The document outlines a project to design paired spiral resonator (PSR) structures that can operate as multiband radiators. Different PSR designs will be analyzed using two main feeding techniques: edge discrete port feeding and coaxial probe feeding. Parameters like radiation pattern, efficiency, directivity, beamwidth, and polarization will be evaluated to investigate the performance of the PSRs. Improvements may be explored by rotating the alignment of the bottom spiral. Simulations will be conducted using CST Microwave Studio 2011.

1. Abstract
The objective of this project is to design Paired Spiral Resonator (PSR)
structures to operate as multiband radiators. Squared Spiral PSRs will be
used to regard the dimensions of the ground plane, substrates, spirals width
and gap as previously reported in [10] and [11]. Designs of Single Arm PSR
and Dual Arms PSR will be analysed considering the two main types of
feeding, edge discrete port and coaxial probe feeding techniques, as previous
studies have demonstrated that these two techniques present considerably
better performance compared to others and their radiation characteristics are
approximately similar.
Each technique has advantages and disadvantages in terms of convenience
of implementation and radiation characteristics. An analysis based on antenna
parameters such as radiation pattern and efficiency, mismatch losses,
directivity, 3dB beamwidth, polarization pattern and current distribution will be
held in order to investigate the performance of the PSRs. Improvements in the
performance of the designed PSRs will be further investigated, by rotating the
alignment of the bottom spiral in each case.
The design of the PSRs and their simulations will be supported with the use of
CST Microwave Studio 2011 (Computer Simulation Technology).

2. Project Outline
The purpose of this report is to present all the key aspects which are about to
be analysed in the MSc Final Year Project, entitled ‘’Planar Spirals for
Multiband Antenna Radiators’’. Planar spirals constitute one of the major
basic elements of printed circuit and antennas, in the recent years. The
structure and the advantages of the stacked and interwoven planar spirals
make them suitable for the design of frequency sensitive surfaces (FSS) and
radiating elements of substantially sub-wavelength size. The design of these
structures contributes additional degrees of freedom in tailoring multiband
antennas and their radiation patterns.
The purpose and the objectives of this project are to investigate configurations
of stacked and interwoven pair spiral resonators (PSR) for multiband and
tunable antenna radiators. The impact on the antenna’s parameters will be
analysed in order to achieve the high performance of the interwoven and
stacked spirals. The planar resonator designs and the configurations will be
implemented with the use of electromagnetic simulators and especially
through the use of Computer Simulation Technology (CST) Microwave Studio
2011. The optimization of the layout and the design will be based on
physically realizable geometries accordant to modern fabrication techniques.
The design, the configurations and the measurement of the performance will
be based on different types of feeding techniques and proposing methods to
improve the performance of the PSRs.
The learning outcomes of this project are:
1. The properties of the convoluted spiral resonators and the basic
principles of their design for antenna applications.
2. The modelling concepts for the design of complex electromagnetics
structures, antenna radiating elements and feeders.
3. Skills in operating the full-wave electromagnetic simulation tools (CST
Microwave Studio) and their use for the design of microwave antennas.

3. Table of Contents
Abstract .......................................................................................................................................... 1
Declaration of Originality ........................................................ Error! Bookmark not defined.
Project Outline .............................................................................................................................. 2
Acknowledgements ................................................................. Error! Bookmark not defined.
Table of Contents ......................................................................................................................... 3
List of Figures .......................................................................... Error! Bookmark not defined.
List of Tables ............................................................................ Error! Bookmark not defined.
1 Introduction in Rings and Spirals Resonators ............. Error! Bookmark not defined.
1.1 Split Ring Resonators .............................................. Error! Bookmark not defined.
1.2 Multiple Split-Ring Resonators ............................... Error! Bookmark not defined.
1.3 Spiral Resonators ..................................................... Error! Bookmark not defined.
2 Definitions of Antenna Terms ......................................... Error! Bookmark not defined.
2.1 Radiation Pattern ...................................................... Error! Bookmark not defined.
2.2 Directivity and Radiation Density ........................... Error! Bookmark not defined.
2.3 Radiation Pattern Lobes and Beamwidth ............. Error! Bookmark not defined.
2.4 Antenna Efficiency.................................................... Error! Bookmark not defined.
2.5 Gain ............................................................................ Error! Bookmark not defined.
2.6 Bandwidth .................................................................. Error! Bookmark not defined.
2.7 Return Loss ............................................................... Error! Bookmark not defined.
2.8 Polarisation ................................................................ Error! Bookmark not defined.
3 Feeding Techniques ........................................................ Error! Bookmark not defined.
3.1 Edge Discrete Feeding ............................................ Error! Bookmark not defined.
3.2 Coaxial Probe Feeding ............................................ Error! Bookmark not defined.
3.3 Proximity Coupled Feeding ..................................... Error! Bookmark not defined.
3.4 Aperture Coupled Feeding ...................................... Error! Bookmark not defined.
4 Single Arm Stacked PSR with Edge Discrete Port FeedingError! Bookmark not defined.
4.1 Single Arm Pair Spiral Resonator Configuration . Error! Bookmark not defined.
4.2 Edge Discrete Port Feeding.................................... Error! Bookmark not defined.
4.3 Effect of Variation in Length of Inner Arm............. Error! Bookmark not defined.
4.4 Effect of Bottom Spiral Rotation ............................. Error! Bookmark not defined.
4.5 Effect of Differentiation in Materials ....................... Error! Bookmark not defined.

4. 5 Single Arm Stacked PSR with Coaxial Probe FeedingError! Bookmark not defined.
5.1 Coaxial Probe Feeding at the Terminal of the SpiralError! Bookmark not defined.
5.2 Effect of Bottom Spiral Rotation ............................. Error! Bookmark not defined.
5.3 Coaxial Probe Feeding at the Centre of the SpiralError! Bookmark not defined.
6 Dual Arms Stacked Pair Spiral Resonators ................. Error! Bookmark not defined.
6.1 Dual Arms PSR Configuration ................................ Error! Bookmark not defined.
6.2 Coaxial Probe Terminals Fed Dual Arms PSR .... Error! Bookmark not defined.
6.3 Edge Discrete Port Fed Dual Arms PSR .............. Error! Bookmark not defined.
6.4 Coaxial Probe Centres Fed Dual Arms PSR ....... Error! Bookmark not defined.
6.5 Coaxial Probe Terminal and Centre Fed Dual Arms PSRError! Bookmark not defined.
6.6 Effect of Bottom Spiral Rotation ............................. Error! Bookmark not defined.
6.6.1 Bottom Spiral Rotation in Coaxial Probe Centres Fed Dual Arms
PSR Error! Bookmark not defined.
6.6.2 Bottom Spiral Rotation in Coaxial Probe Centre and Terminal Fed
Dual Arms PSR ................................................................ Error! Bookmark not defined.
6.7 Effect of Shorting-Pin ............................................... Error! Bookmark not defined.
6.7.1 Coaxial Probe Centre Fed Dual Arms PSR, Shorting-Pin at the
Centre Error! Bookmark not defined.
6.7.2 Coaxial Probe Terminal Fed Dual Arms PSR, Shorting-Pin at the
Centre Error! Bookmark not defined.
6.8 Effect of Shorting Pin with Bottom Spiral RotationError! Bookmark not defined.
6.8.1 Bottom Spiral Rotation in Coaxial Probe Centre Fed Dual Arms
PSR, Shorting-Pin at the Centre.................................... Error! Bookmark not defined.
6.8.2 Bottom Spiral Rotation in Coaxial Probe Terminal Fed Dual Arms
PSR, Shorting-Pin at the Centre.................................... Error! Bookmark not defined.
7 General Discussion.......................................................... Error! Bookmark not defined.
8 Conclusions....................................................................... Error! Bookmark not defined.
9 References ........................................................................ Error! Bookmark not defined.
Appendices............................................................................... Error! Bookmark not defined.
Appendix I – Absolute Radiation Patterns of Single Arm Edge Discrete Port
Fed PSR under Real and Ideal Conditions ..................... Error! Bookmark not defined.
Appendix II – Absolute Radiation Patterns of Dual Arms Coaxial Probe
Centre Fed PSR, Shorting-Pin at the Centre under Real and Ideal
Conditions ............................................................................. Error! Bookmark not defined.
Appendix III – Absolute Radiation Patterns of Dual Arms Coaxial Probe
Terminal Fed PSR, Shorting-Pin at the Centre under Real and Ideal
Conditions ............................................................................. Error! Bookmark not defined.