Reduced Size Microstrip Patch Antenna Design

1
Reduced Size Microstrip Patch Antenna Design
AN OVERVIEW

• Presented by
• Dr. Michael Elsdon
• michael.elsdon_at_unn.ac.uk
• Northumbria Communications Research Lab
• School of Computing, Engineering and Information
  Sciences,
• Northumbria University

2
Presentation Overview

• Basic Patch Antenna Operation
• Rationale/Background to Research
• Reduced Size Solutions
• Mathematical Analysis of Slot Loaded Structures
• New Patch Designs
• Summary

3
Definition of an Antenna A usually metallic
device for radiating or receiving radio
waves A transitional structure between free
space and a guiding device Websters
Dictionary
Antenna Radiating
GUIDING DEVICE
FREE SPACE
4
Definition of an Antenna A usually metallic
device for radiating or receiving radio
waves A transitional structure between free
space and a guiding device Websters Dictionary
Antenna Receiving
GUIDING DEVICE
FREE SPACE
5
Standard Patch Antenna
Top View
Side View

• Consists of a metallic strip placed above a
  ground plane

))))
Fringing Electric Fields from the Two Edges of
the Patch Add to Cause Radiation
6
Most Important Design Consideration Resonant
Frequency ?
Er fixed by substrate
7
Examples of Patch Antenna Structures
H-Plane Pattern Perpendicular to Patch
E-Plane Pattern Perpendicular to Patch
Advantages
Disadvantages
Top View
Edge View

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

? / 2
Printed Patch

• Very Low Profile
• Simplicity
• Good Production Repeatability

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

• Substrate Cost
• Limited Beamwidths Possible

• Low Profile
• Improved Bandwidth 10 - 15 for VSWR1.2 1
• Excellent Production Repeatability

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

• Broadband gt15
• Fairly Low Profile

• Substrate Cost
• Limited (Narrow) Beamwidths Possible

Stacked Patches
Stacked Patches
? / 2
Printed Patch
Substrate
Ground Plane
Thanks to S. Foti
8
Examples of Patch Antenna Excitation
Microstrip Feed

• Pros and Cons
• Planar
• Easy to fabricate and match
• Simple to model
• Spurious feed radiation
• Cannot Optimise Feed and Patch Substrate
  requirements

Probe Feed

• Pros and Cons
• Easy to fabricate
• Easy to impedance match
• Non-Planar
• Narrow Bandwidth

9
Examples of Patch Antenna Excitation
Slot-Coupled Microstrip Feed

• Pros and Cons
• Allows independent optimisation of feed and patch
  substrate
• Difficult to fabricate
• Non-planar

Proximity Coupled

• Pros and Cons
• Independent optimisation of feed and patch
  substrate
• Difficult to fabricate
• Non-planar

Thanks to S. Foti for Diagrams
10
Choice of Antenna Structure
Printed Patch Antenna with Microstrip Feed

• Why ?
• Planar
• Easy to fabricate and match
• Simple to model
• Low Profile
• Good production repeatability

11
Typical Example
12
Patch Antenna Summary

• Advantages
• Low Cost using PCB
• Lightweight and thin profile
• Easy integration with MIC

• Disadvantages
• Restricted Bandwidth
• Several losses may reduce efficiency
• Low Gain dictated by size / substrate

• Future Challenges
• Bandwidth Extension Techniques
• Control of Radiation Patterns
• Reducing Losses / increasing efficiency
• Improving feed networks
• Size Reduction techniques

13
Rationale for PhD

• Patch Antenna now established and used in wide
  range of communication systems, e.g. radar,
  satellites, GPS.
• Future requirement for SMALLER Communication
  Systems
• Circuitry associated with comm. systems has
  reduced considerably in size
• This is NOT TRUE of Antennas
• Cost largely based on Size Thus any size
  reduction greatly welcome

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1. Investigate Present Techniques for Reducing
Patch Antenna Size and Identify most
appropriate technique2. Develop Analytical
Model to determine the performance of the
chosen patch structure 3. Analyse the
effect of design parameters on patch
performance and identify associated
trade-offs 4. Propose new designs for
reduced size patch antennas that overcome
some of the trade-offs associated with
present designs
Project Aims
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BACKGROUND Voltage and Current Distribution

• Fields within patch are described by 2D wave
  equation

• Magnetic Wall Boundary

• Associated eigenfunctions are given by

16
BACKGROUND Voltage and Current Distribution
TM01 mode
Current Maxima Voltage Minima
TM02 mode
TM03 mode
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BACKGROUND Voltage and Current Distribution
TM01 mode
TM02 mode
Current Minima Voltage Maxima
TM03 mode
18
Methods of Reducing Patch Size

• High Permittivity Substrate
• Folded Patch
• Shorting Pin
• Slot Loaded Ground Plane
• Slot Loaded Patch
• Miscellaneous Techniques

19
1. Use of High Permittivity Substrate
Principle of Operation
Resonant Frequency of Conventional Patch
Obvious way to reduce patch size is to increase er
Side View
Top View
20
fo 3GHz

• Problems
• Such substrates are often ceramic based and thus
  more expensive
• Q Factor increases with permittivity, thus
  reducing BW
• Higher permittivity often equivalent to high
  dielectric losses (1)

21
2. Folded Patch

• Principle of Operation
• Method involves use of an inverted U-shape
  structure
• Excited current path of the TMmn mode is
  lengthened
• Reduced resonant frequency for a fixed
  projection area
• Allows incorporation of air substrate for
  increased bandwidth

22
2. Folded Patch

• Problems
• Non Planar Structure
• Size Reduction at expense of increased volume
• Complex Manufacturing Process

23
3. Shorted Patch

• Principle of Operation
• Use of an edge shorted patch (a) makes the
  patch operate as a ?/4 structure
• Antennas Physical length is reduced by ½ for
  a fixed operating frequency
• Greater size reduction can be achieved using a
  partial shorting wall (b) or a
• single shorting pin (c)

24
Voltage Distribution

• Principle of Operation
• Null-voltage point for TM01 mode exists at
  centre of patch
• Size reduction achieved by shifting the null
  voltage point
• Shifting shorting pin towards radiating patch
  edge shifts null-voltage point, thus
• reducing resonant frequency
• Maximum size reduction achieved when shorting
  pin placed at centre of
• radiating patch edge

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• Problems
• Strict manufacturing tolerances (feed must be
  close to shorting pin)
• May be difficult to excite using a planar feed
• Presence of shorting pin / plane produces a dip
  in the E-plane radiation
• Large levels of cross-polarisation in the
  H-plane

27
4. Slot Loaded Ground Plane

• Principle of Operation
• Insertion of slots in the ground plane meanders
  the current path of TM modes
• Results in reduced resonant frequency and hence
  size reduction
• Meandering effect of the ground plane
  effectively lowers the Q factor, thus
• suggesting increased BW

28
E-Plane Pattern

• Problems
• Significant back radiation
• Less power available to transmit

29
5. Slot Loaded Patch
Standard Patch Antenna
Slot Loaded Patch Antenna

• Principle of Operation
• Insertion of slots in patch lengthens current
  path
• Reduced Resonant frequency and size reduction
• With correct selection of slot dimension, can
  produce reduced size, dual
• frequency and wideband patch antennas

30
Basic Slot Loaded Patch Example
31
Best Solution Slot Loaded Patch ?

• High Permittivity Substrate
• reduced BW, increased dielectric losses,
  increased cost
• 2. Folded Patch
• increased volume, complex manufacturing process
• 3. Shorting Pin
• problems with radiation pattern, feeding and
  manufacturing tolerances
• 4. Slot Loaded Ground Plane
• problems with back radiation, less transmission
  power
• 5. Slot Loaded Patch
• can produce wide range of designs
• Reduced Size Single Frequency, Dual
  Frequency, Wideband

32
Still Problems with Slot Loaded Patch Antennas !

• Lack of theoretical investigation to support
  design of reduced size slot loaded structures
• Lack of Research into the trade-offs from such
  designs
• Little work exists on the use of planar fed
  reduced size patch antennas

33
Mathematical Analysis of Slot Loaded Structures

• Several possible modelling approaches for
  analysing patch performance
• Transmission Line, Cavity, Co-planar multi-port
  network, full-wave modelling
• Need to ascertain the most suitable approach for
  slot loaded structures

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Possible Modelling Approaches

• Full-wave Modelling
• Involves the solution of Maxwells equations for
  the electric current distributions on the patch
• Requires considerable computer resources and
  yields little physical insight
• Transmission Line Model
• Based upon the assumption that the patch is a
  wide microstrip transmission line
• Presence of slot loading changes the structure
  of the patch suggesting this assumption is no
  longer valid
• Cavity Model
• Treats patch as a thin cavity TMz mode cavity
  with magnetic walls
• Only applicable for geometries for which the
  wave equation can be solved by separation of
  variables (e.g. square, rectangular, circular)
• Coplanar Multiport Network Model with
  Segmentation
• Generalisation of Cavity Model
• Suitable for Irregular Geometries

35
ExampleSegmentation Analysis of Slot Loaded
Patch

• Modelling Steps
• Decompose patch into regular elemental segments
• Develop Multi-port Network Models of each segment
• Synthesise each segment to reconstruct original
  patch structure

36
Step 1 Patch Decomposed into 4 Segments
37
Step 2 Alpha and Beta Sections Recombined to
form gamma segment




38
Interaction between ports

39
Step 2 Alpha and Beta Sections Recombined to
form gamma segment




40
Step 3 Gamma Segments Recombinedto form
original patch structure


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Simulated and Practical Results
Zin VSWR
BW 1.32
BW 1.25
Z050


Res. Freq Imag(Zin)0
42
Simulated and Practical Results
Modelling Technique Resonant Frequency (GHz) Input Impedance (O) VSWR BW (21)
Segmentation 2.836 650 1.25
Practical 2.856 625 1.32

• Reasons for Differences
• Manufacturing Tolerances
• Approximation of fringing field extension
• Dielectric properties of PCB not accurately
  defined

43
Effect of Slot Dimensions on Antenna Design
Important Performance Characteristics (from
circuit viewpoint)

• Operating Frequency
• Input Impedance
• Bandwidth

FOCUS OF THIS INVESTIGATION
Important Performance Characteristics (from
far-field viewpoint)

• Radiation Pattern
• Polarisation
• Gain
• Beamwidth

44
Definition of Slot Parameters
Slot Length (Ls), Slot Width (Ws), Slot Position
(Xs), Slot Position (Ys)


45
Effect of Increasing Slot Length

• KEY FEATURES
• SMALL frequency reduction of 0.1GHz
• Increased Input Impedance

46

• KEY FEATURE
• SMALL bandwidth reduction

47
Effect of Increasing Slot Width

• KEY FEATURES
• SIGNIFICANT Frequency reduction of 0.3GHz
• SIGNIFICANTLY increased input Impedance

48

• KEY FEATURE
• SIGNIFICANT bandwidth reduction

49
Effect of Increasing Slot Position (Xs)

• KEY FEATURES
• SIGNIFICANT frequency reduction of 0.24GHz
• MARGINAL effect on input Impedance

50

• KEY FEATURE
• SIGNIFICANT bandwidth reduction

51
Effect of Increasing Slot Position (Ys)

• KEY FEATURES
• SMALL frequency reduction of 0.1GHz
• SIGNIFICANTLY increased input Impedance

52

• KEY FEATURE
• SMALL bandwidth reduction

53
SUMMARY Effect of Slot Parameters on Performance
of TM01 Mode
Variable Frequency Zin Bandwidth
Ws ? f01? Zin01? BW01 ?
Ls? (Ls lt L/2) (L/2 lt Ls lt 3L/4) (Ls gt 3L/4) f01 ? f01 ? f01 ? Zin01? Zin01? Zin01? BW01 ? BW01 ? BW01 ?
xs? (xs lt L/4) (L/4 lt xs lt L/2) (L/2 lt xs lt 3L/4) (xs gt 3L/4) f01? f01? f01? f01? Zin01? Zin01? Zin01? Zin01? BW01 ? BW01 ? BW01 ? BW01 ?
ys? (ys lt L/2) (ys lt L/2) f01 ? f01 ? Zin01? Zin01? BW01? BW01?


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Major Outcomes

• Operation
• Placement of Slot effects different TMmn modes
• Slot width largely effects characteristics of
  TM0n modes
• Slot length has most effect on TMm0 modes

• Most Significant Trade-Offs
• Increased Input Impedance difficulty in
  feeding
• Reduced Bandwidth

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Design of Reduced Size Patch Antennas

• Design Goals
• Maximum Frequency reduction for a given patch
  size
• Maintain Input Impedance of practical value
• Maximise Impedance Bandwidth

• Challenges
• Significant trade-offs between these performance
  parameters
• Not possible to simultaneously optimise each one
• Designer must therefore achieve BEST patch
  structure for given application

56
Design based on modification of TM01 mode
BASIC PATCH ANTENNA Current Distribution of TM01
mode
57


58
Final Design
59
Practical Results
Proposed Design Reference Antenna
Resonant Frequency, GHz 2.45 2.45
Size Reduction, 55 0
Return Loss, dB -23 -29
VSWR Bandwidth, 1.22 1.904
Input Impedance, O 50 330
Measured Gain, dB 5.8 6.1
Patch Length L mm 30 39.4

• Performance Summary
• 55 Size Reduction
• Input Impedance of 50O
• Reduced VSWR Bandwidth

Reference Antenna Conventional Rectangular Patch
60
Design based on Creation of TM0d mode

• Previous design
• Operates by modification of TM01 mode
• Limitation
• Impedance matching network is required
• New Structure
• Operates by creating an additional TM0d mode
• Advantages
• Has input impedance of 50O
• Can use direct feed
• No impedance matching required

61

Two New Antenna Designs

• DESIGN A
• Creates new TM0d mode by insertion of
  two slots close to non-radiating edge
• Slot dimensions and position control frequency
  and input impedance

Design A
62
Typical Current Paths
TM01 mode (f3.19GHz)
TM0d mode (f2.86GHz)

• TM0d mode has different current path to TM01
  mode
• TM0d mode has different frequency and impedance
  response

63

Two New Antenna Designs

• DESIGN A
• Creates new TM0d mode by insertion of
  two slots close to non-radiating edge
• Slot dimensions and position control frequency
  and input impedance

Design B
Design A

• DESIGN B
• Incorporates additional slot in centre
• Increases current path of TM0d mode
• Greater Size Reduction

64
Key Design Features

• Primary Performance Goals
• Resonant frequency
• Input impedance
• Bandwidth

• Controlling Parameters
• Slot Length
• Slot Width
• Slot Position

NO UNIQUE SOLUTION FOR PATCH DESIGN

• General Conclusions on patch design
• Slot Separation results more predictable when
  slots this is kept low
• Slot Width for a given slot length, Zin
  increases with slot width
• Thus Zin Ws should be small
• Slot Length Controls resonant frequency and
  input impedance

65
Final Designs
Design B
Design A
66

Practical Results
Design A
Design B
Reference
Reference Antenna Conventional Rectangular
Patch with impedance matching network
67

Practical Results
Design A Design B Reference Antenna
Resonant Frequency, GHz 2.778 2.338 3.15
Size Reduction, 12 40 NA
Return Loss, dB -16.5 -35 -35
VSWR Bandwidth, 1.25 1.4 1.904
Input Impedance, O 50 50 330
Measured Gain, dB 4.2 3.7 6.1

• Performance Summary
• 12 and 40 Size Reduction respectively
• No Impedance matching n/w required
• Reduced VSWR Bandwidth
• Reduced Gain

Reference Antenna Conventional Rectangular
Patch with impedance matching network
68
EXTENSION Planar Fed Dual Frequency Design
69

Practical Results
f1 GHz f2 GHz
Resonant Frequency, GHz 3.18 3.51
Return Loss, dB -38 -18.6
VSWR Bandwidth, 1.57 0.41
Input Impedance, O 50 50
Gain, dB 5.9 5.1
70

Practical Results
f2
f1

• Dual Frequency Operation achieved by operating
  using TM01 and TM0d modes
• Impedance Matching at both frequencies achieved
  using inset feed

71
Reduced Size Designs with Circular Polarisation
Application of Slot Loading to Nearly Square CP
Patch Antenna
EMANIM.lnk
72
Linear and Circular Polarisation
Linear Polarisation
For CP E1 E2 d 900
73
Generation of Circular PolarisationDual Feed
EMANIM.lnk

• Principle of Operation
• Two adjacent sides of square patch are fed to
  excite TM01 and TM10 modes
• Feed network ensures equal amplitude split and
  900 phase difference between two modes

74
Generation of Circular PolarisationSingle Feed

• Principle of Operation
• TM01 and TM10 modes having slightly different
  frequencies
• TM01 mode leads by 450 / TM10 mode lags by -450
• dl is controls phase shift between two modes

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Basic Reduced Size CP Patch Antenna Design

• Design Goals
• Maximum Frequency Reduction
• Input Impedance Matching
• Wide Impedance Bandwidth
• Minimize Axial Ratio
• Maximise Axial Ratio Bandwidth
• Maximise perturbation segment

• Trade-offs with size reduction
• Reduced perturbation size (dl)
• Increased input impedance
• Reduced axial ratio bandwidth

76
Improved Reduced Size CP Patch Antenna Design
Design 1
77
l1 mm dl mm Frequency GHz Input Impedance CP BW
0 0.81 2.95 245 1.5
4 0.81 2.94 250 1.4
8 0.71 2.826 290 1.2
12 0.51 2.643 330 1.1
16 0.41 2.409 475 1.1

• Advantages
• Larger Perturbation segment
• Relaxed Tolerances
• Greater Axial Ratio bandwidth
• Lower Input Impedance
• Greater Practical Size reduction

New Design
l1 mm dl mm Frequency GHz Input Impedance CP BW
0 0.71 2.95 310 1.2
4 0.71 2.925 330 0.92
8 0.61 2.805 400 0.7
12 0.41 2.639 750 0.59
16 0.21 2.396 1200 0.49
Reference Antenna
78
Contributions

• Rigorous Investigation of Slot Loaded Patch
  Antennas
• Application of segmentation modelling to
  these structures
• Determined relationship between slot
  parameters and antenna performance
• Highlighted associated trade-offs
• Proposed, Designed and Implemented new Planar Fed
  Reduced Size Antenna Design
• Linear Polarised Antenna using TM01 mode
• Linear Polarised Antenna using TM0d mode
• Circular Polarised Antenna using TM01 / TM10
  mode
• Dual Frequency LP antenna using TM01 and TM0d
  modes

79
Publications and Presentations

• M. Elsdon, A. Sambell and S. Gao, Inset
  Microstrip-line Fed Dual Frequency
  Microstrip Patch Antenna,12th International
  Conference on AP, Exeter, England, No. 491,
  Volume 1, pp28-30, 31st March 3rd April 2003
• 2. M. Elsdon, A. Sambell and S. Gao, Novel
  Compact Harmonic-Suppressed Planar-Fed
  Microstrip Antenna, 5th European Personal
  Mobile Communications Conference, Glasgow,
  Scotland, No. 492, pp1-4, 22nd 25th April 2003
  
• 3. M. Elsdon, A. Sambell, S. Gao and Y. Qin,
  Compact Circular Polarised Patch Antenna
  with Relaxed Manufacturing Tolerance and
  Improved Axial Ratio Bandwidth, IEE
  Electronic Letters, Volume 39, No. 18,
  p1296-1298, 4th September 2003
• 4. Y. Qin, S. Gao, A. Sambell, E. Korolkewicz
  and M. Elsdon, Broadband Patch Antenna with
  Ring Slot Coupling, IEE Electronic Letters,
  Volume 40, No. 1, pp5-6, 8th January 2004
• 5. M. Elsdon, A. Sambell, S. Gao and Y. Qin,
  Planar Fed Compact Circular Polarised
  Microstrip Antenna with Triangular Slot
  Loading, Microwave and Optical Technology
  Letters, Issue 413, pp226-228, 5th May 2004
• 6. D. Smith, M. Leach, M. Elsdon and S. J. Foti,
  Using Invisible Region Wave Vectors For
  Determining The Properties Of Microwave Antennas
  And Imaging Fields, 4th Int. Symp. On
  Communication Systems, Networks And Digital
  Signal Processing, CSNDSP-04, Newcastle UK, pp.
  248-251, July 2004.

80
Publications and Presentations

• 7. D. Smith, M. Leach, M. Elsdon and S. J. Foti,
  Imaging Of Concealed Objects From Scalar
  Microwave Holograms, RF and Microwaves Conf.,
  RFM-04 Malaysia, pp. 127-131, Oct. 2004.
• 8. D. Smith, M. Leach, M. Elsdon and S. J. Foti,
  Holographic Reconstruction of Dish Antenna
  Measurements, Int. Symp. On Antennas, JINA-04,
  Nice France, pp. 308-309, Nov. 2004.
• 9. L.S.K. Dampanaboina, D. Smith, M. Leach, M.
  Elsdon, S.J. Foti, Microwave Antenna Imaging for
  Medical Diagnostics, Britains Top Young
  Engineers Competition, House of Commons, LONDON,
  14th Dec. 2004.
• 10. Y. Qin, S. Gao, M. Elsdon and A. Sambell,
  Broadband high efficiency active antenna
  for RF Front-End application, IEEE Asia
  Pacific Microwave Conference 2005.
• 11. D. Smith, M. Leach, M. Elsdon and S. J. Foti,
  Imaging Dielectric Objects from Scalar
  Intensity Patterns by means of Indirect
  Holography, IEEE AP-S International Symposium
  and USNC / URSI National Radio Science
  Meeting, pp?-?, July 2005
• M. Elsdon, A. Sambell, and Y. Qin, Reduced
  Size Direct Planar Fed Patch Antenna, IEE
  Electronic Letters, Volume 41, No. 16,
  p884-886, 4th Aug. 2005

81
Publications and Presentations

• D. Smith, M. Leach, M. Elsdon, M.J. Fernando and
  S. J. Foti, Imaging Of Dielectric Objects
• Reconstructed Using Indirect Holographic
  Intensity Patterns, 9th International Conference
  on Electromagnetics in Advanced Applications
  (ICEAA 05), pp401-404, Sept. 12-16, 2005, Torino,
  Italy
• 14. M. Elsdon, Microwave Imaging using Indirect
  Synthetic Reference Beam Holography, Invited
  Lecture, Calgary University, December 2005.
• 15. M. J. FDO, M. Elsdon, M. Leach, D. Smith,
  S.J. Foti, Breast Cancer Detection using
  Microwave Holographic Imaging, Britains Top
  Young Engineers Competition, House of Commons,
  LONDON, Dec. 2005.
• 16. Y. Qin, S. Gao, A. Sambell, M. Elsdon, and
  E. Korelkiewicz, Design of a Broadband
  Square Ring Slot Coupled Patch Antenna,
  Microwave and Optical Technology Letters,
  Issue 475,2005
• 17. M. Elsdon, D. Smith, M. Leach. S. Foti,
  Microwave Imaging of Concealed Metal Objects
  using a Novel Indirect Holographic Method,
  Microwave and Optical Technology Letters,
  Issue 476, December 2005
• 18. M. Elsdon, M. Leach, D. Smith, S. Foti,
  Microwave Imaging at Northumbria University,
  MIAS-IRC Spring School, Oxford University, 19
  24th March 2006.

82
Publications and Presentations

• M. Elsdon, D. Smith, M. Leach. S. Foti,
  Experimental Investigation of Breast Tumor
• Imaging Using Indirect Microwave Holography,
  Microwave and Optical Technology Letters,
  Issue 483, March 2006
• 20. D. Smith and M. Elsdon, Breast Cancer
  detection using Microwave Holography, Invited
  Lecture, Newcastle University Medical School,
  May 15th 2006.
• 21. M. Elsdon, and Y. Qin, Dual Frequency
  Planar Fed Microstrip Patch Antenna,
  Microwave and Optical Technology Letters,
  Issue 486, pp1053-1054, June 2006
• 22. D. Smith, M. Leach, M. Elsdon, S.J. Foti,
  Indirect Holographic Techniques for Determining
  Antenna Radiation Characteristics and Imaging
  Aperture Fields, IEEE Antennas and
  Propagation Magazine, accepted, 2006
• 23. M. Leach, M. Elsdon, S.J. Foti and D.Smith,
  Imaging Dielectric Objects Using a Novel
  Synthetic Off-Axis Holographic Technique,
  Microwave and Optical Technology Letters,
  accepted 2006
• 24. M. Elsdon, M. Leach, M.J. FDO, S.J. Foti, D.
  Smith, Early Stage Breast Cancer Detection using
  Indirect Microwave Holography, European
  Microwave Conference, Manchester, pp?-?,
  September 10-15 2006

83
Publications and Presentations

• D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S.
  J. Foti, 3D Microwave Imaging for
• Medical and Security Applications,
  International RF and Microwave Conference,
• pp?-?, Malaysia, Sept. 12-14 2006
• D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J.
  Foti, Medical Imaging using a
• Microwave Indirect Holographic Technique,
  Mediterranean Microwave Symposium,
• Genoa, pp?-?, September 19-21 2006
• 27. M.J. Fdo, M. Elsdon, M. Leach, D. Smith,
  S.J. Foti, A Holographic Solution for
• Concealed Object Detection, The
  Mediterranean Journal of Computers and
• Networks, Vol. 4, No. 2, pp. 160-165,
  October 2006.
• D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J.
  Foti, A Method for 3D Breast Cancer
• Imaging Using Microwave Holography,
  International Symposium on Antennas
• and Propagation, Singapore, pp?-?,
  November 1-4 2006
• 29. D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S.
  J. Foti, A Microwave Indirect
• Holographic System for Security and
  Medical Imaging Applications, European
• Conference on Antennas and
  Propagation, France, pp?-?, November 6-10 2006

84
Acknowledgements
Prof. A Sambell Director of Studies Prof. B.
Cryan 2nd Supervisor Dr. D. Smith 2nd
Supervisor Prof. S. Foti for advice and
fruitful discussions
85
Thank You for Your Attention
86
Important Design Considerations
Resonant Frequency
Input Impedance at Resonance
Fractional Bandwidth
87
Important Design Considerations
Q Factor
(antenna loss factors)
Efficiency
Gain
Directivity