A. Cereti

Time domain reflectrometry: Calibration techniques for accurate measurement of the dielectric properties of various materials

In this work, an extensive theoretical and experimental analysis has been carried out on the main factors that affect the accurate evaluation of dielectric properties using time domain reflectometry (TDR). Dielectric constant measurements have been performed under different experimental conditions for various types of materials having a wide range of permittivity values. Interpretation of the results on the basis of the transmission-line theory emphasizes the importance of a suitable calibration procedure that takes into account several critical aspects, some of which seem to have been disregarded or underestimated in the literature. Qualitative and quantitative information is given on the kind of corrections needed in order to significantly improve the reliability of the TDR technique for permittivity measurements.

Electromagnetic propagation features of ground penetrating radars for the exploration of martian subsurface

In this work, the effects of magnetic inclusions in a Mars-like soil are considered with reference to the electromagnetic propagation features of ground-penetrating radars (GPRs). Low-frequency and time-domain techniques, using L-C-R meters and TDR instruments, respectively, are implemented in laboratory experimental set-ups in order to evaluate complex permittivity and permeability and wave velocity for different scenarios of a dielectric background medium (silica) with magnetic inclusions (magnetite). Attenuation and maximum detection ranges have also been evaluated by taking into account a realistic GPR environment, which includes the transmitting/receiving antenna performance and the complex structure of the subsurface. The analysis and the interpretation of these results shed new light on the significant influence of magnetic inclusions on the performance of Martian orbiting and rover-driven GPRs.

Shorted-end probes for accurate permittivity measurements with time-domain reflectometry

An investigation is presented on the use of short-circuit terminations in two-wire transmission lines employed as probes in standard time-domain-reflectometry (TDR) setups. Experimental permittivity results are given for different configurations and materials, and these data are compared with those achievable using conventional open-type terminations. The possibility of both improving the accuracy and simplifying the procedures of TDR measurements using shorted-end probes is illustrated.