239:
parallel flat surfaces. They are widely used in many applications, for instance in WiFi Access Points. Directional antennas concentrate the power in a specific direction, called the bore sight, and are widely used in point to point applications, like wireless bridges and satellite communications. Sectorial antennas concentrate the power in a wider region, typically embracing 45º, 60º, 90º or 120º. They are routinely deployed in
Cellular towers.
27:
238:
Transmitting antennas can be
Omnidirectional, Directional, or Sectorial, depending on the way in which the antenna power is oriented. An omnidirectional antenna will distribute the power equally in every direction of a plane, so the radiation pattern has the shape of a sphere squeezed between two
915:
Experience has shown that line-of-sight propagation holds only for about the first 3 meters. Beyond 3 meters propagation losses indoors can increase at up to 30 dB per 30 meters in dense office environments. This is a good rule-of-thumb, in that it is conservative (it overstates path loss in
252:
which states that the loss is proportional to the square of the distance and the square of the frequency. Additionally losses are incurred in most radio links, including atmospheric attenuation by gases, rain, fog and clouds. Fading due to variations of the channel, multipath losses and antenna
425:
782:
In some cases, it is convenient to consider the loss due to distance and wavelength separately, but in that case, it is important to keep track of which units are being used, as each choice involves a differing constant offset. Some examples are provided below.
769:
895:
Because of building obstructions such as walls and ceilings, propagation losses indoors can be significantly higher. This occurs because of a combination of attenuation by walls and ceilings, and blockage due to equipment, furniture, and even people.
179:
it passes through. A link budget is a design aid, calculated during the design of a communication system to determine the received power, to ensure that the information is received intelligibly with an adequate
234:
system, the primary source of loss is the decrease of the signal power as it spreads over an increasing area while it propagates, proportional to the square of the distance (geometric spreading).
311:
687:
The loss due to propagation between the transmitting and receiving antennas, often called the path loss, can be written in dimensionless form by normalizing the distance to the wavelength:
293:), which may be dependent on the communications protocol in use, the link will be useful for sending data. The amount by which the received power exceeds receiver sensitivity is called the
693:
188:
are taken into account by adding some margin depending on the anticipated severity of its effects. The amount of margin required can be reduced by the use of mitigating techniques such as
1173:
159:, to the receiver. It is an equation giving the received power from the transmitter power, after the attenuation of the transmitted signal due to propagation, as well as the
869:
840:
811:
681:
648:
578:
549:
516:
487:
458:
615:
927:
Guided media such as coaxial and twisted pair electrical cable, radio frequency waveguide and optical fiber have losses that are exponential with distance.
937:
This means that there is always a crossover distance beyond which the loss in a guided medium will exceed that of a line-of-sight path of the same length.
1101:
1269:
1023:
has been able to maintain the link at a higher than expected bitrate through a series of improvements, such as increasing the antenna size from 64
253:
misalignment. In non line of sight links, diffraction and reflection losses are the most important since the direct path is not available.
261:
In practical situations (deep space telecommunications, weak signal DXing etc.) other sources of signal loss must also be accounted for
1209:
1131:
1184:
887:) divided by frequency, and by inserting the proper conversion factors between km or miles and meters, and between MHz and (1/s).
1299:
1043:
flyby, in addition to the 70-m antenna, two 34-m antennas and twenty-seven 25-m antennas were used to increase the gain by 5.6
1304:
91:
420:{\displaystyle P_{\text{RX}}=P_{\text{TX}}+G_{\text{TX}}-L_{\text{TX}}-L_{\text{FS}}-L_{M}+G_{\text{RX}}-L_{\text{RX}}\,}
63:
764:{\displaystyle L_{\text{FS}}{\text{(dB)}}=20\log _{10}\left(4\pi {{\text{distance}} \over {\text{wavelength}}}\right)}
1279:
1061:
110:
911:
Older buildings may have even greater internal losses than new buildings due to materials and line of sight issues.
70:
916:
most cases). Actual propagation losses may vary significantly depending on building construction and layout.
48:
1254:
77:
1109:
44:
875:
These alternative forms can be derived by substituting wavelength with the ratio of propagation velocity (
1056:
776:
249:
152:
59:
944:
became practical only with the development of ultra-transparent glass fibers. A typical path loss for
941:
305:
A link budget equation including all these effects, expressed logarithmically, might look like this:
290:
228:
1227:
847:
818:
789:
659:
626:
556:
527:
494:
465:
436:
593:
37:
775:
When substituted into the link budget equation above, the result is the logarithmic form of the
1076:
181:
140:
957:
8:
84:
901:
1066:
1020:
268:
The cabling between the radios and antennas may introduce significant additional loss.
219:
measurement, so adding decibels is equivalent to multiplying the actual power ratios.
1203:
1125:
1071:
988:
945:
189:
148:
136:
1225:
1294:
1002:
The Moon must be above the horizon in order for EME communications to be possible.
919:
The attenuation of the signal is highly dependent on the frequency of the signal.
1012:
585:
289:
If the estimated received power is sufficiently large (typically relative to the
128:
172:
1047:
dB, providing additional link margin to be used for a 4× increase in bitrate.
1019:
dB as of 2002) and lowest link budgets of any telecommunications circuit. The
1288:
1274:
984:
277:
156:
651:
519:
271:
160:
964:
of the Moon is very low (maximally 12% but usually closer to 7%), and the
1081:
294:
265:
The transmitting and receiving antennas may be partially cross-polarized.
203:
Received power (dBm) = transmitted power (dBm) + gains (dB) − losses (dB)
1145:
980:
144:
995:
In practice, this limits the use of this technique to the spectrum at
965:
931:
581:
216:
168:
1264:
26:
1259:
1226:
176:
164:
908:
on both sides results in about 6 dB loss per wall at 2.4 GHz.
1040:
976:
905:
621:
margin, body loss, polarization mismatch, other losses, ...) (dB)
212:
969:
961:
618:
185:
132:
231:
948:
is 0.2 dB/km, far lower than any other guided medium.
193:
256:
1035:
dB gain, and upgrading to low noise electronics for a 0.5
996:
208:
274:
losses due to a partially obstructed line of sight path.
16:
Accounting of signal gains and losses in communications
850:
821:
792:
771:(where distance and wavelength are in the same units)
696:
662:
629:
596:
559:
530:
497:
468:
439:
314:
1280:
Small satellites link budget (with python examples)
51:. Unsourced material may be challenged and removed.
951:
863:
834:
805:
763:
675:
642:
609:
572:
543:
510:
481:
452:
419:
248:The free space loss is easily calculated using
1286:
1015:spacecraft have the highest known path loss (308
987:effects), high power (more than 100 watts) and
683:, receiver losses (coax, connectors, ...) (dB)
551:, transmitter losses (coax, connectors...) (dB)
199:A simple link budget equation looks like this:
972:return distance is extreme (around 250 to 310
1275:Python link budget calculator for satellites
280:induced signal power losses in the receiver.
922:
211:), Power gains and losses are expressed in
184:. Randomly varying channel gains such as
1221:
1219:
934:will be in terms of dB per unit distance.
890:
416:
243:
111:Learn how and when to remove this message
1146:"Tutorial on Basic Link Budget Analysis"
1255:Link budget calculator for wireless LAN
1216:
257:Transmission line and polarization loss
1287:
1270:Example LTE, GSM and UMTS Link Budgets
1208:: CS1 maint: archived copy as title (
1130:: CS1 maint: archived copy as title (
991:(more than 20 dB) must be used.
871:(dB) ≈ 36.6 dB + 20 log10 + 20 log10
842:(dB) ≈ −27.55 dB + 20 log10 + 20 log10
813:(dB) ≈ 32.45 dB + 20 log10 + 20 log10
139:system; from a transmitter, through a
131:gains and losses that a communication
1260:Point-to-point link budget calculator
49:adding citations to reliable sources
20:
1265:MUOS Link budget calculator/planner
222:
13:
1006:
194:multiple-input and multiple-output
14:
1316:
1248:
1062:Antenna gain-to-noise-temperature
1039:dB gain in 2000–2001. During the
979:depending on VHF-UHF band used,
489:, transmitter output power (dBm)
25:
958:Earth–Moon–Earth communications
952:Earth–Moon–Earth communications
207:Power levels are expressed in (
127:is an accounting of all of the
36:needs additional citations for
1300:Telecommunications engineering
1166:
1138:
1094:
956:Link budgets are important in
1:
1087:
864:{\displaystyle L_{\text{FS}}}
835:{\displaystyle L_{\text{FS}}}
806:{\displaystyle L_{\text{FS}}}
676:{\displaystyle L_{\text{RX}}}
643:{\displaystyle G_{\text{RX}}}
573:{\displaystyle L_{\text{FS}}}
544:{\displaystyle L_{\text{TX}}}
511:{\displaystyle G_{\text{TX}}}
482:{\displaystyle P_{\text{TX}}}
453:{\displaystyle P_{\text{RX}}}
1228:"Voyager Telecommunications"
610:{\displaystyle L_{\text{M}}}
7:
1305:Radio frequency propagation
1181:www.corningcablesystems.com
1057:Friis transmission equation
1050:
777:Friis transmission equation
300:
250:Friis transmission equation
10:
1321:
284:
942:fiber-optic communication
923:In waveguides and cables
617:, miscellaneous losses (
1233:. descanso.jpl.nasa.gov
1106:people.deas.harvard.edu
891:Non-line-of-sight radio
904:" wood stud wall with
865:
836:
807:
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677:
644:
611:
574:
545:
512:
483:
460:, received power (dBm)
454:
421:
244:Simplifications needed
167:and other losses, and
1077:Multipath propagation
866:
837:
808:
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678:
645:
612:
575:
546:
513:
484:
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182:signal-to-noise ratio
171:of the signal in the
1190:on 28 September 2007
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557:
528:
495:
466:
437:
312:
291:receiver sensitivity
141:communication medium
45:improve this article
1112:on 1 September 2005
1067:Isotropic radiator
1021:Deep Space Network
989:high-gain antennas
861:
832:
803:
761:
673:
640:
607:
570:
541:
508:
479:
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1072:Radiation pattern
970:770,000 kilometre
946:single-mode fiber
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637:
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567:
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476:
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215:(dB), which is a
190:antenna diversity
137:telecommunication
135:experiences in a
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1239:
1238:
1232:
1223:
1214:
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1189:
1183:. Archived from
1178:
1170:
1164:
1163:
1161:
1159:
1150:
1142:
1136:
1135:
1129:
1121:
1119:
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1108:. Archived from
1098:
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1038:
1034:
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1026:
1018:
975:
900:For example, a "
886:
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879:, approximately
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223:In radio systems
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1245:
1236:
1234:
1230:
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1201:
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1193:
1191:
1187:
1176:
1174:"Archived copy"
1172:
1171:
1167:
1157:
1155:
1148:
1144:
1143:
1139:
1123:
1122:
1115:
1113:
1102:"Archived copy"
1100:
1099:
1095:
1090:
1053:
1044:
1036:
1032:
1028:
1024:
1016:
1013:Voyager program
1009:
1007:Voyager program
973:
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925:
893:
882:
880:
855:
851:
849:
846:
845:
826:
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797:
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749:
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667:
663:
661:
658:
657:
634:
630:
628:
625:
624:
601:
597:
595:
592:
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586:free space loss
564:
560:
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555:
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531:
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525:
502:
498:
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493:
492:
473:
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410:
406:
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384:
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309:
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287:
259:
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117:
106:
100:
97:
54:
52:
42:
30:
17:
12:
11:
5:
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1297:
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1282:
1277:
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1267:
1262:
1257:
1250:
1249:External links
1247:
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1243:
1215:
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1137:
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1008:
1005:
1004:
1003:
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953:
950:
940:Long distance
924:
921:
913:
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909:
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889:
873:
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854:
843:
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796:
773:
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1022:
1014:
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994:
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990:
986:
985:Doppler shift
982:
978:
971:
967:
963:
959:
949:
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943:
938:
935:
933:
928:
920:
917:
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903:
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852:
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823:
815:
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739:
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728:
723:
719:
715:
712:
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690:
689:
688:
664:
656:
653:
631:
623:
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598:
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583:
561:
553:
532:
524:
521:
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491:
470:
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441:
433:
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407:
403:
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385:
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377:
368:
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355:
351:
342:
338:
329:
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308:
307:
306:
298:
296:
292:
279:
278:Doppler shift
276:
273:
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267:
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262:
254:
251:
237:
236:
235:
233:
230:
229:line-of-sight
220:
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210:
202:
201:
200:
197:
195:
191:
187:
183:
178:
174:
170:
169:amplification
166:
162:
161:antenna gains
158:
157:optical fiber
154:
150:
146:
142:
138:
134:
130:
126:
115:
112:
104:
93:
90:
86:
83:
79:
76:
72:
69:
65:
62: –
61:
60:"Link budget"
57:
56:Find sources:
50:
46:
40:
39:
34:This article
32:
28:
23:
22:
19:
1235:. Retrieved
1192:. Retrieved
1185:the original
1180:
1168:
1156:. Retrieved
1152:
1140:
1114:. Retrieved
1110:the original
1105:
1096:
1010:
955:
939:
936:
929:
926:
918:
914:
894:
876:
874:
781:
774:
686:
652:antenna gain
520:antenna gain
429:
304:
288:
272:Fresnel zone
260:
247:
226:
206:
198:
124:
122:
107:
98:
88:
81:
74:
67:
55:
43:Please help
38:verification
35:
18:
1153:sss-mag.com
1082:RF planning
1031:m for a 1.2
983:format and
885:10 m/s
650:, receiver
295:link margin
217:logarithmic
145:radio waves
125:link budget
1289:Categories
1237:2017-08-04
1194:12 January
1116:12 January
1088:References
999:and above.
981:modulation
751:wavelength
584:, usually
101:March 2016
71:newspapers
968:over the
966:path loss
960:. As the
932:path loss
740:π
729:
582:path loss
404:−
378:−
365:−
352:−
177:repeaters
153:waveguide
1204:cite web
1126:cite web
1051:See also
746:distance
301:Equation
213:decibels
196:(MIMO).
173:receiver
165:feedline
143:such as
1295:Budgets
1041:Neptune
1027:m to 70
906:drywall
430:where:
285:Endgame
175:or any
85:scholar
1158:4 June
1045:
1037:
1033:
1029:
1025:
1017:
974:
962:albedo
902:2 by 4
619:fading
227:For a
186:fading
133:signal
87:
80:
73:
66:
58:
1231:(PDF)
1188:(PDF)
1177:(PDF)
1149:(PDF)
654:(dBi)
522:(dBi)
232:radio
155:, or
149:cable
129:power
92:JSTOR
78:books
1210:link
1196:2022
1160:2023
1132:link
1118:2022
1011:The
930:The
709:(dB)
588:(dB)
163:and
64:news
997:VHF
720:log
209:dBm
192:or
47:by
1291::
1218:^
1206:}}
1202:{{
1179:.
1151:.
1128:}}
1124:{{
1104:.
977:dB
857:FS
828:FS
799:FS
779:.
724:10
716:20
703:FS
669:RX
636:RX
580:,
566:FS
537:TX
504:TX
475:TX
446:RX
412:RX
399:RX
373:FS
360:TX
347:TX
334:TX
321:RX
297:.
151:,
147:,
123:A
1240:.
1212:)
1198:.
1162:.
1134:)
1120:.
883:×
881:3
877:c
853:L
824:L
795:L
758:)
737:4
733:(
713:=
699:L
665:L
632:G
603:M
599:L
562:L
533:L
500:G
471:P
442:P
408:L
395:G
391:+
386:M
382:L
369:L
356:L
343:G
339:+
330:P
326:=
317:P
114:)
108:(
103:)
99:(
89:·
82:·
75:·
68:·
41:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
