volume | PIER Journals

Abstract

A methodology for estimating the complex permittivity of liquid dielectrics is presented in a rectangular waveguide using the Ku-band (10-15 GHz, WR75). A two-dimensional finite difference time-domain (FDTD) model with perfectly matched layers (PMLs) serves as the forward solver, and TE₁₀ modal projection provides the simulated scattering parameters. Subsequently, a gradient-free Nelder-Mead inversion extracts the real and imaginary parts of the permittivity from the measured S₁₁ and S₂₁ parameters. This approach is implemented in a multilayer fixture, which enables leak-tight loading while remaining analytically simple. Validation on air and water shows good agreement between simulation and measurement across 10-15 GHz, and results at 12 GHz are consistent with independent X-band extractions. This approach is computationally efficient, practical for experimentation, and can be extended to other liquids and multilayers.

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Ms. Omaima Talmoudi

Dr. Lahcen Ait Benali

Prof. Jaouad Terhzaz

Professor Abdelwahed Tribak