antenna concepts class
Post on 04-Jun-2018
224 Views
Preview:
TRANSCRIPT
-
8/13/2019 Antenna Concepts Class
1/127
Antenna Theory
Basic Principles for PracticalApplications
2004
-
8/13/2019 Antenna Concepts Class
2/127
Outline
Brief History
Antenna Building Blocks
Antenna System
Antenna System Tests
Radiation
Antenna Performance
Break
Antenna Construction
Pattern Evaluation
Cell Planning Considerations
Down Tilt
Break
Intermodulation Interference
Obstructions
Antenna Concealment
New Concepts
-
8/13/2019 Antenna Concepts Class
3/127
Pioneers of EM Theory & Antennas
Thales (600 BC): Observed sparks when silkrubbed on amber, natural stones attracted
Gilbert (1600 AD), Franklin (1750), Coulomb,
Gauss, Volta (1800), Oersted (1819), Ampere(1820), Ohm, Faraday, Henry (1831), Maxwell
(1873)
-
8/13/2019 Antenna Concepts Class
4/127
The First Antenna
Heinrich Rudolph Hertzs (1886) built firstradio system:
-
8/13/2019 Antenna Concepts Class
5/127
The First Wireless (Radio)
Guglielmo Marconi:
- Repeated Hertzs experiments
- Built first radio system to signal over
large distances: England to Newfoundland
- Proved radio waves bend around earth
- Also applied technology to ships
-
8/13/2019 Antenna Concepts Class
6/127
-
8/13/2019 Antenna Concepts Class
7/127
-
8/13/2019 Antenna Concepts Class
8/127
F0(MHz) (Meters) (Inches)
30 10.0 393.680 3.75 147.6
160 1.87 73.8
280 1.07 42.2
460 0.65 25.7
800 0.38 14.8960 0.31 12.3
1700 0.18 6.95
2000 0.15 5.90
F0
Dipole
-
8/13/2019 Antenna Concepts Class
9/127
-
8/13/2019 Antenna Concepts Class
10/127
-
8/13/2019 Antenna Concepts Class
11/127
-
8/13/2019 Antenna Concepts Class
12/127
Understanding the Mysterious dB
A dB is 1/10thof a Bel (Named after Alexander Graham Bell)
A dB is measured on a logarithmic scale
A dB or Decibel originally comes from quantifying signal strengths in terms
of relative loudness as registered by the human ear
dB in the RF world is the difference between two signal strengths
Blahblahblah bl ah
-
8/13/2019 Antenna Concepts Class
13/127
A single dipoleradiates with a
doughnut pattern
An isotropic radiatorradiates equally in
ALL directions
The gain of an antenna comparedto a dipole is in dBd
The gain of an antenna comparedto an isotropic radiator is in dBi
eg: 3dBd = 5.17dBi
dBd and dBi
2.17dB
The dipole is 2.17dB higher in gain
-
8/13/2019 Antenna Concepts Class
14/127
dBm Absolute signal strength relative to 1 milliwatt
1 mWatt = 0 dBm
1 Watt = +30 dBm
10 Watts = +40 dBm
20 Watts = +43 dBm
dBc Signal strength relative to a signal of known strength, in
this case: the carrier signal
dBm and dBc
Note: The
Logarithmic Scale
10 x log10(Power Ratio)
How and why is dBc used with base station antenna specs?
Pay attentionGroup quiz later!
-
8/13/2019 Antenna Concepts Class
15/127
Basic Antenna System
Antenna
Jumper Cable
Feeder Cable
Surge Arrestor
Jumper Cable
Radio
-
8/13/2019 Antenna Concepts Class
16/127
Full System Sweep
Antenna
Jumper Cable
Feeder Cable
Surge Arrestor
Jumper Cable
Radio
3 different tests
Return Loss
VSWR Distance to Fault (DTF)
-
8/13/2019 Antenna Concepts Class
17/127
Impedance
Examples:
Wireless = 50
Old TV = 300
Cable TV = 75
These 3 tests measure the reflected voltages caused
by change of impedance in a transmission line. Impedance is measured in ohms ().
where Z is defined as impedance and iscomplex
Z = R + j X
R = resistance and X = reactance bothmeasured in ohms
V = I x R
or V = I x Z
-
8/13/2019 Antenna Concepts Class
18/127
Impedance
InnerConductor
Dielectric(Foam)
Outer
Conductor
Cover (Jacket)
dD
History note:
Older CATV coax had air dielectricutilizing plastic discs to support thecenter conductor.
-
8/13/2019 Antenna Concepts Class
19/127
Antenna
50 ohms
Source
=
50 ohms
Cable=
50 ohms
Match!
Impedance
-
8/13/2019 Antenna Concepts Class
20/127
Return Loss
A typical system alwayshas some nominal
impedance mismatch.Here the Return Loss is10 log (0.08 / 10) = -21dB
Inc
iden
t:
10W
Re
flec
ted:
0.08W
50
51
PASS!
Transmitted: 9.92W
-
8/13/2019 Antenna Concepts Class
21/127
-
8/13/2019 Antenna Concepts Class
22/127
Antenna
50 ohms
System Failures
Source
=
50 ohms
Cable
=50 ohms
-
8/13/2019 Antenna Concepts Class
23/127
Antenna
50 ohms
System Failures
When an impedance mismatch occurs in an RF subsystem, an amount
of RF energy is reflected back to the source.
95 ohms
Source
=
50 ohms
Mismatch!
Smashed!
-
8/13/2019 Antenna Concepts Class
24/127
When something is wrong, much more energy
will reflect causing performance failures.Here
the Return Loss is10 log (4.1 / 10) =-3.87dB
50
95
FAIL!
Inc
iden
t:
10W
Re
flec
ted:4.1
W
System Failures
Transmitted: 5.9W
-
8/13/2019 Antenna Concepts Class
25/127
System Failures
-
8/13/2019 Antenna Concepts Class
26/127
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.
C) 122 to 127ft-lbs
A
Mini Group Quiz!
RF components have some reflection but damaged components will cause largerreflections and in that case creates a system to fail.
Positive Stop Connector
- up to 70 ft-lbs
-
8/13/2019 Antenna Concepts Class
27/127
VSWR
Voltage Standing Wave Ratio (VSWR) is
related to Return Loss. The difference is that
VSWR is read as a ratio instead of in dB.
Here the VSWR is
VSWR = (1+(10^21/20)) / (1-(10^21/20))
Or
-21dB RL = 1.195:1 VSWR
50
51
PASS!
Inc
iden
t:
10W
Re
flec
ted:
0.0
8W
Transmitted: 9.92W
-
8/13/2019 Antenna Concepts Class
28/127
VSWR
-
8/13/2019 Antenna Concepts Class
29/127
VSWR
Here the VSWR is
VSWR = (1+(10^3.8/20)) / (1-(10^3.8/20))
or-3.84 dB RL = 4.60:1 VSWR
50
95
FAIL!
Inc
iden
t:
10W
Re
flec
ted:4.1
W
Transmitted: 5.9W
-
8/13/2019 Antenna Concepts Class
30/127
VSWR
-
8/13/2019 Antenna Concepts Class
31/127
DTF
Trave
ltime(m
s)
Trave
ltime
(ms
)Fault
These tests work best when
used as a references.
Test results may be swayed
by variables such as vector
addition and subtraction of
phase, interfering signals
and cable lengths.
Consider matching current
test results to previously
recorded tests and look for
changes.
-
8/13/2019 Antenna Concepts Class
32/127
DTF
-
8/13/2019 Antenna Concepts Class
33/127
Effect of VSWR
VSWRReturn
Loss (dB)
Transmission
Loss (dB)
Power
Reflected (%)
Power
Trans. (%)
1.00
1.10
1.20
1.30
1.40
1.50
2.00
-
-26.4
-20.8
-17.7
-15.6
-14.0
-9.5
0.00
0.01
0.04
0.08
0.12
0.18
0.51
0.0
0.2
0.8
1.7
2.8
4.0
11.1
100.0
99.8
99.2
98.3
97.2
96.0
88.9
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!
-
8/13/2019 Antenna Concepts Class
34/127
Source: COMSEARCH
3D View
Antenna Pattern
Sh i A t P tt
-
8/13/2019 Antenna Concepts Class
35/127
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 are stacked vertically, the flatter the beam is and the higher
the antenna coverage or gain in the general direction of the horizon.
-
8/13/2019 Antenna Concepts Class
36/127
Shaping Antenna Patterns (con t . . .)
Stacking 4 dipoles
vertically in line changesthe pattern shape(squashes the doughnut)and increases the gainover single dipole.
The peak of the horizontalor vertical patternmeasures the gain.
The little lobes, illustratedin the lower section, aresecondary minor lobes.
Apertureof Dipoles
VerticalPattern
HorizontalPattern
4 DipolesVertically Stacked
Single Dipole
GENERAL STACKING RULE:
Collinear elements (in-line vertically).
Optimum spacing (for non-electrical tilt) is approximately 0.9.
Doubling the number of elements increases gain by 3 dB, and reducesvertical beamwidth by half.
-
8/13/2019 Antenna Concepts Class
37/127
-
8/13/2019 Antenna Concepts Class
38/127
Gain References (dBd and dBi)
An isotropic antenna isa 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 ormore radiating elements
phased together
0 (dBd) = 2.15 (dBi)
Isotropic (dBi)
Dipole (dBd)
Gain
Isotropic Pattern
3 (dBd) = 5.15 (dBi)
Dipole Pattern
-
8/13/2019 Antenna Concepts Class
39/127
Principles of Antenna GainDirectional Antennas
Top View
0 dBd
3 dBd
6 dBd
9 dBd
-3 dB
180
90
-3 dB
45
-3 dB
Omni AntennaSide View
0 dBd
3 dBd
6 dBd
9 dBd
60
-3 dB
-3 dB
30
-3 dB
7.5
-3 dB
15-3 dB
-
8/13/2019 Antenna Concepts Class
40/127
-
8/13/2019 Antenna Concepts Class
41/127
Gain vs. Length
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
10
15
20
25
G=10 log ( )2.2 pL We2
-
8/13/2019 Antenna Concepts Class
42/127
Gain vs. Beamwidths
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
10
15
20
25
G=10 log ( )29000AzBWEIBW
-
8/13/2019 Antenna Concepts Class
43/127
Antenna Gain
Gain (dBi) = Directivity (dBi)Losses (dB)
Losses: Conductor
Dielectric
ImpedancePolarization
Measure Using Gain by Comparison
-
8/13/2019 Antenna Concepts Class
44/127
Polarization
Electric and magnetic fields are
interdependent => Electromagnetic wave
Time-changing electric field generates
magnetic field, vice versa
An antennas polarization is a characteristic of
the EM wave, i.e. electric fields orientation
If antenna and incoming EM wave are co-polarized => Max response from antenna
-
8/13/2019 Antenna Concepts Class
45/127
BREAK
-
8/13/2019 Antenna Concepts Class
46/127
Various Radiator Designs
Patch 800/900 MHz
Directed Dipole
MAR
Microstrip Annular Ring
Dipole 1800/1900/UMTSDirected Dipole
Diversity (Dual-Pol)Directed Dipole
Elements
-
8/13/2019 Antenna Concepts Class
47/127
Dipoles
Single Dipole Crossed Dipole
-
8/13/2019 Antenna Concepts Class
48/127
Feed Harness Construction
Series Feed Center Feed(Hybrid)
CorporateFeed
-
8/13/2019 Antenna Concepts Class
49/127
Feed Harness Construction (cont . . .)
Advantages:
Disadvantages:
Center Feed
(Hybrid)
Frequency
independent main
lobe direction
Reasonably
simple feed
system
Not as versatile as
corporate (less
bandwidth, less
beam shaping)
Corporate Feed
Frequency
independent main
beam direction
More beam
shaping ability,
side lobe
suppression
Complex feed
system
Series Feed
Minimal feed losses
Simple feed system
BEAMTILT
450 455 460 465 470 MHz+2
+1
0
+1
+2
ASP-705
-
8/13/2019 Antenna Concepts Class
50/127
-
8/13/2019 Antenna Concepts Class
51/127
Microstrip 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)
-
8/13/2019 Antenna Concepts Class
52/127
Air Microstrip Network
-
8/13/2019 Antenna Concepts Class
53/127
Dielectric Substrate Microstrip
S ki Di l
-
8/13/2019 Antenna Concepts Class
54/127
Stacking Dipoles
4 Dipoles
8 Dipoles
1 Dipole
2 Dipoles
-
8/13/2019 Antenna Concepts Class
55/127
Azimuth Omni AntennaVertical Pattern
-
8/13/2019 Antenna Concepts Class
56/127
Directional Array AntennaPattern Simulation
-
8/13/2019 Antenna Concepts Class
57/127
Main Lobe
What is it?
The main lobe is the radiation patternlobe that contains the majority portion of
radiated energy.
Why is it useful?
Shaping of the pattern allows the
contained coverage necessary forinterference-limited system designs.
How is it measured?
The main lobe is characterized using a
number of the measurements which will
follow.
35 TotalMain Lobe
Half-Power Beamwidth
-
8/13/2019 Antenna Concepts Class
58/127
Half-Power BeamwidthHorizontal and Vertical
What is it?
The angular span between the half-power(-3 dB) points measured on the cut of the
antennas main lobe radiation pattern.
Why is it useful?
It allows system designers to
choose the optimum characteristicsfor coverage vs. interference
requirements.
How is it measured?
It is measured using data collected from
antenna range testing.
1/2 Power
Beamwidth
What is T-Mobile standard?
Most applications require 65 degrees in
azimuth, ~5 degrees in elevation.
-
8/13/2019 Antenna Concepts Class
59/127
Front-To-Back Ratio
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?
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 T-Mobile standard?
30 dB throughout the region that is +/- 45 degrees directly back of the
main lobe.
F/B Ratio
0 dB - 25 dB = 25 dB
-
8/13/2019 Antenna Concepts Class
60/127
Sidelobe Level
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 lobeenergy to be tailored to the
antennas 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.
Sidelobe Level
(-20 dB)
-
8/13/2019 Antenna Concepts Class
61/127
N ll Fill
-
8/13/2019 Antenna Concepts Class
62/127
Null Fill
Important for antennas with narrow elevation beamwidths.
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)
Rece
ivedLevel(dBm)
Transmit Power = 1 W
Base Station Antenna Height = 40 m
Base Station Antenna Gain = 18 dBi
Elevation Beamwidth = 6.5
U Sid l b S i
-
8/13/2019 Antenna Concepts Class
63/127
Upper Sidelobe Suppression
What is it?
Upper sidelobe suppression (USLS) is an array
optimization technique that reduces theundesirable 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 T-Mobile standard?
Upper side lobes must be at least18 dB from the main lobe through
zenith.
-
8/13/2019 Antenna Concepts Class
64/127
C P l R ti (CPR)
-
8/13/2019 Antenna Concepts Class
65/127
Cross-Pol Ratio (CPR)
What is it?
CPR is a comparison of the co-pol vs. cross-pol
pattern performance of a dual-polarizedantenna 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 dual-pol array to
distinguish between orthogonal EM 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.
What is T-Mobile standard?
16 dB minimum for azimuth pattern.
-40
-35
-30
-25
-20
-15
-10
-5
0
120
TYPICAL
-40
-35
-30
-25
-20
-15
-10
-5
0
120
LOG
Co-Polarization
Cross-Polarization
(Source @ 90)
H i t l B T ki
-
8/13/2019 Antenna Concepts Class
66/127
Horizontal Beam Tracking
What is T-Mobile standard?
The beams shall track within 1 dB over the 3
dB horizontal beamwidth.
What is it?
It refers to the beam tracking between the two
beams of a +/-45 polarization diversity antennaover 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.
120
+45-45Array Array
B S i t
-
8/13/2019 Antenna Concepts Class
67/127
Beam Squint
What 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 polarizationdiversity 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 T-Mobile 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
10% of the 3 dB beamwidth.
-3 dB +3 dB
Squint/2
HorizontalBoresite
S t P R ti (SPR)
-
8/13/2019 Antenna Concepts Class
68/127
Sector Power Ratio (SPR)
What is it?
SPR is a ratio expressed in percentage of the
power outside the desired sector to the powerinside the desired sector created by an
antennas 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 T-Mobile standard?
(Being studied.)PUndesired
SPR (%) = X 100
PDesired
300
60
60
300
120
DESIRED
UNDESIRED
-
8/13/2019 Antenna Concepts Class
69/127
Percentageof
capacityloss
overlapping angle in degree
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 Capacity
By: Chin-Chun Lee et, al IEEE
TRANSACTIONS ON VEHICULAR
TECHNOLOGY, VOL. 47, NO. 3,
AUGUST 1998
120 Sector Overlay Issues
Qualitatively, excessive overlay also
reduces capacity of TDMA and GSM
systems.
The Impact:
-
8/13/2019 Antenna Concepts Class
70/127
The Impact:Lower Co-Channel Interference/Better Capacity & Quality
The rapid roll-off of the lower lobes of
the log periodic antennas create larger,
better defined conesof silence behind the array.
Much smaller softer hand-off area
Dramatic call quality improvement
5% - 10 % capacity enhancement
Log Per iodics (Example)
In a three sector site, traditional
antennas produce a high degree ofimperfect power control or sector
overlap.
Imperfect sectorization presents
opportunities for:
Increased softer hand-offs
Interfering signals Dropped calls
Reduced capacity
Tradit ional Flat Panels
65 90
65 90
-
8/13/2019 Antenna Concepts Class
71/127
Key antenna parameters to examine closely
Antenna-Based System Improvements
Roll off
at -/+ 60
-10 dB
points
HorizontalAnt/AntIsolation
-16dB -12dB
-7dB -6dB
120Cone of Silence with >40dB
Front-to-Back Ratio
60Area of Poor Silence with>27dB Front-to-Back Ratio
Standard 85 Panel AntennaLog Periodic
74 83
74 83
Next Sector
Ant/AntIsolation
-35dB -18dB
Coneof Silence
Dipole vs LP Element
-
8/13/2019 Antenna Concepts Class
72/127
Dipole vs. LP Element
Azimuth Pattern Comparison:
1850 MHz, 2-Deg EDT
-50
-40
-30
-20
-10
0
-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180
Azimuth Angle (Degrees)
Amplitude(d
B)
System Issues
-
8/13/2019 Antenna Concepts Class
73/127
System Issues
Choosing sector antennas
Downtiltelectrical vs. mechanical
RET optimization
Passive intermodulation (PIM)
Return loss through coax
Pattern distortion, alignment, orientation
Antenna isolation
-
8/13/2019 Antenna Concepts Class
74/127
Choosing Sector Antennas
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.
-
8/13/2019 Antenna Concepts Class
75/127
3 x 90 Antennas
-
8/13/2019 Antenna Concepts Class
76/127
3 x 90 Antennas
5 dB
4390
HorizontalOverlayPattern
3 x 65 Antennas
-
8/13/2019 Antenna Concepts Class
77/127
3 x 65 Antennas
24
6 dB
65
HorizontalOverlayPattern
-
8/13/2019 Antenna Concepts Class
78/127
Beam Downtilt
In urban areas, service and frequency utilization are
frequently improved by directing maximum radiation power at
an area below the horizon.
ThisTechnique:
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.
-
8/13/2019 Antenna Concepts Class
79/127
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!
-
8/13/2019 Antenna Concepts Class
80/127
Electrical/Mechanical Downtilt
Mechanical Electrical
-
8/13/2019 Antenna Concepts Class
81/127
Mechanical Downtilt Mounting Kit
-
8/13/2019 Antenna Concepts Class
82/127
Mechanical Downtilt
Pattern Analogy: Rotating a Disk
Mechanical Tilt Causes:
Beam Peak to Tilt Below Horizon
Back Lobe to Tilt Above Horizon
At 90 No Tilt
-
8/13/2019 Antenna Concepts Class
83/127
Mechanical Downtilt Coverage
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
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
80 1064Mechanical Tilt
Elevation Pattern Azimuth Pattern
Sample Antenna
-
8/13/2019 Antenna Concepts Class
84/127
0 Mechanical Downtilt
85
Sample Antenna
-
8/13/2019 Antenna Concepts Class
85/127
7 Mechanical Downtilt
93
Sample Antenna
-
8/13/2019 Antenna Concepts Class
86/127
15 Mechanical Downtilt
123
Sample Antenna
-
8/13/2019 Antenna Concepts Class
87/127
20 Mechanical Downtilt
Horizontal
3 dB Bandwidth
Undefined
Managing Beam Tilt
-
8/13/2019 Antenna Concepts Class
88/127
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 ofphase 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 and their physical spacing.
GENERATINGElectrical BEAMTILT
Dipoles Fed w/ Uniform Phase Dipoles Fed w/ Sequential Phase
ExciterPhase
Energy
in
Exciter
El t i l D tilt
-
8/13/2019 Antenna Concepts Class
89/127
Electrical Downtilt
Pattern Analogy: Forming a Cone Out of a Disk
Electrical Tilt Causes:
Beam Peak to Tilt Below Horizon
Back Lobe to Tilt Below Horizon
All portions of the Pattern Tilts
Cone of the Beam Peak Pattern
El t i l D tilt C
-
8/13/2019 Antenna Concepts Class
90/127
Electrical Downtilt Coverage
0
10
20
30
40
5060
708090100
110
120130
140
150
160
170
180
190
200
210
220
230
240
250 260 270 280 290
300
310
320
330
340
350
80 1064Electrical Tilt
0
10
20
30
40
5060
708090100
110
120130
140
150
160
170
180
190
200
210
220
230
240
250 260 270 280 290
300
310
320
330
340
350
Elevation Pattern Azimuth Pattern
M h i l El t i l D tilt
-
8/13/2019 Antenna Concepts Class
91/127
Mechanical vs. Electrical Downtilt
With Variable Electrical Downtilt (VED)
-
8/13/2019 Antenna Concepts Class
92/127
With Variable Electrical Downtilt (VED),
you can adjust anywhere in seconds.
Sample Antenna3 El t i l D tilt
-
8/13/2019 Antenna Concepts Class
93/127
3 Electrical Downtilt
Sample Antenna8 El i l D il
-
8/13/2019 Antenna Concepts Class
94/127
8 Electrical Downtilt
Sample AntennaO l El i l D il
-
8/13/2019 Antenna Concepts Class
95/127
Overlay Electrical Downtilt
3
6
8
Remote Electrical Downtilt (RET)O ti i ti
-
8/13/2019 Antenna Concepts Class
96/127
Optimization
ANMS
Future
ATC100 Series
ATC200 Series
-
8/13/2019 Antenna Concepts Class
97/127
BREAK
Causes of Inter Modulation Distortion
-
8/13/2019 Antenna Concepts Class
98/127
Causes of Inter-Modulation Distortion
Ferromagnetic materials in the current path:
Steel
Nickel Plating or Underplating
Current Disruption:
Loosely Contacting Surfaces
Non-Conductive Oxide Layers Between Contact
Surfaces
Intermod InterferenceWhere?
-
8/13/2019 Antenna Concepts Class
99/127
Where?
F1
TxF1
Tx
F2
RxF3
RECEIVER-PRODUCED
F3
TxF1
Tx
F2
RxF3
TRANSMITTER-PRODUCED
F2
F1
Rx3
ANTENNA-PRODUCED
DUP
F2
Tx1
Tx2
CO
M
B
F3
Rx
F3
ELSEWHERE
Tx1
Tx2
Remember dBc?
-
8/13/2019 Antenna Concepts Class
100/127
IMDInter-Modulation Distortion
PIMPassive Inter-Modulation
dBc with antennas work like this
- 2 tones @ 20Watts = 43dBm
- Scan for 3rdorder of those 2 carriers
- If 3rdorder = -110dBm then that = -153dBc
110dBm + 43dBm = 153dBc
PCS A-BandProduct Frequencies Two-Signal IM
-
8/13/2019 Antenna Concepts Class
101/127
Product Frequencies, Two-Signal IMFIM= nF1 mF2
Example: F1= 1945 MHz; F2= 1930 MHz
1 1 Second 1F1+ 1F2 3875
1F11F2 15
2 1 Third 2F1+ 1F2 5820
*2F11F2 19601 2 Third 2F2+ 1F1 5805
*2F21F1 1915
2 2 Fourth 2F1+ 2F2 7750
2F12F2 30
3 2 Fifth 3F1+ 2F2 9695*3F12F2 1975
2 3 Fifth 3F2+ 2F1 9680
*3F22F1 1900
Product Product Productn m Order Formulae Frequencies (MHz)
*Odd-order difference products fall in-band.
Two-Signal IMOdd-Order Difference Products
-
8/13/2019 Antenna Concepts Class
102/127
Odd-Order Difference Products
Example: F1= 1945 MHz; F2= 1930 MHz
F = F1- F2= 15
Third Order: F1+ F; F2-F
Fifth Order: F1+ 2F; F2- 2F
Seventh Order:: F1+ 3F; F2- 3F
Higher than the highest lower than the lowestnone in-between
F
5th
F22F
3F22F1
1900
F2
F2
1930
F1
F1
1945
3rd
2F1F2
1960
F1+ F
5th
F1+ 2F
3F12F2
1975
3rd
2F
2F2F1
1915
F2F
2F
F F
PCS Duplexed IM
-
8/13/2019 Antenna Concepts Class
103/127
Own Rx Any Rx
Tx Rx Band Band IM Equations
Band Frequency Frequency IM Order IM Order Own Rx Band Any Rx Band
A 1930-1945 1850-1865 11th 5th =6*Tx(low)-5*Tx(high)=1855 =3*Tx(low)-2*Tx(high)=1900
B 1950-1965 1870-1885 11th 7th =6*Tx(low)-5*Tx(high)=1875 =4*Tx(low)-3*Tx(high)=1905
C 1975-1990 1895-1910 11th 11th =6*Tx(low)-5*Tx(high)=1900 =6*Tx(low)-5*Tx(high)=1900
A Band IM
-
8/13/2019 Antenna Concepts Class
104/127
11th1855
9th1870
7th1885
5th1900
3rd1915 1930 1945
Channel Bandwidth
Block (MHz) Frequencies
C 30 1895-1910, 1975-1990
C1 15 1902.5-1910, 1982.5-1990
C2 15 1895-1902-5, 1975-1982.5
C3 10 1895-1900, 1975-1980
C4 10 1900-1905, 1980-1985
C5 10 1905-1910, 1985-1990
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 Plan
A and F Band IM
-
8/13/2019 Antenna Concepts Class
105/127
3rd1895 1935 1975
Channel Bandwidth
Block (MHz) Frequencies
C 30 1895-1910, 1975-1990
C1 15 1902.5-1910, 1982.5-1990
C2 15 1895-1902-5, 1975-1982.5
C3 10 1895-1900, 1975-1980
C4 10 1900-1905, 1980-1985
C5 10 1905-1910, 1985-1990
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 Plan
System VSWR Calculator
-
8/13/2019 Antenna Concepts Class
106/127
Frequency (MHz): 895.00
System
Component
Max.
VSWR
Return
Loss (dB)Cable Type
Cable
Length (m)
Cable
Length (ft)
Insertion
Loss (dB)
Reflections
at input
Antenna 1.33 16.98 0.0983
Top 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 0.0484
Surge Suppressor 1.07 29.42 0.20 0.0329
Bottom Jumper 1.07 29.42 2 1.83 6.00 0.13 0.0338
1.59
Jumper Cable Types: 0.1216
FSJ4-50B 1.28
LDF4-50A 18.3
Main Feedline Cable Types: 0.2372
LDF5-50A 1.62
LDF6-50 12.5
LDF7-50A
VXL5-50
VXL6-50 1.59
VXL7-50
Return Loss (dB) VSWR feet meters
28.00 1.0829 4.00 1.22
Estimated System Reflection:
Estimated System VSWR:
Estimated System Return Loss (dB):
Return Loss to VSWR converter Feet to meters converter
Maximum System Reflection:
Maximum System VSWR:
Maximum System Return Loss (dB):
Total Insertion Loss (dB):
LDF4-50A
LDF5-50A
LDF4-50A
Antenna Pattern Distortions
-
8/13/2019 Antenna Concepts Class
107/127
Antenna Pattern Distortions
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.
105 Horizontal PatternNo Obstacle
-
8/13/2019 Antenna Concepts Class
108/127
No Obstacle
Antenna
880 MHz300
105330
270
240
210
180
150
120
60
30
0
90
-5
0
+5
+10
+15
-10
105 Horizontal PatternObstruction at -10 dB Point
-
8/13/2019 Antenna Concepts Class
109/127
Obstruction at -10 dB Point
330
300
270
240
210
180
150
120
90
60
30
0
Antenna
880 MHz
0
-10 dB Point
Building
Corner
105 Horizontal PatternObstruction at -6 dB Point
-
8/13/2019 Antenna Concepts Class
110/127
Obstruction at -6 dB Point
330
300
270
240
210
180
150
120
90
60
30
0
880 MHz
Antenna
0 -6 dB Point
Building
Corner
-
8/13/2019 Antenna Concepts Class
111/127
90 Horizontal PatternNo Obstacle
-
8/13/2019 Antenna Concepts Class
112/127
No Obstacle
Antenna
880 MHz
330
300
270
240
210
180
150
120
90
60
30
0
-5
0
+5
+10
+15
-10
90 Horizontal Pattern0.5 l Diameter Obstacle at 0
-
8/13/2019 Antenna Concepts Class
113/127
0.5 l Diameter Obstacle at 0
330
300
270
240
210
180
150
120
90
60
30
0
880 MHz
Antenna
0
12
90 Horizontal Pattern0.5 l Diameter Obstacle at 45
-
8/13/2019 Antenna Concepts Class
114/127
0.5 l Diameter Obstacle at 45
330
300
270
240
210
180
150
120
90
60
30
0
880 MHz
Antenna
845
90 Horizontal Pattern0.5 l Diameter Obstacle at 60
-
8/13/2019 Antenna Concepts Class
115/127
0.5 l Diameter Obstacle at 60
330
300
270
240
210
180
150
120
60
30
0
90
880 MHz
Antenna
660
90 Horizontal Pattern0.5 l Diameter Obstacle at 80
-
8/13/2019 Antenna Concepts Class
116/127
0.5 l Diameter Obstacle at 80
330
300
270
240
210
180
150
120
60
30
0
90
880 MHz
Antenna
80
General Rule
A h d b f f b i ( 0 W )
-
8/13/2019 Antenna Concepts Class
117/127
Area that needs to be free of obstructions (> 0.57 WL)
Antenna90 horizontal (3 dB) beamwidth
Maximum Gain
3 dB Point(45)
6 dB Point(60)
10 dB Point
(80 - 90)
> 12 WL
> 3 WLWL
Attenuation Provided By Vertical
S ti f Di l A t
-
8/13/2019 Antenna Concepts Class
118/127
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.
IsolationindB
Separation of Dipole Antennas
Attenuation Provided By Horizontal
S ti f Di l A t
-
8/13/2019 Antenna Concepts Class
119/127
Separation of Dipole Antennas
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).
IsolationindB
Pattern Distortions
-
8/13/2019 Antenna Concepts Class
120/127
tan =
d = D *tan
tan 1 = 0.01745
Note: tan 10 = 0.1763 10 *0.01745 = 0.1745
dD
a
Antenna Elevation Pattern
-
8/13/2019 Antenna Concepts Class
121/127
Base Station Antenna w/ 4 Deg EDT
-50
-40
-30
-20
-10
0
-180 -150 -120 -90 -60 -30 0 30 60 90 120 150 180
Elevation Angle (Degree)
Amplitud
e(dB)
Gain Points of a Typical Main Lobe(Relative to Maximum Gain)
-
8/13/2019 Antenna Concepts Class
122/127
( )
-3dB point below bore sight.
-6dB point 1.35 * below bore sight.
-10 dB point 1.7 * below bore sight.
Vertical
BeamWidth= 2
(-3dB point)
-
8/13/2019 Antenna Concepts Class
123/127
-
8/13/2019 Antenna Concepts Class
124/127
Performance of Sample PCS AntennaBehind Camouflage (" Fiberglass)
-
8/13/2019 Antenna Concepts Class
125/127
1.2
1.3
1.4
1.5
1.6
1.7
10 2 3 4 5 6 7 8 9 10 11 12
Distance of Camouflage (Inches) (Dim. A)
VSWR(W
orstCase)
W/Plain Facade W/Ribbed Facade Without Facade
FIBERGLASS
PANEL
DIM A
CellSiteAnt.
1/4 1/2 1 21-1/2
330 30
0 90
330 30
0
102
-
8/13/2019 Antenna Concepts Class
126/127
Distance
FromFiberglass
No Fiberglass
300
270
240
210
180
150
120
60
90
-20
-25
-30
-35
-40
-45
-50
-55
330
300
270
240
210
180
150
120
60
30
0 68
90
-20
-25
-30
-35
-40
-45
-50
-15
1.5" to Fiberglass
3" to Fiberglass
300
270
240
210
180
150
120
60
90
-25
-30
-35
-40
-45
-50
-55
-20
330 30
0
112
330
30
077
-
8/13/2019 Antenna Concepts Class
127/127
DistanceFrom
Fiberglass
6" to Fiberglass
300
270
240
210
180
150
120
60
-20
-25
-30
-35
-40
-45
-50
-15
90
4" to Fiberglass
300
270
240
210
180
150
120
60
90
-20
-25
-30
-35
-40
-45
-50
-15
330
300
270
240
210
180
150
120
60
30
0 108
90
-20
-25
-30
-35
-40
-45
-50
-15
top related