This paper presents a free-space reflection measurement technique for estimating dielectric constant and loss tangent of different materials, demonstrated for rock samples, at S-band. The method is non-contact as well as non-invasive, which is used to characterize the electromagnetic properties of different materials (in our case, rock samples) at S-band in a non-anechoic chamber environment. The technique involves measurement of reflected signals (S11 data from Vector Network Analyzer) from the material under test (MUT) as well as for the surroundings. By taking the inverse-Fourier Transform of S11 data, the impulse-response corresponding to the reflected power from the MUT can be estimated. The proposed scheme overcomes the portability issue as well as the requirement of an anechoic environment. The measurement system consists of a single antenna (centered at 2.5 GHz), rock samples (i.e. material under test (MUT)), a perfectly conducting plate and a mounting fixture. By processing and analyzing the reflection coefficient data, the values of dielectric constant and loss tangent are calculated using the proposed algorithms which take care of clutter removal as well. The technique is validated using the estimated values of rock samples corresponding to their composition values available in the literature and found to be in good agreement. Estimation of dielectric properties of rock samples will be used to validate algorithms for science studies using SAR data of Chandrayaan-2 and other planetary missions. Hence, this measurement process will play a key role towards understanding of surface composition and features of the planetary bodies.
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