Complex Permittivity and Thickness Evaluation of Low-Loss Dielectrics From Uncalibrated Free-Space Time-Domain Measurements
Uğur Cem Hasar, Yunus Kaya, Hamdullah Öztürk, Mucahit Izginli, Joaquim J. Barroso, Omar M. Ramahi, Mehmet Ertuğrul
Abstract
A free-space time-domain method is proposed to retrieve dielectric constant (<inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>), conductivity (<inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>), and thickness (<inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula>) of metal-backed low-loss dielectric samples using calibration-independent reflected power peak measurements. Its algorithm is validated by numerical calculations and simulations (CST Microwave Studio) using a sine-modulated Gaussian window. A sensitivity analysis is followed to examine its performance considering the dependencies of reflected power peaks with respect to <inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>. Free-space time-domain measurements have been implemented after transforming frequency-domain measurements into time-domain ones to extract <inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> of polypropylene, polyethylene, and polyoxymethylene samples.