1. 03ELD030 :: FINAL YEAR PROJECT Asymmetric CoPlanar Strip Antenna Optimiser
Student Mr Daniel Birkett ( )
Course MEng Electronic & Electrical
Engineering Ext.
Supervisor Dr J A Flint

2. Asymmetric CoPlanar Strip
Asymmetric CoPlanar Stripline
Asymmetric Strips S1,S2 have unequal widths: W1!=W2
CoPlanar Conductors in the same plane
Asymmetric CoPlanar Strip
Antenna Optimiser

3. Asymmetric CoPlanar Strip
Abstract
The aim of the project was to create a tool to aid the design of Asymmetric CoPlanar Strip antennas
Uses of such antennas can be found in equipment including mobile communications.
The asymmetric coplanar folded dipole is an appealing choice for two primary reasons:
It can be constructed using printed circuit technology
Its input impedance can be made to match that of printed circuit transmission lines.
The input impedance depends on three quantities:
The impedance of the transmission line mode
The impedance of the dipole mode
The impedance step-up ratio.
The project proposal was set by Dr J A Flint, who required an application to simplify the analysis required in antenna design as part of his research in wireless systems.
The project itself focusing around use with 3rd Generation, 3G operating frequencies
Asymmetric CoPlanar Strip
Antenna Optimiser

4. Asymmetric CoPlanar Strip
Objective(s)
“Develop a computer based system capable of analysing the properties of asymmetric coplanar strip antennas using principally physical dimensions” 
Validate theoretical design equations through full field quasi-static simulations, using Finite Element Analysis software.
Evaluate unknown electrical characteristics using antenna modelling software.
Design software modules to implement theoretical calculations for arbitrary parameters.
Create a Graphical User Interface to consolidate software modules and display appropriate analytical information.
Asymmetric CoPlanar Strip
Antenna Optimiser

5. Objective (1) :: Characteristic Impedance
Validate theoretical design equations through full field quasi-static simulations, using Finite Element Analysis software.
ACPS full field simulation
Simulation interacting with boundary
The capacitance can be calculated by either using the energy stored or charge.
The equation to calculate the characteristic impedance is
The characteristic impedance calculated through the theoretical design equations is within 6% of the value calculated through FEA
Asymmetric CoPlanar Strip
Antenna Optimiser

6. Objective (2) :: Dipole Impedance
Evaluate unknown electrical characteristics using antenna modelling software.
The computer program AWAS for Windows (Analysis of Wire Antennas and Scatterers) is capable of analyzing wire antennas operating in the transmitting and receiving modes, as well as analyzing wire scatterers. The technique is based on the two-potential equation for the distribution of wire currents. This integro-differential equation is solved numerically, using the method of moments with a polynomial (power-series) approximation for the current distribution
The analysis method requires only a small number of polynomial coefficients (about 6 to 9 per wavelength).
It can analyze structures up to about 100 wavelengths in total wire length.
The program can analyze arbitrary structures that are assembled from straight-line wire segments (of circular cross sections). Each wire segment is assumed to have its own radius. Each segment connects two points in space, referred to as nodes. Each node is defined by three Cartesian coordinates (x,y,z)
“The kernel of the program can be used on a stand-alone basis, or it can be incorporated into a user-written program, such as an optimization procedure for antenna synthesis”
Asymmetric CoPlanar Strip
Antenna Optimiser

7. Objective (3) :: Calculation Flow
Design software modules to implement theoretical calculations for arbitrary parameters.
The input impedance depends on three quantities:
The impedance of the transmission line mode
The impedance of the dipole mode
The impedance step-up ratio.
Asymmetric CoPlanar Strip
Antenna Optimiser

8. Objective (4) :: ACPS Optimiser
Create a Graphical User Interface to consolidate software modules and display appropriate analytical information.
Asymmetric CoPlanar Strip
Antenna Optimiser

9. Asymmetric CoPlanar Strip
Conclusion
From the objectives set: all have been completed successfully.
The tool created, greatly simplifies the design process by a magnitude.
The tool provides a GUI which rivals the older AWAS shell
Future devolvement could be extended in numerous ways, including:
Admittance and scattering parameters
The presence of a conducting ground plane or a dielectric
Specific wave data
- The system is capable of analysing the impedance properties of a folded dipole antenna using its physical dimensions. It evaluates the unknown electrical characteristics via utilising AWAS’ numerical kernel and, uses software modules to implement the theoretical calculations for arbitrary parameters. As well as providing a Graphical User Interface to consolidate the software modules and display appropriate analytical information.
Although utilising only a fifth of the kernel capability (due to the project specifications): the tool, uniquely, implements this successfully. - The numerical kernel is capable of analysing antennas in far greater detail than required of it within the project objectives
(specific wave data) plane waves, near and far field wave information.
Asymmetric CoPlanar Strip
Antenna Optimiser

10. Asymmetric CoPlanar Strip
Any Questions
Asymmetric CoPlanar Strip
Antenna Optimiser