Antenna Technology for Mobile Networks Part I

1
Antenna TechnologyforMobile NetworksPart I

• Research Seminar 4th July 20007
• Professor Stephen J Foti

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Mobile Network System Architecture(BASED ON
NORTEL MATRA SYSTEM)
3
Antennas for Mobile Telecom Networks
4
The Environmental Problem
URBAN CLUTTER
RURAL CLUTTER
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A Solution!
15m Flagpole Dual-Polarised Tri-Sector or Omni
This Polarisation Diverse Antenna System Provides
Similar Performance to the Vertically Polarised
Spatial Diversity Systems of the Previous Slide
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Presentation Outline

• Evolution of Antenna System Requirements
• Overview of Antennas
• Basic Concepts
• Antenna Arrays
• Coverage Considerations
• Diversity Systems
• Spatial Diversity
• Polarisation Diversity
• Examples of Design Solutions
• Multi-Beam SMART Antenna Intro
• Future Requirements

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Wireless Communication Milestones(FROM ANTENNAS
AND PROPAGATION FOR WIRELESS COMMUNICATION
SYSTEMS, S. R. SAUNDERS, WILEY 1999)

• 1873 Maxwell Predicts EM Waves
• 1888 Hertz Demos Radio Waves
• 1897 Marconi Demos Mobile Wireless Comms. to
  Ships
• 1924 US Police 1st use Mobile Comms.
• 1945 Arthur C.Clarke Proposes Geostationary
  Comms. Satellites
• 1957 Soviet Union Launches Sputnik 1 Comm.
  Satellite
• 1969 Bell Labs (US) Invent Cellular Concept
• 1979 NTT Cellular System (Japan)
• 1981 NMT (Scandinavia)
• 1983 AMPS Cellular Frequencies Allocated (US)

• 1985 TACS (Europe)
• 1988 JTACS Cellular System (Japan)
• 1991 USDC (US)
• 1991 GSM Cellular System Deployed (Europe)
• 1993 DECT DCS (Europe)
• 1993 PHS Cordless System (Japan)
• 1995 IS95 CDMA (US)
• 1998 Iridium Global Satellite System Launched
• 2002 IMT-2000 3rd Generation Cellular Mobile
  Systems Deployed

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Evolution of Antenna System Requirements
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Late 80s

• SYSTEM OPERATION
  ANTENNA REQUIREMENT
• 900 MHz BAND (UK) MODEST MANUFACT.
  TOL.
• SPATIAL DIVERSITY - LOW TRAFFIC VERTICALLY
  POLARISED
• 
  OMNI
• SPATIAL DIVERSITY - HIGH TRAFFIC VERTICALLY
  POLARISED
• 
  SECTOR
• Low Intermod Products
• INITIAL ROLL-OUT 0 to 2 Deg. ELECTRICAL
• 
  DOWN-TILT
• MATURE ROLL-OUT 4 to 10 Deg.
  ELECTRICAL
• 
  DOWN-TILT

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Early - Mid 90s

• SYSTEM OPERATION ANTENNA
  REQUIREMENT
• 1800 MHz BAND (UK) TIGHTER MANUFACT. TOL.
• POLARISATION DIVERSITY DUAL-POLARISATION
• Low Cross-Polarisation
• High Isolation
• DUAL-BAND DUAL-BAND / DUAL-
• 
  POLARISATION

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Late 90s

• SYSTEM OPERATION
  ANTENNA REQUIREMENT
• ADJUSTABLE COVERAGE VARIABLE
  DOWN-TILT
• INCREASED TRAFFIC CAPACITY TWIN BEAM
  ANTENNA
• STEALTH SOLUTIONS VARIOUS Lamp Post,
  Flag
• 
  Pole, In-Sign, etc.

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The New Millennium!

• SYSTEM OPERATION ANTENNA
  REQUIREMENT
• 3RD GENERATION (UMTS) WIDE BAND /
  VERTICAL
• 
  POLARISATION
  DUAL-POLARISATION
• TRI-BAND TRI-BAND /
  DUAL-POLARISATION
• 
  WITH VARIABLE DOWN-TILTS
• INCREASED TRAFFIC CAPACITY MULTI-BEAM SMART
• 
  ANTENNAS
• PICOCELLS HIDDEN INDOOR ANTENNAS

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UK Operator Spectrum Licences (GSM900)
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UK Operator Spectrum Licences (DCS1800)
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UK Operator Spectrum Licences (3G)
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Overview of Antennas
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Frequency Band Definitions

• GSM900 870 to 960 MHz 9.5
  Bandwidth
• GSM1800 1710 to 1880 MHz 9.5
  Bandwidth
• UMTS 1900 to 2170 MHz 13.3
  Bandwidth

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Fundamental Linearly Polarised Radiating Elements

• Elements Most Appropriate to BTS Antennas
• Dipoles
• In Free Space Omni-Directional in H-Plane
• With Reflectors Directional
• Patches
• Printed
• Suspended
• Stacked

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Dipoles in Free- Space (Omni-Directional in
H-Plane)

• Simplicity
• Suitable for Omni-Directional Applications
• Low Cost

• Very Narrow Bandwidth 5 - 10 for VSWR 1.2
  1
• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

Thin Dipole
? / 2

• Simplicity
• Suitable for Omni-Directional Applications
• Low Cost

• Narrow Bandwidth 7 - 12 for
  VSWR 1.2 1
• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

Cylindrical Version
Flat Version
Wide Dipole
? / 2
Cylindrical Version
Flat Version

• Larger Structure
• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

• Broadband ( gt15)
• Suitable for Omni-Directional Applications

Bi-Conical Dipole
lt? / 2
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Dipoles with Reflector (Directional in H-Plane)

• Narrow Bandwidth 5 - 10 for
  VSWR 1.2 1
• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

• Wide Range of H-Plane Beamwidths Possible

Thin Dipole Reflector
? / 2

• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

Cylindrical Version
Flat Version

• Wide Range of H-Plane Beamwidths Possible
• Improved Bandwidth 7 - 12 for
  VSWR 1.2 1

Wide Dipole Reflector
? / 2

• Larger Structure
• BALUN Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

Cylindrical Version
Flat Version

• Broadband ( gt 15)
• Wide Range of H-Plane Beamwidths Possible

Bi-Conical Dipole Reflector
lt? / 2
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Patches (Directional in E-Plane H-Plane)
Advantages
Disadvantages
Top View
Edge View

• Very Low Profile
• Simplicity
• No BALUN Required
• Good Production Repeatability

• Ultra Narrow Bandwidth 1 for VSWR 1.2 1
• Substrate Cost
• Limited Beamwidths Possible

? / 2
Printed Patch
Printed Patch
? / 2
Patch
Ground Plane
Substrate

• Low Profile
• Improved Bandwidth 10 - 15 for VSWR1.2 1
• No BALUN Required
• Excellent Production Repeatability

• Substrate Cost
• Limited Beamwidths Possible

? / 2
Suspended Patch
Suspended Patch
Suspended Patch
? / 2
Ground Plane
Substrate
Suspended Patches

• Broadband ( gt15 )
• Fairly Low Profile

• Substrate Cost
• Limited (Narrow) Beamwidths Possible

? / 2
Stacked Patches
Patch
? / 2
Printed Patch
Substrate
Ground Plane
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Linearly Polarised Element Feeding / Excitation
Methods

• Dipole Feeding
• Coaxial BALUNs
• Printed BALUNs
• Patch Feeding
• Microstrip
• Probe
• Slot Coupled Microstrip

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Dipole Fed by Coaxial BALUN(Linear Polarisation)
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Dipole Fed by Printed BALUN(Linear Polarisation)
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Patch Feeding(Linear Polarisation)
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Dual-Polarised Radiating Elements

• Elements Most Appropriate to BTS Antennas
• Crossed-Dipoles
• With Reflectors Directional
• Dual-Polarised Patches
• Printed
• Suspended
• Note /- 45o Dual-Slant Polarisation Only
  Considered because of Industry Standard (Based
  upon the ability to achieve identical principal
  plane radiation patterns for these two
  polarisations due to symmetry)

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Dual-Polarised Radiating Elements
Advantages
Disadvantages
Side View
Front View

• Narrow Bandwidth 5 - 10 for
  VSWR 1.2 1
• BALUNs Required for Coaxial Feeding (Labour
  Cost)
• Difficult Production Repeatability (Solder
  Connections)

• Range of Beamwidths Possible

Dipoles Reflector

• Ultra Narrow Bandwidth 1 for VSWR 1.2 1
• Substrate Cost
• Limited Beamwidths Possible

• Very Low Profile
• Simplicity
• No BALUN Required
• Good Production Repeatability

Printed Patch
Printed Patch
Patch
Ground Plane
Substrate

• Low Profile
• Improved Bandwidth 10 - 15 for VSWR1.2 1
• No BALUN Required
• Excellent Production Repeatability

• Substrate Cost
• Limited Beamwidths Possible

Suspended Patch
Suspended Patch
Substrate
Ground Plane
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Crossed-Dipoles Fed by Coaxial BALUNs(Dual-Polari
sation)
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Crossed-Dipoles Fed by Printed BALUNs(Dual-Polari
sation)
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Suspended Patches Fed by Slot-Coupled Microstrip
Typical Technique(Dual-Polarisation)
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Suspended Patches Fed by Slot-Coupled Microstrip
Inotek Antennas Technique (Patent Pending)
(Dual-Polarisation)
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Polarisation(Azimuth Patterns for /- 45o
Dual-Polar Antenna Shown)
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Polarisation Orthogonality(Orthogonality for /-
45o Dual-Polar Antenna Shown)
Orthogonality The polarisation Mismatch Loss
between the polarisations associated with the two
antenna ports (that are nominally /-45o slant
linear polarisations) in a particular direction.
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Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
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Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
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Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
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Some Specs

• Squint
• Squint Deviation of the beam peak from the
  desired direction
• Azimuth Squint Typical specification is /- 2o,
  referenced to 0o
• Elevation Squint Typical specification is /-
  0.5o referenced to desired electrical downtilt
• Note Squint specifications apply to both /- 45o
  Polarisations
• Tracking
• Tracking Difference between the co-polar
  pattern level associated with the 45o Port the
  co-polar pattern level associated with the -45o
  Port _at_ each direction in space
• Azimuth Tracking Typical specification is /-
  1dB over /- 60o
• Elevation Tracking Typical specification is /-
  1dB over the 10 dB beamwidth

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Polarisation Orthogonality Spec

• Orthogonality
• Figure of Merit for Dual-Polarised Antenna
• Orthogonality The polarisation Mismatch Loss
  between the polarisations associated with the two
  antenna ports (that are nominally /-45o slant
  linear polarisations) in a particular direction.
• Orthogonality Affects the Achievable Diversity
  Gain of a Diversity Receiver on the Uplink
• A Typical Orthogonality Specification is lt -10
  dB over /- 45o Azimuth, lt -7 dB over /- 60o
  Azimuth and lt-10 dB over the 3 dB Beamwidth in
  Elevation

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Passive Inter-modulation Products

• Caused by any non-linearity in signal path when
  two or more carriers present, for example
• Metal-to-metal contacts
• Dissimilar metals
• Poor Solder Joints
• Certain plating constituents (nickel, for
  example)
• The effect is to generate undesired
  inter-modulation products _at_ (nfC1mfC2), n,m
  1,2,3..
• If in Uplink Band can cause interference
• Typical Specification for Antennas is -153 dBc
  with two
  20
  watt carriers

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Isolation

• Specification gt 30 dB between 45o -45o Ports
  of Dual-Polarised Antenna Between All Ports of
  Multi-Band Antennas (over full bands)
• Isolation Plot Example (Inotek Antennas Type
  2212 UMTS Antenna)