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Antenna Technology for Mobile Networks Part I

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Title: Antenna Technology for Mobile Networks Part I


1
Antenna TechnologyforMobile NetworksPart I
  • Research Seminar 4th July 20007
  • Professor Stephen J Foti

2
Mobile Network System Architecture(BASED ON
NORTEL MATRA SYSTEM)
3
Antennas for Mobile Telecom Networks
4
The Environmental Problem
URBAN CLUTTER
RURAL CLUTTER
5
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
6
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

7
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

8
Evolution of Antenna System Requirements
9
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

10
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

11
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.

12
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

13
UK Operator Spectrum Licences (GSM900)
14
UK Operator Spectrum Licences (DCS1800)
15
UK Operator Spectrum Licences (3G)
16
Overview of Antennas
17
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

18
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

19
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
20
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
21
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
22
Linearly Polarised Element Feeding / Excitation
Methods
  • Dipole Feeding
  • Coaxial BALUNs
  • Printed BALUNs
  • Patch Feeding
  • Microstrip
  • Probe
  • Slot Coupled Microstrip

23
Dipole Fed by Coaxial BALUN(Linear Polarisation)
24
Dipole Fed by Printed BALUN(Linear Polarisation)
25
Patch Feeding(Linear Polarisation)
26
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)

27
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
28
Crossed-Dipoles Fed by Coaxial BALUNs(Dual-Polari
sation)
29
Crossed-Dipoles Fed by Printed BALUNs(Dual-Polari
sation)
30
Suspended Patches Fed by Slot-Coupled Microstrip
Typical Technique(Dual-Polarisation)
31
Suspended Patches Fed by Slot-Coupled Microstrip
Inotek Antennas Technique (Patent Pending)
(Dual-Polarisation)
32
Polarisation(Azimuth Patterns for /- 45o
Dual-Polar Antenna Shown)
33
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.
34
Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
35
Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
36
Radiation Patterns
9 Element PCS Antenna 0 degree downtilt
37
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

38
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

39
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

40
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)
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