Antenna Theory Andrew

Antenna Theory Basic Principles For Daily Applications

Base Station Antenna Systems March 2009

PRIVATE AND CONFIDENTIAL © CommScope

1

Base Station Antenna Technology Evolution Antenna Core Technology Omni Vertical Directional Polarization

Air Interfaces

Dominate Application

DualPol® MIMO

DualPol® Dual Band RET Capacity Improvement Interference Reduction with Frequency MIMO MIMO

Significant Application

Digital Beam Former SDMA Capacity

SmartBeam® Capacity” Load Balance MIMO

Low Application

AMPS GSM CDMA W-CDMA WiMAX TD-SCDMA LTE


2

Dipole

¼λ

F0

¼λ

F0 (MHz)

λ (Meters)

λ (Inches)

30

10.0

393.6

80

3.75

147.6

160

1.87

73.8

280

1.07

42.2

460

0.65

25.7

800

0.38

14.8

960

0.31

12.3

1700

0.18

6.95

2000

0.15

5.9


3

3D View Antenna Pattern

Source: COMSEARCH PRIVATE AND CONFIDENTIAL © CommScope

4

Understanding The Mysterious “dB” dBd

Signal strength relative to a dipole in empty space

dBi

Signal strength relative to an isotropic radiator

dB

Difference between two signal strengths

dBm

Absolute signal strength relative to 1 milliwatt 1 mWatt = 0 dBm Note: The 1 Watt = 30 dBm Logarithmic Scale 20 Watts = 43 dBm 10 * log10 (Power Ratio)

dBc

Signal strength relative to a signal of known strength, in this case: the carrier signal Example: –150 dBc = 150 dB below carrier signal If two carriers are 20 Watt each = 43 dBm –150 dBc = –107 dBm or ~0.02 pWatt or ~1 microvolt


5

Effect Of VSWR Good VSWR is only one component of an efficient antenna. VSWR

Return Loss (dB)

Transmission Loss (dB)

Power Power Reflected (%) Trans. (%)

1.00

∞

0.00

0.0

100.0

1.10

26.4

0.01

0.2

99.8

1.20

20.8

0.04

0.8

99.2

1.30

17.7

0.08

1.7

98.3

1.40

15.6

0.12

2.8

97.2

1.50

14.0

0.18

4.0

96.0

2.00

9.5

0.51

11.1

88.9


6

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.


7

Shaping Antenna Patterns (Continued) Aperture of Dipoles

Vertical Pattern

Single Dipole

Horizontal Pattern

• 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 4 Dipoles Vertically Stacked

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. PRIVATE AND CONFIDENTIAL © CommScope

8

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.


9

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 one radiating element (physically possible).

•

A gain antenna is two or more radiating elements phased together.

Isotropic Pattern Dipole Pattern

Isotropic (dBi) Dipole (dBd) Gain dBi dBd

3 (dBd) = 5.14 (dBi) 0 (dBd) = 2.14 (dBi)


10

Principles Of Antenna Gain Omni Antenna, Side View

Directional Antennas, Top View

-3 dB

0 dBd

0 dBd

60° -3 dB

+3 dBd

+3 dBd

30°

180° -3 dB

-3 dB

+6 dBd

+6 dBd

15°

90°

-3 dB -3 dB

7.5°

+9 dBd

+9 dBd

45°

-3 dB -3 dB


11

Theoretical Gain Of Antennas (dBd) 3 dB Horizontal Aperture (Influenced by Grounded Back “Plate”)

# of Radiators Vertically Spaced (0.9λ)

360° 180° 120° 105°

Typical Length of Antenna (ft.)

90°

60°

45°

33°

800/900 MHz PCS

DCS Vertical 1800/1900 Beamwidth

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°

3

4.5

7.5

8.5

9.5

15.1

3

1.5

20°

4

6

9

10

11

16.6

4

2

15°

6

7.5

10.5

11.5

18.1

6

3

10°

8

9

12

13

19.6

8

4

7.5°

10.5 12.5 13.5 12

14

15

12.5 13.5 15.5 16.5 14

15

17

18

Could be horizontal radiator pairs for narrow horizontal apertures.


12

Antenna Gain

•

Gain (dBi) = Directivity (dBi) – Losses (dB)

•

Losses:

•

Measure using ‘Gain by Comparison’

Conductor Dielectric Impedance Polarization


13

Antenna Polarization

•

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 PRIVATE AND CONFIDENTIAL © CommScope

14

Various Radiator Designs Elements

Dipole

1800/1900/UMTS Directed Dipole™

DualPol® (XPol) Directed Dipole™

Patch

800/900 MHz Directed Dipole™

MAR Microstrip Annular Ring


15

Dipoles

Single Dipole

Crossed Dipole


16

Feed Harness Construction ASP705

ASP705K

LBX-6513DS

Center Feed (Hybrid)

Corporate Feed

(Old Style)

Series Feed


17

Feed Harness Construction (Continued) Center Feed (Hybrid)

Series Feed Advantages

• Minimum feed losses • Simple feed system

• Frequency •

Disadvantages

• Not as versatile as

BEAMTILT

+2° +1° 0° +1° +2°

ASP-705 450

455

460

independent main lobe direction Reasonably simple feed system

465

470 MHz

corporate (less bandwidth, less beam shaping)

Corporate Feed • Frequency independent main beam direction • More beam shaping ability, sidelobe suppression

• Complex feed system


18

Feed Networks

•

Coaxial cable – Best isolation – Constant impedance – Constant phase

•

Microstripline, corporate feeds – Dielectric substrate – Air substrate


19

Microstrip Feed Lines

•

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)


20

Air Microstrip Network


21

LBX-3316-VTM Using Hybrid Cable/Air Stripline


22

LBX-3319-VTM Using Hybrid Cable/Air Stripline


23

DB812 Omni Antenna Vertical Pattern


24

932DG65T2E-M Pattern Simulation


25

Key Antenna Pattern Objectives 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


26

Main Lobe What is it? The main lobe is the radiation pattern lobe that contains the majority portion of radiated energy.

35° 35° Total Total Main Main Lobe Lobe

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.


27

Half-Power Beamwidth Horizontal And Vertical 1/2 1/2 Power Power Beamwidth Beamwidth

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.

30

30

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.



28

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. 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!


What is Andrew standard?

F/B F/B Ratio Ratio @ @ 180 180 degrees degrees 00 dB dB –– 25 25 dB dB == 25 25 dB dB

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. PRIVATE AND CONFIDENTIAL © CommScope

29

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 Sidelobe Level Level (–20 (–20 dB) dB)

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. PRIVATE AND CONFIDENTIAL © CommScope

30

Null Filling What is it? Null filling is an array optimization technique that reduces the null between the lower lobes in the elevation plane.

Why is it useful? For arrays with a narrow vertical beamwidth (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 peak of 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! PRIVATE AND CONFIDENTIAL © CommScope

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Null Filling Important For Antennas With Narrow Elevation Beamwidths

Received Level (dBm)

Null Filled to 16 dB Below Peak 0

Transmit Power = 1 W

-20

Base Station Antenna Height = 40 m

-40

Base Station Antenna Gain = 16 dBd

-60

Elevation Beamwidth = 6.5°

-80 -100 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Distance (km)


32

Upper Sidelobe Suppression What is it?

First Upper Sidelobe Suppression

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. PRIVATE AND CONFIDENTIAL © CommScope

33

Orthogonality What is it?

δ

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).


Decorrelation between the Green and Blue Lines δ = 0°, XPol = –∞ dB δ = 5°, XPol = –21 dB δ =10°, XPol = –15 dB δ =15°, XPol = –11 dB δ =20°, XPol = –9 dB δ =45°, XPol = –3 dB δ = 50°, XPol = –2.3 dB δ =60°, XPol = –1.2 dB δ =70°, XPol = –0.54 dB δ =80°, XPol = –0.13 dB δ =90°, XPol = 0 dB XPol = 20 log ( sin (δ)) PRIVATE AND CONFIDENTIAL © CommScope

34

Cross-Pol Ratio (CPR) 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.

120° 0 -5 -10 -15 -20 -25 -30 -35

Typical

-40

Co-Polarization

120°

Cross-Polarization (Source @ 90°)

0 -5 -10 -15 -20 -25 -30 -35 -40

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. PRIVATE AND CONFIDENTIAL © CommScope

35

Horizontal Beam Tracking What is it? It refers to the beam tracking between the two beams of a +/–45° polarization diversity antenna over a specified angular range.

120° 120°

Why is it useful? For optimum diversity performance, the beams should track as closely as possible.

–45° Array

+45° Array

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 Andrew standard? The Andrew beam tracking standard is +/–1 dB over the 3 dB horizontal beamwidth.


36

Beam Squint Horizontal Boresite

What is it? The amount of pointing error of a given beam referenced to mechanical boresite.

Why is it useful?

Squint Squint –3 dB

θ/2 θ

+3 dB

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.


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. PRIVATE AND CONFIDENTIAL © CommScope

37

Sector Power Ratio (SPR) 120° 120° 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? 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? Desired

It is mathematically derived from the measured range data.

Σ P

What is Andrew standard? Andrew Directed Dipole™ style antennas have SPR’s typically less than 2 percent.

Undesired

300

SPR (%) =

60 60

Undesired

X 100

Σ P

300

Desired


38

Antenna–Based System Improvements Key Antenna Parameters To Examine Closely 932LG Directed Dipole™

Standard 85° Panel Antenna –7 dB

74° 74°

–16 dB

–35 dB

120° Cone of Great Silence with >40 dB Front-to-Back Ratio

Roll off at -/+ 60° -10 dB points Horizontal Ant/Ant Isolation Next Sector Ant/Ant Isolation Cone of Silence

–6 dB

83° 83°

–12 dB

–18 dB

60° Area of Poor Silence with >27 dB Front-to-Back Ratio PRIVATE AND CONFIDENTIAL © CommScope

39

Key Antenna Pattern Objectives n rba al an u b b r r U Su Ru

Azimuth Beam

•

Beam tracking vs. frequency

• • • •

1

1

1

Squint

1

1

1

Roll-off past the 3 dB points

1

2

3

Front-to-back ratio

1

1

2

Cross-pol beam tracking

1

1

1

Beam tracking vs. frequency

1

2

3

Ratings:

Upper sidelobe suppression

1

2

3

1 = Always important

Lower null fill

3

3

2

2 = Sometimes important

Cross-pol beam tracking

2

2

3

3 = Seldom important

Limited to sub-bands on broadband models

Elevation Beam

• • • •


40

Key Antenna Pattern Objectives (Continued) n rba al an u b b r r U Su Ru

Downtilt

• • • •

Electrical vs. mechanical tilt

1

1

3

Absolute tilt

2

2

3

Electrical tilt vs. frequency

1

2

3

Effective gain on the horizon

1

2

3

2

1

1

Gain

•

Close to the theoretical value (directivity minus losses)

Note: Pattern shaping reduces gain.

Ratings: 1 = Always important 2 = Sometimes important 3 = Seldom important


41

Advanced Antenna Technology Adaptive Array (AA)

• •

Planar array

•

External digital signal processing (DSP) controls the antenna pattern

4, 6, and 8 column vertical pol designs for WiMAX and TD-SCDMA*

•

Often calibration ports are used

• • •

A unique beam tracks each mobile Adaptive nulling of interfering signals Increased signal to interference ratio performance benefits

* Time Division Spatial Code Division Multiple Access


42

Advanced Antenna Technology MIMO Systems

2 x 2 MIMO Spatial Multiplexing

•

Multiple Input Multiple Output (MIMO)

•

A DualPol® RET for 2x2 MIMO, two separated for 4x4 MIMO

•

External DSP extracts signal from interference

•

Spatial multiplexing works best in a multi-path environment

•

Capacity gains due to multiple antennas

•

Space Time Block Coding is a diversity MIMO mode


43

Advanced Antenna Technology SmartBeam® Antenna Family • 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)


44

Advanced Antenna Technology SmartBeam® 3-Way Model

35°

Azimuth patterns measured at 1710–2180 MHz with no radome.

65°

90°

105°


45

Advanced Antenna Technology SmartBeam® 3-Way Model

35°

Elevation patterns measured at 1710–2180 MHz with no radome.

65°

90°

105°


46

System Issues • 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


47

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 comparisons


48

3 x 120° Antennas 120° Horizontal Overlay Pattern 0 -5 -10

Examples

-15

VPol

-20

Low Band

-25 -30

DB874H120 DB878H120

-35

49°

-40

3 dB PRIVATE AND CONFIDENTIAL © CommScope

49

3 x 90° Antennas 90° Horizontal Overlay Pattern 0

Examples

-5 -10

XPol

-15

Low Band DB854DG90 DB842H90 DB856DG90 DB844H90 DB858DG90 DB848H90 LBX-9012 LBV-9012 LBX-9013

-20 -25 -30

44°

VPol

-35 -40

High Band

5 dB

DB932DG90 DB950G85 HBX-9016 UMWD-09014B UMWD-09016

UMW-9015


50

3 x 65° Antennas 65° Horizontal Overlay Pattern

Examples XPol

0

Low Band CTSDG-06513 DB844H65 CTSDG-06515 DB848H65 CTSDG-06516 LBV-6513 DB854DG65 DB856DG65 DB858DG65 LBX-6513 LBX-6516

-5 -10 -15 -20 -25 -30

19°

VPol

-35 -40

High Band

10 dB

UMWD-06513 UMWD-06516 UMWD-06517 HBX-6516 HBX-6517

PCS-06509 HBV-6516 HBV-6517


51

Special Narrow Beam Applications

4-Sector Site (45°)

Road

6-Sector Site (33°)

Repeater Narrow Donor, Wide Coverage Antennas Rural Roadway PRIVATE AND CONFIDENTIAL © CommScope

52

Test Drive Route

HA RR YH

35

ST

EM

M O

RE GA LR

OW

183

AIR PO RT F

RW Y.

IN E

S M

N

S

FR

W

O

C

KI

N

G

Y

BI

R

D

N LA

E

IN

CELL SITE

W

O

O

D

R

O

AD

M

TO O

R

S

TR

T EE

N PRIVATE AND CONFIDENTIAL © CommScope

53

Polarization Diversity Tests

DB854HV90 DB854DD90

1 DRIVE TESTS

Test A

. Test B

+45°/-45° (Slant 45°)

2 0°/90° (H/V)

A

HANDHELD

1A

2A

B

MOBILE

1B

2B


54

Slant 45° / Hand-Held In Car Space Diversity vs. Slanted +45°/–45° -40

Test Set-Up and Uplink Signal Strength Measurements DB833

DB854DD90

A

E

-50

Red

DB833 B

Green

9dB

Signal Strength (dBm)

TEST 1A

9dB

Black

Blue

11dB 7.5 ft.

-60

-70

-80 moving away from tower

moving towards tower

-90

-100

moving crossface Uplink Signal Strength

Vert Left

Vert Right

Slant Div

Slant Div


55

Slant 45° / Hand-Held In Car Space Diversity vs. Slanted +45°/–45°

TEST 1A

Difference Between Strongest Uplink Signals

Signal Strength (dB)

16 12 8 4

Slant ±45° Improvement

0 -4 -8 Difference Between Polarization Diversity and Space Diversity Average Difference


56

Slant 45° / Mobile With Glass Mount Space Diversity vs. Slanted +45°/-45° -40

Test Set-Up and Uplink Signal Strength Measurements DB833

DB854DD90

A

E

9dB

Signal Strength (dBm)

TEST 1B

Black

Red

-50

Green

DB833 B

9dB Blue

11dB 7.5 ft.

-60

-70

moving away from tower

moving towards tower

-80

-90

moving crossface Uplink Signal Strength

Vert Left

Vert Right

Slant Div

Slant Div PRIVATE AND CONFIDENTIAL © CommScope

57

Slant 45° / Mobile With Glass Mount Space Diversity vs. Slanted +45°/-45°

TEST 1B

Difference Between Strongest Uplink Signals

Signal Strength (dB)

16 12 8 4 0 -4

Slant ±45° Degradation

-8

Difference Between Polarization Diversity and Space Diversity Average Difference PRIVATE AND CONFIDENTIAL © CommScope

58

Rysavy Research


59

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


60

The Impact Lower Co-Channel Interference/Better Capacity And Quality In a three sector site, traditional antennas produce a high degree of imperfect power control or sector overlap.

Traditional Flat Panels 65°

90°

Imperfect sectorization presents opportunities for:

• • • •

Increased softer hand-offs Interfering signals Dropped calls Reduced capacity

The rapid roll-off of the lower lobes of the Andrew Directed Dipole™ antennas create larger, better defined ‘cones of silence’ behind the array.

• • •

Andrew Directed Dipole™ 65°

90°

Much smaller softer hand-off area Dramatic call quality improvement 5%–10% capacity enhancement PRIVATE AND CONFIDENTIAL © CommScope

61

120° Sector Overlay Issues 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 . . . 15 Percentage of capacity loss

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

10 5 0

15 10 5 0 Overlapping angle in degree

Qualitatively, excessive overlay also reduces capacity of TDMA and GSM systems.


62

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


63

Soft and Softer Handoff Examples Softer Handoff

Two-Way Soft Handoff Three-Way Soft Handoff


64

Beam Downtilt 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.


65

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!


66

Electrical/Mechanical Downtilt (Continued)

Mechanical

Electrical


67

DB5083 Downtilt Mounting Kit 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. PRIVATE AND CONFIDENTIAL © CommScope

68

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


69

Mechanical Downtilt Coverage 110

100

90

80

110

70

130

90

80

70 60

120

60

120

100

140

50

130

50 140

40

30

150

30

150

40

160

20

160

20

170

10

170

10

180

0

180

0

190

350

190

350

340

200 210

330 320

220 230

310 300

240 250

260

270

280

290

Elevation Pattern

200

340

210

330 320

220 230

310 240

300 250

260

270

280

290

Azimuth Pattern

Mechanical Tilt 0° 4° 6° 8° 10° PRIVATE AND CONFIDENTIAL © CommScope

70

0° Mechanical Downtilt Quiz

What is the vertical beamwidth of a 4-element array?

85°


71

7° Mechanical Downtilt

93°


72

15° Mechanical Downtilt

123°


73

20° Mechanical Downtilt Horizontal 3 dB Bandwidth Undefined


74

Managing Beam Tilt •

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.

Generating Beam Tilt Dipoles Fed In Phase

Dipoles Fed Out of Phase

Energy

Exciter

Phase Exciter

Wa v e Fron t

in


75

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 At ± 90°, tilt below horizon All the pattern tilts

Cone of the Beam Peak Pattern


76

Electrical Downtilt Coverage 110

100

90

80

110

70

120

90

80

70 60

120

60

140

40

140

50

130

50

130

100

20

160

20

160

30

150

30

150

40

170

10

170

10

180

0

180

0

190

350

190

350

340

200 210

330 320

220 230

310 300

240 250

260

270

280

290

Elevation Pattern Electrical Tilt

200

340

210

330 320

220 230

310 240

300 250

260

270

280

290

Azimuth Pattern 0° 4° 6° 8° 10° PRIVATE AND CONFIDENTIAL © CommScope

77

Mechanical Vs. Electrical Downtilt 340

350

0

10

20 30

330

40

320

50

310

60

300

70

290

80

280

90

270

100

260

110

250

120

240 130

230 140

220 210

150 200

190

180

170

160

Mechanical

Electrical


78

Remote Electrical Downtilt (RET) Optimization

ATM200-002 RET Device (Actuator)

Local PC

ATC200-LITE-USB Portable Controller

Local PC

ANMS™ Remote Locations

ATC300-1000 Rack Mount Controller Network Server


79

Intermod Interference Where? F3

F1 Tx F1

Rx F3

F2

Tx F1

F2

Receiver-Produced

Transmitter-Produced

Tx F2

Tx F2

F1 F2

F1 F3

Tx1 F2 Tx2

Rx F3

Elsewhere

Rx F3 Tx1 Tx2

C O M B

F3

DUP Rx3 RF Path-Produced PRIVATE AND CONFIDENTIAL © CommScope

80

High Band Product Frequencies, Two-Signal IM FIM = nF1 ± mF2 Example: F1 = 1945 MHz; F2 = 1930 MHz

n

m

Product Order

1

1

Second

2

1

1

Product Formulae

Product Frequencies (MHz)

1F1 + 1F2 1F1 – 1F2

3875 15

Third

2F1 + 1F2 *2F1 – 1F2

5820 1960

2

Third

2F2 + 1F1 *2F2 – 1F1

5805 1915

2

2

Fourth

2F1 + 2F2 2F1 – 2F2

7750 30

3

2

Fifth

3F1 + 2F2 *3F1 – 2F2

9695 1975

2

3

Fifth

3F2 + 2F1 *3F2 – 2F1

9680 1900

*Odd-order difference products fall in-band. PRIVATE AND CONFIDENTIAL © CommScope

81

Two-Signal IM Odd-Order Difference Products Example: F1 = 1945 MHz; F2 = 1930 MHz ΔF = F1 - F2 = 15 F2 1930

F1 1945 ΔF dBc

2F2 – F1 1915

3F2 – 2F1 1900

ΔF

2ΔF 5th

2F1 – F2 1960

3rd

ΔF F2

F1

dBm

3F1 – 2F2 1975

2ΔF 3rd

5th

Third Order: F1 + ΔF; F2 - ΔF Fifth Order: F1 + 2ΔF; F2 - 2ΔF Seventh Order: F1 + 3ΔF; F2 - 3ΔF Higher than the highest – lower than the lowest – none in-between PRIVATE AND CONFIDENTIAL © CommScope

82

PCS A Band Intermodulation 11th 1855

9th 1870

7th 1885

5th 1900

3rd 1915

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

1930

1945

FCC Broadband PCS Band Plan 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).


83

PCS A & F Band Intermodulation 3rd 1895

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

1935

1975

FCC Broadband PCS Band Plan 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).


84

Causes Of IMD • Ferromagnetic materials in the current path: - Steel - Nickel plating or underplating

• Current disruption: - Loosely contacting surfaces - Non-conductive oxide layers between contact surfaces


85

System VSWR Calculator System VSWR Calculator Version 9.0 Frequency (MHz): Component Used? No No No No No No No No No No No No Yes

2 2 2 2 2 2 2 2 2 2 2 2 1

2 2 2 2 2 2 2 2 2 2 2 2 1

850.00

18-Mar-09

System Component

Max. VSWR

Return Loss (dB)

Antenna or Load Jumper Tower Mounted Amp Jumper Top Diplexer or Bias Tee Jumper Main Feed Line Jumper Bias Tee Jumper Surge Suppressor Jumper Bottom Diplexer or Duplexer Jumper

1.50 1.05 1.20 1.09 1.15 1.09 1.07 1.09 1.15 1.09 1.07 1.09 1.20 1.08

13.98 32.26 20.83 27.32 23.13 27.32 29.42 27.32 23.13 27.32 29.42 27.32 20.83 28.30

Andrew

CommScope

Cable Type / Component Loss (dB) VXL7-50 2 LDF4-50A

0.20 2 0.20 2.00 8 4 0.10 2.00 0.10 3.00 0.10 FSJ4-50B 1.00

Cable Length (m)

Cable Length (ft)

1.83

6.00

1.83

6.00

1.83 200.00 30.48 11.00 1.83

6.00 656.17 100.00 36.09 6.00

1.83

6.00

27.30

89.57

Ins Loss w/2 Conn (dB) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.00

% of Est. Reflections at System input Reflection 87.2% 0.1003 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 0.0% 0.0000 12.8% 0.0385 100.0%

Legacy Jumper / TL Cables 1/2 inch Superflexible Copper 1/2 inch Foam Copper

FSJ4-50B LDF4-50A

1/2 inch Superflexible Aluminum 1/2 inch Foam Alum inum

Legacy Transmission Lines 7/8 inch Copper 1 1/4 inch Copper 1 5/8 inch Copper 7/8 inch Very Flexible Copper 1 1/4 inch Very Flexible Copper 1 5/8 inch Very Flexible Copper 7/8 inch Virtual Air Copper Yes

1 5/8 inch Virtual Air Copper 7/8 inch Aluminum 1 1/4 inch Aluminum 1 5/8 inch Aluminum

Andrew

LDF5-50A LDF6-50 LDF7-50A VXL5-50 VXL6-50 VXL7-50 AVA5-50 AVA7-50 AL5-50 AL7-50

CR 540 SFX 500 FXL 540

Estimated Conn Loss ( 2per cable)

0.028

Typical System Reflection: Typical System VSWR: Typical System Return Loss (dB):

0.1074 1.24 19.4

Worst System Reflection: Worst System VSWR: Worst System Return Loss (dB):

0.1387 1.32 17.2

CommScope

CR 1070 CR 1480 CR 1873

Total Insertion Loss (dB): Return Loss to VSWR converter

FXL 780 FXL 1480 FXL 1873

Return Loss (dB) 17.00

3.00 Feet to meters converter

VSWR

Feet

meters

1.33

100.00

30.48

No


86

Possible Cascaded VSWR Results Possible results (at a given frequency) when Antenna and TMA are interconnected with different electrical length jumpers. 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!

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

87

Recommended Antenna/TMA Qualification Test 50 ohm load

Antenna

6 foot LDF4-50A Adapter or jumper to bypass TMA

6 foot LDF4-50A

TMA

TMA

12 foot LDF4-50A

Transmission Line

20 foot FSJ4-50

Antenna Return Loss Diagram

12 foot LDF4-50A

Transmission Line

20 foot FSJ4-50

TMA Return Loss Diagram


88

Attenuation Provided By Vertical Separation Of Dipole Antennas 70

60

Isolation in dB

50

40

z MH 0 0 20

Hz M 0 85

MH 0 45

z

MH 0 16

z

7

Hz M 5

4

Hz M 0

30

20

10

1 (0.3) (30.48)

2 (0.61)

3 (0.91)

5 (1.52)

10 (3.05)

20 (6.1)

30 (9.14)

50 (15.24)

100

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. 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. PRIVATE AND CONFIDENTIAL © CommScope

89

Attenuation Provided By Horizontal Separation Of Dipole Antennas 80

z MH 0 200

Isolation in dB

70

M 850

60

Hz

M 450

50

M 150

30

10 (3.05) (304.8)

Hz

Hz 70 M Hz 50 M z H 30 M

40

20

Hz

20 (6.1)

30 (9.14)

50 (15.24)

100 (30.48)

200 (60.96)

300 (91.44)

500 (152.4)

1000

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).


90

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.

Additional information on metal obstructions can also be found online at: www.akpce.com/page2/page2.html


91

Pattern Distortions Side Of Building Mounting

Building


92

90° Horizontal Pattern Obstruction @ –10 dB Point 340

350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

70

-25 -30

280

80

-35 270

90

-40

260

100

0° 3½'

110

250

120

240

Antenna

–10 dB Point

Building Corner

130

230 220

140 150

210 200

190 180

170

160


93


350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

-35 270

90

-40

260

100

250

0°

–6 dB Point

' 3½

110

240

120 230

Antenna

Building Corner

130 220

140 210

150 200

190 180

170

160


94


350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

–3 dB Point

-35 270

90

-40

260

100

250

0°

' 3½

110

240

120 230

Building Corner

Antenna

130 220

140 210

150 200

190 180

170

160


95

90° Horizontal Pattern 0.51λ Diameter Obstacle @ 0° 340

350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

-35 270

90

-40

260

100

250

0° 12λ

110

240

120 230

Antenna

130 220

140 210

150 200

190 180

170

160


96


350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

-35 270

90

-40

260

45°

100

250

8λ

110

240

120 230

Antenna

130 220

140 210

150 200

190 180

170

160


97


350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

-35 270

90

-40

60°

260

100

250

6λ

110

240

120 230

Antenna

130 220

140 210

150 200

190 180

170

160

Additional information on metal obstructions can also be found online at www.akpce.com/page2/page2.html. PRIVATE AND CONFIDENTIAL © CommScope

98


350

0

10

20

0

330 320

30 40

-5 -10

310

50

-15

300

880 MHz

60

-20 290

0

-25 -30

280

80

-35 270

90

-40

260

100

250

80°

110

240

120 230

3λ

Antenna

130 220

140 210

150 200

190 180

170

160

Additional information on metal obstructions can also be found online at www.akpce.com/page2/page2.html. PRIVATE AND CONFIDENTIAL © CommScope

99

General Rule Area That Needs To Be Free Of Obstructions (> 0.51λ) Maximum Gain > 12 WL

>

8

W

L

3 dB Point (45°)

W >6 WL

> 3 WL

6 dB Point (60°)

L

10 dB Point (80– 90°)

Antenna 90° horizontal (3 dB) beamwidth PRIVATE AND CONFIDENTIAL © CommScope

100

Pattern Distortions

D

θ

d

d D d = D x tan θ tan 1° = 0.01745 for 0° < θ< 10° : tan θ = θ x tan 1° tan θ =

Note: tan 10° = 0.1763

10 x 0.01745 = 0.1745 PRIVATE AND CONFIDENTIAL © CommScope

101

Gain Points Of A Typical Main Lobe

θº θ° Relative to Maximum Gain

Vertical Beam Width= 2 x θ° (–3 dB point)

–3 dB point θ° below boresite. –6 dB point 1.35 x θ° below boresite. –10 dB point 1.7x θ° below boresite.


102

Changes In Antenna Performance In The Presence Of: Non-Conductive Obstructions

90° PCS Antenna

Fiberglass Panel

Dim “A”


103

Performance Of 90° PCS Antenna Behind Camouflage (¼" Fiberglass)

Horizontal Aperture

120°

FIBERGLASS PANEL

110° DIM “A”

100° 90° 80° 1/2 λ

1/4 λ

1-1/2 λ

1λ

3/4 λ

2λ

70° 0

1

2

3

4

5

6

7

8

9

10

11

12

Distance of Camouflage (Inches) (Dim. A) PRIVATE AND CONFIDENTIAL © CommScope

104

Performance Of 90° PCS Antenna Behind Camouflage (¼" Fiberglass)

VSWR (Worst Case)

1.7 1.6

FIBERGLASS PANEL

1.5 DIM “A”

1.4 1.3 1/4 λ

1.2 0

1

1/2 λ

2

3

1-1/2 λ

1λ

4

5

6

7

8

9

2λ

10

11

12

Distance of Camouflage (Inches) (Dim. A) W/Plain Façade

W/Ribbed Façade

Without Facade PRIVATE AND CONFIDENTIAL © CommScope

105

Distance From Fiberglass 0° 330°

30°

90°

300°

0° 330°

60°

270°

90°

90°

-55

-55

-50

-50 -45

-45 -40

240°

-40

240°

120°

-35 -25 -20

120°

-35 -30

-30

210°

102°

300°

60°

270°

30°

210°

150°

-25 -20

150°

180°

180° 0°

No Fiberglass

330°

30°

300°

68°

3" to Fiberglass

60°

270°

90° -50 -45 -40 -35

240°

120°

-30 -25

210°

-20 -15

150°

180°

1.5" to Fiberglass PRIVATE AND CONFIDENTIAL © CommScope

106

Distance From Fiberglass 0° 330°

30°

300°

0°

77°

270°

90°

240°

60°

90°

-50

-50

-45

-45

-40

-40

-35

-35

240°

120°

-30 -20 -15

120°

-30 -25

-25

210°

112°

300°

60°

270°

30°

330°

210°

150°

-20 -15

150°

180°

180° 0°

4" to Fiberglass

30°

330°

108°

300°

6" to Fiberglass

60°

270°

90° -50 -45 -40 -35

240°

120°

-30 -25

210°

-20 -15

150°

180°

9" to Fiberglass PRIVATE AND CONFIDENTIAL © CommScope

107

Antenna Theory Andrew

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