Dispersion engineering of transmission line metamaterial structures

Program Code: 

Dr Greg Milford (g.milford@adfa.edu.au)

Description of Work: 


The non-conventional propagation characteristics of left hand transmission lines (LH TL) offer a new degree of freedom for the design of high frequency wave-guiding and wave-radiating components. A distinguishing feature of LH TL structures is the nature of the frequency dependent propagation coefficient, from left-handed to right-handed as frequency increases across the pass-band. A number of interesting applications have been proposed for 1D and 2D LH TL structures (frequency selective waveguides, leaky wave antennas, etc), however accurate characterisation and control of the dispersion characteristic is necessary for these ambitions to be realised. This project will investigate the application of evolutionary computation (EC) methods to the optimisation-based extraction of the LH TL unit cell dispersion characteristic from frequency response data. As this extraction process is based on equivalent circuit modelling of the unit cell structures, the project will also involve investigations into the selection of appropriate equivalent circuit models for various LH TL structures to accurately capture the unit cell’s frequency dependence. The application of these techniques to better LH TL unit cell design will also be explored.

Expected Background knowledge and skills:

  • Good theoretical understanding of electromagnetic and microwave engineering
  • Good programming skills and experience with one or more computational tools. (Matlab, C, Fortran, etc).
  • Experience with commercial circuit and full wave simulation tools desirable.

Description of work:

  • Investigate planar topologies that produce LH TL unit cells, and develop appropriate equivalent circuit models for these structures.
  • Determine the applicability and limitations of using equivalent circuit based optimisation methods for extracting the dispersion characteristic from simulated and measured frequency response data.
  • Use this knowledge to devise new LH TL structures with superior performance characteristics.
  • Design, fabricate and characterise the performance of demonstration LH TL structures.