Fast Scattering Parameter Measurements based on Linear Frequency Ramps for Broadband Microwave Tomography Systems
M. Mallach, P. Gebhardt, and T. Musch Institute of Electronic Circuits, Ruhr-Universität Bochum
Universitaetsstrasse 150, 44780 Bochum, Germany firstname.lastname@example.org
Microwave tomography (MWT) is an imaging method that has been investigated as alternative or complementary technique for industrial process monitoring and multiphase flow imaging. These applications require fast scattering parameter measurements, which is one major challenge designing MWT systems. In this work, we propose a concept for very fast broadband transmission measurements (sweep time 1 ms) based on highly linear analog frequency ramps. The concept was validated by measurements of different reference microwave devices in the frequency range from 0.7 GHz to 5.5 GHz using homodyne single-channel prototype electronics. The measurement results are in very good agreement with the results obtained using a commercial vector network analyzer (VNA). Furthermore, in order to demonstrate the applicability of the concept for multiphase flow imaging, scattering parameter measurements of an 8-port MWT sensor were conducted using the single-channel prototype electronics and a 2x8 switching matrix. Qualitative approximations of the permittivity distributions in case of different static dielectric phantoms modeling oil/water-in-gas and water/gas-in-oil flow distributions were successfully reconstructed.
Keywords Microwave tomography, oil-gas-water flow imaging, scattering parameter
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