43:
448:
356:
511:
100:
523:
463:(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 Recently these antennas have been superseded by electronically tuned antenna matching devices. Most examples were wound with
112:
639:. In order to operate in axial-mode, the circumference should be equal to the wavelength. 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 (
1093:
The gain of the helical antenna strongly depends on the reflector. 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
443:
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.
592:
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
549:, 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
479:
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
387:
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.
487:
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
581:, 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
1015:
827:
344:, 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
1088:
561:
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.
601:(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)". The IEEE defines the sense of polarisation as:
938:
719:
597:, 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,
605:"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"
518:
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.
948:
494:
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.
756:
661:
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
593:
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
1026:
328:, 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
371:
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
609:
Thus a right-handed helix radiates a wave which is right-handed, the electric field vector rotating clockwise looking in the direction of propagation.
502:
Specialized normal-mode helical antennas are used as transmitting antennas for FM radio and television broadcasting stations on the VHF and UHF bands.
620:
signals the handedness of the receiving antenna must be the same as the transmitting antenna; left-hand polarized antennas suffer a severe loss of
1526:
1098:. 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.
213:
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.
1251:
1299:
1634:
875:
431:
in which one or more different linear windings are wound on a single former and spaced so as to provide an efficient balance between
439:
for the radiating element at a particular resonant frequency. Many examples of this type have been used extensively for 27 MHz
680:
514:
End-fire helical satellite communications antenna, Scott Air Force base, Illinois, USA. Satellite communication systems often use
1437:
1249:
Djordjević, A.R.; Zajić, A.G. & Ilić, M.M. (2006). "Enhancing the gain of helical antennas by shaping the ground conductor".
573:
is often used where the relative orientation of the transmitting and receiving antennas cannot be easily controlled, such as in
1892:
399:
to between 25 and 35 Ω base impedance. This does not seem to be adverse to operation or matching with a normal 50 Ω
1175:
1010:{\displaystyle {\text{HPBW}}\simeq {\frac {5}{2}}{{\frac {C}{\lambda }}{\sqrt {\frac {NS}{\lambda }}}}\ {\text{degrees}}}
1395:
271:
parallel to the helix axis. These are used for compact antennas for portable hand held as well as mobile vehicle mount
1866:
1684:
1233:
1191:
275:, and in larger scale for UHF television broadcasting antennas. In bifilar or quadrifilar implementations, broadside
86:
64:
57:
1297:
Djordjević, A.R.; Zajić, A.G.; Ilić, M.M. & Stueber, G.L. (December 2006). "Optimization of helical antennas".
313:(axial distance between successive turns) is significantly less than a quarter wavelength, the antenna is called a
17:
290:
helical antenna, the diameter and pitch of the helix are comparable to a wavelength. The antenna functions as a
667:
it operates more in normal mode where the gain direction is a donut shape to the sides instead of out the ends.
822:{\displaystyle {\text{Gain}}\simeq 15\left({\frac {C}{\lambda }}\right)^{2}\left({\frac {NS}{\lambda }}\right)}
104:
1506:
298:
radio waves. These are used for satellite communication. Axial mode operation was discovered by physicist
1531:
1430:
1083:{\displaystyle {\text{FNBW}}\simeq {\frac {115}{C}}{\sqrt {\frac {\lambda ^{3}}{NS}}}\ {\text{degrees}}}
460:
1897:
1769:
1174:
IEEE Standard Test
Procedures for Antennas (Report) (Reaffirmed ed.). IEEE-SA Standards Board /
1764:
1674:
578:
267:, with maximum radiation at right angles to the helix axis. For monofilar designs the radiation is
225:
51:
471:
rod as a former. The usually flexible or ridged radiator is then covered with a PVC or polyolefin
1664:
1473:
322:
264:
1846:
1784:
1521:
1423:
542:
68:
1382:
1501:
617:
594:
550:
515:
336:
it is shorter than a quarter-wavelength long. Therefore, normal-mode helices can be used as
295:
276:
103:
Array of four axial-mode helical antennas used as a satellite tracking-acquisition antenna,
1809:
1709:
1581:
1556:
1345:
1260:
671:
570:
490:
360:
534:
When the helix circumference is near the wavelength of operation, the antenna operates in
459:
Multi-frequency versions with manual plug-in taps have become the mainstay for multi-band
8:
1729:
1621:
1576:
658:
613:
440:
291:
268:
1349:
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1207:
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1719:
1659:
1654:
1551:
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1316:
1276:
621:
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472:
392:
391:
An effect of using a helical conductor rather than a straight one is that the matching
337:
333:
233:
1856:
1749:
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1138:
747:
section acting as an impedance transformer between the helix and the ground plate.
447:
355:
318:
294:
radiating a beam off the ends of the helix, along the antenna's axis. It radiates
240:
1296:
309:
If the circumference of the helix is significantly less than a wavelength and its
1836:
1799:
1774:
1689:
1516:
1496:
1481:
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183:
1183:
1861:
1794:
1779:
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236:
31:
190:. A helical antenna made of one helical wire, the most common type, is called
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1841:
1734:
1724:
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1566:
1337:
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1156:
1126:
598:
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364:
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is the number of turns and S is the spacing between turns. Most designs use
510:
111:
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1704:
1611:
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1178:(published 10 December 2008). 9 October 2003 . § 11.1, p 61.
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468:
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229:
99:
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554:
539:
210:
1851:
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1455:
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when receiving right-circularly-polarized signals, and vice versa.
616:, such as horizontal or vertical polarisation, but when receiving
522:
186:
consisting of one or more conducting wires wound in the form of a
1107:
1095:
869:
483:
These popular designs are still in common use as of 2018 and the
403:, provided the connecting feed is the electrical equivalent of a
1415:
1226:
427:
Another example of the type as used in mobile communications is
1825:
933:{\displaystyle G_{\text{dBi}}=10\log _{10}\left(3.45N\right)~.}
674:
in axial mode ranges between 100 and 200 Ω, approximately
464:
205:
In most cases, directional helical antennas are mounted over a
1336:
194:, while antennas with two or four wires in a helix are called
1804:
714:{\displaystyle Z\simeq 140\left({\frac {C}{\lambda }}\right)}
187:
1365:
582:
452:
396:
612:
Helical antennas can receive signals with any type of
1029:
951:
878:
759:
683:
359:
A common form of normal-mode helical antenna is the "
1356:
340:
monopoles, an alternative to center- or base-loaded
657:). The number of turns in the helix determines how
530:
communication, working frequency app. 2.45 GHz
1082:
1009:
932:
821:
713:
627:The dimensions of the helix are determined by the
553:along the axis, off the ends of the antenna. The
367:, with the rubber sleeve removed from the antenna.
1884:
1228:. Jurong, Singapore: Pearson Education SE Asia.
635:) of the radio waves used, which depends on the
497:
419: wavelength at the frequency of operation.
209:, while omnidirectional designs may not be. The
1344:(3rd ed.). McGraw-Hill Higher Education.
1252:IEEE Antennas and Wireless Propagation Letters
743:coaxial cable is often done by a quarter wave
1431:
1300:IEEE Transactions on Antennas and Propagation
750:The maximum directive gain is approximately:
732:is the wavelength. Impedance matching (when
1393:
1155:
1125:
348:useful as antennas for mobile and portable
1438:
1424:
1396:"The basics of quadrifilar helix antennas"
228:of the aerial are small compared with the
87:Learn how and when to remove this message
521:
509:
446:
354:
110:
98:
50:This article includes a list of general
1366:Stutzman, Warren; Thiele, Gary (1998).
1292:
1290:
728:is the circumference of the helix, and
14:
1885:
1223:
480:effective vertical radiation pattern.
475:which provides a resilient and rugged
363:" used in portable radios. A handheld
317:helix. The antenna acts similar to a
304:
224:helical antenna, the diameter and the
1419:
1176:American National Standards Institute
1129:(March 1949). "The Helical Antenna".
505:
422:
1370:(2nd ed.). John Wiley and Sons.
1287:
1219:
1217:
395:is changed from the nominal 50
149:) Insulating supports for the helix,
36:
1359:Antenna Theory, Analysis and Design
232:. The antenna acts similarly to an
24:
56:it lacks sufficient corresponding
25:
1914:
1867:Circularly disposed antenna array
1685:Folded inverted conformal antenna
1445:
1375:
1214:
1020:The beamwidth between nulls is:
263:, similar to these antennas is
41:
526:Axial-mode helical antenna for
352:on the HF, VHF, and UHF bands.
1342:Antennas: For all applications
1340:; Marhefka, Ronald J. (2002).
1242:
1200:
1167:
1149:
1119:
13:
1:
1893:Radio frequency antenna types
1357:Balanis, Constantine (1982).
1163:(2nd ed.). MacGraw Hill.
1113:
942:The half-power beamwidth is:
498:Helical broadcasting antennas
455:TV broadcasting antenna, 1954
1507:Dielectric resonator antenna
1196:. IEEE Std 149-1979 (R2008).
7:
1184:10.1109/IEEESTD.1979.120310
1101:
279:radiation can be realized.
115:Axial-mode helical antenna:
10:
1919:
1143:10.1109/JRPROC.1949.231279
739:to standard 50 or 75
545:mode, in which instead of
461:single-sideband modulation
29:
1818:
1770:Regenerative loop antenna
1620:
1472:
1454:
1368:Antenna Theory and Design
855:so the gain is typically
579:spacecraft communications
160:) Reflector ground plane,
138:) Coaxial cable feedline,
1765:Reflective array antenna
1675:Corner reflector antenna
1273:10.1109/LAWP.2006.873946
1131:Proceedings of the I.R.E
350:communications equipment
171:) Helical radiating wire
30:Not to be confused with
1665:Collinear antenna array
1313:10.1109/MAP.2006.323359
71:more precise citations.
1847:Reconfigurable antenna
1810:Yagi–Uda antenna
1785:Short backfire antenna
1522:Folded unipole antenna
1361:. John Wiley and Sons.
1224:Tomasi, Wayne (2004).
1084:
1011:
934:
823:
715:
531:
519:
456:
368:
259:wave vertical and the
175:
108:
1502:Crossed field antenna
1085:
1012:
935:
824:
716:
595:circular polarisation
551:circular polarisation
525:
513:
450:
358:
114:
102:
1819:Application-specific
1710:Log-periodic antenna
1582:Rubber ducky antenna
1557:Inverted vee antenna
1532:Ground-plane antenna
1394:Slade, Bill (2015).
1027:
949:
876:
757:
681:
618:circularly polarized
516:circularly polarized
491:rubber ducky antenna
451:Normal-mode helical
429:spaced constant turn
361:rubber ducky antenna
296:circularly polarized
277:circularly polarized
1730:Offset dish antenna
1577:Random wire antenna
1350:2002aaa..book.....K
1265:2006IAWPL...5..138D
614:linear polarisation
305:Normal-mode helical
292:directional antenna
1872:Television antenna
1720:Microstrip antenna
1660:Choke ring antenna
1655:Cassegrain antenna
1552:Inverted-F antenna
1464:Isotropic radiator
1383:"Helical antennas"
1080:
1007:
930:
819:
711:
567:radio transmission
532:
520:
506:Axial-mode helical
473:heat-shrink tubing
457:
423:Mobile HF helicals
369:
338:electrically short
334:resonant frequency
330:inductively loaded
269:linearly polarized
243:, equivalent to a
234:electrically short
176:
127:) Central support,
109:
1880:
1879:
1857:Reference antenna
1750:Parabolic antenna
1670:Conformal antenna
1592:Turnstile antenna
1487:Biconical antenna
1078:
1074:
1070:
1069:
1046:
1033:
1005:
1001:
996:
995:
979:
968:
955:
926:
886:
813:
784:
763:
705:
559:radiation pattern
401:transmission line
332:monopole; at its
326:radiation pattern
261:radiation pattern
97:
96:
89:
16:(Redirected from
1910:
1898:Antennas (radio)
1831:Corner reflector
1645:Beverage antenna
1607:Umbrella antenna
1572:Monopole antenna
1527:Franklin antenna
1440:
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67:this article by
58:inline citations
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1837:Evolved antenna
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1800:Vivaldi antenna
1775:Rhombic antenna
1700:Helical antenna
1690:Fractal antenna
1635:AS-2259 Antenna
1616:
1547:Helical antenna
1517:Discone antenna
1497:Coaxial antenna
1482:Batwing antenna
1474:Omnidirectional
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1403:Orban Microwave
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1208:"Gain of Helix"
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63:Please help to
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27:Type of antenna
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1795:Sterba antenna
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1780:Sector antenna
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1755:Plasma antenna
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1587:Sloper antenna
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1562:J-pole antenna
1559:
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1512:Dipole antenna
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1387:Antenna-Theory
1377:
1376:External links
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1307:(6): 107–115.
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1259:(1): 138–140.
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1137:(3): 263–272.
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543:traveling wave
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105:Pleumeur-Bodou
95:
94:
49:
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40:
32:Spiral antenna
26:
9:
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2:
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1842:Ground dipole
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1725:Moxon antenna
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1567:Mast radiator
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541:
538:. This is a
537:
529:
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485:constant turn
481:
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467:wire using a
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454:
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366:
365:two-way radio
362:
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343:
342:whip antennas
339:
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324:
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302:
301:
300:John D. Kraus
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48:
39:
38:
33:
19:
1790:Slot antenna
1760:Quad antenna
1745:Planar array
1740:Phased array
1715:Loop antenna
1705:Horn antenna
1699:
1612:Whip antenna
1597:T2FD antenna
1546:
1542:Halo antenna
1537:G5RV antenna
1406:. Retrieved
1402:
1386:
1367:
1358:
1341:
1304:
1298:
1256:
1250:
1244:
1225:
1202:
1169:
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1134:
1130:
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1092:
1019:
941:
862:
858:
849:
845:
831:
749:
723:
669:
626:
611:
608:
591:
571:polarisation
564:
535:
533:
528:wireless LAN
501:
489:
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458:
428:
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390:
370:
345:
329:
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221:
217:
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207:ground plane
204:
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164:
153:
142:
131:
120:
83:
74:
55:
1640:AWX antenna
1622:Directional
1492:Cage aerial
1338:Kraus, J.D.
1157:Kraus, J.D.
1127:Kraus, J.D.
659:directional
569:, circular
540:nonresonant
433:capacitance
315:normal-mode
218:normal mode
200:quadrifilar
69:introducing
1887:Categories
1408:2023-03-06
1114:References
629:wavelength
599:J.D. Kraus
555:main lobes
536:axial mode
477:waterproof
469:fiberglass
437:inductance
321:, with an
284:axial mode
230:wavelength
52:references
1833:(passive)
1695:Gizmotchy
1602:T-antenna
1456:Isotropic
1053:λ
1036:≃
993:λ
977:λ
958:≃
906:
811:λ
782:λ
766:≃
745:stripline
703:λ
688:≃
672:impedance
670:Terminal
637:frequency
587:microwave
393:impedance
222:broadside
211:feed line
192:monofilar
1852:Rectenna
1650:Cantenna
1321:30832513
1281:31971392
1161:Antennas
1159:(1988).
1102:See also
1094:several
870:decibels
664:C < λ
441:CB radio
346:helicals
288:end-fire
241:monopole
107:, France
77:May 2012
1903:Helices
1447:Antenna
1346:Bibcode
1331:General
1261:Bibcode
1108:Telstar
1077:degrees
1004:degrees
861:= 3.45
848:= 0.23
655:
641:
557:of the
417:
405:
385:
373:
282:In the
257:
245:
216:In the
196:bifilar
184:antenna
65:improve
1826:ALLISS
1319:
1279:
1232:
1190:
1073:
1000:
925:
832:where
724:where
585:up to
465:copper
237:dipole
182:is an
54:, but
1805:WokFi
1449:types
1399:(PDF)
1317:S2CID
1277:S2CID
839:C = λ
735:C = λ
311:pitch
226:pitch
198:, or
188:helix
1230:ISBN
1188:ISBN
1032:FNBW
954:HPBW
914:3.45
842:and
762:Gain
622:gain
577:and
435:and
1309:doi
1269:doi
1180:doi
1139:doi
1041:115
897:log
885:dBi
868:In
691:140
583:VHF
565:In
453:UHF
286:or
239:or
220:or
1889::
1401:.
1385:.
1315:.
1305:48
1303:.
1289:^
1275:.
1267:.
1255:.
1216:^
1186:.
1135:37
1133:.
1096:dB
901:10
893:10
769:15
589:.
408:1
376:1
178:A
1439:e
1432:t
1425:v
1411:.
1389:.
1352:.
1348::
1323:.
1311::
1283:.
1271::
1263::
1257:5
1238:.
1210:.
1182::
1145:.
1141::
1066:S
1063:N
1057:3
1044:C
989:S
986:N
974:C
966:2
963:5
928:.
921:)
917:N
910:(
890:=
881:G
866:.
863:N
859:G
853:,
850:C
846:S
834:N
816:)
807:S
804:N
798:(
792:2
787:)
779:C
774:(
741:Ω
737:)
730:λ
726:C
708:)
700:C
695:(
685:Z
652:4
649:/
645:λ
633:λ
631:(
414:2
411:/
397:Ω
382:4
379:/
254:4
251:/
248:1
167:S
163:(
156:R
152:(
145:E
141:(
134:C
130:(
123:B
119:(
90:)
84:(
79:)
75:(
61:.
34:.
20:)
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