Ugur Cem Hasar

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In this paper, we investigate the effect of non-uniformities (enlargement of current passage, non-equal surface current densities, etc.) in axial as well as transverse directions of a porous silicon Fabry-Perot (FP) cavity as well as loss nature of bulk silicon on spectral properties of this cavity, even that cavity is created with an anisotropic etching(More)
A promising microwave non-resonant method has been proposed for accurate constitutive parameter measurement of magnetic materials. The method eliminates the undesired ripples in the extracted parameters by using a medium-loss reference sample and employing one reflection and one transmission measurements. In addition, it is non-iterative and based on(More)
We propose an effective microwave method for reference-plane-invariant and thickness-independent constitutive parameters measurement of thin materials. A function depending only on the interface reflection coefficient to facilitate fast computations of constitutive parameters is derived. In addition to the extraction of sample thickness, the method can also(More)
An effective method for extraction of electromagnetic properties of bianisotropic biaxial omega-type metamaterial (MM) slabs from waveguide measurements is presented. The method relies on measurements of S-parameters of two MM slab configurations (transverse and longitudinal) to extract electromagnetic properties endowed with strong bianisotropic coupling.(More)
A calibration-independent method is proposed for accurate complex permittivity (<inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>) determination of dielectric samples from raw scattering parameter measurements without resorting to any information of thickness (<inline-formula> <tex-math notation="LaTeX">$L$(More)
Calibration-dependent methods, before starting to measurements, require some sort of expensive calibration kits, which could reduce the accuracy of measurements due to the application of imperfect calibration standards. To eliminate such problems and reduce the overall cost of the measurement setup, in this research paper, a novel calibration-independent(More)
A simple procedure is proposed for the unique permittivity determination of low-loss materials using transmission-only measurements. The procedure utilizes phase measurements at two frequencies corresponding to any extreme values of the transmission properties. We derived a simple relation for the permittivity extraction.
It is well recognized that near-field effects become dominant when the metamaterial (MM) is in resonance. In addition, any inaccurate information of the location of reference planes, and the effective length can seriously affect the accuracy of retrieved electromagnetic properties of MMs. By considering all these issues, in this research paper, we propose a(More)
We apply a complete uncertainty analysis, not studied in the literature, to investigate the dependences of retrieved electromagnetic properties of two MM slabs (the first one with only split-ring resonators (SRRs) and the second with SRRs and a continuous wire) with single-band and dual-band resonating properties on the measured/simulated scattering(More)
We investigate the effect of fabrication parameters (nonequal surface current densities, impurities inside the structure, etc.) and loss factor on reflectivity and transmittivity measurements from porous silicon Fabry-Pe&#x0301;rot cavities with finite-size substrate thicknesses. We apply the formalism based on wave cascade matrix method for obtaining(More)