Antenna Concepts
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Transcript of Antenna Concepts
www.Telecom-Cloud.net
Harish Vadada
Brief History
Antenna Building Blocks
Antenna System
Antenna System Tests
Radiation
Antenna Performance
Pattern Evaluation
Cell Planning Considerations
Down Tilt
Break
Intermodulation Interference
ObstructionsAntenna Performance
Break
Antenna Construction
Antenna Concealment
New Concepts
Thales (600 BC): Observed sparks when silk rubbed on amber, natural stones attracted
Gilbert (1600 AD), Franklin (1750), Coulomb, Gauss, Volta (1800), Oersted (1819), Ampere (1820), Ohm, Faraday, (1819), Ampere (1820), Ohm, Faraday, Henry (1831), Maxwell (1873)
Heinrich Rudolph Hertz’s (1886) built first radio system:
Guglielmo Marconi:- Repeated Hertz’s experiments- Built first radio system to signal over
large distances: England to Newfoundland- Proved radio waves bend around earth- Proved radio waves bend around earth- Also applied technology to ships
FFFF0000 (MHz)(MHz)(MHz)(MHz) λλλλ (Meters)(Meters)(Meters)(Meters) λλλλ (Inches)(Inches)(Inches)(Inches)
30303030 10.010.010.010.0 393.6393.6393.6393.6
80808080 3.753.753.753.75 147.6147.6147.6147.6¼ ¼ ¼ ¼ λλλλ
Dipole
80808080 3.753.753.753.75 147.6147.6147.6147.6
160160160160 1.871.871.871.87 73.873.873.873.8
280280280280 1.071.071.071.07 42.242.242.242.2
460460460460 0.650.650.650.65 25.725.725.725.7
800800800800 0.380.380.380.38 14.814.814.814.8
960960960960 0.310.310.310.31 12.312.312.312.3
1700170017001700 0.180.180.180.18 6.956.956.956.95
2000200020002000 0.150.150.150.15 5.905.905.905.90
FFFF0000 ¼ ¼ ¼ ¼ λλλλ
¼ ¼ ¼ ¼ λλλλ
Dipoles and the Antenna
A single dipole has a “doughnut” shaped pattern
Need to “flatten” the “doughnut” to concentrate the signal to where it is wanted, at ground level
Understanding the Mysterious “dB”–––– A dB is 1/10A dB is 1/10A dB is 1/10A dB is 1/10thththth of a “Bel” (Named after Alexander Graham of a “Bel” (Named after Alexander Graham of a “Bel” (Named after Alexander Graham of a “Bel” (Named after Alexander Graham
Bell)Bell)Bell)Bell)
–––– A dB is measured on a logarithmic scaleA dB is measured on a logarithmic scaleA dB is measured on a logarithmic scaleA dB is measured on a logarithmic scale
–––– A dB or “Decibel” originally comes from quantifying signal A dB or “Decibel” originally comes from quantifying signal A dB or “Decibel” originally comes from quantifying signal A dB or “Decibel” originally comes from quantifying signal
strengths in terms strengths in terms strengths in terms strengths in terms of relative loudness as registered by the of relative loudness as registered by the of relative loudness as registered by the of relative loudness as registered by the
human earhuman earhuman earhuman ear
–––– dB in the RF world is the difference between two signal dB in the RF world is the difference between two signal dB in the RF world is the difference between two signal dB in the RF world is the difference between two signal
strengthsstrengthsstrengthsstrengths
Blah
blahblah bl ah
A single dipole A single dipole A single dipole A single dipole radiates with a radiates with a radiates with a radiates with a
An isotropic radiator An isotropic radiator An isotropic radiator An isotropic radiator radiates equally inradiates equally inradiates equally inradiates equally in
dBd and dBi
radiates with a radiates with a radiates with a radiates with a doughnut patterndoughnut patterndoughnut patterndoughnut pattern
radiates equally inradiates equally inradiates equally inradiates equally inALL directionsALL directionsALL directionsALL directions
The gain of an antenna compared The gain of an antenna compared The gain of an antenna compared The gain of an antenna compared to a dipole is in “dBd”to a dipole is in “dBd”to a dipole is in “dBd”to a dipole is in “dBd”
The gain of an antenna compared The gain of an antenna compared The gain of an antenna compared The gain of an antenna compared to an isotropic radiator is in “dBi”to an isotropic radiator is in “dBi”to an isotropic radiator is in “dBi”to an isotropic radiator is in “dBi”eg: 3dBd = 5.17dBieg: 3dBd = 5.17dBieg: 3dBd = 5.17dBieg: 3dBd = 5.17dBi
2.17dB2.17dB2.17dB2.17dB
The dipole is 2.17dB higher in gainThe dipole is 2.17dB higher in gainThe dipole is 2.17dB higher in gainThe dipole is 2.17dB higher in gain
“dBm”“dBm”“dBm”“dBm” –––– Absolute signal strength relative to 1 milliwattAbsolute signal strength relative to 1 milliwattAbsolute signal strength relative to 1 milliwattAbsolute signal strength relative to 1 milliwatt
1 mWatt1 mWatt1 mWatt1 mWatt ==== 0 dBm0 dBm0 dBm0 dBm
1 Watt1 Watt1 Watt1 Watt ==== +30 dBm+30 dBm+30 dBm+30 dBm
10 Watts10 Watts10 Watts10 Watts ==== +40 dBm+40 dBm+40 dBm+40 dBm
20 Watts20 Watts20 Watts20 Watts ==== +43 dBm+43 dBm+43 dBm+43 dBm
“dBm and dBc”
Note: TheNote: TheNote: TheNote: TheLogarithmic ScaleLogarithmic ScaleLogarithmic ScaleLogarithmic Scale10 x log10 x log10 x log10 x log10101010 (Power Ratio)(Power Ratio)(Power Ratio)(Power Ratio)
“dBc”“dBc”“dBc”“dBc” –––– Signal strength Signal strength Signal strength Signal strength relativerelativerelativerelative to a signal of known strength, in to a signal of known strength, in to a signal of known strength, in to a signal of known strength, in
this case: the this case: the this case: the this case: the carriercarriercarriercarrier signalsignalsignalsignal
How and why is dBc used with base station antenna specs?How and why is dBc used with base station antenna specs?How and why is dBc used with base station antenna specs?How and why is dBc used with base station antenna specs?
Pay attention Pay attention Pay attention Pay attention –––– Group quiz later!Group quiz later!Group quiz later!Group quiz later!
Basic Antenna System
• Antenna
• Jumper Cable
• Feeder Cable• Feeder Cable
• Surge Arrestor
• Jumper Cable
• Radio
Full System Sweep
• 3 different tests
• Return Loss• VSWR• Distance to Fault (DTF)
• Antenna
• Jumper
Cable
• Feeder
Cable
• Surge
Arrestor
• Jumper
• Distance to Fault (DTF)
Impedance
• These 3 tests measure the reflected voltages caused by change of impedance in a transmission line.
• Impedance is measured in ohms (Ω).
V = I x R
or V = I x Z
Examples:
• Wireless = 50Ω
• Old TV = 300Ω
• Cable TV = 75Ω
where Z is defined as impedance and is complex
Z = R + j X
R = resistance and X = reactance both measured in ohms
or V = I x Z
Impedance
Outer Outer Outer Outer ConductorConductorConductorConductor
Cover (Jacket)Cover (Jacket)Cover (Jacket)Cover (Jacket)
ddddDDDD
Inner Inner Inner Inner ConductorConductorConductorConductor
Dielectric Dielectric Dielectric Dielectric (Foam)(Foam)(Foam)(Foam)
History note:
•Older CATV coax had air dielectric utilizing plastic disc’s to support the center conductor.
AntennaAntennaAntennaAntenna
50 ohms50 ohms50 ohms50 ohms
Source Source Source Source ====50 ohms50 ohms50 ohms50 ohms
Cable Cable Cable Cable ====
Impedance
====50 ohms50 ohms50 ohms50 ohms
Match!
Return Loss
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
W
51Ω51Ω51Ω51Ω
Transmitted: 9.92WTransmitted: 9.92WTransmitted: 9.92WTransmitted: 9.92W
A typical system A typical system A typical system A typical system alwaysalwaysalwaysalways has some nominal has some nominal has some nominal has some nominal
impedance mismatch.impedance mismatch.impedance mismatch.impedance mismatch. Here the Return Loss is Here the Return Loss is Here the Return Loss is Here the Return Loss is
10 log (0.08 / 10) = 10 log (0.08 / 10) = 10 log (0.08 / 10) = 10 log (0.08 / 10) = ----21dB21dB21dB21dB
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
W
50505050ΩΩΩΩ PASS!PASS!PASS!PASS!
Return Loss
* Limit lines should be provided by system design engineers.
AntennaAntennaAntennaAntenna
50 ohms50 ohms50 ohms50 ohms
Source Source Source Source ====50 ohms50 ohms50 ohms50 ohms
Cable Cable Cable Cable ====50 ohms50 ohms50 ohms50 ohms50 ohms50 ohms50 ohms50 ohms
AntennaAntennaAntennaAntenna
50 ohms50 ohms50 ohms50 ohms
System Failures
95 ohms95 ohms95 ohms95 ohmsSource Source Source Source ====50 ohms50 ohms50 ohms50 ohms
Smashed!Smashed!Smashed!Smashed!
When an impedance mismatch occurs in an RF subsystem, an When an impedance mismatch occurs in an RF subsystem, an When an impedance mismatch occurs in an RF subsystem, an When an impedance mismatch occurs in an RF subsystem, an amount of RF energy is reflected back to the source. amount of RF energy is reflected back to the source. amount of RF energy is reflected back to the source. amount of RF energy is reflected back to the source.
Mismatch!
95Ω95Ω95Ω95ΩIn
cid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
System Failures
Transmitted: 5.9WTransmitted: 5.9WTransmitted: 5.9WTransmitted: 5.9W
When something is wrong, much more When something is wrong, much more When something is wrong, much more When something is wrong, much more
energy will reflect causing performance energy will reflect causing performance energy will reflect causing performance energy will reflect causing performance
failures.failures.failures.failures. Here the Return Loss is Here the Return Loss is Here the Return Loss is Here the Return Loss is
10 log (4.1 / 10) =10 log (4.1 / 10) =10 log (4.1 / 10) =10 log (4.1 / 10) = ----3.87dB3.87dB3.87dB3.87dB50505050ΩΩΩΩ
FAIL!FAIL!FAIL!FAIL!
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
System Failures
System Failures
What is the “standard” torque spec of a 7/16 DIN?
A) 18 to 22 ft-lbs.
B) 50 to 55 ft-lbs. A
Mini Group Quiz!
“Positive Stop” Connector- up to 70 ft-lbs
B) 50 to 55 ft-lbs.
C) 122 to 127ft-lbs
A
RF components have some reflection but damaged components will cause RF components have some reflection but damaged components will cause RF components have some reflection but damaged components will cause RF components have some reflection but damaged components will cause larger reflections and in that case creates a system to fail.larger reflections and in that case creates a system to fail.larger reflections and in that case creates a system to fail.larger reflections and in that case creates a system to fail.
VSWR
51Ω51Ω51Ω51ΩIn
cid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
W
Transmitted: 9.92WTransmitted: 9.92WTransmitted: 9.92WTransmitted: 9.92W
Voltage Standing Wave Ratio (VSWR) is Voltage Standing Wave Ratio (VSWR) is Voltage Standing Wave Ratio (VSWR) is Voltage Standing Wave Ratio (VSWR) is
related to Return Loss. The difference is related to Return Loss. The difference is related to Return Loss. The difference is related to Return Loss. The difference is
that VSWR is read as a ratio instead of in that VSWR is read as a ratio instead of in that VSWR is read as a ratio instead of in that VSWR is read as a ratio instead of in
dB.dB.dB.dB. Here the VSWR is Here the VSWR is Here the VSWR is Here the VSWR is
VSWR = (1+(10^21/20)) / (1VSWR = (1+(10^21/20)) / (1VSWR = (1+(10^21/20)) / (1VSWR = (1+(10^21/20)) / (1----(10^21/20))(10^21/20))(10^21/20))(10^21/20))
OrOrOrOr
----21dB RL = 1.195:1 VSWR21dB RL = 1.195:1 VSWR21dB RL = 1.195:1 VSWR21dB RL = 1.195:1 VSWR
50505050ΩΩΩΩ
PASS!PASS!PASS!PASS!
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
WR
efl
ecte
d: 0
.08
W
VSWR
VSWR
95Ω95Ω95Ω95ΩIn
cid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Transmitted: 5.9WTransmitted: 5.9WTransmitted: 5.9WTransmitted: 5.9W
Here the VSWR is Here the VSWR is Here the VSWR is Here the VSWR is
VSWR = (1+(10^3.8/20)) / (1VSWR = (1+(10^3.8/20)) / (1VSWR = (1+(10^3.8/20)) / (1VSWR = (1+(10^3.8/20)) / (1----(10^3.8/20))(10^3.8/20))(10^3.8/20))(10^3.8/20))
or
-3.84 dB RL = 4.60:1 VSWR50505050ΩΩΩΩ
FAIL!FAIL!FAIL!FAIL!
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Incid
ent
: 1
0W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
Refl
ecte
d:4
.1W
VSWR
DTF
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Fault
These tests work best when These tests work best when These tests work best when These tests work best when
used as a references. used as a references. used as a references. used as a references.
Test results may be swayed Test results may be swayed Test results may be swayed Test results may be swayed
by variables such as vector by variables such as vector by variables such as vector by variables such as vector
addition and subtraction of addition and subtraction of addition and subtraction of addition and subtraction of
phase, interfering signals phase, interfering signals phase, interfering signals phase, interfering signals
and cable lengths. and cable lengths. and cable lengths. and cable lengths.
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
Tra
vel ti
me(m
s)
and cable lengths. and cable lengths. and cable lengths. and cable lengths.
Consider matching current Consider matching current Consider matching current Consider matching current
test results to previously test results to previously test results to previously test results to previously
recorded tests and look for recorded tests and look for recorded tests and look for recorded tests and look for
changes.changes.changes.changes.
DTF
Effect of VSWR
VSWRVSWRVSWRVSWRReturnReturnReturnReturnLoss (dB)Loss (dB)Loss (dB)Loss (dB)
TransmissionTransmissionTransmissionTransmissionLoss (dB)Loss (dB)Loss (dB)Loss (dB)
PowerPowerPowerPowerReflected (%)Reflected (%)Reflected (%)Reflected (%)
PowerPowerPowerPowerTrans. (%)Trans. (%)Trans. (%)Trans. (%)
1.00 −∞ 0.00 0.0 100.0
Good VSWR is only one component of an efficient antenna system.
Note: 2 dB in Return Loss is much smaller than 2 dB of forward gain!
1.10
1.20
1.30
1.40
1.50
2.00
−26.4
−20.8
−17.7
−15.6
−14.0
−9.5
0.01
0.04
0.08
0.12
0.18
0.51
0.2
0.8
1.7
2.8
4.0
11.1
99.8
99.2
98.3
97.2
96.0
88.9
Source: Source: Source: Source: COMSEARCHCOMSEARCHCOMSEARCHCOMSEARCH
3D View Antenna Pattern
Shaping Antenna PatternsShaping Antenna PatternsShaping Antenna PatternsShaping Antenna Patterns
Vertical arrangement of properly phased dipoles allows Vertical arrangement of properly phased dipoles allows Vertical arrangement of properly phased dipoles allows Vertical arrangement of properly phased dipoles allows
control of radiation patterns at the horizon as well as control of radiation patterns at the horizon as well as control of radiation patterns at the horizon as well as control of radiation patterns at the horizon as well as
above and below the horizon. above and below the horizon. above and below the horizon. above and below the horizon.
The more dipoles are stacked vertically, the flatter the The more dipoles are stacked vertically, the flatter the The more dipoles are stacked vertically, the flatter the The more dipoles are stacked vertically, the flatter the
“beam” is and the higher the antenna coverage or “gain” in “beam” is and the higher the antenna coverage or “gain” in “beam” is and the higher the antenna coverage or “gain” in “beam” is and the higher the antenna coverage or “gain” in
the general direction of the horizon.the general direction of the horizon.the general direction of the horizon.the general direction of the horizon.
Shaping Antenna Patterns Shaping Antenna Patterns Shaping Antenna Patterns Shaping Antenna Patterns (cont . . .)(cont . . .)(cont . . .)(cont . . .)
Stacking 4 dipoles vertically in line changes the pattern shape (squashes the doughnut) and increases the gain over single dipole.
The peak of the horizontal or vertical
Aperture Aperture Aperture Aperture of Dipolesof Dipolesof Dipolesof Dipoles
Vertical Vertical Vertical Vertical PatternPatternPatternPattern
Horizontal Horizontal Horizontal Horizontal PatternPatternPatternPattern
Single DipoleSingle DipoleSingle DipoleSingle Dipole
horizontal or vertical pattern measures the gain.
The little lobes, illustrated in the lower section, are secondary minor lobes.
4 Dipoles 4 Dipoles 4 Dipoles 4 Dipoles Vertically Vertically Vertically Vertically StackedStackedStackedStackedGENERAL STACKING RULE:GENERAL STACKING RULE:GENERAL STACKING RULE:GENERAL STACKING RULE:
• Collinear elements (in-line vertically).
• Optimum spacing (for non-electrical tilt) is approximately 0.9λ.
• Doubling the number of elements increases gain by 3 dB, and reduces
vertical beamwidth by half.
What is it?What is it?What is it?What is it?
Antenna gain is a comparison of the power/field characteristics of a device under test (DUT) to a specified gain standard.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
Gain is directly associated with link budget: coverage distance and/or obstacle penetration (buildings, foliage, etc).
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing. The reference gain standard must always be specified.
Gain References (dBd and dBi) Gain References (dBd and dBi) Gain References (dBd and dBi) Gain References (dBd and dBi)
An isotropic antenna is a single point in space radiating in a perfect sphere (not physically possible)
A dipole antenna is
Isotropic (dBi)Isotropic (dBi)Isotropic (dBi)Isotropic (dBi)Dipole (dBd)Dipole (dBd)Dipole (dBd)Dipole (dBd)GainGainGainGain
Isotropic PatternIsotropic PatternIsotropic PatternIsotropic Pattern
Dipole PatternDipole PatternDipole PatternDipole Pattern
A dipole antenna is one radiating element (physically possible)
A gain antenna is two or more radiating elements phased together
0 (dBd) = 2.15 (dBi)0 (dBd) = 2.15 (dBi)0 (dBd) = 2.15 (dBi)0 (dBd) = 2.15 (dBi)
3 (dBd) = 5.15 (dBi)3 (dBd) = 5.15 (dBi)3 (dBd) = 5.15 (dBi)3 (dBd) = 5.15 (dBi)
Principles of Antenna GainPrinciples of Antenna GainPrinciples of Antenna GainPrinciples of Antenna GainDirectional AntennasDirectional AntennasDirectional AntennasDirectional AntennasDirectional AntennasDirectional AntennasDirectional AntennasDirectional AntennasTop ViewTop ViewTop ViewTop ViewTop ViewTop ViewTop ViewTop View
0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd
+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
180180°°
Omni AntennaOmni AntennaOmni AntennaOmni AntennaOmni AntennaOmni AntennaOmni AntennaOmni AntennaSide ViewSide ViewSide ViewSide ViewSide ViewSide ViewSide ViewSide View
0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd0 dBd
+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd
6060°°
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
3030°°
+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd
+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
9090°°
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
4545°°
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd+3 dBd
+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd+6 dBd
+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd+9 dBd
3030°°--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
7.57.5°°
--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
1515°°--------3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB
Theoretical Gain of Antennas (dBd)Theoretical Gain of Antennas (dBd)Theoretical Gain of Antennas (dBd)Theoretical Gain of Antennas (dBd)
Half Power Azimuth Beam WidthHalf Power Azimuth Beam WidthHalf Power Azimuth Beam WidthHalf Power Azimuth Beam Width(Influenced by Grounded Back “Plate”)(Influenced by Grounded Back “Plate”)(Influenced by Grounded Back “Plate”)(Influenced by Grounded Back “Plate”)
Typical LengthTypical LengthTypical LengthTypical Lengthof Antenna (ft.)of Antenna (ft.)of Antenna (ft.)of Antenna (ft.)
vert
ically s
paced
(0
.9vert
ically s
paced
(0
.9vert
ically s
paced
(0
.9vert
ically s
paced
(0
.9λλ λλ )) ))
800/900 DCS 1800 VerticalMHzPCS 1900 Beamwidth360° 180° 120° 105° 90° 60° 45° 33°
1 0 3 4 5 6 8 9 10.5 1' 0.5' 60°
2 3 6 7 8 9 11 12 13.6 2' 1' 30°
# o
f R
ad
iato
rs#
of
Rad
iato
rs#
of
Rad
iato
rs#
of
Rad
iato
rsvert
ically s
paced
(0
.9vert
ically s
paced
(0
.9vert
ically s
paced
(0
.9vert
ically s
paced
(0
.9
3 4.5 7.5 8.5 9.5 10.5 12.5 13.5 15.1 3' 1.5' 20°
4 6 9 10 11 12 14 15 16.6 4' 2' 15°
6 7.5 10.5 11.5 12.5 13.5 15.5 16.5 18.1 6' 3' 10°
8 9 12 13 14 15 17 18 19.6 8' 4' 7.5°
Gain vs. LengthGain vs. LengthGain vs. LengthGain vs. Length
Gain
(dBi)
10
15
20
25
65° Az BW 90° Az BW 120° Az BW
Antenna Length (wavelengths)
Gain
(dBi)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 150
5 G=10 log ( )2.2 π L We
λ2
Gain vs. BeamwidthsGain vs. BeamwidthsGain vs. BeamwidthsGain vs. Beamwidths
Gain
(dBi)
10
15
20
25
65° Az BW 90° Az BW 120° Az BW
Elevation Half Power Beamwidth (deg)
Gain
(dBi)
2 4 6 8 10 12 14 16 18 20 22 24 26 28 300
5 G=10 log ( )29000AzBW EIBW
Antenna GainAntenna GainAntenna GainAntenna Gain
Gain (dBi) = Directivity (dBi) – Losses (dB)
Losses: Conductor
Dielectric
Impedance
PolarizationPolarization
Measure Using ‘Gain by Comparison’
Electric and magnetic fields are interdependent => Electromagnetic wave
Time-changing electric field generates magnetic field, vice versa
An antenna’s polarization is a An antenna’s polarization is a characteristic of the EM wave, i.e. electric field’s orientation
If antenna and incoming EM wave are co-polarized => Max response from antenna
Various Radiator Designs
DipoleDipoleDipoleDipole 1800/1900/UMTS1800/1900/UMTS1800/1900/UMTS1800/1900/UMTSDirected Dipole™Directed Dipole™Directed Dipole™Directed Dipole™
Diversity (DualDiversity (DualDiversity (DualDiversity (Dual----Pol)Pol)Pol)Pol)Directed Dipole™Directed Dipole™Directed Dipole™Directed Dipole™
ElementsElementsElementsElements
PatchPatchPatchPatch 800/900 MHz800/900 MHz800/900 MHz800/900 MHzDirected Dipole™Directed Dipole™Directed Dipole™Directed Dipole™
MARMARMARMARMicrostrip Annular RingMicrostrip Annular RingMicrostrip Annular RingMicrostrip Annular Ring
Directed Dipole™Directed Dipole™Directed Dipole™Directed Dipole™ Directed Dipole™Directed Dipole™Directed Dipole™Directed Dipole™
Dipoles
Single DipoleSingle DipoleSingle DipoleSingle Dipole Crossed DipoleCrossed DipoleCrossed DipoleCrossed Dipole
Series FeedSeries FeedSeries FeedSeries Feed Center FeedCenter FeedCenter FeedCenter Feed(Hybrid)(Hybrid)(Hybrid)(Hybrid)
CorporateCorporateCorporateCorporateFeedFeedFeedFeed
Feed Harness Construction (cont . . .)
Advantages:Advantages:Advantages:Advantages:
Center FeedCenter FeedCenter FeedCenter Feed(Hybrid)(Hybrid)(Hybrid)(Hybrid)
Frequency Frequency Frequency Frequency independent independent independent independent main lobe main lobe main lobe main lobe directiondirectiondirectiondirection Reasonably Reasonably Reasonably Reasonably
Corporate FeedCorporate FeedCorporate FeedCorporate Feed
Frequency Frequency Frequency Frequency independent independent independent independent main beam main beam main beam main beam directiondirectiondirectiondirection More beam More beam More beam More beam
Series FeedSeries FeedSeries FeedSeries Feed
Minimal feed lossesMinimal feed lossesMinimal feed lossesMinimal feed losses
Simple feed systemSimple feed systemSimple feed systemSimple feed system
Disadvantages:Disadvantages:Disadvantages:Disadvantages:
directiondirectiondirectiondirection Reasonably Reasonably Reasonably Reasonably simple feed simple feed simple feed simple feed systemsystemsystemsystem
Not as Not as Not as Not as versatile as versatile as versatile as versatile as corporate corporate corporate corporate (less (less (less (less bandwidth, bandwidth, bandwidth, bandwidth, less beam less beam less beam less beam shaping)shaping)shaping)shaping)
directiondirectiondirectiondirection More beam More beam More beam More beam shaping shaping shaping shaping ability, side ability, side ability, side ability, side lobe lobe lobe lobe suppressionsuppressionsuppressionsuppression
Complex Complex Complex Complex feed systemfeed systemfeed systemfeed system
BEAMTILTBEAMTILTBEAMTILTBEAMTILT
450450450450 455455455455 460460460460 465465465465 470470470470 MHzMHzMHzMHz+2+2+2+2°°°°
+1+1+1+1°°°°
0000°°°°
+1+1+1+1°°°°
+2+2+2+2°°°°
ASPASPASPASP----705705705705
Feed NetworksFeed NetworksFeed NetworksFeed Networks
Cable
Microstripline, Corporate Feeds
– Dielectric Substrate
– Air Substrate– Air Substrate
T-Line Feed and Radiator
Microstrip Feed LinesMicrostrip Feed LinesMicrostrip Feed LinesMicrostrip Feed Lines
Dielectric Substrate
– uses ‘printed circuit’ technology
– power limitations
– dielectric substrate causes loss (1.0 dB/m)
Air Substrate
– metal strip spaced above a groundplane
– minimal solder or welded joints
– laser cut or punched
– air substrate cause minimal loss (0.5 dB/m)
Air Microstrip Network
Dielectric Substrate Microstrip
Stacking Dipoles
4 Dipoles
8 Dipoles
1 Dipole
2 Dipoles
Azimuth Omni AntennaVertical Pattern
What is it?What is it?What is it?What is it?
The main lobe is the radiation pattern lobe that contains the majority portion of radiated energy.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
Shaping of the pattern allows the contained coverage necessary for interference-
35° TotalMain Lobe
necessary for interference-limited system designs.
How is it measured?How is it measured?How is it measured?How is it measured?
The main lobe is characterized using a number of the measurements which will follow.
What is it?What is it?What is it?What is it?
The angular span between the half-power (-3 dB) points measured on the cut of the antenna’s main lobe radiation pattern.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
It allows system designers to choose the optimum characteristics for coverage vs.
1/2 PowerBeamwidth
characteristics for coverage vs. interference requirements.
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing.
What is it?What is it?What is it?What is it?
The ratio in dB of the maximum directivity of an antenna to its directivity in a specified rearward direction.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
It characterizes unwanted interference on the backside of the main lobe. The larger the the main lobe. The larger the number, the better!
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing.
F/B Ratio
0 dB - 25 dB = 25 dB
What is it?What is it?What is it?What is it?
Sidelobe level is a measure of a particular sidelobe or angular group of sidelobes with respect to the main lobe.Why is it useful?Why is it useful?Why is it useful?Why is it useful?
Sidelobe level or pattern shaping allows the minor lobe energy to be tailored to
Sidelobe Level
(-20 dB)
lobe energy to be tailored to the antenna’s intended use. See Null Fill and Upper Sidelobe Suppression.
How is it measured?How is it measured?How is it measured?How is it measured?
It is always measured with respect to the main lobe in dB.
What is it?What is it?What is it?What is it?
Null Filling is an array optimization techniquethat reduces the null between the lower lobes in the elevation plane.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
For arrays with a narrow vertical beam-width (less than 12°), null filling significantly improves signal intensity in all coverage targets below the main lobe.all coverage targets below the main lobe.
How is it measured?How is it measured?How is it measured?How is it measured?
Null fill is easiest explained as the relative dB difference between the peakof the main beam and the depth of the 1st lower null.
Important for antennas with narrow elevation beamwidths.
Null Filled to 16 dB Below Peak
0
Receiv
ed L
evel (d
Bm
)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-100
-80
-60
-40
-20
0
Distance (km)
Receiv
ed L
evel (d
Bm
)
Transmit Power = 1 W
Base Station Antenna Height = 40 m
Base Station Antenna Gain = 18 dBi
Elevation Beamwidth = 6.5°
What is it?What is it?What is it?What is it?
Upper sidelobe suppression (USLS) is an array optimization technique that reduces the undesirable sidelobes above the main lobe.Why is it useful?Why is it useful?Why is it useful?Why is it useful?
For arrays with a narrow vertical beamwidth (less than 12°), USLS can significantly reduce interference due to multi-path or when the antenna is to multi-path or when the antenna is mechanically downtilted.
How is it measured?How is it measured?How is it measured?How is it measured?
USLS is the relative dB difference between the peak of the main beam peak of the first upper sidelobe.
What is it?What is it?What is it?What is it?
The ability of an antenna to discriminate between two EM waves whose polarization difference is 90 degrees.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
Orthogonal arrays within a single antenna allow for polarization diversity. (As opposed to spatial
δ
diversity. (As opposed to spatial diversity.)
How is it measured?How is it measured?How is it measured?How is it measured?
The difference between the co-polar pattern and the cross-polar pattern, usually measured in the boresite (the direction of the main signal).
δ = 0°, XPol = -∞ dBδ = 5°, XPol =-21 dBδ =10°, XPol =-15 dBδ =15°, XPol =-11 dBδ =20°, XPol = -9 dBδ =30°, XPol = -5 dBδ =40°, XPol =-1.5 dB
XPol = 20 log ( tan (XPol = 20 log ( tan (XPol = 20 log ( tan (XPol = 20 log ( tan (δδδδ))))))))
What is it?What is it?What is it?What is it?
CPR is a comparison of the co-pol vs. cross-pol pattern performance of a dual-polarized antenna generally over the sector of interest (alternatively over the 3 dB beamwidth).Why is it useful?Why is it useful?Why is it useful?Why is it useful?
It is a measure of the ability of a dual-pol array to distinguish between orthogonal EM waves. The better the CPR, the better the
-40
-35
-30
-25
-20
-15
-10
-5
0
120°
TYPICALTYPICALTYPICALTYPICAL
Co-PolarizatiCross-waves. The better the CPR, the better the
performance of polarization diversity.
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing and compares the two plots in dB over the specified angular range.
-40
-35
-30
-25
-20
-15
-10
-5
0
120°
LOGLOGLOGLOG
Polarization
Cross-Polarization (Source @ 90°)
What is it?What is it?What is it?What is it?
It refers to the beam tracking between the two beams of a +/-45° polarization diversity antenna over a specified angular range.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
For optimum diversity performance, the beams should track as closely as possible.
120°
+45°-45°Array Array
possible.
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing and compares the two plots in dB over the specified angular range.
What is it?What is it?What is it?What is it?
The amount of pointing error of a given beam referenced to mechanical boresite.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
The beam squint can affect the sector coverage if it is not at mechanical boresite. It can also affect the performance of the polarization diversity style
-3 dB +3 dB
Squintθ/2
θ
HorizontalBoresite
polarization diversity style antennas if the two arrays do not have similar patterns.
How is it measured?How is it measured?How is it measured?How is it measured?
It is measured using data collected from antenna range testing.
What is it?What is it?What is it?What is it?
SPR is a ratio expressed in percentage of the power outside the desired sector to the power inside the desired sector created by an antenna’s pattern.
Why is it useful?Why is it useful?Why is it useful?Why is it useful?
It is a percentage that allows comparison of various antennas. The
120°
comparison of various antennas. The better the SPR, the better the interference performance of the system.How is it measured?How is it measured?How is it measured?How is it measured?
It is mathematically derived from the measured range data.
PUndesired
SPR (%) =
X 100PDesired
300
60Σ
60
300Σ
DESIRED
UNDESIRED
“On the Capacity and Outage Probability of a CDMA Heirarchial Mobile System with Perfect/Imperfect Power Control and Sectorization”By: Jie ZHOU et, al IEICE TRANS FUNDAMENTALS, VOL.E82-A , NO.7 JULY 1999. . . From the numerical results, the user capacities are dramatically decreased as the imperfect power control increases and the overlap between the sectors (imperfect sectorization) increases . . .
“Effect of Soft and Softer Handoffs
120° Sector Overlay Issues
Per
cent
age
ofca
paci
ty lo
ss
overlapping angle in degree
“Effect of Soft and Softer Handoffs on CDMA System Capacity”By: Chin-Chun Lee et, al IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 47, NO. 3, AUGUST 1998Qualitatively, excessive overlay also reduces capacity of TDMA and GSM systems.
The Impact: Lower Co-Channel Interference/Better Capacity & Quality
In a three sector site, traditional In a three sector site, traditional In a three sector site, traditional In a three sector site, traditional antennas produce a high degree of antennas produce a high degree of antennas produce a high degree of antennas produce a high degree of imperfect power control or sector imperfect power control or sector imperfect power control or sector imperfect power control or sector overlap.overlap.overlap.overlap.
Imperfect sectorization presents Imperfect sectorization presents Imperfect sectorization presents Imperfect sectorization presents opportunities for:opportunities for:opportunities for:opportunities for:
Increased softer handIncreased softer handIncreased softer handIncreased softer hand----offsoffsoffsoffs
Interfering signalsInterfering signalsInterfering signalsInterfering signals
Dropped callsDropped callsDropped callsDropped calls
Traditional Flat PanelsTraditional Flat PanelsTraditional Flat PanelsTraditional Flat Panels
The rapid rollThe rapid rollThe rapid rollThe rapid roll----off of the lower lobes off of the lower lobes off of the lower lobes off of the lower lobes of the log periodic antennas create of the log periodic antennas create of the log periodic antennas create of the log periodic antennas create larger, better defined “cones larger, better defined “cones larger, better defined “cones larger, better defined “cones of silence” behind the array.of silence” behind the array.of silence” behind the array.of silence” behind the array.
Much smaller softer handMuch smaller softer handMuch smaller softer handMuch smaller softer hand----off areaoff areaoff areaoff area
Dramatic call quality improvementDramatic call quality improvementDramatic call quality improvementDramatic call quality improvement
5% 5% 5% 5% ---- 10 % capacity enhancement10 % capacity enhancement10 % capacity enhancement10 % capacity enhancement
Log Periodics (Example)Log Periodics (Example)Log Periodics (Example)Log Periodics (Example)
Dropped callsDropped callsDropped callsDropped calls
Reduced capacityReduced capacityReduced capacityReduced capacity65656565°°°° 90909090°°°°
65656565°°°° 90909090°°°°
Key antenna parameters to examine closely…
Antenna-Based System Improvements
Roll offat -/+ 60°
-10 dBpoints
-7dB -6dB
Standard 85° Panel AntennaLog Periodic
74° 83°
74747474°°°° 83838383°°°°
HorizontalAnt/AntIsolation
-16dB -12dB
120°Cone of Silence with >40dB Front-to-Back Ratio
60°Area of Poor Silence with >27dB Front-to-Back Ratio
Next SectorAnt/AntIsolation
-35dB -18dB
Coneof Silence
Azimuth Pattern Comparison: 1850 MHz, 2-Deg EDT
-10
0
Am
plitu
de (
dB)
-50
-40
-30
-20
-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180
Azimuth Angle (Degrees)
Am
plitu
de (
dB)
Choosing sector antennas
Downtilt – electrical vs. mechanical
RET optimization
Passive intermodulation (PIM) Passive intermodulation (PIM)
Return loss through coax
Pattern distortion, alignment, orientation
Antenna isolation
Choosing Sector Antennas
For 3 sector cell sites, what performance differences For 3 sector cell sites, what performance differences For 3 sector cell sites, what performance differences For 3 sector cell sites, what performance differences
can be expected from the use of antennas with can be expected from the use of antennas with can be expected from the use of antennas with can be expected from the use of antennas with
different horizontal apertures?different horizontal apertures?different horizontal apertures?different horizontal apertures?
Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:Criteria:
Area of service indifference between adjacent sectors (“ping-pong” area).
For comparison, use 6 dB differentials.
Antenna gain and overall sector coverage.
3 x 120° Antennas
120120°°Horizontal Horizontal Overlay Overlay PatternPattern3 dB3 dB3 dB3 dB3 dB3 dB3 dB3 dB5757575757575757°°°°°°°°
3 x 90° Antennas
4343434343434343°°°°°°°° 9090°°Horizontal Horizontal Overlay Overlay PatternPattern
5 dB5 dB5 dB5 dB5 dB5 dB5 dB5 dB
3 x 65° Antennas
2424242424242424°°°°°°°° 6565°°Horizontal Horizontal Overlay Overlay PatternPattern
6 dB6 dB6 dB6 dB6 dB6 dB6 dB6 dB
Beam Downtilt
In urban areas, service and frequency utilization are In urban areas, service and frequency utilization are In urban areas, service and frequency utilization are In urban areas, service and frequency utilization are
frequently improved by directing maximum radiation power frequently improved by directing maximum radiation power frequently improved by directing maximum radiation power frequently improved by directing maximum radiation power
at an area below the horizon.at an area below the horizon.at an area below the horizon.at an area below the horizon.
ThisThisThisThisThisThisThisThis Technique:Technique:Technique:Technique:Technique:Technique:Technique:Technique:
Improves coverage of open areas close to the base station.
Allows more effective penetration of nearby buildings, particular high-traffic lower levels and garages.
Permits the use of adjacent frequencies in the same general region.
Electrical/Mechanical Downtilt
Mechanical downtilt lowers main beam, raises back lobe.
Electrical downtilt lowers main beam and lowers back lobe.
A combination of equal electrical and mechanical downtilts lowers main beam and brings back lobe onto the horizon!
Electrical/Mechanical Downtilt
MechanicalMechanicalMechanicalMechanical ElectricalElectricalElectricalElectrical
Mechanical Downtilt Mounting Kit
Mechanical Downtilt
Mechanical Tilt Causes:
• Beam Peak to Tilt Below Horizon
• Back Lobe to Tilt Above
Pattern Analogy: Rotating a Disk
• Back Lobe to Tilt Above Horizon
• At ± 90° No Tilt
Mechanical Downtilt Coverage
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190 350
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190 350 190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350
8°0° 10°6°4°Mechanical Tilt
Elevation Pattern Azimuth Pattern
Sample Antenna0° Mechanical Downtilt
8585858585858585°°°°°°°°8585858585858585°°°°°°°°
Sample Antenna7° Mechanical Downtilt
9393939393939393°°°°°°°°9393939393939393°°°°°°°°
Sample Antenna15° Mechanical Downtilt
123123123123123123123123°°°°°°°°123123123123123123123123°°°°°°°°
Sample Antenna20° Mechanical Downtilt
HorizontalHorizontalHorizontalHorizontal3 dB Bandwidth 3 dB Bandwidth 3 dB Bandwidth 3 dB Bandwidth UndefinedUndefinedUndefinedUndefined
Managing Beam Tilt
For the radiation pattern to show maximum gain in the For the radiation pattern to show maximum gain in the For the radiation pattern to show maximum gain in the For the radiation pattern to show maximum gain in the direction of the horizon, each stacked dipole must be fed from direction of the horizon, each stacked dipole must be fed from direction of the horizon, each stacked dipole must be fed from direction of the horizon, each stacked dipole must be fed from the signal source “in phase”. Feeding vertically arranged the signal source “in phase”. Feeding vertically arranged the signal source “in phase”. Feeding vertically arranged the signal source “in phase”. Feeding vertically arranged dipoles “out of phase” will generate patterns that “look up” or dipoles “out of phase” will generate patterns that “look up” or dipoles “out of phase” will generate patterns that “look up” or dipoles “out of phase” will generate patterns that “look up” or “look down”.“look down”.“look down”.“look down”.
The degree of beam tilt is a function of the phase shift of one The degree of beam tilt is a function of the phase shift of one The degree of beam tilt is a function of the phase shift of one The degree of beam tilt is a function of the phase shift of one dipole relative to the adjacent dipole and their physical spacing.dipole relative to the adjacent dipole and their physical spacing.dipole relative to the adjacent dipole and their physical spacing.dipole relative to the adjacent dipole and their physical spacing.
GGGGGGGGENERATINGENERATINGENERATINGENERATINGENERATINGENERATINGENERATINGENERATING Electrical BElectrical BElectrical BElectrical BElectrical BElectrical BElectrical BElectrical BEAMEAMEAMEAMEAMEAMEAMEAM TTTTTTTTILTILTILTILTILTILTILTILTGGGGGGGGENERATINGENERATINGENERATINGENERATINGENERATINGENERATINGENERATINGENERATING Electrical BElectrical BElectrical BElectrical BElectrical BElectrical BElectrical BElectrical BEAMEAMEAMEAMEAMEAMEAMEAM TTTTTTTTILTILTILTILTILTILTILTILT
Dipoles Fed w/ Uniform PhaseDipoles Fed w/ Uniform PhaseDipoles Fed w/ Uniform PhaseDipoles Fed w/ Uniform Phase Dipoles Fed w/ Sequential PhaseDipoles Fed w/ Sequential PhaseDipoles Fed w/ Sequential PhaseDipoles Fed w/ Sequential Phase
ExciterPhase
Energy
inininin
Exciter
¼¼¼¼λλλλ
Electrical Downtilt
Electrical Tilt Causes:
• Beam Peak to Tilt Below Horizon
• Back Lobe to Tilt Below
Pattern Analogy: Forming a Cone Out of a Disk
• Back Lobe to Tilt Below Horizon
• All portions of the Pattern Tilts
“Cone” of the Beam Peak Pattern
Electrical Downtilt Coverage
0
10
20
30
40
50
60
708090100
110
120
130
140
150
160
170
180 0
10
20
30
40
50
60
708090100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250260 270 280
290
300
310
320
330
340
350
8°0° 10°6°4°Electrical Tilt
190
200
210
220
230
240
250260 270 280
290
300
310
320
330
340
350
Elevation Pattern Azimuth Pattern
Mechanical vs. Electrical Downtilt
0 1020
30
40
50
60
70
80280
290
300
310
320
330
340350
90
100
110
120
130
140
150
160170180190
200
210
220
230
240
250
260
270
With Variable Electrical Downtilt (VED), With Variable Electrical Downtilt (VED), With Variable Electrical Downtilt (VED), With Variable Electrical Downtilt (VED), you can adjust anywhere in seconds.you can adjust anywhere in seconds.you can adjust anywhere in seconds.you can adjust anywhere in seconds.
Sample Antenna3° Electrical Downtilt
Sample Antenna 8° Electrical Downtilt
Sample Antenna Overlay Electrical Downtilt
33333333°°°°°°°°
66666666°°°°°°°°
88888888°°°°°°°°
Remote Electrical Downtilt (RET)Optimization
ANMSANMS
Future
ATC100 Series
ATC200 Series
Causes of Inter-Modulation Distortion
Ferromagnetic materials in the current path:
– Steel
– Nickel Plating or Underplating
Current Disruption: Current Disruption:
– Loosely Contacting Surfaces
– Non-Conductive Oxide Layers Between Contact Surfaces
“Intermod” InterferenceWhere?
F1
TxF1
TxF2
RxF3
RECEIVER-PRODUCED
F3
TxF1
TxF2
RxF3
TRANSMITTER-PRODUCED
F2
F1
Rx3
ANTENNA-PRODUCED
DUP
F2
Tx1
Tx2
COMB
F3
RxF3
ELSEWHERE
Tx1
Tx2
Remember dBc?
IMD – Inter-Modulation Distortion
PIM – Passive Inter-Modulation
“dBc” with antennas work like this
- 2 tones @ 20Watts = 43dBm
- Scan for 3rd order of those 2 carriers
- If 3rd order = -110dBm then that = -153dBc
110dBm + 43dBm = 153dBc
PCS A-BandProduct Frequencies, Two-Signal IMFIM = nF1 ± mF2
Example: F1 = 1945 MHz; F2 = 1930 MHz
1 1 Second 1F1 + 1F2 38751F1 – 1F2 15
2 1 Third 2F1 + 1F2 5820*2F1 – 1F2 1960
ProductProductProductProduct ProductProductProductProduct ProductProductProductProductnnnn mmmm OrderOrderOrderOrder FormulaeFormulaeFormulaeFormulae Frequencies (MHz)Frequencies (MHz)Frequencies (MHz)Frequencies (MHz)
*2F1 – 1F2 1960
1 2 Third 2F2 + 1F1 5805*2F2 – 1F1 1915
2 2 Fourth 2F1 + 2F2 77502F1 – 2F2 30
3 2 Fifth 3F1 + 2F2 9695*3F1 – 2F2 1975
2 3 Fifth 3F2 + 2F1 9680*3F2 – 2F1 1900
*Odd-order difference products fall in-band.
Two-Signal IMOdd-Order Difference Products
Example: F1 = 1945 MHz; F2 = 1930 MHz
∆F = F1 - F2 = 15
∆F
3F2 – 2F1
1900
F2
1930
F1
1945 2F1 – F2
1960
F1 + ∆F3F1 – 2F2
1975
2F2 – F1
1915
F2 – ∆F∆F ∆F
Third Order: F1 + ∆F; F2 - ∆F
Fifth Order: F1 + 2∆F; F2 - 2∆F
Seventh Order:: F1 + 3∆F; F2 - 3∆F
“Higher than the highest – lower than the lowest – none in-between”
5th
F2 – 2∆F
1900
F2 F1 3rd
5th
F1 + 2∆F
1975
3rd
2∆F 2∆F
PCS Duplexed IM
Own RxOwn RxOwn RxOwn RxAny RxAny RxAny RxAny RxTxTxTxTx RxRxRxRx BandBandBandBand BandBandBandBand IM EquationsIM EquationsIM EquationsIM Equations
BandBandBandBandFrequencyFrequencyFrequencyFrequencyFrequencyFrequencyFrequencyFrequencyIM OrderIM OrderIM OrderIM OrderIM OrderIM OrderIM OrderIM OrderOwn Rx BandOwn Rx BandOwn Rx BandOwn Rx Band Any Rx BandAny Rx BandAny Rx BandAny Rx BandAAAA 1930193019301930----1945194519451945 1850185018501850----1865186518651865 11th11th11th11th 5th5th5th5th =6*Tx(low)=6*Tx(low)=6*Tx(low)=6*Tx(low)----5*Tx(high)=18555*Tx(high)=18555*Tx(high)=18555*Tx(high)=1855 =3*Tx(low)=3*Tx(low)=3*Tx(low)=3*Tx(low)----
2*Tx(high)=19002*Tx(high)=19002*Tx(high)=19002*Tx(high)=1900
BBBB 1950195019501950----1965196519651965 1870187018701870----1885188518851885 11th11th11th11th 7th7th7th7th =6*Tx(low)=6*Tx(low)=6*Tx(low)=6*Tx(low)----5*Tx(high)=18755*Tx(high)=18755*Tx(high)=18755*Tx(high)=1875 =4*Tx(low)=4*Tx(low)=4*Tx(low)=4*Tx(low)----3*Tx(high)=19053*Tx(high)=19053*Tx(high)=19053*Tx(high)=1905
CCCC 1975197519751975----1990199019901990 1895189518951895----1910191019101910 11th11th11th11th 11th11th11th11th =6*Tx(low)=6*Tx(low)=6*Tx(low)=6*Tx(low)----5*Tx(high)=19005*Tx(high)=19005*Tx(high)=19005*Tx(high)=1900 =6*Tx(low)=6*Tx(low)=6*Tx(low)=6*Tx(low)----5*Tx(high)=19005*Tx(high)=19005*Tx(high)=19005*Tx(high)=1900
A Band IM
1850 1870 1890 1910 1930 1950 1970 1990
Unlicensed
20 MHz
C-3 C-3 C-4C-4 C-5 C-5
11th11th11th11th1851851851855555
9th9th9th9th1871871871870000
7th7th7th7th1881881881885555
5th5th5th5th1901901901900000
3rd3rd3rd3rd1911911911915555
1931931931930000
1941941941945555
1860 1880 1900 1920 1940 1960 1980
C-1 C-1C-2 C-2
ChannelChannelChannelChannel BandwidthBandwidthBandwidthBandwidthBlockBlockBlockBlock (MHz)(MHz)(MHz)(MHz) FrequenciesFrequenciesFrequenciesFrequencies
CCCC 30303030 1895189518951895----1910, 19751910, 19751910, 19751910, 1975----1990199019901990
C1C1C1C1 15151515 1902.51902.51902.51902.5----1910, 1982.51910, 1982.51910, 1982.51910, 1982.5----1990199019901990
C2C2C2C2 15151515 1895189518951895----1902190219021902----5, 19755, 19755, 19755, 1975----1982.51982.51982.51982.5
C3C3C3C3 10101010 1895189518951895----1900, 19751900, 19751900, 19751900, 1975----1980198019801980
C4C4C4C4 10101010 1900190019001900----1905, 19801905, 19801905, 19801905, 1980----1985198519851985
C5C5C5C5 10101010 1905190519051905----1910, 19851910, 19851910, 19851910, 1985----1990199019901990
Note: Some of the original C Block licenses (Originally 30 MHz each) were split into multiplelicenses (C-1 and C-2: 15 MHz; C-3, C-4, and C-5: 10MHz).
FCC Broadband PCS Band PlanFCC Broadband PCS Band PlanFCC Broadband PCS Band PlanFCC Broadband PCS Band Plan
A and F Band IM
1850 1870 1890 1910 1930 1950 1970 1990
Unlicensed
20 MHz
C-3 C-3 C-4C-4 C-5 C-5
3rd3rd3rd3rd1891891891895555
1931931931935555
1971971971975555
1860 1880 1900 1920 1940 1960 1980
C-1 C-1C-2 C-2
ChannelChannelChannelChannel BandwidthBandwidthBandwidthBandwidthBlockBlockBlockBlock (MHz)(MHz)(MHz)(MHz) FrequenciesFrequenciesFrequenciesFrequencies
CCCC 30303030 1895189518951895----1910, 19751910, 19751910, 19751910, 1975----1990199019901990
C1C1C1C1 15151515 1902.51902.51902.51902.5----1910, 1982.51910, 1982.51910, 1982.51910, 1982.5----1990199019901990
C2C2C2C2 15151515 1895189518951895----1902190219021902----5, 19755, 19755, 19755, 1975----1982.51982.51982.51982.5
C3C3C3C3 10101010 1895189518951895----1900, 19751900, 19751900, 19751900, 1975----1980198019801980
C4C4C4C4 10101010 1900190019001900----1905, 19801905, 19801905, 19801905, 1980----1985198519851985
C5C5C5C5 10101010 1905190519051905----1910, 19851910, 19851910, 19851910, 1985----1990199019901990
Note: Some of the original C Block licenses (Originally 30 MHz each) were split into multiplelicenses (C-1 and C-2: 15 MHz; C-3, C-4, and C-5: 10MHz).
FCC Broadband PCS Band PlanFCC Broadband PCS Band PlanFCC Broadband PCS Band PlanFCC Broadband PCS Band Plan
System VSWR CalculatorFrequency (MHz): 895.00
System Component
Max. VSWR
Return Loss (dB)
Cable TypeCable
Length (m)Cable
Length (ft)Insertion Loss (dB)
Reflections at input
Antenna 1.33 16.98 0.0983Top Jumper 1.07 29.42 2 1.22 4.00 0.08 0.0239
Main Feed Line 1.11 25.66 1 30.48 100.00 1.18 0.0484Surge Suppressor 1.07 29.42 0.20 0.0329
Bottom Jumper 1.07 29.42 2 1.83 6.00 0.13 0.03381.59
Jumper Cable Types: 0.1216FSJ4-50B 1.28
Estimated System Reflection: Estimated System VSWR:
LDF4-50A
LDF5-50A
LDF4-50A
FSJ4-50B 1.28LDF4-50A 18.3
Main Feedline Cable Types: 0.2372LDF5-50A 1.62LDF6-50 12.5LDF7-50AVXL5-50VXL6-50 1.59VXL7-50
Return Loss (dB) VSWR feet meters28.00 1.0829 4.00 1.22
Estimated System VSWR: Estimated System Return Loss (dB):
Return Loss to VSWR converter Feet to meters convert er
Maximum System Reflection: Maximum System VSWR:
Maximum System Return Loss (dB):
Total Insertion Loss (dB):
Antenna Pattern Distortions
Conductive (metallic) obstruction in the path Conductive (metallic) obstruction in the path Conductive (metallic) obstruction in the path Conductive (metallic) obstruction in the path of transmit and/or receive antennas may of transmit and/or receive antennas may of transmit and/or receive antennas may of transmit and/or receive antennas may distort antenna radiation patterns in a way distort antenna radiation patterns in a way distort antenna radiation patterns in a way distort antenna radiation patterns in a way that causes systems coverage problems and that causes systems coverage problems and that causes systems coverage problems and that causes systems coverage problems and degradation of communications services.degradation of communications services.degradation of communications services.degradation of communications services.degradation of communications services.degradation of communications services.degradation of communications services.degradation of communications services.
A few basic precautions will prevent pattern A few basic precautions will prevent pattern A few basic precautions will prevent pattern A few basic precautions will prevent pattern distortions.distortions.distortions.distortions.
105° Horizontal Pattern No Obstacle
880 MHz880 MHz880 MHz880 MHz300°
105105105105105105105105°°°°°°°°
330°
60°
30°
0°
-5
0
+5
+10
+15
-10
AntennaAntennaAntennaAntenna
270°
240°
210°180°
150°
120°
90°
105° Horizontal Pattern Obstruction at -10 dB Point
330°
300° 60°
30°0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
0°
-10 dB PointBuildingBuildingBuildingBuilding
CornerCornerCornerCorner
105° Horizontal Pattern Obstruction at -6 dB Point
330°
300° 60°
30°0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
0° -6 dB Point
BuildingBuildingBuildingBuildingCornerCornerCornerCorner
105° Horizontal Pattern Obstruction at -3 dB Point
330°
300° 60°
30°0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
0°-3 dB Point
BuildingBuildingBuildingBuildingCornerCornerCornerCorner
90° Horizontal Pattern No Obstacle
880 MHz880 MHz880 MHz880 MHz
330°
300° 60°
30°0°
-5
0
+5
+10
+15
-10
AntennaAntennaAntennaAntenna
270°
240°
210°180°
150°
120°
90°
90° Horizontal Pattern 0.5 l Diameter Obstacle at 0°
330°
300° 60°
30°0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
0°
12λλλλ
90° Horizontal Pattern 0.5 l Diameter Obstacle at 45°
330°
300° 60°
30°0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
8λ8λ8λ8λ
45°
90° Horizontal Pattern 0.5 l Diameter Obstacle at 60°
330°
300° 60°
30°
0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
6λ6λ6λ6λ60°
90° Horizontal Pattern 0.5 l Diameter Obstacle at 80°
330°
300° 60°
30°
0°
880 MHz880 MHz880 MHz880 MHz
270°
240°
210°180°
150°
120°
90°
AntennaAntennaAntennaAntenna
3λ3λ3λ3λ80°
General Rule Area that needs to be free of obstructions (> 0.57 WL)Area that needs to be free of obstructions (> 0.57 WL)Area that needs to be free of obstructions (> 0.57 WL)Area that needs to be free of obstructions (> 0.57 WL)
Maximum Gain
3 dB Point(45°)
6 dB Point
> 12 WL
Antenna90° horizontal (3 dB) beamwidth
6 dB Point(60°)
10 dB Point(80° - 90°)
> 3 WLWLWLWLWL
70
60
50
40
30
Isola
tion in d
B
Attenuation Provided By VerticalSeparation of Dipole Antennas
1 2 3 5 10 20 30 50 100(0.3) (0.61) (0.91) (1.52) (3.05) (6.1) (9.14) (15.24)(30.48)
30
20
10
Antenna Spacing in Feet (Meters)The values indicated by these curves are approximate because of coupling which exists between the antenna and transmission line. Curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas. Values are measured between the physical center of the tower antennas and the antennas are mounted directly above the other, with no horizontal offset (collinear). No correction factor is required for the antenna gains.
Isola
tion in d
B
80
70
60
50
40
Attenuation Provided By HorizontalSeparation of Dipole Antennas
Isola
tion in d
B
10 20 30 50 100 200 300 500 1000(3.05) (6.1) (9.14) (15.24) (30.48) (60.96) (91.44) (152.4)(304.8)
40
30
20
Antenna Spacing in Feet (Meters)
Curves are based on the use of half-wave dipole antennas. The curves will also provide acceptable results for gain type antennas if (1) the indicated isolation is reduced by the sum of the antenna gains and (2) the spacing between the gain antennas is at least 50 ft. (15.24 m) (approximately the far field).
Isola
tion in d
B
Pattern Distortions
a
tan tan tan tan aaaa ====
dddd ==== D D D D **** tan tan tan tan aaaa
tan 1tan 1tan 1tan 1°°°° ==== 0.017450.017450.017450.01745
Note: tan 10Note: tan 10Note: tan 10Note: tan 10°°°° = 0.1763 10 = 0.1763 10 = 0.1763 10 = 0.1763 10 **** 0.01745 = 0.01745 = 0.01745 = 0.01745 = 0.17450.17450.17450.1745
ddddDDDD
Base Station Antenna w/ 4 Deg EDT
-20
-10
0
Am
plitu
de (
dB)
-50
-40
-30
-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180
Elevation Angle (Degree)
Am
plitu
de (
dB)
Gain Points of a Typical Main Lobe(Relative to Maximum Gain)
Vertical Vertical Vertical Vertical BeamBeamBeamBeam
Width= 2 Width= 2 Width= 2 Width= 2 aaaa((((----3dB point)3dB point)3dB point)3dB point)
aaaa
aaaa
----3dB point 3dB point 3dB point 3dB point aaaa°°°° below bore sight.below bore sight.below bore sight.below bore sight.
----6dB point 1.35 6dB point 1.35 6dB point 1.35 6dB point 1.35 **** aaaa°°°° below bore sight.below bore sight.below bore sight.below bore sight.
----10 dB point 1.7 10 dB point 1.7 10 dB point 1.7 10 dB point 1.7 **** aaaa°°°° below bore sight.below bore sight.below bore sight.below bore sight.
((((----3dB point)3dB point)3dB point)3dB point)
Changes In Antenna PerformanceIn The Presence of:
Non-Conductive Obstructions, such as Screens
FIBERGLASSFIBERGLASSFIBERGLASSFIBERGLASSPANELPANELPANELPANEL
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
Cell S
ite A
nte
nna
DIM “A”DIM “A”DIM “A”DIM “A”
Performance of Sample PCS AntennaBehind Camouflage (¼" Fiberglass)
100100100100°°°°
110110110110°°°°
120120120120°°°°
Hor
izon
tal A
pert
ure
FIBERGLASSFIBERGLASSFIBERGLASSFIBERGLASS
PANELPANELPANELPANEL
DIM “A”DIM “A”DIM “A”DIM “A”C
ell S
ite A
nt.
Cell S
ite A
nt.
Cell S
ite A
nt.
Cell S
ite A
nt.
70707070°°°°
80808080°°°°
90909090°°°°
11110000 2222 3333 4444 5555 6666 7777 8888 9999 10101010 11111111 12121212
1/4 1/4 1/4 1/4 1/4 1/4 1/4 1/4 λλλλλλλλ 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 λλλλλλλλ 1 1 1 1 1 1 1 1 λλλλλλλλ 2 2 2 2 2 2 2 2 λλλλλλλλ11111111--------1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 λλλλλλλλ3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 λλλλλλλλ
Distance of Camouflage (Inches) (Dim. A)
Hor
izon
tal A
pert
ure
1.51.51.51.5
1.61.61.61.6
1.71.71.71.7
VS
WR
(W
orst
Cas
e)
Performance of Sample PCS AntennaBehind Camouflage (¼" Fiberglass)
FIBERGLASSFIBERGLASSFIBERGLASSFIBERGLASS
PANELPANELPANELPANEL
DIM “A”DIM “A”DIM “A”DIM “A”
Cell S
ite A
nt.
Cell S
ite A
nt.
Cell S
ite A
nt.
Cell S
ite A
nt.
1.21.21.21.2
1.31.31.31.3
1.41.41.41.4
11110000 2222 3333 4444 5555 6666 7777 8888 9999 10101010 11111111 12121212Distance of Camouflage (Inches) (Dim. A)
VS
WR
(W
orst
Cas
e)
W/Plain Facade W/Ribbed Facade Without Facade
1/4 1/4 1/4 1/4 1/4 1/4 1/4 1/4 λλλλλλλλ 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 λλλλλλλλ 1 1 1 1 1 1 1 1 λλλλλλλλ 2 2 2 2 2 2 2 2 λλλλλλλλ11111111--------1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 λλλλλλλλ
Distance From Fiberglass
No FiberglassNo FiberglassNo FiberglassNo Fiberglass
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0°
90°
9090909090909090°°°°°°°°
-20
-25
-30
-35
-40
-45
-50
-55
3" to Fiberglass3" to Fiberglass3" to Fiberglass3" to Fiberglass
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0° 102102102102102102102102°°°°°°°°
90°
-25
-30
-35
-40
-45
-50
-55
-20
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0° 6868686868686868°°°°°°°°
90°
-20
-25
-30
-35
-40
-45
-50
-15
1.5" to Fiberglass1.5" to Fiberglass1.5" to Fiberglass1.5" to Fiberglass
Distance From Fiberglass
6" to Fiberglass6" to Fiberglass6" to Fiberglass6" to Fiberglass
330°
300°
270°
240°
210° 180
°
150°
120°
60°
30°
0°
111111111111111122222222°°°°°°°°
-20
-25
-30
-35
-40
-45
-50
-15
90°
4" to Fiberglass4" to Fiberglass4" to Fiberglass4" to Fiberglass
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0°7777777777777777°°°°°°°°
90°
-20
-25
-30
-35
-40
-45
-50
-15
9" to Fiberglass9" to Fiberglass9" to Fiberglass9" to Fiberglass
330°
300°
270°
240°
210° 180
°
150°
120°
60°
30°
0° 101010101010101088888888°°°°°°°°
90°
-20
-25
-30
-35
-40
-45
-50
-15