138 research outputs found
Error-Corrected Reflection and Transmission Scattering Parameters of a Two-Port Device
No full textWe present an error correction algorithm for extraction of reflection and transmission scattering (S-) parameters of a two-port device without resorting to a complete two-port calibration. It is shown that S-parameters of thru and nonreflecting line connections in addition to S-parameters of an unknown device (and its reversed orientation) are needed for extracting full S-parameters of the device. For validation, we performed simulations for a chiral metamaterial (transmission asymmetric) and carried out measurements of S-parameters of an asymmetrically loaded waveguide section (reflection asymmetric)
Electromagnetic Characterization of Thin Dielectric Materials From Amplitude-Only Measurements
No full textA method is proposed for unique and accurate permittivity (epsilon(r)) extraction of low-loss thin samples from reference-plane-invariant amplitude-only measurements without resorting to the information of explicit permittivity of a sample holder. Thanks to the amplitude-only measurements, it is possible to bypass the increased phase uncertainty of scattering parameters and retrieve unique epsilon(r). An uncertainty analysis is followed to investigate improved accuracy attained by our method. Waveguide measurements at the X-band are next conducted to measure epsilon(r) of polyethylene and polyvinyl chloride samples with different lengths (the sample holder is a soda-lime glass) for validation of the method and for comparison its accuracy with other methods. From the comparison, we note that reference-plane-dependent methods necessitate precise knowledge of sample location for accurate epsilon(r) retrieval. Besides, it is observed that while compared reference-plane-invariant techniques either require that the sample holder does not move while positioning the sample over it or produce more than one solution for epsilon(r) measurement of low-loss dielectric samples, our method removes these two problems
Parameter Retrieval of Bianisotropic Metamaterials Without Application of the Passivity Principle
No full textIn this article, a microwave method has been proposed for accurate parameter retrieval of bianisotropic metamaterial (MM) slabs without enforcing the passivity principle. Thanks to the introduced asymmetrical even and odd reflection coefficients, not only is our method free from singularity-point problem (the argument of a square-root function crosses the negative real axis) explicit expressions for electromagnetic properties but it is also resistant to random noises more than the conventional method that strictly requires the application of the passivity principle. Our new method has been validated by measured and simulated scattering parameters of a fabricated Omega-type bianisotropic MM slab with C-shaped rings
Planar chiral metamaterial absorber composed of new crescent shaped split ring resonators
No full textThickness-invariant permittivity determination of materials from calibration-independent measurements
No full textAnalysis of Near-Field Effects for Electromagnetic Properties of Pasteur Chiral Metamaterial Slabs
No full textThis letter proposes a correct and robust retrieval method for extraction of electromagnetic properties of Pasteur chiral metamaterial (MM) slabs having asymmetrical transmission properties when near-field effects are present. The ray-tracing method has been applied to derive underlying equations for semi-infinite reflection coefficients of these slabs. A U-shaped Pasteur chiral MM slab was considered as a test slab to examine the near field effects on extracted semi-infinite reflection coefficients. It is noted that near-field effects should be taken into account for correct electromagnetic properties of Pasteur chiral MMs especially around resonance regions
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