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class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Wendelantenne" title="Wendelantenne – German" lang="de" hreflang="de" data-title="Wendelantenne" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Antena_helicoidal" title="Antena helicoidal – Spanish" lang="es" hreflang="es" data-title="Antena helicoidal" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A2%D9%86%D8%AA%D9%86_%D9%85%D8%A7%D8%B1%D9%BE%DB%8C%DA%86%DB%8C" title="آنتن مارپیچی – Persian" lang="fa" hreflang="fa" data-title="آنتن مارپیچی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Antenne_h%C3%A9lice_axiale" title="Antenne hélice axiale – French" lang="fr" hreflang="fr" data-title="Antenne hélice axiale" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%8A%D5%A1%D6%80%D5%B8%D6%82%D6%80%D5%A1%D5%B1%D6%87_%D5%A1%D5%B6%D5%BF%D5%A5%D5%B6%D5%A1%D5%B6%D5%A5%D6%80" title="Պարուրաձև անտենաներ – Armenian" lang="hy" hreflang="hy" data-title="Պարուրաձև անտենաներ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Antenna_elicoidale" title="Antenna elicoidale – Italian" lang="it" hreflang="it" data-title="Antenna elicoidale" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A1%D0%BF%D0%B8%D1%80%D0%B0%D0%BB%D1%8C%D0%B4%D1%96_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D0%B0%D0%BB%D0%B0%D1%80" title="Спиральді антенналар – Kazakh" lang="kk" hreflang="kk" data-title="Спиральді антенналар" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/H%C3%A9lix_sug%C3%A1rz%C3%B3" title="Hélix sugárzó – Hungarian" lang="hu" hreflang="hu" data-title="Hélix sugárzó" data-language-autonym="Magyar" data-language-local-name="Hungarian" 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div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="/wiki/Spiral_antenna" title="Spiral antenna">Spiral antenna</a>.</div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 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.ambox{display:none!important}}</style><table class="box-More_footnotes_needed plainlinks metadata ambox ambox-style ambox-More_footnotes_needed" role="presentation"><tbody><tr><td class="mbox-image"><div class="mbox-image-div"><span typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/40px-Text_document_with_red_question_mark.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/60px-Text_document_with_red_question_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Text_document_with_red_question_mark.svg/80px-Text_document_with_red_question_mark.svg.png 2x" data-file-width="48" data-file-height="48" /></span></span></div></td><td class="mbox-text"><div class="mbox-text-span">This article includes a list of <a href="/wiki/Wikipedia:Citing_sources#General_references" title="Wikipedia:Citing sources">general references</a>, but <b>it lacks sufficient corresponding <a href="/wiki/Wikipedia:Citing_sources#Inline_citations" title="Wikipedia:Citing sources">inline citations</a></b>.<span class="hide-when-compact"> Please help to <a href="/wiki/Wikipedia:WikiProject_Reliability" title="Wikipedia:WikiProject Reliability">improve</a> this article by <a href="/wiki/Wikipedia:When_to_cite" title="Wikipedia:When to cite">introducing</a> more precise citations.</span> <span class="date-container"><i>(<span class="date">May 2012</span>)</i></span><span class="hide-when-compact"><i> (<small><a href="/wiki/Help:Maintenance_template_removal" title="Help:Maintenance template removal">Learn how and when to remove this message</a></small>)</i></span></div></td></tr></tbody></table> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Traqueur_acquisition.JPG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/Traqueur_acquisition.JPG/220px-Traqueur_acquisition.JPG" decoding="async" width="220" height="293" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/Traqueur_acquisition.JPG/330px-Traqueur_acquisition.JPG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/32/Traqueur_acquisition.JPG/440px-Traqueur_acquisition.JPG 2x" data-file-width="1728" data-file-height="2304" /></a><figcaption>Array of four axial-mode helical antennas used as a satellite tracking-acquisition antenna, <a href="/wiki/Pleumeur-Bodou_Ground_Station" title="Pleumeur-Bodou Ground Station">Pleumeur-Bodou</a>, France</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Helical_antenna_principle.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Helical_antenna_principle.png/220px-Helical_antenna_principle.png" decoding="async" width="220" height="150" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/0/0b/Helical_antenna_principle.png 1.5x" data-file-width="300" data-file-height="205" /></a><figcaption>Axial-mode helical antenna:<style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style><div class="plainlist"><ul><li>(<b><span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">B</span></span></b>) Central support,</li><li>(<b><span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">C</span></span></b>) Coaxial cable feedline,</li><li>(<b><span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">E</span></span></b>) Insulating supports for the helix,</li><li>(<b><span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">R</span></span></b>) Reflector ground plane,</li><li>(<b><span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">S</span></span></b>) Helical radiating wire</li></ul></div></figcaption></figure> <p>A <b>helical antenna</b> is an <a href="/wiki/Antenna_(radio)" title="Antenna (radio)">antenna</a> consisting of one or more conducting wires wound in the form of a <a href="/wiki/Helix" title="Helix">helix</a>. A helical antenna made of one helical wire, the most common type, is called <i>monofilar</i>, while antennas with two or four wires in a helix are called <i>bifilar</i>, or <i>quadrifilar</i>, respectively. </p><p>In most cases, directional helical antennas are mounted over a <a href="/wiki/Ground_plane" title="Ground plane">ground plane</a>, while omnidirectional designs may not be. The <a href="/wiki/Feed_line" class="mw-redirect" title="Feed line">feed line</a> is connected between the bottom of the helix and the ground plane. Helical antennas can operate in one of two principal modes: normal or axial. </p><p>In the <i>normal mode</i> or <i>broadside</i> helical antenna, the diameter and the <a href="/wiki/Screw_thread#Lead,_pitch,_and_starts" title="Screw thread">pitch</a> of the aerial are small compared with the <a href="/wiki/Wavelength" title="Wavelength">wavelength</a>. The antenna acts similarly to an <a href="/wiki/Electrically_short" class="mw-redirect" title="Electrically short">electrically short</a> <a href="/wiki/Dipole_antenna" title="Dipole antenna">dipole</a> or <a href="/wiki/Monopole_antenna" title="Monopole antenna">monopole</a>, equivalent to a <style data-mw-deduplicate="TemplateStyles:r1214402035">.mw-parser-output .sfrac{white-space:nowrap}.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tion{display:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center}.mw-parser-output .sfrac .num{display:block;line-height:1em;margin:0.0em 0.1em;border-bottom:1px solid}.mw-parser-output .sfrac .den{display:block;line-height:1em;margin:0.1em 0.1em}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style><span class="sfrac">⁠<span class="tion"><span class="num">1</span><span class="sr-only">/</span><span class="den">4</span></span>⁠</span> wave vertical and the <a href="/wiki/Radiation_pattern" title="Radiation pattern">radiation pattern</a>,<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2018)">citation needed</span></a></i>]</sup> similar to these antennas is <a href="/wiki/Omnidirectional_antenna" title="Omnidirectional antenna">omnidirectional</a>, with maximum radiation at right angles to the helix axis. For monofilar designs the radiation is <a href="/wiki/Linear_polarization" title="Linear polarization">linearly polarized</a> parallel to the helix axis. These are used for compact antennas for portable hand held as well as mobile vehicle mount <a href="/wiki/Two-way_radio" title="Two-way radio">two-way radios</a>, and in larger scale for UHF television broadcasting antennas. In bifilar or quadrifilar implementations, broadside <a href="/wiki/Circular_polarization" title="Circular polarization">circularly polarized</a> radiation can be realized. </p><p>In the <i>axial mode</i> or <i>end-fire</i> helical antenna, the diameter and pitch of the helix are comparable to a wavelength. The antenna functions as a <a href="/wiki/Directional_antenna" title="Directional antenna">directional antenna</a> radiating a beam off the ends of the helix, along the antenna's axis. It radiates <a href="/wiki/Circular_polarization" title="Circular polarization">circularly polarized</a> radio waves. These are used for satellite communication. Axial mode operation was discovered by physicist <a href="/wiki/John_D._Kraus" title="John D. Kraus">John D. Kraus</a><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Normal-mode_helical">Normal-mode helical</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=1" title="Edit section: Normal-mode helical"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>If the circumference of the helix is significantly less than a wavelength and its <i>pitch</i> (axial distance between successive turns) is significantly less than a quarter wavelength, the antenna is called a <i>normal-mode</i> helix. The antenna acts similar to a <a href="/wiki/Monopole_antenna" title="Monopole antenna">monopole antenna</a>, with an <a href="/wiki/Omnidirectional_antenna" title="Omnidirectional antenna">omnidirectional</a> <a href="/wiki/Radiation_pattern" title="Radiation pattern">radiation pattern</a>, radiating equal power in all directions perpendicular to the antenna's axis. However, because of the inductance added by the helical shape, the antenna acts like an <i>inductively loaded</i> monopole; at its <a href="/wiki/Resonant_frequency" class="mw-redirect" title="Resonant frequency">resonant frequency</a> it is shorter than a quarter-wavelength long. Therefore, normal-mode helices can be used as <a href="/wiki/Electrically_short" class="mw-redirect" title="Electrically short">electrically short</a> monopoles, an alternative to center- or base-loaded <a href="/wiki/Whip_antenna" title="Whip antenna">whip antennas</a>, in applications where a full sized quarter-wave monopole would be too big. As with other electrically short antennas, the gain, and thus the communication range, of the helix will be less than that of a full sized antenna. Their compact size makes <i>helicals</i> useful as antennas for mobile and portable <a href="/wiki/Two-way_radio" title="Two-way radio">communications equipment</a> on the HF, VHF, and UHF bands.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> </p> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:UHF_CB_with_rubber_ducky_exposed.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/UHF_CB_with_rubber_ducky_exposed.jpg/220px-UHF_CB_with_rubber_ducky_exposed.jpg" decoding="async" width="220" height="165" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/UHF_CB_with_rubber_ducky_exposed.jpg/330px-UHF_CB_with_rubber_ducky_exposed.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c5/UHF_CB_with_rubber_ducky_exposed.jpg/440px-UHF_CB_with_rubber_ducky_exposed.jpg 2x" data-file-width="1280" data-file-height="960" /></a><figcaption>A common form of normal-mode helical antenna is the "<a href="/wiki/Rubber_ducky_antenna" title="Rubber ducky antenna">rubber ducky antenna</a>" used in portable radios. A handheld <a href="/wiki/Two-way_radio" title="Two-way radio">two-way radio</a>, with the rubber sleeve removed from the antenna.</figcaption></figure><p><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup>The loading provided by the helix allows the antenna to be physically shorter than its electrical length of a quarter-wavelength. This means that for example a <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1214402035"><span class="sfrac">⁠<span class="tion"><span class="num"> 1 </span><span class="sr-only">/</span><span class="den">4</span></span>⁠</span> wave antenna at 27 MHz is 2.7 m (110 inches; 8.9 feet) long and is physically quite unsuitable for mobile applications. The reduced size of a helical provides the same radiation pattern in a much more compact physical size with only a slight reduction in signal performance. </p><p>An effect of using a helical conductor rather than a straight one is that the matching <a href="/wiki/Impedance_matching" title="Impedance matching">impedance</a> is changed from the nominal 50 <a href="/wiki/Ohm" title="Ohm">Ω</a> to between 25 and 35 Ω base impedance. This does not seem to be adverse to operation or matching with a normal 50 Ω <a href="/wiki/Transmission_line" title="Transmission line">transmission line</a>, provided the connecting feed is the electrical equivalent of a <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1214402035"><span class="sfrac">⁠<span class="tion"><span class="num"> 1 </span><span class="sr-only">/</span><span class="den">2</span></span>⁠</span> wavelength at the frequency of operation.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Mobile_HF_helicals">Mobile HF helicals</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=2" title="Edit section: Mobile HF helicals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Another example of the type as used in mobile communications is <i>spaced constant turn</i> in which one or more different linear windings are wound on a single former and spaced so as to provide an efficient balance between <a href="/wiki/Capacitance" title="Capacitance">capacitance</a> and <a href="/wiki/Inductance" title="Inductance">inductance</a> for the radiating element at a particular resonant frequency. Many examples of this type have been used extensively for 27 MHz <a href="/wiki/Citizens_band_radio" title="Citizens band radio">CB radio</a> with a wide variety of designs originating in the US and Australia in the late 1960s. To date many millions of these ‘helical antennas’ have been mass-produced for mainly mobile vehicle use and reached peak production during the CB Radio boom-times during the 1970s to late 1980s and used worldwide. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Helical_UHF_TV_broadcast_antenna.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Helical_UHF_TV_broadcast_antenna.jpg/110px-Helical_UHF_TV_broadcast_antenna.jpg" decoding="async" width="110" height="353" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Helical_UHF_TV_broadcast_antenna.jpg/165px-Helical_UHF_TV_broadcast_antenna.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Helical_UHF_TV_broadcast_antenna.jpg/220px-Helical_UHF_TV_broadcast_antenna.jpg 2x" data-file-width="441" data-file-height="1416" /></a><figcaption>Normal-mode helical <a href="/wiki/UHF" class="mw-redirect" title="UHF">UHF</a> TV broadcasting antenna, 1954</figcaption></figure> <p>Multi-frequency versions with manual plug-in taps have become the mainstay for multi-band <a href="/wiki/Single-sideband_modulation" title="Single-sideband modulation">single-sideband modulation</a> (SSB) HF communications with frequency coverage over the whole HF spectrum from 1 MHz to 30 MHz with from 2 to 6 dedicated frequency tap points tuned at dedicated and allocated frequencies in the land mobile, marine, and aircraft bands. Recently these antennas have been superseded by electronically tuned antenna matching devices.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> Most examples were wound with <a href="/wiki/Copper" title="Copper">copper</a> wire using a <a href="/wiki/Fiberglass" title="Fiberglass">fiberglass</a> rod as a former. The usually flexible or ridged radiator is then covered with a PVC or polyolefin <a href="/wiki/Heat-shrink_tubing" title="Heat-shrink tubing">heat-shrink tubing</a> which provides a resilient and rugged <a href="/wiki/Waterproofing" title="Waterproofing">waterproof</a> covering for the finished mobile antenna. The fibreglass rod was then usually glued and/or crimped to a brass fitting and screw mounted onto an insulated base affixed to a vehicle roof, guard or bull-bar mount. This mounting provided a ground plane or reflector (provided by the vehicle) for an effective vertical radiation pattern.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> </p><p>These popular designs are still in common use as of 2018<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Helical_antenna&action=edit">[update]</a></sup> and the <i>constant turn</i> design originating in Australia have been universally adapted as standard FM receiving antennas for many factory produced motor vehicles as well as the existing basic style of aftermarket HF and VHF mobile helical. Another common use for broadside helixes is in the so-called <i><a href="/wiki/Rubber_ducky_antenna" title="Rubber ducky antenna">rubber ducky antenna</a></i> found on most portable VHF and UHF radios using a steel or copper conductor as the radiating element and usually terminated to a BNC/TNC style or screw on connector for quick removal.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (December 2019)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading3"><h3 id="Helical_broadcasting_antennas">Helical broadcasting antennas</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=3" title="Edit section: Helical broadcasting antennas"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Specialized normal-mode helical antennas <i>(see photo)</i> are used as transmitting antennas for <a href="/wiki/Television_broadcasting" class="mw-redirect" title="Television broadcasting">television broadcasting</a> stations on the VHF and UHF bands.<sup id="cite_ref-NAB1975_2-0" class="reference"><a href="#cite_note-NAB1975-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 342">: 342 </span></sup> These consist of a <a href="/wiki/Helix" title="Helix">helical</a> conductor around a tubular steel pole, mounted on standoff insulators. The element consists of two equal length helices, a right-hand and a left-hand, joined at the center.<sup id="cite_ref-NAB1975_2-1" class="reference"><a href="#cite_note-NAB1975-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page: 362">: 362 </span></sup> The rod and the surface of the pole under it act as a leaky <a href="/wiki/Transmission_line" title="Transmission line">transmission line</a>, radiating radio waves perpendicular to the pole. The antenna is fed at the bottom, and unlike other normal-mode helicals functions as a <a href="/wiki/Traveling-wave_antenna" title="Traveling-wave antenna">traveling-wave antenna</a>, with the amplitude of the current decreasing going up the shaft as the energy is radiated. At top the current is down by 40 dB, so there isn't much reflection. To radiate perpendicularly, the length of each turn must be a multiple of the <a href="/wiki/Wavelength" title="Wavelength">wavelength</a>, in most antennas 2 wavelengths. The antenna has a <a href="/wiki/Bandwidth_(signal_processing)" title="Bandwidth (signal processing)">bandwidth</a> of only 6-7%, so to make it adjustable to different frequencies the element is divided into multiple vertical "bays", with a phase-adjustment "collar" between each, to keep the phase constant along the length of the tower. </p> <div class="mw-heading mw-heading2"><h2 id="Axial-mode_helical">Axial-mode helical</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=4" title="Edit section: Axial-mode helical"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Hammer_Ace_SATCOM_Antenna.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Hammer_Ace_SATCOM_Antenna.jpg/220px-Hammer_Ace_SATCOM_Antenna.jpg" decoding="async" width="220" height="148" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Hammer_Ace_SATCOM_Antenna.jpg/330px-Hammer_Ace_SATCOM_Antenna.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Hammer_Ace_SATCOM_Antenna.jpg/440px-Hammer_Ace_SATCOM_Antenna.jpg 2x" data-file-width="2810" data-file-height="1890" /></a><figcaption>End-fire helical satellite communications antenna, Scott Air Force base, Illinois, USA. Satellite communication systems often use <a href="/wiki/Circular_polarisation" class="mw-redirect" title="Circular polarisation">circularly polarized</a> radio waves, because the satellite antenna may be oriented at any angle in space without affecting the transmission, and axial-mode (end-fire) helical antennas are often used as the ground antenna.</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Telstar_1_replica.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Telstar_1_replica.jpg/220px-Telstar_1_replica.jpg" decoding="async" width="220" height="246" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Telstar_1_replica.jpg/330px-Telstar_1_replica.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Telstar_1_replica.jpg/440px-Telstar_1_replica.jpg 2x" data-file-width="1151" data-file-height="1287" /></a><figcaption>Quadrifilar helical command antenna <i>(top)</i> on the <a href="/wiki/Telstar_1" title="Telstar 1">Telstar 1</a> <a href="/wiki/Communications_satellite" title="Communications satellite">communications satellite</a>, 1961</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Helical_antenna.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/2/25/Helical_antenna.jpg/220px-Helical_antenna.jpg" decoding="async" width="220" height="381" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/25/Helical_antenna.jpg/330px-Helical_antenna.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/25/Helical_antenna.jpg/440px-Helical_antenna.jpg 2x" data-file-width="517" data-file-height="896" /></a><figcaption>Axial-mode helical antenna for <a href="/wiki/Wireless_LAN" title="Wireless LAN">wireless LAN</a> communication, working frequency app. 2.45 GHz</figcaption></figure> <p>When the helix circumference is near the wavelength of operation, the antenna operates in <i>axial mode</i>. This is a <a href="/wiki/Resonance" title="Resonance">nonresonant</a> <a href="/wiki/Traveling_wave_antenna" class="mw-redirect" title="Traveling wave antenna">traveling wave</a> mode, in which instead of <a href="/wiki/Standing_wave" title="Standing wave">standing waves</a>, the waves of current and voltage travel in one direction, up the helix from the feedpoint in a transmitting antenna and down the helix toward the feedpoint in a receiving antenna. Instead of radiating linearly polarized waves normal to the antenna's axis, it radiates a beam of radio waves with <a href="/wiki/Circular_polarisation" class="mw-redirect" title="Circular polarisation">circular polarisation</a> along the axis, off the ends of the antenna. The <a href="/wiki/Main_lobe" title="Main lobe">main lobes</a> of the <a href="/wiki/Radiation_pattern" title="Radiation pattern">radiation pattern</a> are along the axis of the helix, off both ends. Since in a directional antenna only radiation in one direction is wanted, the other end of the helix is terminated in a flat metal sheet or screen reflector to reflect the waves forward. </p><p>In <a href="/wiki/Radio_transmission" class="mw-redirect" title="Radio transmission">radio transmission</a>, circular <a href="/wiki/Polarisation_(waves)" class="mw-redirect" title="Polarisation (waves)">polarisation</a> is often used where the relative orientation of the transmitting and receiving antennas cannot be easily controlled, such as in <a href="/wiki/Animal_tracking" class="mw-redirect" title="Animal tracking">animal tracking</a> and <a href="/wiki/Satellite_communications" class="mw-redirect" title="Satellite communications">spacecraft communications</a>, or where the polarisation of the signal may change, so end-fire helical antennas are frequently used for these applications. Since large helices are difficult to build and unwieldy to steer and aim, the design is commonly employed only at higher frequencies, ranging from <a href="/wiki/VHF" class="mw-redirect" title="VHF">VHF</a> up to <a href="/wiki/Microwave" title="Microwave">microwave</a>. </p><p>The helix of the antenna can twist in two possible directions: right-handed or left-handed, the former having the same form as that of a common corkscrew. The 4-helix array in the first illustration uses left-handed helices, while all other illustrations show right-handed helices. In an axial-mode helical antenna the direction of twist of the helix determines the polarisation of the emitted wave. Two mutually incompatible conventions are in use for describing waves with <a href="/wiki/Circular_polarisation" class="mw-redirect" title="Circular polarisation">circular polarisation</a>,<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (October 2024)">citation needed</span></a></i>]</sup> so the relationship between the handedness (left or right) of a helical antenna, and the type of circularly-polarized radiation it emits is often described in ways that appear to be ambiguous. However, <a href="/wiki/John_D._Kraus" title="John D. Kraus">J.D. Kraus</a> (the inventor of the helical antenna) states "The left-handed helix responds to left-circular polarisation, and the right handed helix to right-circular polarisation (IEEE definition)".<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> The IEEE defines the sense of polarisation as: </p> <dl><dd>"the sense of polarization, or handedness ... is called right handed (left handed) if the direction of rotation is clockwise (anti-clockwise) for an observer looking in the direction of propagation"<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup></dd></dl> <p>Thus a right-handed helix radiates a wave which is right-handed, the electric field vector rotating clockwise looking in the direction of propagation. </p><p>Helical antennas can receive signals with any type of <a href="/wiki/Linear_polarisation" class="mw-redirect" title="Linear polarisation">linear polarisation</a>, such as horizontal or vertical polarisation, but when receiving <a href="/wiki/Circular_polarization" title="Circular polarization">circularly polarized</a> signals the handedness of the receiving antenna must be the same as the transmitting antenna; left-hand polarized antennas suffer a severe loss of <a href="/wiki/Gain_(electronics)" title="Gain (electronics)">gain</a> when receiving right-circularly-polarized signals, and vice versa. </p><p>The dimensions of the helix are determined by the <a href="/wiki/Wavelength" title="Wavelength">wavelength</a> (<span class="texhtml mvar" style="font-style:italic;">λ</span>) of the radio waves used, which depends on the <a href="/wiki/Frequency" title="Frequency">frequency</a>. In order to operate in axial-mode, the circumference should be equal to the wavelength.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> The pitch angle should be 13°, which is a pitch distance (distance between each turn) of 0.23 times the circumference, which means the spacing between the coils should be approximately one-quarter of the wavelength (<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1214402035"><span class="sfrac">⁠<span class="tion"><span class="num"> <span class="texhtml mvar" style="font-style:italic;">λ</span> </span><span class="sr-only">/</span><span class="den">4</span></span>⁠</span>).<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2018)">citation needed</span></a></i>]</sup> The number of turns in the helix determines how <a href="/wiki/Directional_antenna" title="Directional antenna">directional</a> the antenna is: more turns improves the gain in the direction of its axis at both ends (or at one end, when a ground plate is used), at a cost of gain in the other directions. When <span class="nowrap"><span class="texhtml mvar" style="font-style:italic;">C < λ</span></span> it operates more in normal mode where the gain direction is a donut shape to the sides instead of out the ends. </p><p>Terminal <a href="/wiki/Electrical_impedance" title="Electrical impedance">impedance</a> in axial mode ranges between 100 and 200 Ω, approximately<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (April 2018)">citation needed</span></a></i>]</sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Z\simeq 140\left({\frac {C}{\lambda }}\right)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>Z</mi> <mo>≃</mo> <mn>140</mn> <mrow> <mo>(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>C</mi> <mi>λ</mi> </mfrac> </mrow> <mo>)</mo> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Z\simeq 140\left({\frac {C}{\lambda }}\right)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ded8dc6e5cf277a4087fcf603c43e3c71333ed9c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:14.677ex; height:6.176ex;" alt="{\displaystyle Z\simeq 140\left({\frac {C}{\lambda }}\right)}"></span></dd></dl> <p>where <span class="texhtml mvar" style="font-style:italic;">C</span> is the circumference of the helix, and <span class="texhtml mvar" style="font-style:italic;">λ</span> is the wavelength. Impedance matching (when <span class="nowrap"><span class="texhtml mvar" style="font-style:italic;">C = λ</span>)</span> to standard 50 or 75 <a href="/wiki/Ohm_(unit)" class="mw-redirect" title="Ohm (unit)">Ω</a> coaxial cable is often done by a quarter wave <a href="/wiki/Stripline" title="Stripline">stripline</a> section acting as an impedance transformer between the helix and the ground plate. </p><p>The maximum directive gain is approximately:<sup id="cite_ref-:0_6-0" class="reference"><a href="#cite_note-:0-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{Gain}}\simeq 15\left({\frac {C}{\lambda }}\right)^{2}\left({\frac {NS}{\lambda }}\right)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>Gain</mtext> </mrow> <mo>≃</mo> <mn>15</mn> <msup> <mrow> <mo>(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>C</mi> <mi>λ</mi> </mfrac> </mrow> <mo>)</mo> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msup> <mrow> <mo>(</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mrow> <mi>N</mi> <mi>S</mi> </mrow> <mi>λ</mi> </mfrac> </mrow> <mo>)</mo> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{Gain}}\simeq 15\left({\frac {C}{\lambda }}\right)^{2}\left({\frac {NS}{\lambda }}\right)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/a86570bd41f9f0d432ffe920ad135be9ce09ba55" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:25.635ex; height:6.509ex;" alt="{\displaystyle {\text{Gain}}\simeq 15\left({\frac {C}{\lambda }}\right)^{2}\left({\frac {NS}{\lambda }}\right)}"></span></dd></dl> <p>where <span class="texhtml mvar" style="font-style:italic;">N</span> is the number of turns and S is the spacing between turns. Most designs use <span class="nowrap"><span class="texhtml mvar" style="font-style:italic;">C = λ</span></span> and <span class="nowrap"><span class="texhtml"><i>S</i> = 0.23 <i>C</i></span> ,</span> so the gain is typically <span class="nowrap"><span class="texhtml"><i>G</i> = 3.45 <i>N</i></span> .</span> In <a href="/wiki/Decibel" title="Decibel">decibels</a>, the gain is <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle G_{\text{dBi}}=10\log _{10}\left(3.45N\right)~.}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>G</mi> <mrow class="MJX-TeXAtom-ORD"> <mtext>dBi</mtext> </mrow> </msub> <mo>=</mo> <mn>10</mn> <msub> <mi>log</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>10</mn> </mrow> </msub> <mo>⁡</mo> <mrow> <mo>(</mo> <mrow> <mn>3.45</mn> <mi>N</mi> </mrow> <mo>)</mo> </mrow> <mtext> </mtext> <mo>.</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle G_{\text{dBi}}=10\log _{10}\left(3.45N\right)~.}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e98c8682e290d6a746aa56231d735c3b425f0dd1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:24.487ex; height:2.843ex;" alt="{\displaystyle G_{\text{dBi}}=10\log _{10}\left(3.45N\right)~.}"></span> </p><p>The half-power beamwidth is:<sup id="cite_ref-:0_6-1" class="reference"><a href="#cite_note-:0-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{HPBW}}\simeq {\frac {5}{2}}{{\frac {C}{\lambda }}{\sqrt {\frac {NS}{\lambda }}}}\ {\text{degrees}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>HPBW</mtext> </mrow> <mo>≃</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>5</mn> <mn>2</mn> </mfrac> </mrow> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mi>C</mi> <mi>λ</mi> </mfrac> </mrow> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mfrac> <mrow> <mi>N</mi> <mi>S</mi> </mrow> <mi>λ</mi> </mfrac> </msqrt> </mrow> </mrow> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>degrees</mtext> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{HPBW}}\simeq {\frac {5}{2}}{{\frac {C}{\lambda }}{\sqrt {\frac {NS}{\lambda }}}}\ {\text{degrees}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/79f7c2d4a7161282e6f0263fa3cba644604a3522" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.338ex; width:29.743ex; height:6.176ex;" alt="{\displaystyle {\text{HPBW}}\simeq {\frac {5}{2}}{{\frac {C}{\lambda }}{\sqrt {\frac {NS}{\lambda }}}}\ {\text{degrees}}}"></span></dd></dl> <p>The beamwidth between nulls is: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{FNBW}}\simeq {\frac {115}{C}}{\sqrt {\frac {\lambda ^{3}}{NS}}}\ {\text{degrees}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mtext>FNBW</mtext> </mrow> <mo>≃</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>115</mn> <mi>C</mi> </mfrac> </mrow> <mrow class="MJX-TeXAtom-ORD"> <msqrt> <mfrac> <msup> <mi>λ</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>3</mn> </mrow> </msup> <mrow> <mi>N</mi> <mi>S</mi> </mrow> </mfrac> </msqrt> </mrow> <mtext> </mtext> <mrow class="MJX-TeXAtom-ORD"> <mtext>degrees</mtext> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\text{FNBW}}\simeq {\frac {115}{C}}{\sqrt {\frac {\lambda ^{3}}{NS}}}\ {\text{degrees}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/8d2ea6b23a0822a36801352084ebeddad601315c" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.005ex; width:29.401ex; height:7.676ex;" alt="{\displaystyle {\text{FNBW}}\simeq {\frac {115}{C}}{\sqrt {\frac {\lambda ^{3}}{NS}}}\ {\text{degrees}}}"></span></dd></dl> <p>The gain of the helical antenna strongly depends on the reflector.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The above classical formulas assume that the reflector has the form of a circular resonator (a circular plate with a rim) and the pitch angle is optimal for this type of reflector. Nevertheless, these formulas overestimate the gain by several <a href="/wiki/Decibel" title="Decibel">dB</a>.<sup id="cite_ref-helix_8-0" class="reference"><a href="#cite_note-helix-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> The optimal pitch that maximizes the gain for a flat ground plane is in the range 3–10° and it depends on the wire radius and antenna length.<sup id="cite_ref-helix_8-1" class="reference"><a href="#cite_note-helix-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=5" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Telstar" title="Telstar">Telstar</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=6" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-columns references-column-width" style="column-width: 25em;"> <ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFKraus,_J.D.1949" class="citation journal cs1"><a href="/wiki/John_D._Kraus" title="John D. Kraus">Kraus, J.D.</a> (March 1949). "The Helical Antenna". <i>Proceedings of the I.R.E</i>. <b>37</b> (3): 263–272. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FJRPROC.1949.231279">10.1109/JRPROC.1949.231279</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proceedings+of+the+I.R.E.&rft.atitle=The+Helical+Antenna&rft.volume=37&rft.issue=3&rft.pages=263-272&rft.date=1949-03&rft_id=info%3Adoi%2F10.1109%2FJRPROC.1949.231279&rft.au=Kraus%2C+J.D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-NAB1975-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-NAB1975_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-NAB1975_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://www.worldradiohistory.com/Archive-NAB-Engineering/NAB-6th-Edition/TV-Antennas-NAB-engineering-Handbook-6th-Edition.pdf"><i>National Association of Broadcasters Engineering Handbook, 6th Ed</i></a> <span class="cs1-format">(PDF)</span>. Washington D.C.: National Association of Broadcasters. 1975.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=National+Association+of+Broadcasters+Engineering+Handbook%2C+6th+Ed.&rft.place=Washington+D.C.&rft.pub=National+Association+of+Broadcasters&rft.date=1975&rft_id=https%3A%2F%2Fwww.worldradiohistory.com%2FArchive-NAB-Engineering%2FNAB-6th-Edition%2FTV-Antennas-NAB-engineering-Handbook-6th-Edition.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKraus,_J.D.1988" class="citation book cs1"><a href="/wiki/John_D._Kraus" title="John D. Kraus">Kraus, J.D.</a> (1988). <i>Antennas</i> (2nd ed.). MacGraw Hill.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Antennas&rft.edition=2nd&rft.pub=MacGraw+Hill&rft.date=1988&rft.au=Kraus%2C+J.D.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation report cs1">IEEE Standard Test Procedures for Antennas (Report) (Reaffirmed ed.). IEEE-SA Standards Board / <a href="/wiki/American_National_Standards_Institute" title="American National Standards Institute">American National Standards Institute</a> (published 10 December 2008). 9 October 2003 [15 December 1977]. § 11.1, p 61. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FIEEESTD.1979.120310">10.1109/IEEESTD.1979.120310</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-471-08032-2" title="Special:BookSources/0-471-08032-2"><bdi>0-471-08032-2</bdi></a>. IEEE Std 149-1979 (R2008).</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=report&rft.btitle=IEEE+Standard+Test+Procedures+for+Antennas&rft.pages=%C2%A7-11.1%2C+p-61&rft.edition=Reaffirmed&rft.pub=IEEE-SA+Standards+Board+%2F+American+National+Standards+Institute&rft.date=2003-10-09&rft_id=info%3Adoi%2F10.1109%2FIEEESTD.1979.120310&rft.isbn=0-471-08032-2&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.cv.nrao.edu/~demerson/helixgain/helix.htm">"Gain of Helix"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Gain+of+Helix&rft_id=https%3A%2F%2Fwww.cv.nrao.edu%2F~demerson%2Fhelixgain%2Fhelix.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-:0-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFTomasi2004" class="citation book cs1">Tomasi, Wayne (2004). <i>Electronic Communication Systems - Fundamentals through Advanced</i>. Jurong, Singapore: Pearson Education SE Asia. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/981-247-093-X" title="Special:BookSources/981-247-093-X"><bdi>981-247-093-X</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Electronic+Communication+Systems+-+Fundamentals+through+Advanced&rft.place=Jurong%2C+Singapore&rft.pub=Pearson+Education+SE+Asia&rft.date=2004&rft.isbn=981-247-093-X&rft.aulast=Tomasi&rft.aufirst=Wayne&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDjordjević,_A.R.Zajić,_A.G.Ilić,_M.M.2006" class="citation journal cs1">Djordjević, A.R.; Zajić, A.G. & Ilić, M.M. (2006). "Enhancing the gain of helical antennas by shaping the ground conductor". <i><a href="/wiki/IEEE_Antennas_and_Wireless_Propagation_Letters" title="IEEE Antennas and Wireless Propagation Letters">IEEE Antennas and Wireless Propagation Letters</a></i>. <b>5</b> (1): 138–140. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2006IAWPL...5..138D">2006IAWPL...5..138D</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FLAWP.2006.873946">10.1109/LAWP.2006.873946</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:31971392">31971392</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Antennas+and+Wireless+Propagation+Letters&rft.atitle=Enhancing+the+gain+of+helical+antennas+by+shaping+the+ground+conductor&rft.volume=5&rft.issue=1&rft.pages=138-140&rft.date=2006&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A31971392%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1109%2FLAWP.2006.873946&rft_id=info%3Abibcode%2F2006IAWPL...5..138D&rft.au=Djordjevi%C4%87%2C+A.R.&rft.au=Zaji%C4%87%2C+A.G.&rft.au=Ili%C4%87%2C+M.M.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> <li id="cite_note-helix-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-helix_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-helix_8-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDjordjević,_A.R.Zajić,_A.G.Ilić,_M.M.Stueber,_G.L.2006" class="citation journal cs1">Djordjević, A.R.; Zajić, A.G.; Ilić, M.M. & Stueber, G.L. (December 2006). "Optimization of helical antennas". <i><a href="/wiki/IEEE_Transactions_on_Antennas_and_Propagation" title="IEEE Transactions on Antennas and Propagation">IEEE Transactions on Antennas and Propagation</a></i>. <b>48</b> (6): 107–115. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FMAP.2006.323359">10.1109/MAP.2006.323359</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:30832513">30832513</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=IEEE+Transactions+on+Antennas+and+Propagation&rft.atitle=Optimization+of+helical+antennas&rft.volume=48&rft.issue=6&rft.pages=107-115&rft.date=2006-12&rft_id=info%3Adoi%2F10.1109%2FMAP.2006.323359&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A30832513%23id-name%3DS2CID&rft.au=Djordjevi%C4%87%2C+A.R.&rft.au=Zaji%C4%87%2C+A.G.&rft.au=Ili%C4%87%2C+M.M.&rft.au=Stueber%2C+G.L.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></span> </li> </ol></div> <dl><dt>General</dt></dl> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKraus,_J.D.Marhefka,_Ronald_J.2002" class="citation book cs1"><a href="/wiki/John_D._Kraus" title="John D. Kraus">Kraus, J.D.</a>; Marhefka, Ronald J. (2002). <i>Antennas: For all applications</i> (3rd ed.). McGraw-Hill Higher Education. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2002aaa..book.....K">2002aaa..book.....K</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Antennas%3A+For+all+applications&rft.edition=3rd&rft.pub=McGraw-Hill+Higher+Education&rft.date=2002&rft_id=info%3Abibcode%2F2002aaa..book.....K&rft.au=Kraus%2C+J.D.&rft.au=Marhefka%2C+Ronald+J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBalanis,_Constantine1982" class="citation book cs1">Balanis, Constantine (1982). <i>Antenna Theory, Analysis and Design</i>. John Wiley and Sons.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Antenna+Theory%2C+Analysis+and+Design&rft.pub=John+Wiley+and+Sons&rft.date=1982&rft.au=Balanis%2C+Constantine&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFStutzman,_WarrenThiele,_Gary1998" class="citation book cs1">Stutzman, Warren; Thiele, Gary (1998). <i>Antenna Theory and Design</i> (2nd ed.). John Wiley and Sons.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Antenna+Theory+and+Design&rft.edition=2nd&rft.pub=John+Wiley+and+Sons&rft.date=1998&rft.au=Stutzman%2C+Warren&rft.au=Thiele%2C+Gary&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Helical_antenna&action=edit&section=7" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.antenna-theory.com/antennas/travelling/helix.php">"Helical antennas"</a>. <i>Antenna-Theory</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Antenna-Theory&rft.atitle=Helical+antennas&rft_id=http%3A%2F%2Fwww.antenna-theory.com%2Fantennas%2Ftravelling%2Fhelix.php&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFSlade,_Bill2015" class="citation web cs1">Slade, Bill (2015). <a rel="nofollow" class="external text" href="https://www.orbanmicrowave.com/_files/ugd/0b7a13_a1dd11999f184f68803e087791124bfa.pdf">"The basics of quadrifilar helix antennas"</a> <span class="cs1-format">(PDF)</span>. <i>Orban Microwave</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2023-03-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Orban+Microwave&rft.atitle=The+basics+of+quadrifilar+helix+antennas&rft.date=2015&rft.au=Slade%2C+Bill&rft_id=https%3A%2F%2Fwww.orbanmicrowave.com%2F_files%2Fugd%2F0b7a13_a1dd11999f184f68803e087791124bfa.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AHelical+antenna" class="Z3988"></span></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl 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title="Batwing antenna">Batwing antenna</a></li> <li><a href="/wiki/Biconical_antenna" title="Biconical antenna">Biconical antenna</a></li> <li><a href="/wiki/Cage_aerial" title="Cage aerial">Cage aerial</a></li> <li><a href="/wiki/Coaxial_antenna" title="Coaxial antenna">Coaxial antenna</a></li> <li><a href="/wiki/Crossed_field_antenna" title="Crossed field antenna">Crossed field antenna</a></li> <li><a href="/wiki/Dielectric_resonator_antenna" title="Dielectric resonator antenna">Dielectric resonator antenna</a></li> <li><a href="/wiki/Dipole_antenna" title="Dipole antenna">Dipole antenna</a></li> <li><a href="/wiki/Discone_antenna" title="Discone antenna">Discone antenna</a></li> <li><a href="/wiki/Folded_unipole_antenna" title="Folded unipole antenna">Folded unipole antenna</a></li> <li><a href="/wiki/Charles_Samuel_Franklin#High-efficiency_Medium-wave_Transmitting_Antenna" title="Charles Samuel Franklin">Franklin antenna</a></li> <li><a href="/wiki/Whip_antenna#Gain_and_radiation_resistance" title="Whip antenna">Ground-plane antenna</a></li> <li><a href="/wiki/G5RV_antenna" title="G5RV antenna">G5RV antenna</a></li> <li><a href="/wiki/Halo_antenna" title="Halo antenna">Halo antenna</a></li> <li><a class="mw-selflink selflink">Helical antenna</a></li> <li><a href="/wiki/Inverted-F_antenna" title="Inverted-F antenna">Inverted-F antenna</a></li> <li><a href="/wiki/Inverted_vee_antenna" title="Inverted vee antenna">Inverted vee antenna</a></li> <li><a href="/wiki/J-pole_antenna" title="J-pole antenna">J-pole antenna</a></li> <li><a href="/wiki/Mast_radiator" title="Mast radiator">Mast radiator</a></li> <li><a href="/wiki/Monopole_antenna" title="Monopole antenna">Monopole antenna</a></li> <li><a href="/wiki/Random_wire_antenna" title="Random wire antenna">Random wire antenna</a></li> <li><a href="/wiki/Rubber_ducky_antenna" title="Rubber ducky antenna">Rubber ducky antenna</a></li> <li><a href="/wiki/Sloper_antenna" title="Sloper antenna">Sloper antenna</a></li> <li><a href="/wiki/Turnstile_antenna" title="Turnstile antenna">Turnstile antenna</a></li> <li><a href="/wiki/T2FD_antenna" title="T2FD antenna">T2FD antenna</a></li> <li><a href="/wiki/T-antenna" title="T-antenna">T-antenna</a></li> <li><a href="/wiki/Umbrella_antenna" title="Umbrella antenna">Umbrella antenna</a></li> <li><a href="/wiki/Whip_antenna" title="Whip antenna">Whip antenna</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Directional_antenna" title="Directional antenna">Directional</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adcock_antenna" title="Adcock antenna">Adcock antenna</a></li> <li><a href="/wiki/Near_vertical_incidence_skywave#The_AS-2259_Antenna" title="Near vertical incidence skywave">AS-2259 Antenna</a></li> <li><a href="/wiki/AWX_antenna" title="AWX antenna">AWX antenna</a></li> <li><a href="/wiki/Beverage_antenna" title="Beverage antenna">Beverage antenna</a></li> <li><a href="/wiki/Cantenna" title="Cantenna">Cantenna</a></li> <li><a href="/wiki/Cassegrain_antenna" title="Cassegrain antenna">Cassegrain antenna</a></li> <li><a href="/wiki/Choke_ring_antenna" title="Choke ring antenna">Choke ring antenna</a></li> <li><a href="/wiki/Collinear_antenna_array" title="Collinear antenna array">Collinear antenna array</a></li> <li><a href="/wiki/Conformal_antenna" title="Conformal antenna">Conformal antenna</a></li> <li><a href="/wiki/Corner_reflector_antenna" title="Corner reflector antenna">Corner reflector antenna</a></li> <li><a href="/wiki/Curtain_array" title="Curtain array">Curtain array</a></li> <li><a href="/wiki/Folded_inverted_conformal_antenna" title="Folded inverted conformal antenna">Folded inverted conformal antenna</a></li> <li><a href="/wiki/Fractal_antenna" title="Fractal antenna">Fractal antenna</a></li> <li><a href="/wiki/Gizmotchy" title="Gizmotchy">Gizmotchy</a></li> <li><a class="mw-selflink selflink">Helical antenna</a></li> <li><a href="/wiki/Horn_antenna" title="Horn antenna">Horn antenna</a></li> <li><a href="/wiki/Log-periodic_antenna" title="Log-periodic antenna">Log-periodic antenna</a></li> <li><a href="/wiki/Loop_antenna" title="Loop antenna">Loop antenna</a></li> <li><a href="/wiki/Microstrip_antenna" title="Microstrip antenna">Microstrip antenna</a></li> <li><a href="/wiki/Moxon_antenna" title="Moxon antenna">Moxon antenna</a></li> <li><a href="/wiki/Offset_dish_antenna" title="Offset dish antenna">Offset dish antenna</a></li> <li><a href="/wiki/Patch_antenna" title="Patch antenna">Patch antenna</a></li> <li><a href="/wiki/Phased_array" title="Phased array">Phased array</a></li> <li><a href="/wiki/Planar_array" class="mw-redirect" title="Planar array">Planar array</a></li> <li><a href="/wiki/Parabolic_antenna" title="Parabolic antenna">Parabolic antenna</a></li> <li><a href="/wiki/Plasma_antenna" title="Plasma antenna">Plasma antenna</a></li> <li><a href="/wiki/Quad_antenna" title="Quad antenna">Quad antenna</a></li> <li><a href="/wiki/Reflective_array_antenna" title="Reflective array antenna">Reflective array antenna</a></li> <li><a href="/wiki/Regenerative_loop_antenna" title="Regenerative loop antenna">Regenerative loop antenna</a></li> <li><a href="/wiki/Rhombic_antenna" title="Rhombic antenna">Rhombic antenna</a></li> <li><a href="/wiki/Sector_antenna" title="Sector antenna">Sector antenna</a></li> <li><a href="/wiki/Short_backfire_antenna" title="Short backfire antenna">Short backfire antenna</a></li> <li><a href="/wiki/Slot_antenna" title="Slot antenna">Slot antenna</a></li> <li><a href="/wiki/Sterba_antenna" title="Sterba antenna">Sterba antenna</a></li> <li><a href="/wiki/Vivaldi_antenna" title="Vivaldi antenna">Vivaldi antenna</a></li> <li><a href="/wiki/WokFi" title="WokFi">WokFi</a></li> <li><a href="/wiki/Yagi%E2%80%93Uda_antenna" title="Yagi–Uda antenna">Yagi–Uda antenna</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Application-specific</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ALLISS" title="ALLISS">ALLISS</a></li> <li><a href="/wiki/Corner_reflector" title="Corner reflector">Corner reflector</a> (passive)</li> <li><a href="/wiki/Evolved_antenna" title="Evolved antenna">Evolved antenna</a></li> <li><a href="/wiki/Ground_dipole" title="Ground dipole">Ground dipole</a></li> <li><a href="/wiki/Reconfigurable_antenna" title="Reconfigurable antenna">Reconfigurable antenna</a></li> <li><a href="/wiki/Rectenna" title="Rectenna">Rectenna</a></li> <li><a href="/wiki/Reference_antenna" title="Reference antenna">Reference antenna</a></li> <li><a href="/wiki/Spiral_antenna" title="Spiral antenna">Spiral antenna</a></li> <li><a href="/wiki/Circularly_disposed_antenna_array" title="Circularly disposed antenna array">Circularly disposed antenna array</a></li> <li><a href="/wiki/Television_antenna" title="Television antenna">Television antenna</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Helical_antenna&oldid=1249194769">https://en.wikipedia.org/w/index.php?title=Helical_antenna&oldid=1249194769</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Radio_frequency_antenna_types" title="Category:Radio frequency antenna types">Radio frequency antenna types</a></li><li><a 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