Investigations%20into%20Reduced-Size%20Antennas%20for%20Mobile%20Computing - PowerPoint PPT Presentation

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Investigations%20into%20Reduced-Size%20Antennas%20for%20Mobile%20Computing

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All of them have been designed for operation at 2.4GHz using Agilent ADS Momentum. ... to mitigate multipath problems have been analysed using Agilent ADS Momentum. ... – PowerPoint PPT presentation

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Title: Investigations%20into%20Reduced-Size%20Antennas%20for%20Mobile%20Computing


1
Investigations into Reduced-Size Antennas for
Mobile Computing
  • by
  • Konstanty Bialkowski
  • School of Information Technology Electrical
    Engineering
  • University of Queensland

2
Rationale
  • There is a strong demand for reducing the size of
    mobile computers to open new application areas
  • To meet this demand, reduced-size antennas are
    required
  • New antenna designs have to mitigate problems
    associated with multi-path propagation
  • The viable option are antennas offering diversity

3
Problems with Traditional Antennas
  • Traditional antennas (such as monopoles) are of
    fixed pattern and polarization.
  • The transmitted wave is affected by multi-path
    propagation resulting in large changes in the
    received signal strength
  • In mobile environment, receiving antennas are
    often pattern/polarization mismatched to the
    incident wave

4
Options for Solving Propagation Problems
  • Increase Transmitted Power
  • Disadvantage - battery can ran out quickly
  • Use Antenna Diversity
  • By matching the receiving antenna pattern,
    polarization or field (E or H) the receiving
    system gain can be improved by several dB
  • Advantage
  • The quality of communication link can be improved
    without the need to compensate by an active gain
  • The battery can operate over an extended time
    period

5
Antenna Diversity Options
  • Pattern diversity the antenna pattern is matched
    to the direction from which the wave arrives
  • Polarization diversity the antenna polarization
    is matched to the polarization of the incident
    wave
  • Field diversity antenna elements are selected to
    couple to E or H field, whichever is maximum at a
    given location
  • All the above schemes do not require large
    real estate and can be realized using a single or
    few antenna elements.

6
Antenna Diversity Example
  • The following figures show signals received by
    horizontally and vertically polarized antennas in
    a typical indoor environment.
  • The signals are affected by multi-path
    propagation. However, nulls are at different
    positions.

7
Non-Adaptive and Adaptive Antenna Solutions
  • Non-Adaptive solution offered by fixed-pattern
    antennas featuring high cross-polar component
  • Used in (some of) current designs (Eg PIFA)
  • co-polar and cross-polar components observed in
    far-field radiation pattern.
  • Adaptive Diversity solution-offered by antennas
    with pattern controlled by a switching system
  • Polarization Diversity
  • Signal is received on one of two (or more)
    polarizations, eg Horizontal Vertical, LHCRHC
  • Pattern Diversity
  • Signal is received only from a selected direction

8
Investigated Antennas
  • Ericsson PIFA
  • Smart Clothing IFA
  • Smart Clothing IFA Dual-Band
  • F Shaped Monopole
  • CPW Feed Patch Antenna
  • Single Slot Antenna (LP and CP Polarized)
  • Dual Slot Ring Antenna
  • All of them have been designed for operation at
    2.4GHz using Agilent ADS Momentum.

9
Fully Developed Antennas
  • Smart Clothing IFA
  • Single Slot Ring
  • Single Slot Ring
  • Polarization Diversity
  • Dual Slot Ring
  • Pattern Diversity Antenna

10
IFA (for Smart Clothing)
  • Non-adaptive antenna with high degree of cross
    polarization

Photographs of the developed antenna
11
IFA (for Smart Clothing)
  • 3D Radiation Plot and Current Distributions

12
Single Slot Ring (CP Feed)
  • Circular Polarization (non adaptive) Antenna

Photographs of the developed antenna
13
Single Slot Ring (CP Feed)
  • 3D Radiation and Current Plot shown

14
Single Slot Ring with Perturbation Segments
  • Able to achieve Linear or Circular Polarization
    depending on the state of its switches
  • Photographs of the developed antenna

15
Single Slot Ring Antenna Operation
  • Perturbation segments
  • Are ON circular polarization is obtained
  • Are OFF linear polarization is achieved

16
Single Slot Ring Simulations
  • Current Plots
  • With and without perturbation segments

17
Dual Slot Ring Antenna (1)
  • Pattern Diversity Antenna

Generates 3 independent radiation patterns by
turning ON or OFF P-I-N diodes
18
Dual Slot Ring Antenna (2)
  • Pattern Diversity Antenna
  • Photographs of the developed antenna

19
Dual Slot Ring Antenna(Far field radiation Plots)
20
Dual Slot Ring Antenna(Current Plots)
21
Experimental Results for Antennas
  • The inverted IFA, Single Slot Ring, Single Slot
    Ring with Perturbation Segments and Dual Slot
    Ring antennas have been tested in terms of their
    Return Loss using HP8510 Vector Network Analyser
  • In general, good agreement with the Momentum
    simulated results has been obtained

22
Bluetooth Experimental Setup
  • Includes two Bluetooth Modules connected to
  • Two PCs running Linux 2.4.19 with BlueZ 2.2
  • Uses 'Ping' link application over Bluetooth's
    l2cap layer
  • Using this system, performances of various
    antennas described previously can be assessed in
    real time
  • This task is accomplished by measuring mean
    packet delay and counting error-free packets of
    information received during the transmission
    between the two PCs.

23
Bluetooth Experiment Results
  • Errors Shown in GUI

24
Conclusions
  • Fixed and variable pattern planar antennas to
    mitigate multipath problems have been analysed
    using Agilent ADS Momentum.
  • The antennas parameters have been selected for
    operation with Bluetooth.
  • Developed antennas have been experimentally
    tested.

25
Conclusions (continued)
  • A PC-based system has been developed to assess
    in real time the communication link between
    Bluetooth modules.
  • The system serves as an experimental platform for
    assessing antenna diversity schemes for Bluetooth.
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