471:
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551:
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498:
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244:) will also capture 100 times as much energy as the isotropic antenna when used as a receiving antenna. As a consequence of their directivity, directional antennas also send less (and receive less) signal from directions other than the main beam. This property may avoid interference from other out-of-beam transmitters, and always reduces antenna noise. (Noise comes from every direction, but a desired signal will only come from one approximate direction, so the narrower the antenna's beam, the better the crucial
72:
51:
550:
36:
470:
357:), and efficiency (again, affected by size, but also resistivity of the materials used and impedance matching). These factors are easy to improve without adjusting other features of the antennas or coincidentally improved by the same factors that increase directivity, and so are typically not emphasized.
349:
Gain is also dependent on the number of elements and the tuning of those elements. Antennas can be tuned to be resonant over a wider spread of frequencies but, all other things being equal, this will mean the gain of the aerial is lower than one tuned for a single frequency or a group of frequencies.
405:
373:
uses 35 m dishes at about 1 cm wavelengths. This combination gives the antenna gain of about 100,000,000 (or 80 dB, as normally measured), making the transmitter appear about 100 million times stronger, and a receiver about 100 million times more sensitive,
425:
560:. From left to right, the elements mounted on the boom are called the reflector, driven element, and director. The reflector is easily identified as being a bit longer (5% or more) than all the other elements, and the director(s) a bit shorter (5% or more).
165:
All practical antennas are at least somewhat directional, although usually only the direction in the plane parallel to the earth is considered, and practical antennas can easily be omnidirectional in one plane. The most common directional antenna types are
95:
in beams, when greater concentration of radiation in a certain direction is desired, or in receiving antennas receive radio waves from one specific direction only. This can increase the power transmitted to receivers in that direction, or reduce
318:
of the sky (otherwise the total amount of energy radiated in all directions would sum to more than the transmitter power, which is not possible). In turn this implies that high-gain antennas must be physically large, since according to the
389:
gaining increases the probability of concurrent scheduling of non‐interfering transmissions in a localized area, which results in an immense increase in network throughput. However, the optimum scheduling of concurrent transmission is an
519:
448:
235:
allows more of the transmitted power to be sent in the direction of the receiver, increasing the received signal strength. When receiving, a high gain antenna captures more of the signal, again increasing signal strength. Due to
497:
350:
For example, in the case of wideband TV antennas the fall off in gain is particularly large at the bottom of the TV transmitting band. In the UK this bottom third of the TV band is known as group A.
154:, with a broad radiowave beam width, that allows the signal to propagate reasonably well even in mountainous regions and is thus more reliable regardless of terrain. Low-gain antennas are often used in
353:
Other factors may also affect gain such as aperture (the area the antenna collects signal from, almost entirely related to the size of the antenna but for small antennas can be increased by adding a
192:
These antenna types, or combinations of several single-frequency versions of one type or (rarely) a combination of two different types, are frequently sold commercially as residential
334:
aerials this more or less equates to the gain one would expect from the aerial under test minus all its directors and reflector. It is important not to confuse dB
365:
High gain antennas are typically the largest component of deep space probes, and the highest gain radio antennas are physically enormous structures, such as the
507:
298:, is called dBi. Conservation of energy dictates that high gain antennas must have narrow beams. For example, if a high gain antenna makes a 1
865:
934:
346:; the two differ by 2.15 dB, with the dBi figure being higher, since a dipole has 2.15 dB of gain with respect to an isotropic antenna.
791:
Bilal, Muhammad; et al. (2014). "Time-slotted scheduling schemes for multi-hop concurrent transmission in WPANs with directional antennas".
534:
279:
with an enormous spherical reflector (as opposed to a more usual parabolic reflector), to achieve extremely high gains at specific frequencies.
1389:
704:
674:
1394:
897:
1363:
1181:
842:
663:
Zainah Md Zain; Hamzah Ahmad; Dwi
Pebrianti; Mahfuzah Mustafa; Nor Rul Hasma Abdullah; Rosdiyana Samad; Maziyah Mat Noh (2020).
1131:
572:
237:
1003:
97:
927:
488:
320:
1399:
1266:
240:, these two effects are equal—an antenna that makes a transmitted signal 100 times stronger (compared to an
42:
271:
can also be constructed with high gain, but are less commonly seen. Still other configurations are possible—the
200:
often make use of external directional antennas to give a far greater signal than can be obtained on a standard
1261:
1171:
185:
723:
91:
which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate
1161:
1023:
970:
905:
637:
617:
378:. This beam can cover at most one hundred millionth (10) of the sky, so very accurate pointing is required.
151:
101:
741:
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998:
873:
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462:
386:
245:
88:
1306:
1206:
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602:
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419:, then in Newark, New Jersey and targeting both New York City and Philadelphia in addition to Newark.
205:
178:
57:
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480:
435:
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366:
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is often quoted with respect to a hypothetical antenna that radiates equally in all directions, an
272:
1368:
1216:
1156:
1151:
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818:
800:
597:
370:
291:
241:
666:
Proceedings of the 11th
National Technical Seminar on Unmanned System Technology 2019: NUSYS'19
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847:
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260:
171:
139:, most successfully in flat, open areas where there are no mountains to disrupt radiowaves.
131:, permitting more precise targeting of the radio signals. Most commonly referred to during
323:, the narrower the beam desired, the larger the antenna must be (measured in wavelengths).
1333:
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993:
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162:, which transmits a much narrower beam and is therefore susceptible to loss of signal.
132:
105:
71:
1383:
1338:
1231:
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438:, which was the world's first radio telescope, discovering radio emissions from the
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1038:
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transmitter look like a 100 Watt transmitter, then the beam can cover at most
287:
268:
264:
116:
50:
330:
compared to the maximum intensity direction of a half wave dipole. In the case of
694:
664:
1136:
988:
607:
454:
431:
299:
220:
216:
17:
814:
511:
213:
201:
193:
155:
128:
92:
111:
The extent to which an antenna's angular distribution of radiated power, its
108:
which radiate radio waves over a wide angle, or receive from a wide angle.
1191:
1098:
525:
439:
528:
spacecraft. The HGA (a parabolic antenna) is the large bowl-shaped object.
487:
communication program, it was later used in experiments that revealed the
1348:
1146:
952:
765:
592:
587:
416:
391:
327:
295:
35:
411:
An early example (1922) of a directional AM radio transmitter using a
1322:
251:
There are many ways to make a high-gain antenna; the most common are
115:, is concentrated in one direction is measured by a parameter called
805:
1301:
136:
70:
61:
27:
Radio antenna which has greater performance in specific alignments
912:
916:
836:
Crawford, A.B.; Hogg, D.C.; Hunt, L.E. (July 1961). "Project
326:
Antenna gain can also be measured in dBd, which is gain in
840:: A horn-reflector antenna for space communication".
434:
and his rotating directional radio antenna (1932) in
1315:
1117:
969:
951:
127:) is a directional antenna with a focused, narrow
223:are used in most cases as directional antennas.
928:
8:
868:. Astronomy and astrophysics. History. U.S.
100:from unwanted sources. This contrasts with
508:Goldstone Deep Space Communications Complex
461:(1937), world's second radio telescope and
935:
921:
913:
135:, these antennas are also in use all over
804:
764:For comparison of groups of aerials to a
655:
401:
728:Oxford Reference (oxfordreference.com)
376:provided the target is within the beam
7:
699:. Infobase Publishing. p. 364.
696:Encyclopedia of Space and Astronomy
852:10.1002/j.1538-7305.1961.tb01639.x
742:"Low gain aerial acceptance angle"
25:
1364:Circularly disposed antenna array
1182:Folded inverted conformal antenna
843:The Bell System Technical Journal
768:aerial of the same size / model,
267:of smaller antennas of any kind.
904:. Communications. Evanston, IL:
669:. Springer Nature. p. 535.
549:
533:
518:
496:
469:
447:
424:
404:
49:
34:
573:Amateur radio direction finding
463:first parabolic radio telescope
483:(1960s). Built to support the
294:. This gain, when measured in
1:
1390:Radio frequency antenna types
898:"What are high and low gain?"
1004:Dielectric resonator antenna
872:. 2001-11-05. Archived from
1395:Radio frequency propagation
506:– the 70 m antenna at
489:Cosmic microwave background
1416:
815:10.4218/etrij.14.0113.0703
75:Patch antenna gain pattern
1267:Regenerative loop antenna
693:Joseph A. Angelo (2014).
43:log-periodic dipole array
1262:Reflective array antenna
1172:Corner reflector antenna
491:permeating the universe.
275:used a combination of a
186:corner reflector antenna
102:omnidirectional antennas
1162:Collinear antenna array
906:Northwestern University
638:Radio propagation model
618:Omnidirectional antenna
457:'s homemade antenna in
152:omnidirectional antenna
1344:Reconfigurable antenna
1307:Yagi–Uda antenna
1282:Short backfire antenna
1019:Folded unipole antenna
633:Radio direction finder
510:in the Mojave Desert,
227:Principle of operation
212:. For long and medium
208:receivers usually use
76:
999:Crossed field antenna
870:National Park Service
381:Use of high gain and
246:signal-to-noise ratio
231:When transmitting, a
74:
1316:Application-specific
1207:Log-periodic antenna
1079:Rubber ducky antenna
1054:Inverted vee antenna
1029:Ground-plane antenna
902:qrg.northwestern.edu
640:, Antenna subsection
603:Cassegrain reflector
477:Holmdel Horn Antenna
206:Satellite television
179:log-periodic antenna
1227:Offset dish antenna
1074:Random wire antenna
712:Extract of page 364
682:Extract of page 535
481:Holmdel, New Jersey
436:Holmdel, New Jersey
367:Arecibo Observatory
273:Arecibo Observatory
158:as a backup to the
81:directional antenna
1369:Television antenna
1217:Microstrip antenna
1157:Choke ring antenna
1152:Cassegrain antenna
1049:Inverted-F antenna
961:Isotropic radiator
724:"Low-gain antenna"
598:Cassegrain antenna
371:Deep Space Network
292:isotropic radiator
253:parabolic antennas
242:isotropic radiator
210:parabolic antennas
198:Cellular repeaters
77:
1377:
1376:
1354:Reference antenna
1247:Parabolic antenna
1167:Conformal antenna
1089:Turnstile antenna
984:Biconical antenna
706:978-1-4381-1018-9
676:978-981-15-5281-6
644:Radiation pattern
623:Parabolic antenna
578:Antenna boresight
504:Parabolic antenna
459:Wheaton, Illinois
413:long wire antenna
385:communication in
321:diffraction limit
261:Yagi-Uda antennas
233:high-gain antenna
160:high-gain antenna
121:high-gain antenna
113:radiation pattern
60:radio antenna at
41:A multi-element,
16:(Redirected from
1407:
1400:Antennas (radio)
1328:Corner reflector
1142:Beverage antenna
1104:Umbrella antenna
1069:Monopole antenna
1024:Franklin antenna
937:
930:
923:
914:
909:
885:
884:
882:
881:
862:
856:
855:
833:
827:
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788:
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778:aerialsandtv.com
762:
756:
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752:aerialsandtv.com
749:
748:
738:
732:
731:
720:
714:
710:
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684:
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558:Yagi-Uda antenna
553:
537:
522:
500:
473:
451:
428:
408:
345:
344:
339:
338:
317:
315:
314:
311:
308:
257:helical antennas
172:Yagi-Uda antenna
144:low-gain antenna
53:
38:
21:
18:Low Gain Antenna
1415:
1414:
1410:
1409:
1408:
1406:
1405:
1404:
1380:
1379:
1378:
1373:
1334:Evolved antenna
1311:
1297:Vivaldi antenna
1272:Rhombic antenna
1197:Helical antenna
1187:Fractal antenna
1132:AS-2259 Antenna
1113:
1044:Helical antenna
1014:Discone antenna
994:Coaxial antenna
979:Batwing antenna
971:Omnidirectional
965:
947:
941:
896:
893:
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544:radar in Alaska
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383:millimeter-wave
363:
342:
341:
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229:
142:In contrast, a
106:dipole antennas
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67:
66:
65:
54:
46:
45:
39:
28:
23:
22:
15:
12:
11:
5:
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1402:
1397:
1392:
1382:
1381:
1375:
1374:
1372:
1371:
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1361:
1359:Spiral antenna
1356:
1351:
1346:
1341:
1336:
1331:
1325:
1319:
1317:
1313:
1312:
1310:
1309:
1304:
1299:
1294:
1292:Sterba antenna
1289:
1284:
1279:
1277:Sector antenna
1274:
1269:
1264:
1259:
1254:
1252:Plasma antenna
1249:
1244:
1239:
1234:
1229:
1224:
1219:
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1209:
1204:
1199:
1194:
1189:
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1179:
1174:
1169:
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1159:
1154:
1149:
1144:
1139:
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1127:Adcock antenna
1123:
1121:
1115:
1114:
1112:
1111:
1106:
1101:
1096:
1091:
1086:
1084:Sloper antenna
1081:
1076:
1071:
1066:
1061:
1059:J-pole antenna
1056:
1051:
1046:
1041:
1036:
1031:
1026:
1021:
1016:
1011:
1009:Dipole antenna
1006:
1001:
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991:
986:
981:
975:
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957:
955:
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942:
940:
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917:
911:
910:
892:
891:External links
889:
887:
886:
866:"Horn antenna"
857:
828:
799:(3): 374–384.
783:
757:
733:
715:
705:
685:
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654:
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485:Echo satellite
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133:space missions
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9:
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1339:Ground dipole
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1232:Patch antenna
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1223:
1222:Moxon antenna
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1205:
1203:
1200:
1198:
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1177:Curtain array
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1080:
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1064:Mast radiator
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903:
899:
895:
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890:
876:on 2008-05-12
875:
871:
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858:
853:
849:
846:: 1095–1099.
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269:Horn antennas
266:
265:phased arrays
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63:
59:
52:
44:
37:
19:
1287:Slot antenna
1257:Quad antenna
1242:Planar array
1237:Phased array
1212:Loop antenna
1202:Horn antenna
1118:
1109:Whip antenna
1094:T2FD antenna
1039:Halo antenna
1034:G5RV antenna
901:
878:. Retrieved
874:the original
860:
841:
837:
831:
796:
793:ETRI Journal
792:
786:
777:
774:"Gain graph"
769:
760:
751:
744:. Row ridge
736:
727:
718:
695:
688:
665:
658:
628:Phased array
613:Loop antenna
583:Antenna gain
542:phased-array
415:, built for
380:
375:
364:
361:Applications
352:
348:
325:
288:Antenna gain
286:
283:Antenna gain
276:
250:
232:
230:
221:tower arrays
191:
164:
159:
147:
143:
141:
124:
120:
117:antenna gain
110:
98:interference
85:beam antenna
84:
80:
78:
64:, California
1137:AWX antenna
1119:Directional
989:Cage aerial
608:Directivity
455:Grote Reber
432:Karl Jansky
355:ferrite rod
238:reciprocity
217:frequencies
194:TV antennas
93:radio waves
56:A 70-meter
1384:Categories
880:2008-05-23
806:1801.06018
651:References
512:California
214:wavelength
202:cell phone
156:spacecraft
129:beam width
58:Cassegrain
1330:(passive)
1192:Gizmotchy
1099:T-antenna
953:Isotropic
526:Voyager 2
440:Milky Way
394:problem.
332:Yagi-type
277:line feed
1349:Rectenna
1147:Cantenna
766:wideband
593:Cardioid
588:Cantenna
566:See also
540:A giant
328:decibels
296:decibels
150:) is an
104:such as
944:Antenna
823:2285688
398:Gallery
392:NP-Hard
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89:antenna
1323:ALLISS
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369:. The
340:and dB
263:, and
87:is an
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946:types
819:S2CID
801:arXiv
181:, and
137:Earth
62:GDSCC
838:Echo
701:ISBN
671:ISBN
387:WPAN
300:Watt
184:the
177:the
170:the
119:. A
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417:WOR
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