PRIVATE AND CONFIDENTIAL© CommScope 1
Basic Principles For Daily Applications
Antenna Theory
Base Station Antenna SystemsMarch 2009
PRIVATE AND CONFIDENTIAL© CommScope 2
Base Station Antenna Technology Evolution
Omni Directional
Vertical Polarization
DualPol®MIMO
DualPol®RET
Interference ReductionMIMO
Dual BandCapacity Improvement
with FrequencyMIMO
DigitalBeam Former
SDMACapacity
SmartBeam®
Capacity”Load Balance
MIMO
AntennaCoreTechnology
AMPS
GSM
CDMA
W-CDMA
WiMAX
TD-SCDMA
LTE
AirInterfaces Dominate Application Significant Application Low Application
PRIVATE AND CONFIDENTIAL© CommScope 3
F0 ¼ λ
¼ λ
Dipole
5.90.152000
6.950.181700
12.30.31960
14.80.38800
25.70.65460
42.21.07280
73.81.87160
147.63.7580
393.610.030
λ (Inches)λ (Meters)F0 (MHz)
PRIVATE AND CONFIDENTIAL© CommScope 4
Source: COMSEARCH
3D View Antenna Pattern
PRIVATE AND CONFIDENTIAL© CommScope 5
Understanding The Mysterious “dB”
Signal strength relative to a signal of known strength, in this case: the carrier signalExample: –150 dBc = 150 dB below carrier signalIf two carriers are 20 Watt each = 43 dBm–150 dBc = –107 dBm or ~0.02 pWatt or ~1 microvolt
dBc
Absolute signal strength relative to 1 milliwatt1 mWatt = 0 dBm1 Watt = 30 dBm20 Watts = 43 dBm
dBm
Difference between two signal strengthsdB
Signal strength relative to an isotropic radiatordBi
Signal strength relative to a dipole in empty spacedBd
Note: TheLogarithmic Scale10 * log10 (Power Ratio)
PRIVATE AND CONFIDENTIAL© CommScope 6
Effect Of VSWRGood VSWR is only one component of an efficient antenna.
88.911.10.519.52.00
96.04.00.1814.01.50
97.22.80.1215.61.40
98.31.70.0817.71.30
99.20.80.0420.81.20
99.80.20.0126.41.10
100.00.00.00∞1.00
PowerTrans. (%)
PowerReflected (%)
TransmissionLoss (dB)
ReturnLoss (dB)VSWR
PRIVATE AND CONFIDENTIAL© CommScope 7
Shaping Antenna Patterns
Vertical arrangement of properly phased dipoles allows
control of radiation patterns at the horizon as well as
above and below the horizon. The more dipoles that are
stacked vertically, the flatter the vertical pattern is and the
higher the antenna coverage or ‘gain’ is in the general
direction of the horizon.
PRIVATE AND CONFIDENTIAL© CommScope 8
• 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 pattern measures the gain.
• The little lobes, illustrated in the lower section, are secondary minor lobes.
• 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.
Shaping Antenna Patterns (Continued)
Aperture of Dipoles
Vertical Pattern
Horizontal Pattern
4 Dipoles Vertically Stacked
Single Dipole
PRIVATE AND CONFIDENTIAL© CommScope 9
Gain
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?Gain can be associated with coverage distance and/or obstacle penetration (buildings, foliage, etc).
How is it measured?It is measured using data collected from antenna range testing. The reference gain standard must always be specified.
What is Andrew standard?Andrew conforms to the industry standard of +/–1 dB accuracy.
PRIVATE AND CONFIDENTIAL© CommScope 10
• An isotropic antenna is a single point in space radiating in a perfect sphere (not physically possible).
• A dipole antenna is one radiating element (physically possible).
• A gain antenna is two or more radiating elements phased together.
Gain References (dBd And dBi)
0 (dBd) = 2.14 (dBi)
Isotropic Pattern
3 (dBd) = 5.14 (dBi)
Dipole Pattern
Isotropic (dBi)Dipole (dBd)Gain
dBddBi
PRIVATE AND CONFIDENTIAL© CommScope 11
Principles Of Antenna Gain
0 dBd
+3 dBd
+6 dBd
+9 dBd
--3 dB3 dB
180°
90°
--3 dB3 dB
45°
--3 dB3 dB
Directional Antennas, Top ViewOmni Antenna, Side View
0 dBd 60°
-3 dB
-3 dB
+3 dBd 30°
-3 dB
+9 dBd7.5°
-3 dB
+6 dBd 15°-3 dB
PRIVATE AND CONFIDENTIAL© CommScope 12
# of
Rad
iato
rsVe
rtic
ally
Spa
ced
(0.9λ)
Theoretical Gain Of Antennas (dBd)
Could be horizontal radiator pairs for narrow horizontal apertures.
7.5°4819.618171514131298
10°3618.116.515.513.512.511.510.57.56
15°2416.61514121110964
20°1.5315.113.512.510.59.58.57.54.53
30°1213.61211987632
60°0.5110.598654301
VerticalBeamwidth
DCS 1800/1900
800/900 MHz PCS33°45°60°90°105°120°180°360°
Typical Lengthof Antenna (ft.)
3 dB Horizontal Aperture(Influenced by Grounded Back “Plate”)
PRIVATE AND CONFIDENTIAL© CommScope 13
• Gain (dBi) = Directivity (dBi) – Losses (dB)
• Losses: ConductorDielectricImpedancePolarization
• Measure using ‘Gain by Comparison’
Antenna Gain
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• Vertical polarization– Traditional land mobile use– Omni antennas– Requires spatial separation for diversity– Still recommended in rural, low multipath environments
• Polarization diversity– Slant 45° (+ and –) is now popular– Requires only a single antenna for diversity– Lower zoning impact– Best performance in high and medium multipath
environments
Measured data will be presented in the Systems Section
Antenna Polarization
PRIVATE AND CONFIDENTIAL© CommScope 15
Dipole
Elements
1800/1900/UMTSDirected Dipole™
Patch 800/900 MHzDirected Dipole™
MARMicrostrip Annular Ring
Various Radiator Designs
DualPol® (XPol)Directed Dipole™
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Single Dipole Crossed Dipole
Dipoles
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Feed Harness Construction
Center Feed(Hybrid)
ASP705K
Series Feed
ASP705(Old Style)
LBX-6513DS
CorporateFeed
PRIVATE AND CONFIDENTIAL© CommScope 18
Feed Harness Construction (Continued)
• Complex feed system
• Not as versatile as corporate (less bandwidth, less beam shaping)
Disadvantages
• Frequency independent main beam direction
• More beam shaping ability, sidelobe suppression
• Frequency independent main lobe direction
• Reasonably simple feed system
• Minimum feed losses• Simple feed system
Advantages
Corporate FeedCenter Feed(Hybrid)Series Feed
BEAMTILT
450 455 460 465 470 MHz+2°
+1°
0°
+1°
+2°
ASP-705
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• Coaxial cable– Best isolation
– Constant impedance
– Constant phase
• Microstripline, corporate feeds– Dielectric substrate
– Air substrate
Feed Networks
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• Dielectric substrate
– Uses printed circuit technology
– Power limitations
– Dielectric substrate causes loss (~1.0 dB/m at 2 GHz)
• Air substrate
– Metal strip spaced above a groundplane
– Minimal solder or welded joints
– Laser cut or punched
– Air substrate cause minimal loss (~0.1 dB/m at 2 GHz)
Microstrip Feed Lines
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Air Microstrip Network
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LBX-3316-VTM Using Hybrid Cable/Air Stripline
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LBX-3319-VTM Using Hybrid Cable/Air Stripline
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DB812 Omni AntennaVertical Pattern
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Pattern Simulation
932DG65T2E-M
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For sector antenna, the key pattern objective is to focus as much energy as possible into a desired sector with a desired radius while minimizing unwanted interference to/from all other sectors.
This requires:• Optimized pattern shaping• Pattern consistency over the rated frequency band• Pattern consistency for polarization diversity models• Downtilt consistency
Key Antenna Pattern Objectives
PRIVATE AND CONFIDENTIAL© CommScope 27
What is it?The main lobe is the radiation pattern lobe that contains the majority portion of radiated energy.
Why is it useful?Shaping of the pattern allows the contained coverage necessary for interference-limited system designs.
How is it measured?The main lobe is characterized using a number of the measurements which will follow.
What is Andrew standard?Andrew conforms to the industry standard.
Main Lobe
35° Total35° TotalMain LobeMain Lobe
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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?It allows system designers to choose the optimum characteristics for coverage vs. interference requirements.
How is it measured?It is measured using data collected from antenna range testing.
What is Andrew standard?Andrew conforms to the industry standard.
Horizontal And Vertical1/2 Power1/2 PowerBeamwidthBeamwidth
30 30
Half-Power Beamwidth
PRIVATE AND CONFIDENTIAL© CommScope 29
What is it?The ratio in dB of the maximum directivity of an antenna to its directivity in a specified rearward direction. Note that on a dual-polarized antenna, it is the sum of co-pol and cross-pol patterns.
Why is it useful?It characterizes unwanted interference on the backside of the main lobe. The larger the number, the better!
How is it measured?It is measured using data collected from antenna range testing.
What is Andrew standard?Each data sheet shows specific performance. In general, traditional dipole and patch elements will yield 23–28 dB while the Directed Dipole™ style elements will yield 35–40 dB.
F/B Ratio @ 180 degreesF/B Ratio @ 180 degrees0 dB – 25 dB = 25 dB0 dB – 25 dB = 25 dB
Front-To-Back Ratio
PRIVATE AND CONFIDENTIAL© CommScope 30
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?Sidelobe level or pattern shaping allows the minor lobe energy to be tailored to the antenna’s intended use. See Null Fill and Upper Sidelobe Suppression.
How is it measured?It is always measured with respect to the main lobe in dB.
What is Andrew standard?Andrew conforms to the industry standard.
Sidelobe LevelSidelobe Level(–20 dB)(–20 dB)
Sidelobe Level
PRIVATE AND CONFIDENTIAL© CommScope 31
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?For arrays with a narrow vertical beam-width (less than 12°), null filling significantly improves signal intensity in all coverage targets below the horizon.
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.
What is Andrew standard?Most Andrew arrays will have null fill of 20–30 dB without optimization. To qualify as null fill, we expect no less than 15 and typically 10–12 dB!
Null Filling
PRIVATE AND CONFIDENTIAL© CommScope 32
Null Filled to 16 dB Below Peak
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)
Rec
eive
d Le
vel (
dBm
)
Transmit Power = 1 W
Base Station Antenna Height = 40 m
Base Station Antenna Gain = 16 dBd
Elevation Beamwidth = 6.5°
Important For Antennas With Narrow Elevation Beamwidths
Null Filling
PRIVATE AND CONFIDENTIAL© CommScope 33
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?For arrays with a narrow vertical beamwidth (less than 12°), USLS can significantly reduce interference due to multi-path or when the antenna is mechanically downtilted.
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 Andrew standard?Most of Andrew’s arrays will have USLS of >15 dB without optimization. The goal of all new designs is to suppress the first upper sidelobe to unity gain or lower.
Upper Sidelobe Suppression
First UpperSidelobeSuppression
PRIVATE AND CONFIDENTIAL© CommScope 34
What is it?The ability of an antenna to discriminate between two waves whose polarization difference is 90 degrees.
Why is it useful?Orthogonal arrays within a single antenna allow for polarization diversity. (As opposed to spacial diversity.)
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).
What is Andrew standard?Andrew conforms to the industry standard.
δ = 0°, XPol = –∞ dBδ = 5°, XPol = –21 dBδ =10°, XPol = –15 dBδ =15°, XPol = –11 dBδ =20°, XPol = –9 dBδ =45°, XPol = –3 dBδ =50°, XPol = –2.3 dBδ =60°, XPol = –1.2 dBδ =70°, XPol = –0.54 dBδ =80°, XPol = –0.13 dBδ =90°, XPol = 0 dBXPol = 20 log ( sin (δ))
δ
Orthogonality
Decorrelation between the Green and Blue Lines
PRIVATE AND CONFIDENTIAL© CommScope 35
-40
-35
-30
-25
-20
-15
-10
-5
0
120°
Typical
-40
-35
-30
-25
-20
-15
-10
-5
0
120°
Directed Dipole™
What is Andrew standard?For traditional dipoles, the minimum is 10 dB; however, for the Directed Dipole™ style elements, it increases to 15 dB min.
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?It is a measure of the ability of a cross-pol array to distinguish between orthogonal waves. The better the CPR, the better the performance of polarization diversity.
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. Note: in the rear hemisphere, cross-pol becomes co-pol and vice versa.
Co-PolarizationCross-Polarization (Source @ 90°)
Cross-Pol Ratio (CPR)
PRIVATE AND CONFIDENTIAL© CommScope 36
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?For optimum diversity performance, the beams should track as closely as possible.
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.
+45°–45°Array Array
120°120°
Horizontal Beam Tracking
What is Andrew standard?The Andrew beam tracking standard is +/–1 dB over the 3 dB horizontal beamwidth.
PRIVATE AND CONFIDENTIAL© CommScope 37
–3 dB +3 dB
SquintSquint θ/2
θ
HorizontalBoresiteWhat is it?
The amount of pointing error of a given beam referenced to mechanical boresite.
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 antennas if the two arrays do not have similar patterns.
How is it measured?It is measured using data collected from antenna range testing.
What is Andrew standard?For the horizontal beam, squint shall be less than 10% of the 3 dB beamwidth. For the vertical beam, squint shall be less than 15% of the 3 dB beamwidth or 1 degree, whichever is greatest.
Beam Squint
PRIVATE AND CONFIDENTIAL© CommScope 38
What is it?SPR is a ratio expressed in percentage of the power outside the desired sectorto the power inside the desired sector created by an antenna’s pattern.
Why is it useful?It is a percentage that allows comparison of various antennas. The better the SPR, the better the interference performance of the system.
How is it measured?It is mathematically derived from the measured range data.
What is Andrew standard?Andrew Directed Dipole™ style antennas have SPR’s typically less than 2 percent.
Sector Power Ratio (SPR)
PUndesired
SPR (%) = X 100PDesired
300
60Σ60
300Σ
120°120°
Desired
Undesired
PRIVATE AND CONFIDENTIAL© CommScope 39
83°
60°Area of Poor Silence with
>27 dB Front-to-Back Ratio
Standard 85° Panel Antenna
74°
120°Cone of Great Silence with >40 dB Front-to-Back Ratio
932LG
Directed Dipole™
–16 dB –12 dB
HorizontalAnt/AntIsolation
Roll offat -/+ 60°
–7 dB –6 dB
-10 dBpoints
74° 83°
Next SectorAnt/AntIsolation–35 dB –18 dB
Coneof Silence
Key Antenna Parameters To Examine Closely
Antenna–Based System Improvements
PRIVATE AND CONFIDENTIAL© CommScope 40
Ratings:
1 = Always important
2 = Sometimes important
3 = Seldom important
Azimuth Beam• Beam tracking vs. frequency
Limited to sub-bands on broadband models
• Squint• Roll-off past the 3 dB points• Front-to-back ratio• Cross-pol beam trackingElevation Beam• Beam tracking vs. frequency• Upper sidelobe suppression• Lower null fill• Cross-pol beam tracking
Key Antenna Pattern Objectives
UrbanSuburban
Rural
1 1 1
1 1 11 2 31 1 21 1 1
1 2 31 2 33 3 22 2 3
PRIVATE AND CONFIDENTIAL© CommScope 41
Ratings:
1 = Always important
2 = Sometimes important
3 = Seldom important
Downtilt• Electrical vs. mechanical tilt• Absolute tilt• Electrical tilt vs. frequency• Effective gain on the horizonGain• Close to the theoretical value
(directivity minus losses)
Note: Pattern shaping reduces gain.
Key Antenna Pattern Objectives (Continued)
UrbanSuburban
Rural
1 1 32 2 31 2 31 2 3
2 1 1
PRIVATE AND CONFIDENTIAL© CommScope 42
Adaptive Array (AA)
• Planar array
• External digital signal processing (DSP) controls the antenna pattern
• A unique beam tracks each mobile
• Adaptive nulling of interfering signals
• Increased signal to interference ratio performance benefits
Advanced Antenna Technology
• 4, 6, and 8 column vertical pol designsfor WiMAX and TD-SCDMA*
• Often calibration ports are used
* Time Division Spatial Code Division Multiple Access
PRIVATE AND CONFIDENTIAL© CommScope 43
MIMO Systems
2 x 2 MIMO Spatial Multiplexing
• Multiple Input Multiple Output (MIMO)
• External DSP extracts signal from interference
• Capacity gains due to multiple antennas
Advanced Antenna Technology
• A DualPol® RET for 2x2 MIMO, two separated for 4x4 MIMO
• Spatial multiplexing works best in a multi-path environment
• Space Time Block Coding is a diversity MIMO mode
PRIVATE AND CONFIDENTIAL© CommScope 44
SmartBeam® Antenna Family
Advanced Antenna Technology
• Most flexible and efficient antenna system in the industry
• Solution for the traffic peaks instead of raising the bar everywhere
• Full 3-way remote optimization options- RET – Remote Electrical Tilt (e.g. 0–10°)- RAS – Remote Azimuth Steering (+/– 30°)- RAB – Remote Azimuth Beamwidth (from 35° to 105°)
• Redirect and widen the beam based on traffic requirements• Balance the traffic per area with the capacity per sector• Best utilization of radio capacity per sector• Convenient and low-cost optimization from a remote office• Quick and immediate execution• Scheduled and executed several times a day (e.g. business and residential plan)
PRIVATE AND CONFIDENTIAL© CommScope 45
35° 65°
90° 105°
Advanced Antenna TechnologySmartBeam®
3-Way ModelAzimuth patterns measured at 1710–2180 MHz with no radome.
PRIVATE AND CONFIDENTIAL© CommScope 46
35° 65°
90° 105°
Advanced Antenna TechnologySmartBeam®
3-Way ModelElevation patterns measured at 1710–2180 MHz with no radome.
PRIVATE AND CONFIDENTIAL© CommScope 47
• Choosing sector antennas
• Narrow beam antenna applications
• Polarization—vertical vs. slant 45°
• Downtilt—electrical vs. mechanical
• RET optimization
• Passive intermodulation (PIM)
• Return loss through coax
• Antenna isolation
• Pattern distortion
System Issues
PRIVATE AND CONFIDENTIAL© CommScope 48
For 3 sector cell sites, what performance differences can be expected from the use of antennas with different horizontal apertures?
Criteria
• Area of service indifference between adjacent sectors (ping-pong area)
• For comparison, use 6 dB differentials
• Antenna gain and overall sector coverage comparisons
Choosing Sector Antennas
PRIVATE AND CONFIDENTIAL© CommScope 49
-40
-35
-30
-25
-20
-15
-10
-5
0
120° Horizontal Overlay Pattern
DB874H120DB878H120
Examples
Low Band
3 x 120° Antennas
VPol
3 dB
4949°°
PRIVATE AND CONFIDENTIAL© CommScope 50
-40
-35
-30
-25
-20
-15
-10
-5
0
5 dB
90° Horizontal Overlay Pattern
Examples
DB854DG90 DB842H90DB856DG90 DB844H90DB858DG90 DB848H90LBX-9012 LBV-9012LBX-9013
Low Band
High Band
XPol VPol
3 x 90° Antennas
44°44°
DB932DG90 UMW-9015DB950G85HBX-9016UMWD-09014B UMWD-09016
PRIVATE AND CONFIDENTIAL© CommScope 51
65° Horizontal Overlay Pattern Examples
CTSDG-06513 DB844H65CTSDG-06515 DB848H65CTSDG-06516 LBV-6513DB854DG65DB856DG65DB858DG65LBX-6513LBX-6516
Low Band
High Band
XPol VPol
3 x 65° Antennas
-40
-35
-30
-25
-20
-15
-10
-5
0
19°19°
10 dB
UMWD-06513 PCS-06509 UMWD-06516 HBV-6516 UMWD-06517 HBV-6517HBX-6516HBX-6517
PRIVATE AND CONFIDENTIAL© CommScope 52
6-Sector Site (33°)
Rural Roadway
RepeaterNarrow Donor, Wide Coverage
Antennas
Road
4-Sector Site (45°)
Special Narrow Beam Applications
PRIVATE AND CONFIDENTIAL© CommScope 53
Test Drive Route
MOCKINGBIR
D LANE
REG
AL R
OW
HARRY HINESSTEMMONS FRWY
AIRPORT FRWY.
INWOOD R
OAD
MOTOR STREET
35
183
CELL SITE
N
PRIVATE AND CONFIDENTIAL© CommScope 54
Polarization Diversity Tests
Test A.
Test B
1 2DRIVE TESTS
HANDHELD
MOBILE
1A 2A
1B 2B
A
B
+45°/-45° 0°/90°(Slant 45°) (H/V)
DB854HV90
DB854DD90
PRIVATE AND CONFIDENTIAL© CommScope 55
TEST 1ATEST 1A
Slant 45° / Hand-Held In CarSpace Diversity vs. Slanted +45°/–45°
Test Set-Up and Uplink Signal Strength Measurements-40
Vert Left
Vert Right
Slant Div
SlantDiv
UplinkSignal Strength
Sign
al S
tren
gth
(dB
m) -50
-60
-70
-80
-90
-100
moving awayfrom tower
moving towardstower
moving crossface
EE9dB9dB
7.5 ft.7.5 ft.
AA BB
DB854DD90DB833 DB833
9dB9dBRedRed BlueBlue
11dB11dB
GreenGreen
BlackBlack
PRIVATE AND CONFIDENTIAL© CommScope 56
Difference Between Polarization Diversity and Space DiversityAverage Difference
-8
-4
0
4
8
12
16Si
gnal
Str
engt
h (d
B)
Difference Between Strongest Uplink Signals
Slant 45° / Hand-Held In CarSpace Diversity vs. Slanted +45°/–45° TEST 1ATEST 1A
Slant ±45°Improvement
PRIVATE AND CONFIDENTIAL© CommScope 57
Slant 45° / Mobile With Glass MountSpace Diversity vs. Slanted +45°/-45°
-40 Test Set-Up and Uplink Signal Strength Measurements
Vert Left
Vert Right
Slant Div
SlantDiv
UplinkSignal Strength
Sign
al S
tren
gth
(dB
m)
-90
11dB11dB
GreenGreen
BlackBlack-50
-60
-70
-80
EE9dB9dB
7.5 ft.7.5 ft.
AA BB
DB854DD90DB833 DB833
moving awayfrom tower moving towards
tower
moving crossface
9dB9dB
RedRed BlueBlue
TEST 1BTEST 1B
PRIVATE AND CONFIDENTIAL© CommScope 58
Difference Between Polarization Diversity and Space DiversityAverage Difference
Difference Between Strongest Uplink Signals16
-8
-4
0
4
8
12
Sign
al S
tren
gth
(dB
)
TEST 1BTEST 1B
Slant 45° / Mobile With Glass MountSpace Diversity vs. Slanted +45°/-45°
Slant ±45°Degradation
PRIVATE AND CONFIDENTIAL© CommScope 59
Rysavy Research
PRIVATE AND CONFIDENTIAL© CommScope 60
Future Technology Focus
• Figure 16 shows that HSDPA,1xEV-DO, and 802.16e are all within 2-3 dB of the Shannon bound, indicating that from a link layer perspective, there is not much room for improvement.
• This figure demonstrates that the focus of future technology enhancements should be on improving system performance aspects that improve and maximize the experienced SNRs in the system instead of investigating new air interfaces that attempt to improve the link layer performance. 1 Peter Rysavy of Rysavy Research, “Data Capabilities: GPRS to HSDPA and
Beyond”, 3G Americas, September 2005
PRIVATE AND CONFIDENTIAL© CommScope 61
Lower Co-Channel Interference/Better Capacity And Quality
The rapid roll-off of the lower lobes of the Andrew Directed Dipole™ antennas create larger, better defined ‘cones of silence’behind the array.• Much smaller softer hand-off area• Dramatic call quality improvement• 5%–10% capacity enhancement
Andrew Directed Dipole™
In a three sector site, traditional antennas produce a high degree of imperfect power control or sector overlap.Imperfect sectorization presents opportunities for:• Increased softer hand-offs• Interfering signals• Dropped calls• Reduced capacity
Traditional Flat Panels65° 90°
65°
The Impact
90°
PRIVATE AND CONFIDENTIAL© CommScope 62
On the Capacity and Outage Probability of a CDMA Heirarchial Mobile System with Perfect/Imperfect Power Control and SectorizationBy: 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 on CDMA System CapacityBy: Chin-Chun Lee et, al IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 47, NO. 3, AUGUST 1998
Qualitatively, excessive overlay also reduces capacity of TDMA and GSM systems.
Overlapping angle in degree
Perc
enta
ge o
fca
paci
ty lo
ss
0 5 10 15
5
10
15
0
120° Sector Overlay Issues
PRIVATE AND CONFIDENTIAL© CommScope 63
Hard, Soft, and Softer Handoffs
• Hard Handoff- Used in time division multiplex systems- Switches from one frequency to another- Often results in a ping-pong switching effect
• Soft Handoff- Used in code division multiplex systems- Incorporates a rake receiver to combine signals from multiple cells- Smoother communication without the clicks typical in hard handoffs
• Softer Handoff- Similar to soft handoff except combines signals from multiple adjacent
sectors
PRIVATE AND CONFIDENTIAL© CommScope 64
Soft and Softer Handoff Examples
Softer Handoff
Two-Way Soft Handoff
Three-Way Soft Handoff
PRIVATE AND CONFIDENTIAL© CommScope 65
In urban areas, service and frequency utilization are frequently improved by directing maximum radiation power at an area below the horizon.
This 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.
Beam Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 66
• 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
PRIVATE AND CONFIDENTIAL© CommScope 67
Mechanical Electrical
Electrical/Mechanical Downtilt (Continued)
PRIVATE AND CONFIDENTIAL© CommScope 68
DB5083 downtilt mounting kit is constructed of heavy duty galvanized steel, designed for pipe mounting 12” to 20” wide panel antennas.
• Correct bracket calibration assumes a plumb mounting pipe!
• Check antenna with a digital level.
DB5083 Downtilt Mounting Kit
PRIVATE AND CONFIDENTIAL© CommScope 69
Mechanical tilt causes . . .
• Beam peak to tilt below horizon
• Back lobe to tilt above horizon
• At ± 90°, no tilt
Pattern Analogy—Rotating A Disk
Mechanical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 70
8°0° 10°6°4°Mechanical Tilt
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350
Elevation Pattern
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350
Azimuth Pattern
Mechanical Downtilt Coverage
PRIVATE AND CONFIDENTIAL© CommScope 71
85°
Quiz What is the vertical beamwidth of a 4-element array?
0° Mechanical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 72
93°
7° Mechanical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 73
123°
15° Mechanical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 74
Horizontal 3 dB Bandwidth Undefined
20° Mechanical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 75
• For the radiation pattern to show maximum gain in the direction of the horizon, each stacked dipole must be fed from the signal source in phase.
• Feeding vertically arranged dipoles out of phase will generate patterns that look up or look down.
• The degree of beam tilt is a function of the phase shift of one dipole relative to the adjacent dipole.
Dipoles Fed In Phase
ExciterPhase
Energy
in
Dipoles Fed Out of Phase
Wav
eFr
ont
Exciter
Generating Beam Tilt
Managing Beam Tilt
PRIVATE AND CONFIDENTIAL© CommScope 76
Cone of the Beam Peak Pattern
Electrical tilt causes . . .
• Beam peak to tilt below horizon
• Back lobe to tilt below horizon
• At ± 90°, tilt below horizon
• All the pattern tilts
Pattern Analogy—Forming A Cone Out Of A Disk
Electrical Downtilt
PRIVATE AND CONFIDENTIAL© CommScope 77
8°0° 10°6°4°Electrical Tilt
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350
Elevation Pattern
0
10
20
30
40
50
6070
8090100110
120
130
140
150
160
170
180
190
200
210
220
230
240250
260 270 280290
300
310
320
330
340
350
Azimuth Pattern
Electrical Downtilt Coverage
PRIVATE AND CONFIDENTIAL© CommScope 78
Mechanical Vs. Electrical Downtilt
0 1020
30
40
50
60
70
80
90
100
110
120
130
140
150160
170180190200
210
220
230
240
250
260
270
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290
300
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320
330340
350
Mechanical Electrical
PRIVATE AND CONFIDENTIAL© CommScope 79
Optimization
Remote Electrical Downtilt (RET)ATM200-002
RET Device (Actuator)
Network Server
ATC300-1000Rack Mount Controller
ANMS™
Local PC
ATC200-LITE-USBPortable Controller
Remote Locations
Local PC
PRIVATE AND CONFIDENTIAL© CommScope 80
TxF1
TxF2
RxF3
F2
F1
Receiver-Produced
TxF1
TxF2
RxF3
F3
F2
Transmitter-Produced
Rx3
DUPTx1
Tx2
COMB
F3
F1F2
RF Path-Produced
RxF3
Tx1
Tx2
F1
F2
F3
Elsewhere
Where?
Intermod Interference
PRIVATE AND CONFIDENTIAL© CommScope 81
1 1 Second 1F1 + 1F2 38751F1 – 1F2 15
2 1 Third 2F1 + 1F2 5820*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
Product Product Productn m Order Formulae Frequencies (MHz)
FIM = nF1 ± mF2Example: F1 = 1945 MHz; F2 = 1930 MHz
*Odd-order difference products fall in-band.
Product Frequencies, Two-Signal IM
High Band
PRIVATE AND CONFIDENTIAL© CommScope 82
Odd-Order Difference Products
Two-Signal IM
Example: F1 = 1945 MHz; F2 = 1930 MHzΔF = F1 - F2 = 15
Third Order: F1 + ΔF; F2 - ΔFFifth Order: F1 + 2ΔF; F2 - 2ΔFSeventh Order: F1 + 3ΔF; F2 - 3ΔFHigher than the highest – lower than the lowest – none in-between
ΔF
5th
3F2 – 2F1
1900
F2
F2
1930
F1
F1
1945
3rd
2F1 – F2
1960
5th
3F1 – 2F2
1975
3rd
2F2 – F1
1915ΔF ΔF
dBc
dBm
2ΔF 2ΔF
PRIVATE AND CONFIDENTIAL© CommScope 83
11th1855
9th1870
7th1885
5th1900
3rd1915 1930 1945
Channel BandwidthBlock (MHz) Frequencies
C 30 1895–1910, 1975–1990C1 15 1902.5–1910, 1982.5–1990C2 15 1895–1902.5, 1975–1982.5C3 10 1895–1900, 1975–1980C4 10 1900–1905, 1980–1985C5 10 1905–1910, 1985–1990
Note: Some of the original C block licenses (originally 30 MHz each) were split into multiple licenses (C-1 and C-2: 15 MHz; C-3, C-4, and C-5: 10 MHz).
FCC Broadband PCS Band Plan
PCS A Band Intermodulation
PRIVATE AND CONFIDENTIAL© CommScope 84
3rd1895 1935 1975
Channel BandwidthBlock (MHz) Frequencies
C 30 1895–1910, 1975–1990C1 15 1902.5–1910, 1982.5–1990C2 15 1895–1902.5, 1975–-1982.5C3 10 1895–1900, 1975–1980C4 10 1900–1905, 1980–1985C5 10 1905–1910, 1985–1990
Note: Some of the original C block licenses (originally 30 MHz each) were split into multiple licenses (C-1 and C-2: 15 MHz; C-3, C-4, and C-5: 10 MHz).
FCC Broadband PCS Band Plan
PCS A & F Band Intermodulation
PRIVATE AND CONFIDENTIAL© CommScope 85
• Ferromagnetic materials in the current path:- Steel- Nickel plating or underplating
• Current disruption:- Loosely contacting surfaces- Non-conductive oxide layers between contact surfaces
Causes Of IMD
PRIVATE AND CONFIDENTIAL© CommScope 86
System VSWR CalculatorSystem VSWR Calculator
Version 9.0Frequency (MHz): 850.00 18-Mar-09
System Component Max. VSWR Return Loss (dB)
Cable Type / Component Loss (dB)
Cable Length
(m)
Cable Length (ft)
Ins Loss w/2 Conn
(dB)
% of Est. System
Reflection
Reflections at input
Antenna or Load 1.50 13.98 87.2% 0.10032 2 Jumper 1.05 32.26 2 1.83 6.00 0.00 0.0% 0.00002 2 Tower Mounted Amp 1.20 20.83 0.20 0.00 0.0% 0.00002 2 Jumper 1.09 27.32 2 1.83 6.00 0.00 0.0% 0.00002 2 Top Diplexer or Bias Tee 1.15 23.13 0.20 0.00 0.0% 0.00002 2 Jumper 1.09 27.32 2.00 1.83 6.00 0.00 0.0% 0.00002 2 Main Feed Line 1.07 29.42 8 200.00 656.17 0.00 0.0% 0.00002 2 Jumper 1.09 27.32 4 30.48 100.00 0.00 0.0% 0.00002 2 Bias Tee 1.15 23.13 0.10 11.00 36.09 0.00 0.0% 0.00002 2 Jumper 1.09 27.32 2.00 1.83 6.00 0.00 0.0% 0.00002 2 Surge Suppressor 1.07 29.42 0.10 0.00 0.0% 0.00002 2 Jumper 1.09 27.32 3.00 1.83 6.00 0.00 0.0% 0.00002 2 Bottom Diplexer or Duplexer 1.20 20.83 0.10 0.00 0.0% 0.00001 1 Jumper 1.08 28.30 1.00 27.30 89.57 3.00 12.8% 0.0385
100.0%
Legacy Jumper / TL Cables Andrew CommScope1/2 inch Superflexible Copper FSJ4-50B Estimated Conn Loss ( 2per cable) 0.028
1/2 inch Foam Copper LDF4-50A CR 5401/2 inch Superflexible Aluminum SFX 500 Typical System Reflection: 0.1074
1/2 inch Foam Aluminum FXL 540 Typical System VSWR: 1.24Typical System Return Loss (dB): 19.4
Legacy Transmission Lines Andrew CommScope7/8 inch Copper LDF5-50A CR 1070 Worst System Reflection: 0.1387
1 1/4 inch Copper LDF6-50 CR 1480 Worst System VSWR: 1.321 5/8 inch Copper LDF7-50A CR 1873 Worst System Return Loss (dB): 17.2
7/8 inch Very Flexible Copper VXL5-501 1/4 inch Very Flexible Copper VXL6-50 Total Insertion Loss (dB): 3.001 5/8 inch Very Flexible Copper VXL7-50
7/8 inch Virtual Air Copper AVA5-50 Return Loss to VSWR converter Feet to meters converterYes 1 5/8 inch Virtual Air Copper AVA7-50
7/8 inch Aluminum AL5-50 FXL 7801 1/4 inch Aluminum FXL 1480 17.00 1.33 100.00 30.481 5/8 inch Aluminum AL7-50 FXL 1873
No
meters
Component Used?
Return Loss (dB) VSWR Feet
LDF4-50A
VXL7-50
No
No
No
No
No
No
No
No
No
No
No
YesYes
No
FSJ4-50B
PRIVATE AND CONFIDENTIAL© CommScope 87
Possible Cascaded VSWR Results
If: L = 1.5:1 (14 dB RL Antenna)
S = 1.2:1 (20.8 dB RL TMA)
Then: X (max) = 1.8:1 (10.9 dB RL)
S (min) = 1.25:1 (19.1 dB RL)
Worst case seldom happens in real life, but
be aware that it is possible!
Possible results (at a given frequency) when Antenna and TMA are interconnected with different electrical
length jumpers.
From http://www.home.agilent.com/agilent/editorial.jspx?cc=US&lc=eng&ckey=895674&nid=-35131.0.00&id=895674
PRIVATE AND CONFIDENTIAL© CommScope 88
Antenna
TMA
6 foot LDF4-50A
12 foot LDF4-50A
20 foot FSJ4-50
Transmission Line
Antenna Return Loss Diagram
12 foot LDF4-50A
20 foot FSJ4-50
Transmission Line
TMA
TMA Return Loss Diagram
Adapter or jumper to bypass TMA
50 ohm load
6 foot LDF4-50A
Recommended Antenna/TMA Qualification Test
PRIVATE AND CONFIDENTIAL© CommScope 89
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. If values (1) the spacing is measured between the physical center of the tower antennas and it (2) one antenna is mounted directly above the other, with no horizontal offset collinear). No correction factor is required for the antenna gains.
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)
70
60
50
40
30
20
10
Antenna Spacing in Feet (Meters)
Isol
atio
n in
dB
2000 MHz
850 MHz
450 MHz
160 MHz
75 MHz40 MHz
Attenuation Provided By VerticalSeparation Of Dipole Antennas
PRIVATE AND CONFIDENTIAL© CommScope 90
Attenuation Provided By HorizontalSeparation Of Dipole Antennas
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)
80
70
60
50
40
30
20
Antenna Spacing in Feet (Meters)
Isol
atio
n in
dB
2000 MHz
850 MHz
450 MHz
150 MHz
70 MHz
30 MHz50 MHz
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).
PRIVATE AND CONFIDENTIAL© CommScope 91
Conductive (metallic) obstruction in the path of transmit and/or receive antennas may distort antenna radiation patterns in a way that causes systems coverage problems and degradation of communications services.
A few basic precautions will prevent pattern distortions.
Pattern Distortions
Additional information on metal obstructions can also be found online at: www.akpce.com/page2/page2.html
PRIVATE AND CONFIDENTIAL© CommScope 92
Side Of Building Mounting
Pattern Distortions
Building
PRIVATE AND CONFIDENTIAL© CommScope 93
Antenna
880 MHz
0°
3½' –10 dB Point
BuildingCorner
Obstruction @ –10 dB Point
90° Horizontal Pattern
340
7
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
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250
260
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280
290
300
310
320
350
-40
-35
-30
-25
-20
-15
-10
-5
0
PRIVATE AND CONFIDENTIAL© CommScope 94
880 MHz
Antenna
0°
3½'–6 dB Point
BuildingCorner
Obstruction @ –6 dB Point
90° Horizontal Pattern
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
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230
240
250
260
270
280
290
300
310
320
350
PRIVATE AND CONFIDENTIAL© CommScope 95
880 MHz
Antenna
0°3½'
–3 dB Point
BuildingCorner
Obstruction @ –3 dB Point
90° Horizontal Pattern
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
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310
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350
PRIVATE AND CONFIDENTIAL© CommScope 96
880 MHz
Antenna
0°
12λ
0.51λ Diameter Obstacle @ 0°
90° Horizontal Pattern
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
220
230
240
250
260
270
280
290
300
310
320
350
PRIVATE AND CONFIDENTIAL© CommScope 97
880 MHz
Antenna
8λ
45°
0.51λ Diameter Obstacle @ 45°
90° Horizontal Pattern
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
220
230
240
250
260
270
280
290
300
310
320
350
PRIVATE AND CONFIDENTIAL© CommScope 98
880 MHz
Antenna
6λ
60°
0.51λ Diameter Obstacle @ 60°
90° Horizontal Pattern
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
220
230
240
250
260
270
280
290
300
310
320
350
Additional information on metal obstructions can also be found online at www.akpce.com/page2/page2.html.
PRIVATE AND CONFIDENTIAL© CommScope 99
880 MHz
Antenna3λ
80°
0.51λ Diameter Obstacle @ 80°
90° Horizontal Pattern
Additional information on metal obstructions can also be found online at www.akpce.com/page2/page2.html.
-40
-35
-30
-25
-20
-15
-10
-5
0340
330
0 1020
30
40
50
60
0
80
90
100
110
120
130
140
150160
170180190200
210
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240
250
260
270
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290
300
310
320
350
PRIVATE AND CONFIDENTIAL© CommScope 100
Area That Needs To Be Free Of Obstructions (> 0.51λ)
Antenna90° horizontal (3 dB) beamwidth
Maximum Gain
3 dB Point(45°)
6 dB Point(60°)
10 dB Point(80– 90°)
> 12 WL
> 8 W
L
> 6 WL
> 3 WLWL
General Rule
PRIVATE AND CONFIDENTIAL© CommScope 101
tan θ =d = D x tan θ
tan 1° = 0.01745for 0° < θ< 10° : tan θ = θ x tan 1°
Note: tan 10° = 0.1763 10 x 0.01745 = 0.1745
dD
dθ
D
Pattern Distortions
PRIVATE AND CONFIDENTIAL© CommScope 102
–3 dB point θ° below boresite.–6 dB point 1.35 x θ° below boresite.–10 dB point 1.7x θ° below boresite.
Vertical BeamWidth= 2 x θ°(–3 dB point)
Gain Points Of A Typical Main Lobe
θ°θº
Relative to Maximum GainRelative to Maximum Gain
PRIVATE AND CONFIDENTIAL© CommScope 103
FiberglassPanel
Dim “A”
Non-Conductive Obstructions
Changes In Antenna Performance In The Presence Of:
90°PCS A
ntenna
PRIVATE AND CONFIDENTIAL© CommScope 104
70°
80°
90°
100°
110°
120°
10 2 3 4 5 6 7 8 9 10 11 12
1/4 1/4 λλ 1/2 1/2 λλ 1 1 λλ 2 2 λλ11--1/2 1/2 λλ3/4 3/4 λλ
Distance of Camouflage (Inches) (Dim. A)
Hor
izon
tal A
pertu
re
FIBERGLASSPANEL
DIM “A”
Performance Of 90° PCS AntennaBehind Camouflage (¼" Fiberglass)
PRIVATE AND CONFIDENTIAL© CommScope 105
W/Plain Façade W/Ribbed Façade Without Facade
Performance Of 90° PCS AntennaBehind Camouflage (¼" Fiberglass)
1.2
1.3
1.4
1.5
1.6
1.7
10 2 3 4 5 6 7 8 9 10 11 12Distance of Camouflage (Inches) (Dim. A)
VS
WR
(Wor
st C
ase) FIBERGLASS
PANEL
DIM “A”
1/4 1/4 λλ 1/2 1/2 λλ 1 1 λλ 2 2 λλ11--1/2 1/2 λλ
PRIVATE AND CONFIDENTIAL© CommScope 106
330°
300°
270°
240°
210°
180°150°
120°
60°
30°0°
90°
-20-25
-30-35-40
-45
-50
-55
No Fiberglass
9090°°
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°0°
90°
-20
-25-30
-35
-40
-45
-50
-15
6868°°
1.5" to Fiberglass
330°
300°
270°
240°
210°180°
150°
120°
60°
30°0°
90°
-25-30-35-40
-45
-50
-55
-20
3" to Fiberglass
102102°°
Distance From Fiberglass
PRIVATE AND CONFIDENTIAL© CommScope 107
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0°
-20-25-30-35
-40
-45
-50
-15
90°
6" to Fiberglass
112112°°330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0°
90°
-20-25
-30-35
-40
-45
-50
-15
4" to Fiberglass
7777°°
330°
300°
270°
240°
210°
180°
150°
120°
60°
30°
0°
90°
-20-25-30-35
-40
-45
-50
-15
9" to Fiberglass
108108°°
Distance From Fiberglass