antenna usually will also require an [[antenna tuner]], as it has an unpredictable [[Electrical impedance|impedance]] that varies with frequency.<ref name="ARRLntenna Book">{{cite book
+If used for transmitting, a random wire antenna usually will also require an [[antenna tuner]], as it has an unpredictable [[Electrical impedance|impedance]] that varies with frequency.<ref name=ARRL-Antenna-Book>
+{{cite book
+ | editor1-last = Straw | editor1-first = R. Dean  |display-editors=etal
-  | last = Straw
-  | first = R. Dean
+ | year = 2003
-  | title = The ARRL Antenna Book, 20th Edition
+ | title = The ARRL Antenna Book  |edition=20th
-  | publisher = The ARRL, Inc.
+ | publisher = [[The American Radio Relay League]]
+ | place = Newington, CT
-  | date = 2003
+ | page = 944
-  | location = Newington, Connecticut, USA
+ | isbn = 0-87259-904-3
-  | pages = 944
+}}
-  | isbn = 0-87259-904-3}}</ref> One side of the output of the tuner is connected directly to the antenna, without a [[transmission line]], the other to a good earth [[ground (electricity)|ground]].  A quarter-[[wavelength]] sized wire works best, and unless fed through an [[balun|unun]], a half-wavelength will exceed the matching ability of most tuners.<ref>[http://kb6nu.com/the-almost-random-wire-antenna/ The "Almost Random" Wire Antenna]</ref><ref>[http://www.w0ipl.net/ECom/NVIS/random-l.htm Random length wire]</ref> Even without a good earth, the antenna will also radiate, but it will do so by coupling capacitively to any nearby conducting material; this is not recommended.<ref>The End Fed Half Wave Antenna (Steve Yates, AA5TB) http://www.aa5tb.com/efha.html</ref> The [[ground (electricity)|ground]] for a random wire antenna may be chosen by experimentation. Grounds could be returned to a nearby cold water pipe or a wire approximately one-quarter wavelength long, or can be replaced by randomly laid-out quarter-wavelength [[Counterpoise (ground system)|counterpoise wires]] attached to the ground connection.<ref name="ARRLntenna Book" />
+</ref>
+One side of the output of the tuner is connected directly to the antenna, without a [[transmission line]], the other to a good earth [[ground (electricity)|ground]]. A wire near an odd number of a quarter-[[wavelength|waves]] in length works best; in contrast, a wire near an even number of quarter-wavelengths long, although fine for receiving, on transmit will exceed the matching ability of most small tuners, unless first fed through an [[balun|unun]] with a large transform ratio.<ref>
+{{cite web
+ |title=The "almost random" wire antenna
+ |website=kb6nu.com
+ |date=12 March 2007
+ |url=http://kb6nu.com/the-almost-random-wire-antenna/
+}}
+</ref><ref>
+{{cite web
+ |title=Random length wire
+ |series=[[Near vertical incidence skywave|NVIS]]
+ |website=w0ipl.net
+ |url=http://www.w0ipl.net/ECom/NVIS/random-l.htm
+}}
+</ref>
+Even without a good earth, the antenna will still radiate, although poorly; it will do so by capacitively coupling to any nearby conducting material; this is not recommended.<ref>
+{{cite web
+ |author=Yates, Steve (AA5TB)
+ |title=End-fed half wave antenna
+ |website=aa5tb.com
+ |url=http://www.aa5tb.com/efha.html
+}}
+</ref>
+The [[ground (electricity)|ground]] for a random wire antenna may be chosen by experimentation. The antenna tuner ground could be connected to a nearby cold water pipe (if the pipe used reaches the soil via an all-steel or all-copper segment) or one or several wires laid on the floor or ground, one of which is approximately one-quarter wavelength long, or the ground can be connected to one or several randomly laid-out [[counterpoise (ground system)|counterpoise wires]] under the antenna, at least one of which is a quarter-wavelength.<ref name=ARRL-Antenna-Book/>
+== Footnotes ==
+{{notelist}}
+== See also ==
+* [[Antenna types]]
 == References ==
-{{reflist}}
+{{reflist|25em}}
 {{Antenna Types}}

v t e Antenna types
Isotropic	Isotropic radiator
Omnidirectional	Batwing antenna Biconical antenna Cage aerial Coaxial antenna Crossed field antenna Dielectric resonator antenna Dipole antenna Discone antenna Folded unipole antenna Franklin antenna Ground-plane antenna G5RV antenna Halo antenna Helical antenna Inverted-F antenna Inverted vee antenna J-pole antenna Mast radiator Monopole antenna Random wire antenna Rubber ducky antenna Sloper antenna Turnstile antenna T2FD antenna T-antenna Umbrella antenna Whip antenna
Directional	Adcock antenna AS-2259 Antenna AWX antenna Beverage antenna Cantenna Cassegrain antenna Choke ring antenna Collinear antenna array Conformal antenna Corner reflector antenna Curtain array Folded inverted conformal antenna Fractal antenna Gizmotchy Helical antenna Horn antenna Log-periodic antenna Loop antenna Microstrip antenna Moxon antenna Offset dish antenna Patch antenna Phased array Planar array Parabolic antenna Plasma antenna Quad antenna Reflective array antenna Regenerative loop antenna Rhombic antenna Sector antenna Short backfire antenna Slot antenna Sterba antenna Vivaldi antenna WokFi Yagi–Uda antenna
Application-specific	ALLISS Corner reflector (passive) Evolved antenna Ground dipole Reconfigurable antenna Rectenna Reference antenna Spiral antenna Circularly disposed antenna array Television antenna