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(Meta)material characterisation and thin-film sensing using quasi-optical technique in millimetere wave band

Friday, 21 May, 2010 - 10:00
Campus: Brussels Humanities, Sciences & Engineering campus
Amna Elhawil
phd defence

The work presented in this thesis concerns exploring, developing and analysing methods and
algorithms that are applied to material properties characterisation at millimetre frequencies using
a quasi-optical technology.

Firstly, the quasi-optical measurement technique is shown and a developed calibration method is

Secondly, a novel extension to the Nicolson-Ross-Wier (NRW) algorithm to calculate the
dielectric properties of single-layer materials is illustrated.

Thirdly, the multilayer structure are characterised using two optimisation algorithms: genetic
algorithm (GA) and sequential quadratic programming based on the quasi-Newton (Broyden-
Fletcher-Goldfarb-Shanno) method (BFGS-SQP). A comparison between their ultimate
performance is validated. They have been compared on speed, accuracy and robustness.

After that, developed materials that have a negative refractive index at mm-wave frequency are
shown. a simple and accurate analytical LC model is proposed to compute the
LC resonant frequency response.

The model is verified numerically and experimentally in mm-wave frequency range with a
normal incidence illumination. Moreover, the effect of the geometric parameters has been also
studied. Finally, The application of these designs to characterise tiny amounts of chemicals and
optical sensing is presented.