58:
890:
348:
132:
906:
930:), giving an effective height of half the physical height of the antenna. With an ideal "infinite capacitance" top load wire, the current in the vertical would be constant along its length, giving an effective height equal to the physical height, therefore increasing the radiated power fourfold for the same feed voltage. So the power radiated (or received) by a 'T'-antenna lies between a vertical monopole of the same height and up to four times that.
532:
717:
502:
38:
208:
322:) could be built to be mirror images of each other. However the ease of just laying wires on the ground or raised a few feet above the soil, as opposed to the practical challenge of supporting top hat's horizontal wires up high, at the apex of the vertical section, typically means that the top hat is usually not built as large as the
1344:
1700:
is a variant of the 'T'-antenna used in high-power low-frequency transmitters to reduce ground power losses. It consists of a long capacitive top-load consisting of multiple parallel wires supported by a line of transmission towers, sometimes several miles long. Several vertical radiator wires hang
379:
The top-load capacitance increases as more wires are added, so several parallel horizontal wires are often used, connected together at the center where the vertical wire attaches. Because each wire's electric field impinges on those of adjacent wires, the additional capacitance from each added wire
360:
The left and right sections of horizontal wire across the top of the 'T' carry equal but oppositely-directed currents. Therefore, far from the antenna, the radio waves radiated by each wire are 180° out of phase with the waves from the other wire, and tend to cancel. There is a similar cancellation
326:. Further, any electric fields that reach the ground before they are intercepted by the counterpoise will waste energy warming the soil, whereas stray electric fields high in the air will merely spread out a bit more into loss-free open air, before they eventually reach the wires of the top hat.
1161:
The equivalent circuit of the antenna (including loading coil) is the series combination of the capacitive reactance of the antenna, the inductive reactance of the loading coil, and the radiation resistance and the other resistances of the antenna-ground circuit. So the input impedance is
305:
The wires of the top load are often arranged symmetrically; currents flowing in the oppositely directed symmetrical wires of the top hat cancel each others' fields and so produce no net radiation, with the same cancellation happening in the same way in the ground system. In principle, the
396:) for a given base current. Consequently the 'T'-antenna can radiate more power than a simple vertical monopole of the same height. Similarly, a receiving T-antenna can intercept more power from the same incoming radio wave signal strength than the same height vertical antenna can.
1671:
657:
In the longer wavelength ranges where 'T'-antennas are typically used, the electrical characteristics of antennas are generally not critical for modern radio receivers; reception is limited by natural noise, rather than by the signal power gathered by the receiving antenna.
120:. This is similar to the T-antenna except that the vertical feeder wire, instead of being attached to the center of the horizontal topload wires, is attached at one end. The name comes from its resemblance to an inverted letter "L" (Γ). The T-antenna is an
355:
in a vertical monopole antenna "a" and the ‘T’-antenna "b", showing how the horizontal wire serves to improve the efficiency of the vertical radiating wire. The width of the red area perpendicular to the wire at any point is proportional to the
1701:
down from the top load, each attached to its own ground through a loading coil. The antenna is driven either at one of the radiator wires or more often at one end of the top load, by bringing the wires of the top load diagonally down to the transmitter.
1537:
1677:
1168:
633:, with equal power in all azimuthal directions. The axis of the horizontal wire makes little difference. The power is maximum in a horizontal direction or at a shallow elevation angle, decreasing to zero at the zenith. This makes it a good antenna at
1119:
1010:
705:; the shorter it is, the higher that reactance, and the greater the proportion of the feed current that will be reflected back towards the transmitter. To efficiently drive current into a short transmitting antenna it must be made
1775:
at the top of the antenna where the current must be zero. In the top part "b", the current flows into the horizontal wire in both directions from the middle, increasing the current in the top part of the vertical wire. The
489:, and although capacitive loading at the top does reduce capacitive reactance at the base, usually some residual capacitive reactance remains. For transmitting antennas that must be tuned-out by added inductive reactance from a
863:
of many radial copper cables buried about 30 cm (1 foot) in the earth, extending out from the base of the vertical wire, and connected together at the center. The radials should ideally be long enough to extend beyond the
832:
than a longer antenna; sometimes catastrophically so, far beyond the maximum performance improvement provided by a T-antenna. So at low frequencies, even a 'T'-antenna can have very low radiation resistance, often less than
338:
vertical wire. A greater stored charge causes greater current to flow through the vertical segment between the top and base, and that current in the vertical segment produces the radiation emitted by the T-antenna.
669:
of the feedline, and beyond it, the transmitter's output stage. If mismatched, current sent from the transmitter to the antenna will reflect back down the feedline from the antenna, creating a condition called
1552:
922:
of the antenna, so the antenna should be made as high as possible. Without the horizontal wire, the RF current distribution in the vertical wire would decrease very nearly linearly to zero at the top (
1688:
It can be seen that, since the radiation resistance is usually very low, the major design problem is to keep the other resistances in the antenna-ground system low to obtain the highest efficiency.
368:
at the top of the antenna. More current is required in the vertical wire to charge and discharge this added capacitance during the RF oscillation cycle. The increased currents in the vertical wire (
841:
of the antenna+ground circuit, chiefly the coil and the ground. The resistance in the coil and particularly the ground system must be kept very low to minimize the power dissipated in them.
762:
frequencies, the high antenna capacitance and the high inductance of the loading coil, compared to the short antenna’s low radiation resistance, makes the loaded antenna behave like a high
1712:
parallel loading coils and grounds rather than one, the equivalent loading coil and ground resistance, and therefore the power dissipated in the loading coil and ground, is reduced to
809:
times the driving-point voltage. The insulators at the ends must be designed to withstand these voltages. In high power transmitters the output power is often limited by the onset of
1339:{\displaystyle Z=R_{\mathsf {C}}+R_{\mathsf {D}}+R_{\mathsf {\ell .c.}}+R_{\mathsf {G}}+R_{\mathsf {R}}+j\omega L_{\mathsf {\ell .c.}}-{\frac {1}{\,j\omega C_{\mathsf {ant.}}\,}}~,}
727:, which broadcast the distress call during her sinking in 1912. It was a multiwire 'T' with a 50-metre (160 ft) vertical wire and four 120-metre (400 ft) horizontal wires.
1430:
456:. 'T'-antennas are typically used at low frequencies where building a full-size quarter-wave high vertical antenna is not practical, and the vertical radiating wire is often very
1021:
844:
It can be seen that at low frequencies the design of the loading coil can be challenging: it must have high inductance but very low losses at the transmitting frequency (high
1546:, is the ratio of radiated power to input power from the feedline. Since power dissipated as radiation or as heat is proportional to resistance, the efficiency is given by
899:. The conductor is made of a 'cage' of 6 wires held apart by wooden spreaders. This antenna achieved transatlantic contacts on 1.5 MHz, at a power of 440 W.
872:
frequencies the resistance of the soil becomes a problem, and the radial ground system is usually raised and mounted a few feet above ground, insulated from it, to form a
1854:; all of these, either alone or in combination, limit the transmission of current through the impeding electrical part, and cause voltage changes at its connection point.
93:
or buildings and insulated from them at the ends. A vertical wire is connected to the center of the horizontal wires and hangs down close to the ground, connected to the
731:
The horizontal top section of a 'T'-antenna can also reduce the capacitive reactance at the feedpoint, substituting for a vertical section whose height would be about
824:
is the equivalent resistance of an antenna due to its radiation of radio waves; for a full-length quarter-wave monopole the radiation resistance is around 25
649:("skip") communication. The effect of poor ground conductivity is generally to tilt the pattern up, with the maximum signal strength at a higher elevation angle.
943:
289:
The vertical wire that carries current from the feedpoint at the base to the top; unbalanced current in the vertical segment generates the emitted radio waves.
837:, so the efficiency is limited by other resistances in the antenna and the ground system. The input power is divided between the radiation resistance and the
713:
or its equivalent; the loading coil is conventionally placed at the base of the antenna for accessibility, connected between the antenna and its feedline.
895:
An amateur radio cage 'T'-antenna 18-metre-high (60 ft) by 27-metre-long (90 ft) built in 1922, owned by the
Historic Radio Engineers Club,
599:
increase capacitance to ground and thus radiation resistance and output power, they are often used as transmitting antennas. The cage construction
720:
One of the first uses of 'T' aerials in the early 20th century was on ships, since they could be strung between masts. This is the antenna of
2258:
1154:
This formula shows that the radiated power depends on the product of the base current and the effective height, and is used to determine how many
49:'s facility in Carteret, New Jersey. In this case there are three radiators: the two towers and the center ‘T’-antenna, suspended in the middle.
2718:
2195:
2061:
1708:, so the currents in them are in phase and they can be considered as one radiator. Since the antenna current flows into the ground through
1666:{\displaystyle \eta ={\frac {R_{\mathsf {R}}}{\,R_{\mathsf {C}}+R_{\mathsf {D}}+R_{\mathsf {\ell .c.}}+R_{\mathsf {G}}+R_{\mathsf {R}}\,}}}
797:
To operate over a large frequency range the loading coil often must be adjustable and adjusted when the frequency is changed to limit the
399:
In antennas built for frequencies near or below 600 kHz, the length of an antenna's wire segments is usually shorter than a quarter
918:
The power radiated (or received) by any electrically short vertical antenna, like the 'T'-antenna, is proportional to the square of the
2687:
2505:
2126:
2099:
2025:
1983:
1951:
1888:
255:
2185:
1941:
1910:
2116:
1878:
1780:
and thus the radiated power in each, is proportional to the square of the area of the vertical part of the current distribution.
2455:
805:
also causes a high voltage on the antenna, which is maximum at the current nodes at the ends of the horizontal wire, roughly
233:
1417:
At resonance the capacitive reactance of the antenna is cancelled by the loading coil so the input impedance at resonance
453:
2327:
873:
323:
298:
2251:
330:
The top and ground sections effectively function as oppositely charged reservoirs for augmented storage of excess or
218:
2089:
911:
Cage inverted-L antenna of radio amateur Leroy Moffat, Jr, 5HK at his home in
Oklahoma City, Oklahoma, USA, in 1922.
848:), must carry high currents, withstand high voltages at its ungrounded end, and be adjustable. It is often made of
421:
Despite its improvements over a short vertical, the typical ‘T’-antenna is still not as efficient as a full-height
229:
140:
709:(reactance-free), if the top section has not already done so. The capacitance is usually canceled out by an added
237:
222:
2723:
2590:
128:, with maximum radio power radiated in the direction of the top load wire, off the end with the feeder attached.
2585:
2495:
1681:
1532:{\displaystyle Z_{0}=R_{\mathsf {C}}+R_{\mathsf {D}}+R_{\mathsf {\ell .c.}}+R_{\mathsf {G}}+R_{\mathsf {R}}\,}
2485:
2347:
2294:
1704:
Although the vertical wires are separated, the distance between them is small compared to the length of the
627:
565:
297:
Either wires buried in the ground under the antenna or sometimes wires suspended a few feet above ground (a
121:
1114:{\displaystyle P=R_{\mathsf {R}}I_{0}^{2}\approx 5\left({\frac {\,4\pi \,h\,I_{0}\,}{\lambda }}\right)^{2}}
2667:
2605:
2342:
2244:
2158:
645:
with vertical polarization, but it also radiates enough power at higher elevation angles to be useful for
90:
57:
2713:
2322:
1851:
838:
623:
2630:
2215:
747: its length; if it is long enough, it completely eliminates reactance and obviates any need for a
674:
on the line. This reduces the power radiated by the antenna, and at worst may damage the transmitter.
2530:
2402:
2377:
1847:
1839:
1777:
934:
865:
856:
829:
821:
702:
662:
482:
373:
361:
of radio waves reflected from the ground. Thus the horizontal wires radiate (almost) no radio power.
175:
110:
889:
2550:
2442:
2397:
1731:
896:
798:
381:
191:
179:
131:
125:
124:
antenna, radiating equal radio power in all azimuthal directions, while the inverted-L is a weakly
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770:
666:
148:
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1947:
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2427:
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415:
187:
183:
156:
83:
1005:{\displaystyle R_{\mathsf {R}}\approx 5\left({\frac {\,4\pi \,h\,}{\lambda }}\right)^{2}\,}
392:
The horizontal top load wire can increase radiated power by 2 to 4 times (3 to 6
2657:
2620:
2595:
2520:
2510:
2367:
2337:
2317:
2302:
2267:
665:
is critical: The combination of reactance and resistance at the antenna feedpoint must be
531:
86:
1730:
that of a simple 'T'antenna. The antenna was used in the powerful radio stations of the
2682:
2615:
2600:
2575:
2450:
2407:
2382:
2332:
1843:
1772:
1743:
671:
106:
98:
1918:
2707:
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2500:
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1748:
766:
634:
331:
190:, and triatic antennas. They were invented during the first decades of radio, in the
164:
152:
1680:
1.9-kilometre (1.2-mile) multiple-tuned flattop antenna of the historic 17 kHz
716:
2610:
2580:
2565:
2560:
2535:
2525:
2432:
2417:
2362:
2357:
2352:
1793:
748:
710:
490:
572:
are supporting masts. The feedline to the transmitter or receiver is connected at
268:
The 'T'-type antenna is most easily understood as having three functional parts:
2460:
2312:
755:
642:
486:
365:
207:
172:
102:
94:
37:
1676:
1827:
1797:
1734:
era but has fallen out of favor due to the expense of multiple loading coils.
834:
825:
698:
622:
Since the vertical wire is the actual radiating element, the antenna radiates
501:
400:
828:. Any antenna that is short compared to the operating wavelength has a lower
2515:
849:
759:
407:
168:
160:
89:
consisting of one or more horizontal wires suspended between two supporting
2142:
Moxon, Les (1994). "Chapter 12 HF Antennas". In
Biddulph, Dick (ed.).
2020:(19th ed.). Newington, CT: American Radio Relay League. p. 6‑36.
101:. The shape of the antenna resembles the letter "T", hence the name. The
2672:
2470:
2276:
1705:
706:
646:
448:
186:
with capacitive top-loading; other antennas in this category include the
136:
1946:(2nd ed.). New Delhi, IN: New Age International. pp. 243–244.
17:
721:
393:
178:
broadcasting stations. They can also be used as receiving antennas for
334:, more than what could be stored along the top end of the same height
2646:
1817:
410:. In this circumstance, a ‘T’-antenna is a capacitively top-loaded,
2625:
1675:
715:
346:
130:
1404:
is the apparent capacitance of the antenna at the input terminals
1359:
is the Ohmic resistance of the antenna conductors (copper losses)
2236:
2240:
937:
of an ideal T-antenna with very large top load capacitance is
869:
855:
At low frequencies the antenna requires a good low resistance
201:
2121:. UK: Institution of Electrical Engineers. pp. 379–380.
859:
to be efficient. The RF ground is typically constructed as a
406:
the shortest length of unloaded straight wire that achieves
109:
is connected, between the bottom of the vertical wire and a
2094:(2nd ed.). USA: SciTech Publishing. pp. 389–391.
1767:
At resonance the current is the tail part of a sinusoidal
1424:
is just the sum of the resistances in the antenna circuit
1158:
are required to achieve a given amount of radiated power.
364:
Instead of radiating, the horizontal wires increase the
163:
bands, and are widely used as transmitting antennas for
147:'T'- and inverted-L antennas are typically used in the
2209:
2207:
277:
The horizontal wire top section (sometimes called the
2190:. John Wiley & Sons. pp. 2.8–2.9 (§ 2.2.2).
1555:
1433:
1171:
1024:
946:
769:, with a narrow bandwidth over which it will remain
2639:
2441:
2293:
2275:
2146:(6th ed.). UK: Radio Society of Great Britain.
661:Transmitting antennas are different, and feedpoint
611:
equalizes current in the wires, reducing resistance
1665:
1531:
1338:
1113:
1004:
481:or less. An electrically short antenna has a base
135:Multiwire broadcast T-antenna of early AM station
2220:Virtual Institute of Applied Science (vias.org)
2163:Virtual Institute of Applied Science (vias.org)
1792:600 kHz is close to the bottom end of the
493:, so the antenna can be efficiently fed power.
460:: Only a small fraction of a wavelength long,
2252:
773:to the transmission line, when compared to a
301:) acts like the other plate of the capacitor.
8:
1542:The efficiency of the antenna at resonance,
1377:is the series resistance of the loading coil
799:power reflected back towards the transmitter
2083:
2081:
2079:
2077:
2075:
2073:
2056:. John Wiley & Sons. pp. 299–301.
1978:. Vol. 2. IET. pp. 554, 578–579.
236:. Unsourced material may be challenged and
2259:
2245:
2237:
2091:Radio-Electronic Transmission Fundamentals
1883:(7th ed.). USA: Newnes. p. 761.
1368:is the equivalent series dielectric losses
682:Any monopole antenna that is shorter than
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1902:
1900:
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256:Learn how and when to remove this message
1917:. Antenna design library. Archived from
1909:Edwards, R. J. (G4FGQ) (1 August 2005).
1812:
1810:
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1806:
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1969:
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1771:. In the monopole "a", there is a
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63:An amateur homebuilt inverted-L antenna
2011:
2009:
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1413:is the inductance of the loading coil.
1386:is the resistance of the ground system
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1311:
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1253:
1238:
1223:
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1199:
1184:
1037:
953:
372:) effectively increase the antenna's
7:
388:Efficiency of capacitive top loading
234:adding citations to reliable sources
281:) acts like a plate of a capacitor.
578:. The multiwire toploads used in
25:
2688:Circularly disposed antenna array
2506:Folded inverted conformal antenna
2214:la Porte, Edmund A. (2010).
2157:la Porte, Edmund A. (2010).
2053:Antennas: From theory to practice
1826:, is the conventional symbol for
116:A closely related antenna is the
2184:Balanis, Constantine A. (2011).
2050:Huang, Yi; Boyle, Kevin (2008).
1880:Modern Dictionary of Electronics
904:
888:
641:frequencies, which propagate as
530:
500:
376:and thus the RF power radiated.
206:
56:
36:
2088:Griffith, B. Whitfield (2000).
537:Types of inverted L antennas: (
1976:The Handbook of Antenna Design
1940:Chatterjee, Rajeswari (2006).
1698:multiple-tuned flattop antenna
1:
2719:Radio frequency antenna types
1131:is the height of the antenna,
519:) multiwire (flattop), (
2328:Dielectric resonator antenna
2144:Radio Communication Handbook
2016:Straw, R. Dean, ed. (2000).
868:region near the antenna. At
549:) multiwire (flattop) (
2222:. Radio Antenna Engineering
2165:. Radio Antenna Engineering
2115:Barclay, Leslie W. (2000).
1943:Antenna Theory and Practice
1395:is the radiation resistance
2740:
2591:Regenerative loop antenna
2118:Propagation of Radiowaves
1150:input current in amperes.
1015:so the radiated power is
351:RF current distributions
105:power is applied, or the
43:A 1935 photo of WOR / 710
2586:Reflective array antenna
2496:Corner reflector antenna
1911:"The Simple Tee Antenna"
1877:Graf, Rudolf F. (1999).
1682:Grimeton VLF transmitter
667:matched to the impedance
507:Types of 'T' antennas: (
2486:Collinear antenna array
2187:Modern Antenna Handbook
1974:Rudge, Alan W. (1983).
2668:Reconfigurable antenna
2631:Yagi–Uda antenna
2606:Short backfire antenna
2343:Folded unipole antenna
2216:"Radiation efficiency"
1692:Multiple-tuned antenna
1685:
1667:
1533:
1340:
1137:is the wavelength, and
1115:
1006:
728:
357:
314:) and its counterpart
144:
2323:Crossed field antenna
2018:The ARRL Antenna Book
1679:
1668:
1534:
1341:
1116:
1007:
719:
653:Transmitting antennas
350:
134:
27:Type of radio antenna
2640:Application-specific
2531:Log-periodic antenna
2403:Rubber ducky antenna
2378:Inverted vee antenna
2353:Ground-plane antenna
1921:on 27 September 2008
1778:radiation resistance
1553:
1431:
1169:
1022:
944:
935:radiation resistance
866:displacement current
830:radiation resistance
822:Radiation resistance
703:capacitive reactance
624:vertically polarized
452:and thus a narrower
374:radiation resistance
370:see drawing at right
230:improve this section
2551:Offset dish antenna
2398:Random wire antenna
2159:"Antenna Reactance"
1732:wireless telegraphy
1057:
897:Riverhead, New York
839:'ohmic' resistances
446:, and has a higher
192:wireless telegraphy
182:. They function as
180:shortwave listening
126:directional antenna
2693:Television antenna
2541:Microstrip antenna
2481:Choke ring antenna
2476:Cassegrain antenna
2373:Inverted-F antenna
2285:Isotropic radiator
1798:medium frequencies
1686:
1663:
1529:
1336:
1111:
1043:
1002:
880:Equivalent circuit
751:at the feedpoint.
729:
626:radio waves in an
458:electrically short
412:electrically short
358:
342:
194:era, before 1920.
145:
118:inverted-L antenna
2701:
2700:
2678:Reference antenna
2571:Parabolic antenna
2491:Conformal antenna
2413:Turnstile antenna
2308:Biconical antenna
2197:978-1-118-20975-2
2063:978-0-470-51028-5
1816:The Greek letter
1661:
1332:
1328:
1099:
989:
631:radiation pattern
618:Radiation pattern
343:Capacitance 'hat'
332:deficit electrons
266:
265:
258:
184:monopole antennas
16:(Redirected from
2731:
2724:Antennas (radio)
2652:Corner reflector
2466:Beverage antenna
2428:Umbrella antenna
2393:Monopole antenna
2348:Franklin antenna
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1573:
1563:
1545:
1538:
1536:
1535:
1530:
1527:
1526:
1525:
1512:
1511:
1510:
1497:
1496:
1495:
1473:
1472:
1471:
1458:
1457:
1456:
1443:
1442:
1420:
1409:
1400:
1391:
1382:
1373:
1364:
1355:
1345:
1343:
1342:
1337:
1330:
1329:
1327:
1325:
1324:
1323:
1293:
1288:
1287:
1286:
1258:
1257:
1256:
1243:
1242:
1241:
1228:
1227:
1226:
1204:
1203:
1202:
1189:
1188:
1187:
1142:
1136:
1130:
1120:
1118:
1117:
1112:
1110:
1109:
1104:
1100:
1095:
1093:
1092:
1070:
1056:
1051:
1042:
1041:
1040:
1011:
1009:
1008:
1003:
1000:
999:
994:
990:
985:
971:
958:
957:
956:
920:effective height
908:
892:
847:
813:from the wires.
811:corona discharge
808:
804:
793:
792:
788:
786:
785:
782:
779:
765:
746:
744:
743:
740:
737:
697:
695:
694:
691:
688:
609:
603:
597:
590:
586:
582:
576:
571:
563:
553:
547:
543:) simple, (
541:
534:
523:
517:
513:) simple, (
511:
504:
480:
479:
475:
473:
472:
469:
466:
451:
441:
440:
436:
434:
433:
430:
427:
405:
354:
261:
254:
250:
247:
241:
210:
202:
80:flat-top antenna
60:
48:
47:
40:
21:
2739:
2738:
2734:
2733:
2732:
2730:
2729:
2728:
2704:
2703:
2702:
2697:
2658:Evolved antenna
2635:
2621:Vivaldi antenna
2596:Rhombic antenna
2521:Helical antenna
2511:Fractal antenna
2456:AS-2259 Antenna
2437:
2368:Helical antenna
2338:Discone antenna
2318:Coaxial antenna
2303:Batwing antenna
2295:Omnidirectional
2289:
2271:
2265:
2235:
2225:
2223:
2213:
2212:
2205:
2198:
2183:
2182:
2178:
2168:
2166:
2156:
2155:
2151:
2141:
2140:
2136:
2129:
2114:
2113:
2109:
2102:
2087:
2086:
2071:
2064:
2049:
2048:
2035:
2028:
2015:
2014:
1993:
1986:
1973:
1972:
1961:
1954:
1939:
1938:
1934:
1924:
1922:
1908:
1907:
1898:
1891:
1876:
1875:
1868:
1864:
1859:
1858:
1838:
1834:
1822:
1821:
1815:
1804:
1791:
1784:
1766:
1762:
1757:
1740:
1723:
1722:
1719:
1716:
1715:
1713:
1709:
1694:
1647:
1632:
1608:
1593:
1578:
1576:
1564:
1551:
1550:
1543:
1516:
1501:
1477:
1462:
1447:
1434:
1429:
1428:
1423:
1418:
1412:
1407:
1403:
1398:
1394:
1389:
1385:
1380:
1376:
1371:
1367:
1362:
1358:
1353:
1305:
1297:
1268:
1247:
1232:
1208:
1193:
1178:
1167:
1166:
1145:
1140:
1134:
1128:
1084:
1071:
1065:
1064:
1031:
1020:
1019:
972:
966:
965:
947:
942:
941:
916:
915:
914:
913:
912:
909:
901:
900:
893:
882:
845:
819:
806:
802:
790:
789:
783:
780:
777:
776:
774:
763:
741:
738:
735:
734:
732:
692:
689:
686:
685:
683:
680:
655:
628:omnidirectional
620:
615:
614:
613:
612:
607:
601:
595:
588:
584:
580:
574:
569:
561:
558:
557:
556:
551:
545:
539:
535:
527:
526:
521:
515:
509:
505:
477:
476:
470:
467:
464:
463:
461:
447:
438:
437:
431:
428:
425:
424:
422:
403:
390:
352:
345:
329:
308:capacitance hat
279:capacitance hat
262:
251:
245:
242:
227:
211:
200:
141:Springfield, MA
122:omnidirectional
68:
67:
66:
65:
64:
61:
52:
51:
50:
45:
44:
41:
28:
23:
22:
15:
12:
11:
5:
2737:
2735:
2727:
2726:
2721:
2716:
2706:
2705:
2699:
2698:
2696:
2695:
2690:
2685:
2683:Spiral antenna
2680:
2675:
2670:
2665:
2660:
2655:
2649:
2643:
2641:
2637:
2636:
2634:
2633:
2628:
2623:
2618:
2616:Sterba antenna
2613:
2608:
2603:
2601:Sector antenna
2598:
2593:
2588:
2583:
2578:
2576:Plasma antenna
2573:
2568:
2563:
2558:
2553:
2548:
2543:
2538:
2533:
2528:
2523:
2518:
2513:
2508:
2503:
2498:
2493:
2488:
2483:
2478:
2473:
2468:
2463:
2458:
2453:
2451:Adcock antenna
2447:
2445:
2439:
2438:
2436:
2435:
2430:
2425:
2420:
2415:
2410:
2408:Sloper antenna
2405:
2400:
2395:
2390:
2385:
2383:J-pole antenna
2380:
2375:
2370:
2365:
2360:
2355:
2350:
2345:
2340:
2335:
2333:Dipole antenna
2330:
2325:
2320:
2315:
2310:
2305:
2299:
2297:
2291:
2290:
2288:
2287:
2281:
2279:
2273:
2272:
2266:
2264:
2263:
2256:
2249:
2241:
2234:
2233:
2203:
2196:
2176:
2149:
2134:
2127:
2107:
2100:
2069:
2062:
2033:
2026:
1991:
1984:
1959:
1952:
1932:
1896:
1889:
1865:
1863:
1860:
1857:
1856:
1832:
1802:
1782:
1759:
1758:
1756:
1753:
1752:
1751:
1746:
1744:Dipole antenna
1739:
1736:
1693:
1690:
1674:
1673:
1655:
1650:
1646:
1640:
1635:
1631:
1625:
1622:
1619:
1616:
1611:
1607:
1601:
1596:
1592:
1586:
1581:
1572:
1567:
1561:
1558:
1540:
1539:
1524:
1519:
1515:
1509:
1504:
1500:
1494:
1491:
1488:
1485:
1480:
1476:
1470:
1465:
1461:
1455:
1450:
1446:
1441:
1437:
1421:
1415:
1414:
1410:
1405:
1401:
1396:
1392:
1387:
1383:
1378:
1374:
1369:
1365:
1360:
1356:
1347:
1346:
1335:
1322:
1319:
1316:
1313:
1308:
1304:
1301:
1296:
1291:
1285:
1282:
1279:
1276:
1271:
1267:
1264:
1261:
1255:
1250:
1246:
1240:
1235:
1231:
1225:
1222:
1219:
1216:
1211:
1207:
1201:
1196:
1192:
1186:
1181:
1177:
1174:
1152:
1151:
1143:
1138:
1132:
1122:
1121:
1108:
1103:
1098:
1091:
1087:
1082:
1078:
1075:
1068:
1063:
1060:
1055:
1050:
1046:
1039:
1034:
1030:
1027:
1013:
1012:
998:
993:
988:
983:
979:
976:
969:
964:
961:
955:
950:
910:
903:
902:
894:
887:
886:
885:
884:
883:
881:
878:
818:
815:
679:
676:
672:standing waves
654:
651:
619:
616:
560:
559:
536:
529:
528:
506:
499:
498:
497:
496:
495:
389:
386:
344:
341:
303:
302:
295:
290:
287:
282:
275:
264:
263:
214:
212:
205:
199:
196:
167:stations, and
62:
55:
54:
53:
42:
35:
34:
33:
32:
31:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2736:
2725:
2722:
2720:
2717:
2715:
2712:
2711:
2709:
2694:
2691:
2689:
2686:
2684:
2681:
2679:
2676:
2674:
2671:
2669:
2666:
2664:
2663:Ground dipole
2661:
2659:
2656:
2653:
2650:
2648:
2645:
2644:
2642:
2638:
2632:
2629:
2627:
2624:
2622:
2619:
2617:
2614:
2612:
2609:
2607:
2604:
2602:
2599:
2597:
2594:
2592:
2589:
2587:
2584:
2582:
2579:
2577:
2574:
2572:
2569:
2567:
2564:
2562:
2559:
2557:
2556:Patch antenna
2554:
2552:
2549:
2547:
2546:Moxon antenna
2544:
2542:
2539:
2537:
2534:
2532:
2529:
2527:
2524:
2522:
2519:
2517:
2514:
2512:
2509:
2507:
2504:
2502:
2501:Curtain array
2499:
2497:
2494:
2492:
2489:
2487:
2484:
2482:
2479:
2477:
2474:
2472:
2469:
2467:
2464:
2462:
2459:
2457:
2454:
2452:
2449:
2448:
2446:
2444:
2440:
2434:
2431:
2429:
2426:
2424:
2421:
2419:
2416:
2414:
2411:
2409:
2406:
2404:
2401:
2399:
2396:
2394:
2391:
2389:
2388:Mast radiator
2386:
2384:
2381:
2379:
2376:
2374:
2371:
2369:
2366:
2364:
2361:
2359:
2356:
2354:
2351:
2349:
2346:
2344:
2341:
2339:
2336:
2334:
2331:
2329:
2326:
2324:
2321:
2319:
2316:
2314:
2311:
2309:
2306:
2304:
2301:
2300:
2298:
2296:
2292:
2286:
2283:
2282:
2280:
2278:
2274:
2269:
2262:
2257:
2255:
2250:
2248:
2243:
2242:
2239:
2221:
2217:
2210:
2208:
2204:
2199:
2193:
2189:
2188:
2180:
2177:
2164:
2160:
2153:
2150:
2145:
2138:
2135:
2130:
2128:0-85296-102-2
2124:
2120:
2119:
2111:
2108:
2103:
2101:1-884932-13-4
2097:
2093:
2092:
2084:
2082:
2080:
2078:
2076:
2074:
2070:
2065:
2059:
2055:
2054:
2046:
2044:
2042:
2040:
2038:
2034:
2029:
2027:0-87259-817-9
2023:
2019:
2012:
2010:
2008:
2006:
2004:
2002:
2000:
1998:
1996:
1992:
1987:
1985:0-906048-87-7
1981:
1977:
1970:
1968:
1966:
1964:
1960:
1955:
1953:81-224-0881-8
1949:
1945:
1944:
1936:
1933:
1920:
1916:
1912:
1905:
1903:
1901:
1897:
1892:
1890:0-7506-9866-7
1886:
1882:
1881:
1873:
1871:
1867:
1861:
1853:
1849:
1845:
1841:
1836:
1833:
1829:
1819:
1813:
1811:
1809:
1807:
1803:
1799:
1795:
1789:
1787:
1783:
1779:
1774:
1770:
1769:standing wave
1764:
1761:
1754:
1750:
1749:Mast radiator
1747:
1745:
1742:
1741:
1737:
1735:
1733:
1707:
1702:
1699:
1691:
1689:
1683:
1678:
1648:
1644:
1633:
1629:
1614:
1609:
1605:
1594:
1590:
1579:
1565:
1559:
1556:
1549:
1548:
1547:
1517:
1513:
1502:
1498:
1483:
1478:
1474:
1463:
1459:
1448:
1444:
1439:
1435:
1427:
1426:
1425:
1406:
1397:
1388:
1379:
1370:
1361:
1352:
1351:
1350:
1333:
1306:
1302:
1299:
1294:
1289:
1274:
1269:
1265:
1262:
1259:
1248:
1244:
1233:
1229:
1214:
1209:
1205:
1194:
1190:
1179:
1175:
1172:
1165:
1164:
1163:
1159:
1157:
1149:
1139:
1133:
1127:
1126:
1125:
1106:
1101:
1096:
1089:
1085:
1080:
1076:
1073:
1066:
1061:
1058:
1053:
1048:
1044:
1032:
1028:
1025:
1018:
1017:
1016:
996:
991:
986:
981:
977:
974:
967:
962:
959:
948:
940:
939:
938:
936:
931:
929:
925:
921:
907:
898:
891:
879:
877:
875:
871:
867:
862:
858:
853:
851:
842:
840:
836:
831:
827:
823:
816:
814:
812:
800:
795:
772:
768:
767:tuned circuit
761:
757:
752:
750:
726:
725:
718:
714:
712:
708:
704:
700:
677:
675:
673:
668:
664:
659:
652:
650:
648:
644:
640:
636:
632:
629:
625:
617:
610:
604:
598:
592:
577:
567:
554:
548:
542:
533:
524:
518:
512:
503:
494:
492:
488:
484:
459:
455:
450:
445:
419:
417:
413:
409:
402:
397:
395:
387:
385:
383:
377:
375:
371:
367:
362:
349:
340:
337:
333:
327:
325:
321:
317:
316:ground system
313:
309:
300:
296:
294:
293:Ground system
291:
288:
286:
283:
280:
276:
274:
271:
270:
269:
260:
257:
249:
239:
235:
231:
225:
224:
220:
215:This section
213:
209:
204:
203:
197:
195:
193:
189:
185:
181:
177:
174:
170:
166:
165:amateur radio
162:
158:
154:
150:
142:
138:
133:
129:
127:
123:
119:
114:
112:
108:
104:
100:
96:
92:
88:
87:radio antenna
85:
81:
77:
73:
59:
39:
30:
19:
2714:Power cables
2611:Slot antenna
2581:Quad antenna
2566:Planar array
2561:Phased array
2536:Loop antenna
2526:Horn antenna
2433:Whip antenna
2422:
2418:T2FD antenna
2363:Halo antenna
2358:G5RV antenna
2224:. Retrieved
2219:
2186:
2179:
2167:. Retrieved
2162:
2152:
2143:
2137:
2117:
2110:
2090:
2052:
2017:
1975:
1942:
1935:
1923:. Retrieved
1919:the original
1914:
1879:
1835:
1796:band in the
1794:AM broadcast
1763:
1703:
1697:
1695:
1687:
1541:
1416:
1348:
1160:
1155:
1153:
1123:
1014:
932:
927:
923:
919:
917:
874:counterpoise
860:
854:
843:
820:
796:
771:well matched
753:
749:loading coil
730:
723:
711:loading coil
681:
660:
656:
643:ground waves
621:
606:
600:
594:
579:
573:
555:) cage.
550:
544:
538:
525:) cage.
520:
514:
508:
491:loading coil
420:
414:, vertical
398:
391:
378:
369:
363:
359:
335:
328:
324:counterpoise
320:counterpoise
319:
315:
311:
307:
304:
299:counterpoise
292:
284:
278:
272:
267:
252:
243:
228:Please help
216:
198:How it works
146:
117:
115:
113:connection.
79:
75:
71:
69:
29:
2461:AWX antenna
2443:Directional
2313:Cage aerial
2226:24 February
2169:24 February
1925:23 February
1844:complex sum
924:see drawing
801:. The high
366:capacitance
336:bare headed
173:medium wave
103:transmitter
95:transmitter
91:radio masts
72:‘T’-antenna
2708:Categories
1915:smeter.net
1862:References
1852:resistance
1828:wavelength
1156:metre-amps
817:Resistance
794:monopole.
566:insulators
564:parts are
487:capacitive
401:wavelength
382:diminishes
76:‘T’-aerial
2654:(passive)
2516:Gizmotchy
2423:T-antenna
2277:Isotropic
1848:reactance
1840:Impedance
1755:Footnotes
1615:ℓ
1557:η
1484:ℓ
1303:ω
1290:−
1275:ℓ
1266:ω
1215:ℓ
1097:λ
1077:π
1059:≈
987:λ
978:π
960:≈
850:litz wire
722:RMS
678:Reactance
663:impedance
483:reactance
454:bandwidth
442:vertical
408:resonance
217:does not
169:long wave
161:shortwave
2673:Rectenna
2471:Cantenna
1738:See also
1706:LF waves
1684:, Sweden
707:resonant
647:sky wave
485:that is
444:monopole
416:monopole
356:current.
285:Radiator
273:Top load
246:May 2024
188:umbrella
107:receiver
99:receiver
84:monopole
18:T-aerial
2268:Antenna
1842:is the
1728:
1714:
1146:is the
833:1
787:
775:
745:
733:
724:Titanic
696:
684:
474:
462:
435:
423:
312:top hat
238:removed
223:sources
143:, 1925.
2647:ALLISS
2194:
2125:
2098:
2060:
2024:
1982:
1950:
1887:
1818:lambda
1349:where
1331:
1124:where
857:ground
756:medium
701:has a
159:, and
111:ground
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