570:
1620:
535:
151:
1436:
1961:) shape which made it rigid, so only one set of guy lines was needed, at its wide waist. The pointed lower end of the antenna ended in a large ceramic insulator in the form of a ball-and-socket joint on a concrete base, relieving bending moments on the structure. The first, a 200-meter (665 ft) half-wave mast was installed at radio station WABC's 50 kW Wayne, New Jersey transmitter in 1931. Radial wire ground systems were also introduced during this era.
99:
1806:
343:
22:
1495:
resistance must be kept low, under two ohms, so it consists of a network of cables buried in the earth. Since for an omnidirectional antenna the Earth currents travel radially toward the ground point from all directions, the grounding system usually consists of a radial pattern of buried cables extending outward from the base of the mast in all directions, connected together to the ground lead at a terminal next to the base.
1862:, but was not able to communicate further than a few miles. He discovered by experiment that if he connected one terminal of his transmitter and receiver to a vertical wire suspended overhead, and the other terminal to a metal plate buried in the Earth, he could transmit for longer distances. Marconi's antennas, as well as most other vertical antennas through the 1920s, were constructed of wires suspended by wooden masts.
1818:
323:
1250:. However multipath fading only becomes significant if the signal strength of the skywave is within about 50% (3 dB) of the ground wave. By reducing the height of a monopole slightly the power radiated in the second lobe can be reduced enough to eliminate multipath fading, with only a small reduction in horizontal gain. The optimum height is around 190 electrical degrees or 0.53
299:, wide at the bottom for stability, narrowing to a slender mast. The advantage of this construction is the elimination of guy lines and thus reduction in land area required. These towers can have a triangular or a square cross section, with each leg supported on an insulator. A disadvantage is the wide base of the tower distorts the vertical current pattern on the tower, reducing the
115:
1973:
industry had abandoned the Blaw-Knox design for the narrow, uniform cross section lattice mast used today, which had a better radiation pattern. It was found that reducing the height of the monopole mast from 225 electrical degrees to 190 degrees could eliminate the high angle radio waves that caused fading. Sectional masts were also developed in this era.
383:, vertically polarized radio waves which travel close to the ground surface, following the contour of the terrain. Mast radiators make good ground wave antennas, and are the main type of transmitting antennas used by AM radio stations, as well as other radio services in the MF and LF bands. They also can radiate enough power at higher elevation angles for
1319:
have been built; the tallest masts in the world are around 600 m (2,000 feet). Another constraint in some areas is height restrictions on structures; near airports aviation authorities may limit the maximum height of masts. These constraints often require a mast be used that is shorter than the ideal height.
1742:
to protect the top aircraft warning light. The mast should also have a DC path to ground, so that static electric charges on the mast can drain off. Also at the base is a grounding switch, which is used to connect the mast to the ground system during maintenance operations to ensure that there is
1656:
wrapped around it, mounted on a bracket extending from the concrete base below the antenna insulator, connected to the lighting power source. The secondary winding which provides power to the mast lights is a ring-shaped coil that threads through the toroidal core like two links in a chain, with an
1494:
under the antenna to make contact with the soil to collect the return current. One side of the feedline from the helix house is attached to the mast, and the other side to the ground system. The ground system is in series with the antenna and carries the full antenna current, so for efficiency its
1393:(60 electrical degrees) are seldom used. At this height, the radiation resistance is about 10 ohms, so the typical resistance of a buried ground system, 2 ohms, is about 20% of the radiation resistance, so below this height over 20% of the transmitter power is wasted in the ground system.
525:
Government regulations usually require the power fed to the antenna to be monitored at the antenna base, so the antenna tuning hut also includes an antenna current sampling circuit, which sends its measurements back to the transmitter control room. The hut also usually contains the power supply for
416:
current is often located in a building a short distance away from the mast, so its sensitive electronics and operating personnel will not be exposed to the strong radio waves at the base of the mast. Alternatively it is sometimes located at the base of the mast, with the transmitter room surrounded
1929:
of a vertical monopole antenna over a ground plane. He found that the radiation resistance increased to a maximum at a length of a half wavelength, so a mast around that length had an input resistance that was much higher than the ground resistance, reducing the fraction of transmitter power that
1607:
along their length, to make them more visible to aircraft. Regulations require flashing lights at the top, and (depending on height) at several points along the length of the tower. The high radio frequency voltage on the mast poses a problem for powering the warning lights: the power cable which
1318:
As frequency decreases the wavelength increases, requiring a taller antenna to make a given fraction of a wavelength. Construction costs and land area required increase with height, putting a practical limit on mast height. Masts over 300 m (980 feet) are prohibitively expensive and very few
1972:
interfered with the ground waves, causing an annular region of poor reception at a certain distance from the antenna. It was found that the diamond shape of the Blaw-Knox tower had an unfavorable current distribution which increased the power emitted at high angles. By the 1940s the AM broadcast
1920:
was used as the main broadcasting antenna through the 1920s. It had the disadvantage that it required two masts, twice the construction cost of a single mast antenna, far more land area, and parasitic currents in the masts distorted the radiation pattern. Two historic papers published in 1924 by
1787:
feeding RF power to the colocated antennas pose much the same problem as the aircraft lighting power lines: they have to pass down the tower and across the base insulator and connect to low voltage equipment, so without isolation devices, they will carry the high mast voltage and can short circuit
1550:
in the earth. To reduce this loss these antennas often use a conductive copper ground screen around the mast connected to the buried ground wires, either lying on the ground or elevated a few feet, to shield the ground from the electric field. Another solution is to increase the number of ground
1530:
masts this requires a circular land area extending from the mast 47–136 m (154–446 feet). This is usually planted with grass, which is kept mowed short as tall grass can increase power loss in certain circumstances. If the land area around the mast is too limited for such long radials, they
1498:
The transmitter power lost in the ground resistance, and so the efficiency of the antenna, depends on the soil conductivity. This varies widely; marshy ground or ponds, particularly salt water, provide the lowest resistance ground. The RF current density in the earth, and thus the power loss per
542:
of 3 different height monopole mast radiator antennas mounted on the ground. The distance of the line from the origin at a given elevation angle is proportional to the power density radiated at that angle. For a given power input, the power radiated in horizontal directions increases with height
146:
of triangular cross-section are the most common type. Square lattice masts and tubular masts are also sometimes used. To ensure that the tower is a continuous conductor, the tower's structural sections are electrically bonded at the joints by short copper jumpers which are soldered to each side or
1685:
which prevents the RF current from passing through, but negligible impedance at the lower 50/60 Hz mains frequency, so the AC power can pass through to the lights. A choke is inserted in each of the 3 lines (hot, neutral, safety ground) that make up the power cable. The low voltage end of
1719:
is the operating frequency of the antenna. A parallel resonant circuit has a very high impedance (thousands of ohms) at its resonant frequency, so it blocks the RF current, but low impedance at all other frequencies, allowing the AC lighting power through. This circuit only blocks the specific
1055:
of the antenna with a conjugate reactance in the matching network in the helix house. Due to the finite thickness of the mast, resistance, and other factors the actual antenna current on the mast differs significantly from the ideal sine wave assumed above, and as shown by the graph, resonant
1372:
at one-quarter wavelength, decreases below one-quarter wavelength with the square of the ratio of mast height to wavelength. Other electrical resistances in the antenna system, the ohmic resistance of the mast and the buried ground system, are in series with the radiation resistance, and the
1205:
The above gives the radiation pattern of a perfectly conducting mast over perfectly conducting ground. The actual strength of the received signal at any point on the ground is determined by two factors, the power radiated by the antenna in that direction and the path attenuation between the
1062:
travel horizontally away from the antenna just above the ground, therefore the goal of most mast designs is to radiate a maximum amount of power in horizontal directions. An ideal monopole antenna radiates maximum power in horizontal directions at a height of 225 electrical degrees, about
507:: this can be considered a variation of shunt feed, above. The antenna mast is grounded and a tubular "skirt" of wires is attached to the top of the antenna and hangs down parallel to the mast, surrounding it, to ground level, where it is fed. It has a wider bandwidth than a single tower.
1499:
square meter, increases the closer one gets to the ground terminal at the base of the mast, so the radial ground system can be thought of as replacing the soil with a higher conductivity medium, copper, in the parts of the ground carrying high current density, to reduce power losses.
1531:
can in many cases be replaced by a greater number of shorter radials. The metal support under the mast insulator is bonded to the ground system with conductive metal straps so no voltage appears across the concrete pad supporting the mast, as concrete has poor dielectric qualities.
491:: the bottom of the mast is grounded, and one side of the feedline is connected to the mast part way up, and the other to the ground system under the mast. The impedance of the mast increases along its length, so by choosing the right height to connect, the antenna can be
485:: the mast is supported on an insulator, and is fed at the bottom; one side of the feedline from the helix house is connected to the bottom of the mast and the other to a ground system under the mast. This is the most common feed type, used in most AM radio station masts.
1737:
between the mast and the ground terminal, so that current from a lightning strike to the mast will be conducted to ground. The conductor from the lightning arrester should go directly to a metal ground stake by the shortest path. The top of the mast should have a
1278:
A type of mast with improved anti-fading performance is the sectionalized mast, also called an anti-fading mast. In a sectionalized mast, insulators in the vertical support members divide the mast into two vertically stacked conductive sections, which are fed
1612:(RF) current to the AC power wiring ground, short-circuiting the mast. To prevent this a protective isolator is installed in the lighting power cable at the base of the mast which blocks the RF current while letting the low frequency 50 or 60
475:), in which some of the radio power is reflected back down the feedline toward the transmitter, resulting in inefficiency and possibly overheating the transmitter. From the antenna tuner a short feedline is bolted or brazed to the mast.
219:
of the antenna. To prevent this, additional strain insulators are inserted at intervals in the guy cables to divide the line into nonresonant lengths: Usually segments should be limited to a maximum of one-eighth to one-tenth wavelength
1373:
transmitter power divides proportionally between them. As the radiation resistance decreases more of the transmitter power is dissipated as heat in these resistances, reducing the efficiency of the antenna. Masts shorter than 0.17
1459:
plate; the increased current in the mast required to charge and discharge the topload capacitance each RF cycle increases the radiated power. Since the topload acts electrically like an additional length of mast, this is called
1930:
was lost in the ground system, eliminating the need for a capacitive topload. In a second paper the same year he showed that the amount of power radiated horizontally in ground waves reached a maximum at a mast height of 0.625
290:
1246:. At night when ionospheric reflection is strongest, this results in an annular region of low signal strength around the antenna in which reception may be inadequate, sometimes called a "zone of silence", fading wall or
1025:
1134:
with a maximum in horizontal directions. At heights above a half wavelength the pattern splits and has a second lobe directed into the sky at an angle of about 60°. The reason horizontal radiation is maximum at
1782:
As long as the colocated antennas do not operate at frequencies anywhere near the transmitting frequency of the mast, it is usually possible to isolate them electrically from the voltage on the mast. The
1576:
with respect to the ground. Electrical codes require such exposed high voltage equipment to be fenced off from the public, so the mast and antenna tuning hut are surrounded by a locked fence. Usually a
1214:
to calculate a map of signal strength produced by actual commercially available masts over the actual terrain. This is compared with the audience population distribution to find the best design.
1751:
A tall radio mast is a convenient structure to mount other wireless antennas on, so many radio stations lease space on their towers to other radio services for their antennas. These are called
1303:
without excessive high angle radiation. Practical sectionals with heights of 120 over 120 degrees, 180 over 120 degrees and 180 over 180 degrees are presently in operation with good results.
761:
884:
208:
inserted, usually at the top near the attachment point to the mast, to insulate the conductive cable from the mast, preventing the high voltage on the tower from reaching the ground.
1455:) is sometimes added at the top of the mast to increase the radiated power. This is a round screen of horizontal wires extending radially from the top of the antenna. It acts as a
1905:
to increase the power radiated. During this era, the operation of antennas was little understood, and designs were based on trial and error and half-understood rules of thumb.
1202:
would be a height of 117–341 m (384–1,119 feet), and taller for longwave masts. The high construction costs of such tall masts mean frequently shorter masts are used.
1108:
963:
792:
671:
1179:
are not generally used because above this the power radiated in horizontal directions decreases rapidly due to increasing power wasted into the sky in the second lobe.
513:: also known as an "anti-fading aerial", the mast is divided into two sections with an insulator between them to make two stacked vertical antennas, fed in phase. This
1948:
1524:
1391:
1340:
1301:
1268:
1200:
1177:
1153:
1128:
346:
Guy lines have egg-shaped strain insulators inserted to prevent the high voltage on the mast from reaching the ground, and to break the lines into segments with non-
916:
936:
711:
691:
634:
606:
1608:
runs down the mast from the lights to connect to the mains power line is at the high RF potential of the mast. Without protective equipment it would conduct
1585:
of the antenna. An alternate design is to mount the mast on top of the antenna tuning hut, out of the reach of the public, eliminating the need for a fence.
1482:
For mast radiators the earth under the mast is part of the antenna; the current fed to the mast passes through the air into the ground under the antenna as
1953:
By 1930 the disadvantages of the T antenna led broadcasters to adopt the mast radiator antenna. One of the first types used was the diamond cantilever or
334:" at right. The brown ceramic insulator at the base keeps the mast electrically insulated from the ground. On the left there is an earthing switch and a
495:
to the feedline. This avoids the need to insulate the mast from the ground, eliminates the need for an isolator in the aircraft light power line and the
2269:
1468:
in the guy line a short distance from the mast. Capacity hats are structurally limited to the equivalent of 15-30 degrees of added electrical height.
223:
1526:, 90 electrical degrees) from the mast. No. 10 gauge soft-drawn copper wire is typically used, buried 10 to 25 cm (4 to 10 inches) deep. For
2572:
2458:
1599:
Antenna masts are tall enough that they can be a hazard to aircraft. Aviation regulations require masts to be painted in alternating strips of
1648:
of the transformer are separated by an air gap, wide enough so the high voltage on the antenna cannot jump across. It consists of a ring-shaped
968:
1079:
or 0.625 of a wavelength (this is an approximation valid for a typical finite thickness mast; for an infinitely thin mast the maximum occurs at
3027:
467:
at the operating frequency. Without the antenna tuner the impedance mismatch between the antenna and feedline would cause a condition called
154:
To ensure that the mast acts as a single conductor, the separate structural sections of the mast are connected electrically by copper jumpers.
2524:
2503:
1283:
by separate feedlines. This increases the proportion of power radiated in horizontal directions and allows the mast to be taller than 0.625
1130:) As shown in the diagram, at heights below a half wavelength (180 electrical degrees) the radiation pattern of the antenna has a single
441:) at the base of the mast, to match the transmission line to the mast. This may be located in a waterproof box or a small shed called an
1649:
306:
A country's national radio ministry usually has regulatory authority over the design and operation of radio masts, in addition to local
569:
517:
arrangement enhances low-angle (ground wave) radiation and reduces high-angle (sky wave) radiation. This increases the distance to the
1226:
in the reception area. Some of the radio energy radiated at an angle into the sky is reflected by layers of charged particles in the
3001:
2819:
1503:
311:
1661:
created by the primary winding induces current in the secondary winding without the necessity of a direct connection between them.
1404:
in the antenna tuner to tune it out and make the mast resonant. The high reactance vs the low resistance give the antenna a high
204:. Multiple sets of guys (from 2 to 5) at different levels are used to make the tower rigid against buckling. The guy lines have
2769:
3032:
2471:
1211:
158:
Base-fed masts, the most common type, must be insulated from the ground. At its base, the mast is usually mounted on a thick
1159:
and cancels at high elevation angles, causing most of the power to be emitted in horizontal directions. Heights above 0.625
1413:
2641:
2386:
81:. Its base is usually mounted on a nonconductive support to insulate it from the ground. A mast radiator is a form of
2565:
2420:
723:
34:
1464:" the antenna. Another way to construct a capacity hat is to use sections of the top guy wire set, by inserting the
1889:
band, which limited the vertical height of the radiator to much less than a quarter wavelength, so the antenna was
1865:
One of the first large mast radiators was the experimental tubular 130-meter (420 ft) mast erected in 1906 by
1715:
connected in parallel in the power line. The values of the inductance and capacitance are chosen so the circuit's
1619:
1239:
1210:. The design process of an actual radio mast usually involves doing a survey of soil conductivity, then using an
806:
185:
near the base of the mast, and the cable supplying the current is simply bolted or brazed to the tower. The actual
1581:
is used, but sometimes wooden fences are used to prevent currents induced in a metallic fence from distorting the
826:
211:
Even though they are insulated from the mast the conductive guy cables can act electrically as resonant antennas (
3042:
2904:
1874:
1677:(resistance to AC current) of an inductor increases with the frequency of the current. The isolation choke is a
1490:
to reflect the radio waves. The antenna is fed power between the bottom of the mast and ground so it requires a
608:, the geographical distribution of the listening audience, and terrain. An unsectionalized mast radiator is a
421:
of copper screen to keep radio waves out. The current from the transmitter is delivered to the mast through a
2899:
2809:
1916:
frequencies to broadcasting stations sparked an increase in interest in medium wave antennas. The flattop or
1760:
1419:
At lower frequencies mast radiators are replaced by more elaborate capacitively toploaded antennas such as the
1156:
452:
105:
2493:
1720:
frequency it is tuned to, so if the frequency of the radio transmitter is changed, the trap must be adjusted.
2799:
2661:
2608:
1877:
with which he made the first two-way transatlantic transmission, communicating with an identical antenna in
514:
355:
2981:
2919:
2656:
2558:
2540:
2482:
1604:
1594:
1322:
Antennas significantly shorter than the fundamental resonant length of one-quarter of the wavelength (0.25
503:
50:
2636:
1870:
1776:
1637:
1365:
1032:
534:
359:
2944:
1242:
destructively and partly or completely cancel each other, reducing the signal strength. This is called
200:
attached, usually in sets of 3 at 120° angles, which are anchored to the ground usually with concrete
150:
2844:
2716:
2691:
1926:
1894:
1674:
1600:
1543:
1483:
1477:
1397:
1361:
1052:
1044:
544:
456:
347:
300:
162:
1897:
from 5 to 30 ohms. Therefore, most transmitters used capacitively toploaded antennas like the
1082:
941:
2864:
2756:
2711:
1691:
1665:
1568:
Base-fed mast radiators have a high voltage on the base of the mast, which can deliver a dangerous
1207:
1048:
472:
397:
330:
power is fed to the mast by a wire attached to it, which comes from a matching network inside the "
166:
1435:
769:
642:
3006:
2854:
2794:
2789:
2686:
2598:
2361:
2315:
1909:
1866:
1730:
1716:
1632:
1624:
1356:
of even a short antenna is very close to that of a quarter-wave antenna. However they cannot be
1344:
1040:
464:
448:
443:
331:
182:
178:
74:
26:
2296:"On the Radiation Resistance of a Simple Vertical Antenna at Wave Lengths below the Fundamental"
965:
is the maximum current. At heights of a little less than a multiple of a quarter wavelength,
1534:
For masts near a half-wavelength high (180 electrical degrees) the mast has a voltage maximum (
342:
98:
2991:
2884:
2804:
2726:
2621:
2520:
2514:
2499:
2467:
2203:
1933:
1922:
1890:
1843:
1805:
1784:
1764:
1645:
1582:
1527:
1509:
1506:(FCC) is 120 equally-spaced radial ground wires extending out one quarter of a wavelength (.25
1491:
1461:
1376:
1325:
1286:
1253:
1185:
1162:
1155:
is that at slightly above a half wavelength, the opposite phase radiation from the two lobes
1138:
1113:
795:
613:
539:
426:
216:
212:
190:
616:, the amount of power it radiates at different elevation angles, is determined by its height
2965:
2779:
2741:
2706:
2353:
2307:
1965:
1898:
1839:
1578:
1552:
1465:
1424:
1223:
802:
609:
438:
363:
358:
which radiates equal radio wave power in all horizontal directions. Mast radiators radiate
205:
82:
70:
1572:
to a grounded person touching it. The potential on the mast is typically several thousand
455:
of the feedline to the impedance of the antenna (given by the graph below), and includes a
189:
is usually located in a separate building, which supplies RF power to the tuning hut via a
3037:
2971:
2934:
2909:
2834:
2824:
2681:
2651:
2631:
2616:
2581:
1954:
1882:
1824:
1768:
1743:
no chance that high voltage will be present on the mast when personnel are working on it.
1682:
1678:
1653:
1641:
1609:
1547:
892:
799:
492:
413:
327:
174:
54:
21:
392:
Most radio stations use single masts. Multiple masts fed with radio current at different
2996:
2929:
2914:
2889:
2764:
2721:
2696:
2646:
1859:
1855:
1851:
1828:
1658:
1569:
1539:
921:
817:
696:
676:
619:
591:
496:
418:
125:
121:
104:
Typical 60-meter (200 ft) triangular guyed lattice mast of an AM radio station in
1817:
1616:
AC power pass through up the mast. Several types of isolator devices have been used:
713:. The height of the mast is usually specified in fractions of the wavelength, or in "
3021:
2976:
2869:
2859:
2814:
1739:
1702:
1409:
1315:
band, due to the increasing inefficiency of masts shorter than a quarter wavelength.
1312:
813:
468:
434:
430:
393:
374:
367:
307:
296:
143:
66:
30:
2365:
2319:
2924:
2894:
2879:
2874:
2849:
2839:
2746:
2731:
2676:
2671:
2666:
2342:"On the Optimum Transmitting Wave Length for a Vertical Antenna over Perfect Earth"
1958:
1878:
1756:
1487:
1401:
1353:
1235:
460:
805:
flows up the mast and reflects from the top, and the direct and reflected current
429:) for carrying radio frequency current. At LF and MF frequencies foam insulated
2774:
2626:
2387:"Half Wave Mast Antenna: A 665 foot structure which constitutes a new departure"
1913:
1847:
1695:
1059:
409:
379:
322:
285:{\displaystyle \ {\tfrac {\ 1\ }{8}}\lambda \sim {\tfrac {1}{\ 10\ }}\lambda \ }
186:
129:
78:
58:
2357:
2341:
2311:
2295:
1311:
The lower limit to the frequency at which mast radiators can be used is in the
2545:
1969:
1227:
810:
637:
139:
2400:(5). Mount Morris, Illinois: Techni-Craft Publishing Corp.: 269 November 1931
2829:
2736:
1917:
1902:
1788:
the mast to ground. The transmission lines are isolated by low pass filter
1734:
1712:
1687:
1456:
1420:
1247:
1131:
820:(point of zero current) at the top and a maxima one quarter wavelength down
586:
518:
362:
radio waves, with most of the power emitted at low elevation angles. In the
335:
114:
62:
1368:
which represents power radiated as radio waves, which is around 25–37
1051:. However masts of these lengths can be fed efficiently by cancelling the
1020:{\displaystyle {1 \over 4}\lambda ,{1 \over 2}\lambda ,{3 \over 4}\lambda }
314:(FCC). Plans for a mast must be approved by regulators before building.
165:, which has the compressive strength to support the tower's weight and the
2986:
2784:
2590:
1886:
1789:
1772:
1708:
1670:
1623:
Austin transformer at the base of the WMCA and WNYC transmitter tower in
1535:
1405:
1280:
1036:
1028:
422:
371:
201:
197:
1551:
wires near the mast and bury them very shallowly in a surface layer of
1231:
385:
215:), absorbing and reradiating radio waves from the mast, disturbing the
170:
159:
1792:
consisting of helixes of coaxial cable wound on a nonconductive form.
1775:
antennas consisting of collinear bays of twisted dipole elements, and
1439:
Capacitive "top hat" on mast of AM radio tower in
Hamersley, Australia
2960:
1885:
era before 1920 most long-distance radio stations transmitted in the
1755:. Types of antenna often mounted on mast radiators are: fiberglass
1243:
77:
stations. The conductive steel mast is electrically connected to the
53:
in which the metal structure itself is energized and functions as an
521:
where the ground wave and sky wave are at similar strength at night.
57:. This design, first used widely in the 1930s, is commonly used for
1811:
Fessenden's 130-meter (420 ft) tubular mast radiator from 1906
2939:
2516:
National
Association of Broadcasters Engineering Handbook, 10th Ed
1964:
During the 1930s the broadcast industry recognized the problem of
1618:
1613:
1434:
568:
533:
341:
321:
149:
20:
2352:(6). Institute of Electrical and Electronics Engineers: 833–839.
2306:(6). Institute of Electrical and Electronics Engineers: 823–832.
2248:
2246:
2244:
2242:
2240:
2550:
2022:
2020:
2018:
2016:
2014:
2012:
2010:
1771:
links carrying commercial telecommunications and internet data,
1573:
1230:
and returns to Earth in the reception area. This is called the
303:
and therefore the radiated power, so guyed masts are preferred.
2554:
1234:. At certain distances from the antenna these radio waves are
1043:
the feedline to the antenna. At other lengths the antenna has
400:, which radiate more power in specific directions than others.
2227:
2225:
2208:
McGraw-Hill
Dictionary of Scientific & Technical Terms, 6E
2043:
2041:
2039:
2037:
2035:
1925:
led to the development of the mast radiator. One derived the
1369:
1056:
lengths of a typical tower are closer to 80°, 140°, and 240°.
2086:
2084:
2082:
2080:
2078:
2076:
2074:
2072:
2070:
2068:
1690:
to ground, so high voltage induced in the low voltage end by
794:
meters. The current distribution on the mast determines the
1846:
in 1896 during his development of the first practical radio
1673:, a coil of fine wire wound around a cylindrical form. The
1542:
in the earth above the ground wires near the mast where the
585:
The ideal height of a mast radiator depends on transmission
447:(helix house) next to the mast. The antenna tuning circuit
1831:, a 314-meter (1,030 ft) mast in Hungary built in 1933
1486:(oscillating electric field). The ground also serves as a
1396:
A second problem with electrically short masts is that the
2270:"New tools to co-locate wireless devices with AM antennas"
2150:
2148:
1502:
A standard widely used ground system acceptable to the US
2135:
2133:
2131:
2129:
2127:
2125:
2123:
1206:
transmitting antenna and the receiver, which depends on
463:, to tune out the reactance of the antenna, to make it
1443:
In circumstances in which short masts must be used, a
1222:
A second design goal that affects height is to reduce
257:
231:
1936:
1512:
1379:
1348:
antennas. Electrically short antennas are efficient
1328:
1289:
1256:
1188:
1165:
1141:
1116:
1085:
971:
944:
924:
895:
829:
772:
726:
699:
679:
645:
622:
594:
310:
which cover structural design. In the US this is the
226:
1968:, that at night high angle waves reflected from the
2953:
2755:
2607:
2589:
478:There are several ways of feeding a mast radiator:
1942:
1518:
1385:
1334:
1295:
1262:
1194:
1171:
1147:
1122:
1102:
1019:
957:
930:
910:
878:
786:
755:
705:
685:
665:
628:
600:
433:is usually used. The feedline is connected to an
295:Mast radiators can also be built as free-standing
284:
1842:was invented and patented by radio entrepreneur
1681:, it is constructed to have a high impedance at
1364:. The radiation resistance of the antenna, the
756:{\displaystyle G=360^{\circ }{h \over \lambda }}
673:of the radio waves, equal to the speed of light
499:hazard of high voltages on the base of the mast.
147:"fusion" (arc) welds across the mating flanges.
2346:Proceedings of the Institute of Radio Engineers
2300:Proceedings of the Institute of Radio Engineers
1546:enters the ground. This can cause significant
1238:with the ground waves, and the two radio waves
1031:; at these heights the antenna presents a pure
581:) of a typical base-fed mast radiator vs height
1270:, so this is another common height for masts.
2566:
2434:(6). New York: Teck Publishing Corp.: 462–463
1640:made specifically for this use, in which the
1182:For medium wave AM broadcast band masts 0.625
8:
879:{\displaystyle i(y)=I_{\text{max}}\sin(G-y)}
177:power to drive the antenna is supplied by a
2263:
2261:
1555:pavement, which has low dielectric losses.
2573:
2559:
2551:
196:To keep it upright the mast has tensioned
1935:
1725:Lightning protection and grounding switch
1538:) near its base, which results in strong
1511:
1378:
1327:
1288:
1255:
1187:
1164:
1140:
1115:
1092:
1084:
1004:
988:
972:
970:
949:
943:
938:electrical degrees above the ground, and
923:
894:
849:
828:
776:
771:
743:
737:
725:
698:
678:
655:
644:
621:
593:
256:
230:
225:
2231:
2190:
2166:
2154:
2102:
2090:
2059:
2001:
1027:...(G = 90°, 180°, 270°...) the mast is
553:) through the half-wave monopole (0.5λ,
2252:
2178:
2114:
2047:
2026:
1982:
1408:; the antenna and coil act as a high Q
1400:of the mast is high, requiring a large
73:bands, in particular those used for AM
2210:. The McGraw-Hill Companies, Inc. 2003
2139:
559:) to a maximum at a length of 0.625λ (
1989:
7:
2460:Antenna Engineering Handbook, 3rd Ed
2419:Siemens, Frederick (December 1931).
2340:Ballantine, Stuart (December 1924).
2294:Ballantine, Stuart (December 1924).
2268:Lockwood, Stephen S.; Cox, Bobby L.
1729:At its base, the mast should have a
1698:of the choke is conducted to ground.
1342:, 90 electrical degrees) are called
1212:antenna simulation computer program
1427:which can have higher efficiency.
124:, a freestanding tower antenna in
14:
3002:Circularly disposed antenna array
2820:Folded inverted conformal antenna
1881:, Scotland. However, during the
1686:each choke is bypassed through a
1504:Federal Communications Commission
530:Mast height and radiation pattern
377:cover their listening area using
312:Federal Communications Commission
138:Most mast radiators are built as
2421:"WABC's New "Wire-less" Antenna"
1854:. He initially used horizontal
1816:
1804:
1763:for taxi and delivery services,
1636:– this is a specialized type of
173:applied by the transmitter. The
113:
97:
16:Type of radio frequency antenna
2513:Williams, Edmund, ed. (2007).
1912:in 1920 and the allocation of
1103:{\displaystyle 2\lambda /\pi }
958:{\displaystyle I_{\text{max}}}
918:is the current at a height of
905:
899:
873:
861:
839:
833:
1:
3028:Radio frequency antenna types
1733:consisting of a ball or horn
1657:air gap between the two. The
1360:efficiently due to their low
526:the aircraft warning lights.
354:A single mast radiator is an
2642:Dielectric resonator antenna
2457:Johnson, Richard C. (1993).
809:, creating an approximately
787:{\displaystyle \lambda /360}
666:{\displaystyle \lambda =c/f}
25:A typical mast radiator and
1492:grounding (Earthing) system
389:(skip) radio transmission.
35:Chapel Hill, North Carolina
3059:
2481:Laport, Edmund A. (1952).
2358:10.1109/JRPROC.1924.220011
2312:10.1109/JRPROC.1924.220010
1950:(225 electrical degrees).
1603:and white paint, and have
1592:
1475:
573:Measured base resistance (
483:Series excited (base feed)
439:impedance matching network
179:impedance matching network
61:antennas operating at low
2905:Regenerative loop antenna
2484:Radio Antenna Engineering
1875:Brant Rock, Massachusetts
1761:land mobile radio systems
1703:Parallel resonant circuit
1694:through the interwinding
766:where each degree equals
693:divided by the frequency
396:can be used to construct
338:for lightning protection.
2900:Reflective array antenna
2810:Corner reflector antenna
2495:Communication Structures
2492:Smith, Brian W. (2007).
1943:{\displaystyle \lambda }
1903:inverted L and T antenna
1519:{\displaystyle \lambda }
1462:electrically lengthening
1386:{\displaystyle \lambda }
1335:{\displaystyle \lambda }
1307:Electrically short masts
1296:{\displaystyle \lambda }
1263:{\displaystyle \lambda }
1195:{\displaystyle \lambda }
1172:{\displaystyle \lambda }
1157:interferes destructively
1148:{\displaystyle \lambda }
1123:{\displaystyle \lambda }
453:characteristic impedance
106:Mount Vernon, Washington
2800:Collinear antenna array
1957:. This had a diamond (
1605:aircraft warning lights
1589:Aircraft warning lights
1548:dielectric power losses
425:, a specialized cable (
356:omnidirectional antenna
181:, usually housed in an
2982:Reconfigurable antenna
2945:Yagi–Uda antenna
2920:Short backfire antenna
2657:Folded unipole antenna
2541:Radio masts and towers
2519:. Taylor and Francis.
2487:. McGraw-Hill Book Co.
2255:, p. 25.11-25.12.
2029:, p. 25.25-25.27.
1944:
1707:– this consists of an
1669:– this consists of an
1627:
1595:Aircraft warning light
1520:
1440:
1412:, reducing the usable
1387:
1336:
1297:
1264:
1196:
1173:
1149:
1124:
1104:
1021:
959:
932:
912:
880:
788:
757:
707:
687:
667:
630:
602:
582:
566:
351:
339:
286:
169:to withstand the high
155:
38:
3033:Broadcast engineering
2637:Crossed field antenna
2275:. Kintronic Labs, Inc
2181:, p. 25.8-25.11.
1945:
1871:spark gap transmitter
1777:cellular base station
1773:FM radio broadcasting
1638:isolation transformer
1622:
1521:
1438:
1388:
1366:electrical resistance
1337:
1298:
1265:
1197:
1174:
1150:
1125:
1105:
1022:
960:
933:
913:
881:
789:
758:
708:
688:
668:
631:
603:
572:
545:quarter-wave monopole
537:
345:
325:
287:
153:
24:
2954:Application-specific
2845:Log-periodic antenna
2717:Rubber ducky antenna
2692:Inverted vee antenna
2667:Ground-plane antenna
2050:, p. 25.2-25.4.
2004:, p. 1789-1800.
1934:
1927:radiation resistance
1908:The beginning of AM
1895:radiation resistance
1601:international orange
1544:displacement current
1510:
1484:displacement current
1478:Ground (electricity)
1398:capacitive reactance
1377:
1362:radiation resistance
1326:
1287:
1254:
1186:
1163:
1139:
1114:
1083:
1045:capacitive reactance
969:
942:
922:
911:{\displaystyle i(y)}
893:
827:
770:
724:
697:
677:
643:
620:
592:
412:which generates the
398:directional antennas
360:vertically polarized
301:radiation resistance
224:
2865:Offset dish antenna
2712:Random wire antenna
1692:capacitive coupling
1559:Ancillary equipment
1431:Capacitive toploads
1274:Sectionalized masts
1218:Anti-fading designs
1208:ground conductivity
1049:inductive reactance
816:on the mast with a
612:, and its vertical
435:antenna tuning unit
167:dielectric strength
51:radio mast or tower
3007:Television antenna
2855:Microstrip antenna
2795:Choke ring antenna
2790:Cassegrain antenna
2687:Inverted-F antenna
2599:Isotropic radiator
2498:. Thomas Telford.
2234:, p. 718-720.
2169:, p. 717-718.
2105:, p. 726-729.
2093:, p. 715-716.
2062:, p. 739-755.
1940:
1910:radio broadcasting
1891:electrically short
1867:Reginald Fessenden
1785:transmission lines
1753:colocated antennas
1747:Colocated antennas
1731:lightning arrester
1717:resonant frequency
1650:toroidal iron core
1646:secondary windings
1633:Austin transformer
1628:
1625:Kearny, New Jersey
1516:
1445:capacitive topload
1441:
1383:
1345:electrically short
1332:
1293:
1260:
1192:
1169:
1145:
1120:
1100:
1041:impedance matching
1017:
955:
928:
908:
876:
784:
753:
715:electrical degrees
703:
683:
663:
626:
598:
583:
567:
540:radiation patterns
538:Measured vertical
444:antenna tuning hut
352:
340:
332:antenna tuning hut
282:
274:
248:
213:parasitic elements
183:antenna tuning hut
156:
75:radio broadcasting
39:
27:antenna tuning hut
3015:
3014:
2992:Reference antenna
2885:Parabolic antenna
2805:Conformal antenna
2727:Turnstile antenna
2622:Biconical antenna
2526:978-0-240-80751-5
2505:978-0-7277-3400-6
2204:"capacitance hat"
1923:Stuart Ballantine
1844:Guglielmo Marconi
1683:radio frequencies
1583:radiation pattern
1528:AM broadcast band
1466:strain insulators
1012:
996:
980:
952:
931:{\displaystyle y}
852:
796:radiation pattern
751:
706:{\displaystyle f}
686:{\displaystyle c}
629:{\displaystyle h}
614:radiation pattern
601:{\displaystyle f}
577:) and reactance (
493:impedance matched
427:transmission line
318:Electrical design
281:
273:
271:
265:
247:
242:
236:
229:
217:radiation pattern
206:strain insulators
191:transmission line
89:Structural design
3050:
3043:Antennas (radio)
2966:Corner reflector
2780:Beverage antenna
2742:Umbrella antenna
2707:Monopole antenna
2662:Franklin antenna
2575:
2568:
2561:
2552:
2530:
2509:
2488:
2477:
2465:
2444:
2443:
2441:
2439:
2425:
2416:
2410:
2409:
2407:
2405:
2391:
2383:
2377:
2376:
2374:
2372:
2337:
2331:
2330:
2328:
2326:
2291:
2285:
2284:
2282:
2280:
2274:
2265:
2256:
2250:
2235:
2229:
2220:
2219:
2217:
2215:
2200:
2194:
2188:
2182:
2176:
2170:
2164:
2158:
2152:
2143:
2142:, p. 77-80.
2137:
2118:
2112:
2106:
2100:
2094:
2088:
2063:
2057:
2051:
2045:
2030:
2024:
2005:
1999:
1993:
1992:, p. 24-26.
1987:
1966:multipath fading
1949:
1947:
1946:
1941:
1899:umbrella antenna
1840:monopole antenna
1838:The vertical or
1823:An example of a
1820:
1808:
1579:chain-link fence
1525:
1523:
1522:
1517:
1472:Grounding system
1425:umbrella antenna
1416:of the antenna.
1392:
1390:
1389:
1384:
1341:
1339:
1338:
1333:
1302:
1300:
1299:
1294:
1269:
1267:
1266:
1261:
1224:multipath fading
1201:
1199:
1198:
1193:
1178:
1176:
1175:
1170:
1154:
1152:
1151:
1146:
1129:
1127:
1126:
1121:
1109:
1107:
1106:
1101:
1096:
1078:
1076:
1075:
1072:
1069:
1026:
1024:
1023:
1018:
1013:
1005:
997:
989:
981:
973:
964:
962:
961:
956:
954:
953:
950:
937:
935:
934:
929:
917:
915:
914:
909:
885:
883:
882:
877:
854:
853:
850:
793:
791:
790:
785:
780:
762:
760:
759:
754:
752:
744:
742:
741:
712:
710:
709:
704:
692:
690:
689:
684:
672:
670:
669:
664:
659:
636:compared to the
635:
633:
632:
627:
610:monopole antenna
607:
605:
604:
599:
563:
557:
551:
364:medium frequency
291:
289:
288:
283:
279:
275:
272:
269:
263:
258:
249:
243:
240:
234:
232:
227:
117:
101:
83:monopole antenna
3058:
3057:
3053:
3052:
3051:
3049:
3048:
3047:
3018:
3017:
3016:
3011:
2972:Evolved antenna
2949:
2935:Vivaldi antenna
2910:Rhombic antenna
2835:Helical antenna
2825:Fractal antenna
2770:AS-2259 Antenna
2751:
2682:Helical antenna
2652:Discone antenna
2632:Coaxial antenna
2617:Batwing antenna
2609:Omnidirectional
2603:
2585:
2579:
2537:
2527:
2512:
2506:
2491:
2480:
2474:
2466:. McGraw-Hill.
2463:
2456:
2453:
2448:
2447:
2437:
2435:
2423:
2418:
2417:
2413:
2403:
2401:
2389:
2385:
2384:
2380:
2370:
2368:
2339:
2338:
2334:
2324:
2322:
2293:
2292:
2288:
2278:
2276:
2272:
2267:
2266:
2259:
2251:
2238:
2230:
2223:
2213:
2211:
2202:
2201:
2197:
2189:
2185:
2177:
2173:
2165:
2161:
2153:
2146:
2138:
2121:
2117:, p. 25.5.
2113:
2109:
2101:
2097:
2089:
2066:
2058:
2054:
2046:
2033:
2025:
2008:
2000:
1996:
1988:
1984:
1979:
1955:Blaw-Knox tower
1932:
1931:
1883:radiotelegraphy
1856:dipole antennas
1836:
1835:
1834:
1833:
1832:
1821:
1813:
1812:
1809:
1798:
1769:microwave relay
1749:
1727:
1679:low pass filter
1654:primary winding
1610:radio frequency
1597:
1591:
1566:
1561:
1540:electric fields
1508:
1507:
1480:
1474:
1453:capacitance hat
1447:(also known as
1433:
1375:
1374:
1324:
1323:
1309:
1285:
1284:
1276:
1252:
1251:
1220:
1184:
1183:
1161:
1160:
1137:
1136:
1112:
1111:
1081:
1080:
1073:
1070:
1067:
1066:
1064:
967:
966:
945:
940:
939:
920:
919:
891:
890:
845:
825:
824:
800:radio frequency
768:
767:
733:
722:
721:
695:
694:
675:
674:
641:
640:
618:
617:
590:
589:
561:
555:
549:
532:
414:radio frequency
406:
328:Radio frequency
320:
262:
233:
222:
221:
136:
135:
134:
133:
132:
118:
110:
109:
102:
91:
47:radiating tower
17:
12:
11:
5:
3056:
3054:
3046:
3045:
3040:
3035:
3030:
3020:
3019:
3013:
3012:
3010:
3009:
3004:
2999:
2997:Spiral antenna
2994:
2989:
2984:
2979:
2974:
2969:
2963:
2957:
2955:
2951:
2950:
2948:
2947:
2942:
2937:
2932:
2930:Sterba antenna
2927:
2922:
2917:
2915:Sector antenna
2912:
2907:
2902:
2897:
2892:
2890:Plasma antenna
2887:
2882:
2877:
2872:
2867:
2862:
2857:
2852:
2847:
2842:
2837:
2832:
2827:
2822:
2817:
2812:
2807:
2802:
2797:
2792:
2787:
2782:
2777:
2772:
2767:
2765:Adcock antenna
2761:
2759:
2753:
2752:
2750:
2749:
2744:
2739:
2734:
2729:
2724:
2722:Sloper antenna
2719:
2714:
2709:
2704:
2699:
2697:J-pole antenna
2694:
2689:
2684:
2679:
2674:
2669:
2664:
2659:
2654:
2649:
2647:Dipole antenna
2644:
2639:
2634:
2629:
2624:
2619:
2613:
2611:
2605:
2604:
2602:
2601:
2595:
2593:
2587:
2586:
2580:
2578:
2577:
2570:
2563:
2555:
2549:
2548:
2543:
2536:
2533:
2532:
2531:
2525:
2510:
2504:
2489:
2478:
2472:
2452:
2449:
2446:
2445:
2411:
2378:
2332:
2286:
2257:
2236:
2221:
2195:
2193:, p. 717.
2183:
2171:
2159:
2157:, p. 713.
2144:
2119:
2107:
2095:
2064:
2052:
2031:
2006:
1994:
1981:
1980:
1978:
1975:
1939:
1860:Heinrich Hertz
1829:Lakihegy Tower
1825:Blaw-Knox mast
1822:
1815:
1814:
1810:
1803:
1802:
1801:
1800:
1799:
1797:
1794:
1748:
1745:
1726:
1723:
1722:
1721:
1699:
1662:
1659:magnetic field
1593:Main article:
1590:
1587:
1570:electric shock
1565:
1562:
1560:
1557:
1515:
1476:Main article:
1473:
1470:
1432:
1429:
1382:
1331:
1308:
1305:
1292:
1275:
1272:
1259:
1219:
1216:
1191:
1168:
1144:
1119:
1099:
1095:
1091:
1088:
1039:, simplifying
1016:
1011:
1008:
1003:
1000:
995:
992:
987:
984:
979:
976:
948:
927:
907:
904:
901:
898:
887:
886:
875:
872:
869:
866:
863:
860:
857:
848:
844:
841:
838:
835:
832:
783:
779:
775:
764:
763:
750:
747:
740:
736:
732:
729:
702:
682:
662:
658:
654:
651:
648:
625:
597:
531:
528:
523:
522:
508:
504:Folded unipole
500:
497:electric shock
486:
469:standing waves
419:Faraday shield
405:
402:
375:radio stations
319:
316:
308:building codes
297:lattice towers
278:
268:
261:
255:
252:
246:
239:
122:Blosenbergturm
119:
112:
111:
103:
96:
95:
94:
93:
92:
90:
87:
15:
13:
10:
9:
6:
4:
3:
2:
3055:
3044:
3041:
3039:
3036:
3034:
3031:
3029:
3026:
3025:
3023:
3008:
3005:
3003:
3000:
2998:
2995:
2993:
2990:
2988:
2985:
2983:
2980:
2978:
2977:Ground dipole
2975:
2973:
2970:
2967:
2964:
2962:
2959:
2958:
2956:
2952:
2946:
2943:
2941:
2938:
2936:
2933:
2931:
2928:
2926:
2923:
2921:
2918:
2916:
2913:
2911:
2908:
2906:
2903:
2901:
2898:
2896:
2893:
2891:
2888:
2886:
2883:
2881:
2878:
2876:
2873:
2871:
2870:Patch antenna
2868:
2866:
2863:
2861:
2860:Moxon antenna
2858:
2856:
2853:
2851:
2848:
2846:
2843:
2841:
2838:
2836:
2833:
2831:
2828:
2826:
2823:
2821:
2818:
2816:
2815:Curtain array
2813:
2811:
2808:
2806:
2803:
2801:
2798:
2796:
2793:
2791:
2788:
2786:
2783:
2781:
2778:
2776:
2773:
2771:
2768:
2766:
2763:
2762:
2760:
2758:
2754:
2748:
2745:
2743:
2740:
2738:
2735:
2733:
2730:
2728:
2725:
2723:
2720:
2718:
2715:
2713:
2710:
2708:
2705:
2703:
2702:Mast radiator
2700:
2698:
2695:
2693:
2690:
2688:
2685:
2683:
2680:
2678:
2675:
2673:
2670:
2668:
2665:
2663:
2660:
2658:
2655:
2653:
2650:
2648:
2645:
2643:
2640:
2638:
2635:
2633:
2630:
2628:
2625:
2623:
2620:
2618:
2615:
2614:
2612:
2610:
2606:
2600:
2597:
2596:
2594:
2592:
2588:
2583:
2576:
2571:
2569:
2564:
2562:
2557:
2556:
2553:
2547:
2544:
2542:
2539:
2538:
2534:
2528:
2522:
2518:
2517:
2511:
2507:
2501:
2497:
2496:
2490:
2486:
2485:
2479:
2475:
2469:
2462:
2461:
2455:
2454:
2450:
2433:
2429:
2422:
2415:
2412:
2399:
2395:
2388:
2382:
2379:
2367:
2363:
2359:
2355:
2351:
2347:
2343:
2336:
2333:
2321:
2317:
2313:
2309:
2305:
2301:
2297:
2290:
2287:
2271:
2264:
2262:
2258:
2254:
2249:
2247:
2245:
2243:
2241:
2237:
2233:
2232:Williams 2007
2228:
2226:
2222:
2209:
2205:
2199:
2196:
2192:
2191:Williams 2007
2187:
2184:
2180:
2175:
2172:
2168:
2167:Williams 2007
2163:
2160:
2156:
2155:Williams 2007
2151:
2149:
2145:
2141:
2136:
2134:
2132:
2130:
2128:
2126:
2124:
2120:
2116:
2111:
2108:
2104:
2103:Williams 2007
2099:
2096:
2092:
2091:Williams 2007
2087:
2085:
2083:
2081:
2079:
2077:
2075:
2073:
2071:
2069:
2065:
2061:
2060:Williams 2007
2056:
2053:
2049:
2044:
2042:
2040:
2038:
2036:
2032:
2028:
2023:
2021:
2019:
2017:
2015:
2013:
2011:
2007:
2003:
2002:Williams 2007
1998:
1995:
1991:
1986:
1983:
1976:
1974:
1971:
1967:
1962:
1960:
1956:
1951:
1937:
1928:
1924:
1919:
1915:
1911:
1906:
1904:
1900:
1896:
1892:
1888:
1884:
1880:
1876:
1872:
1868:
1863:
1861:
1857:
1853:
1849:
1845:
1841:
1830:
1826:
1819:
1807:
1795:
1793:
1791:
1786:
1780:
1778:
1774:
1770:
1766:
1765:dish antennas
1762:
1758:
1757:whip antennas
1754:
1746:
1744:
1741:
1740:lightning rod
1736:
1732:
1724:
1718:
1714:
1710:
1706:
1704:
1700:
1697:
1693:
1689:
1684:
1680:
1676:
1672:
1668:
1667:
1663:
1660:
1655:
1651:
1647:
1643:
1639:
1635:
1634:
1630:
1629:
1626:
1621:
1617:
1615:
1611:
1606:
1602:
1596:
1588:
1586:
1584:
1580:
1575:
1571:
1563:
1558:
1556:
1554:
1549:
1545:
1541:
1537:
1532:
1529:
1513:
1505:
1500:
1496:
1493:
1489:
1485:
1479:
1471:
1469:
1467:
1463:
1458:
1454:
1450:
1446:
1437:
1430:
1428:
1426:
1422:
1417:
1415:
1411:
1410:tuned circuit
1407:
1403:
1399:
1394:
1380:
1371:
1367:
1363:
1359:
1355:
1351:
1347:
1346:
1329:
1320:
1316:
1314:
1313:low frequency
1306:
1304:
1290:
1282:
1273:
1271:
1257:
1249:
1245:
1241:
1237:
1233:
1229:
1225:
1217:
1215:
1213:
1209:
1203:
1189:
1180:
1166:
1158:
1142:
1133:
1117:
1097:
1093:
1089:
1086:
1061:
1057:
1054:
1050:
1046:
1042:
1038:
1034:
1030:
1014:
1009:
1006:
1001:
998:
993:
990:
985:
982:
977:
974:
946:
925:
902:
896:
870:
867:
864:
858:
855:
846:
842:
836:
830:
823:
822:
821:
819:
815:
814:standing wave
812:
808:
804:
801:
797:
781:
777:
773:
748:
745:
738:
734:
730:
727:
720:
719:
718:
716:
700:
680:
660:
656:
652:
649:
646:
639:
623:
615:
611:
595:
588:
580:
576:
571:
564:
558:
552:
546:
541:
536:
529:
527:
520:
516:
512:
509:
506:
505:
501:
498:
494:
490:
489:Shunt excited
487:
484:
481:
480:
479:
476:
474:
470:
466:
462:
458:
454:
450:
446:
445:
440:
436:
432:
431:coaxial cable
428:
424:
420:
415:
411:
403:
401:
399:
395:
390:
388:
387:
382:
381:
376:
373:
369:
368:low frequency
365:
361:
357:
349:
344:
337:
333:
329:
324:
317:
315:
313:
309:
304:
302:
298:
293:
276:
266:
259:
253:
250:
244:
237:
218:
214:
209:
207:
203:
199:
194:
192:
188:
184:
180:
176:
172:
168:
164:
161:
152:
148:
145:
144:lattice masts
141:
131:
127:
123:
116:
107:
100:
88:
86:
84:
80:
76:
72:
68:
64:
60:
56:
52:
48:
44:
43:mast radiator
36:
32:
31:radio station
28:
23:
19:
2925:Slot antenna
2895:Quad antenna
2880:Planar array
2875:Phased array
2850:Loop antenna
2840:Horn antenna
2747:Whip antenna
2732:T2FD antenna
2701:
2677:Halo antenna
2672:G5RV antenna
2515:
2494:
2483:
2459:
2436:. Retrieved
2431:
2427:
2414:
2402:. Retrieved
2397:
2393:
2381:
2369:. Retrieved
2349:
2345:
2335:
2323:. Retrieved
2303:
2299:
2289:
2277:. Retrieved
2253:Johnson 1993
2212:. Retrieved
2207:
2198:
2186:
2179:Johnson 1993
2174:
2162:
2115:Johnson 1993
2110:
2098:
2055:
2048:Johnson 1993
2027:Johnson 1993
1997:
1985:
1963:
1959:rhombohedral
1952:
1907:
1893:and had low
1879:Machrihanish
1864:
1858:invented by
1848:transmitters
1837:
1781:
1752:
1750:
1728:
1701:
1664:
1631:
1598:
1567:
1533:
1501:
1497:
1488:ground plane
1481:
1452:
1448:
1444:
1442:
1418:
1402:loading coil
1395:
1357:
1349:
1343:
1321:
1317:
1310:
1277:
1236:out of phase
1221:
1204:
1181:
1060:Ground waves
1058:
888:
765:
714:
584:
578:
574:
560:
554:
548:
524:
510:
502:
488:
482:
477:
461:loading coil
459:, usually a
442:
407:
391:
384:
380:ground waves
378:
353:
305:
294:
210:
195:
157:
137:
59:transmitting
46:
42:
40:
18:
2775:AWX antenna
2757:Directional
2627:Cage aerial
2394:Radio-Craft
2140:Laport 1952
1914:medium wave
1696:capacitance
410:transmitter
404:Feed system
370:(LF) bands
326:Base feed:
187:transmitter
140:guyed masts
130:Switzerland
126:Beromünster
79:transmitter
63:frequencies
3022:Categories
2546:Guyed mast
2473:007032381X
2451:References
2428:Radio News
2404:August 31,
2214:31 October
1990:Smith 2007
1970:ionosphere
1779:antennas.
1228:ionosphere
1033:resistance
811:sinusoidal
638:wavelength
2968:(passive)
2830:Gizmotchy
2737:T-antenna
2591:Isotropic
1938:λ
1918:T-antenna
1852:receivers
1790:inductors
1735:spark gap
1713:capacitor
1688:capacitor
1675:impedance
1652:with the
1514:λ
1457:capacitor
1421:T antenna
1414:bandwidth
1381:λ
1350:radiators
1330:λ
1291:λ
1258:λ
1248:mush zone
1240:interfere
1190:λ
1167:λ
1143:λ
1118:λ
1098:π
1090:λ
1053:reactance
1015:λ
999:λ
983:λ
868:−
859:
807:interfere
774:λ
749:λ
739:∘
647:λ
587:frequency
543:from the
519:mush zone
515:collinear
511:Sectional
457:reactance
366:(MF) and
336:spark gap
277:λ
254:∼
251:λ
198:guy wires
163:insulator
65:, in the
29:of an AM
2987:Rectenna
2785:Cantenna
2535:See also
2371:15 April
2366:51639724
2325:18 April
2320:51654399
1887:longwave
1869:for his
1709:inductor
1671:inductor
1536:antinode
1406:Q factor
1281:in phase
1037:feedline
1029:resonant
798:. The
547:(0.25λ,
465:resonant
423:feedline
350:lengths.
348:resonant
142:. Steel
2582:Antenna
2438:May 26,
2279:7 April
1796:History
1642:primary
1564:Fencing
1553:asphalt
1449:top hat
1232:skywave
1110:= 0.637
1077:
1065:
1035:to the
803:current
449:matches
386:skywave
202:anchors
171:voltage
160:ceramic
55:antenna
49:) is a
3038:Towers
2961:ALLISS
2523:
2502:
2470:
2364:
2318:
1705:(trap)
1358:driven
1352:; the
1244:fading
889:where
471:(high
394:phases
280:
270:
264:
241:
235:
228:
37:, U.S.
2940:WokFi
2584:types
2464:(PDF)
2424:(PDF)
2390:(PDF)
2362:S2CID
2316:S2CID
2273:(PDF)
1977:Notes
1666:Choke
1574:volts
1135:0.625
556:green
417:by a
2521:ISBN
2500:ISBN
2468:ISBN
2440:2015
2406:2014
2373:2020
2327:2020
2281:2020
2216:2022
1850:and
1767:for
1759:for
1711:and
1644:and
1370:ohms
1354:gain
1132:lobe
818:node
550:blue
451:the
408:The
120:The
108:, US
69:and
45:(or
2354:doi
2308:doi
1901:or
1873:at
1827:,
1451:or
1423:or
1047:or
951:max
856:sin
851:max
782:360
735:360
562:red
473:SWR
292:).
33:in
3024::
2430:.
2426:.
2396:.
2392:.
2360:.
2350:12
2348:.
2344:.
2314:.
2304:12
2302:.
2298:.
2260:^
2239:^
2224:^
2206:.
2147:^
2122:^
2067:^
2034:^
2009:^
1614:Hz
717:"
372:AM
267:10
193:.
175:RF
128:,
85:.
71:MF
67:LF
41:A
2574:e
2567:t
2560:v
2529:.
2508:.
2476:.
2442:.
2432:8
2408:.
2398:3
2375:.
2356::
2329:.
2310::
2283:.
2218:.
1460:"
1094:/
1087:2
1074:8
1071:/
1068:5
1010:4
1007:3
1002:,
994:2
991:1
986:,
978:4
975:1
947:I
926:y
906:)
903:y
900:(
897:i
874:)
871:y
865:G
862:(
847:I
843:=
840:)
837:y
834:(
831:i
778:/
746:h
731:=
728:G
701:f
681:c
661:f
657:/
653:c
650:=
624:h
596:f
579:X
575:R
565:)
437:(
260:1
245:8
238:1
220:(
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