Stability and control of nonlinear transmission line metamaterials

Program Code: 

Dr Greg Milford (

Description of Work: 


The inclusion of nonlinear (NL) elements in a distributed left-handed transmission line (LH TL) structure adds an extra dimension to the dispersion engineering potential of these structures. It has been shown that these distributed nonlinear structures display a range of unstable behaviour similar to that observed with lumped devices (eg. radio frequency power amplifiers) and homogenous bulk materials (eg. harmonic generation in nonlinear optical materials). This project will investigate the mechanisms responsible for instability in NL LH TL structures. Previous research at UNSW Canberra has led to methods for detecting and predicting Hopf-type bifurcations in these structures, but much more work needs to be undertaken to further develop theoretical and numerical methods to describe these structures. The knowledge and insight gained from this analysis would then be used to devise design strategies to control and/or exploit these instabilities.

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 the application of traditional control systems theory to NL LH TL structures for stability analysis and performance characterisation.
  • Apply these analysis techniques to the design of NL LH TL structures.
  • Develop techniques for fabricating and controlling distributed nonlinearities.
  • Fabricate and characterise planar NL LH TL structures with distributed nonlinearities for harmonic generation and/or parametric amplification.