Nickolay T. Cherpak

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The electrodynamic characteristics of a high-Q dielectric whispering gallery mode resonator in the form of a hemisphere positioned on an impedance plane were studied. The analysis of the anisotropic resonator was modeled using Maxwell equations and the impedance Leontovich boundary condition. The interaction coefficient A<sub>S</sub><sup>j</sup> of the(More)
Whispering gallery modes (WGMs) were exited in a new type of microstrip circular resonator formed under a conducting disc placed directly on or above a continuous dielectric layer. Resonance frequencies, quality factors, and distributions of the microwave field for different WGMs have been studied numerically and experimentally as a function of distance(More)
The DC transport properties and microwave absorption (at 41 GHz) are measured in a bulk ceramic sample and a film (220 nm thick) of La0.5Sr0.5CoO3−δ. The bulk sample has been cut from a target from which the film was pulsed-laser deposited. It is found that the temperature behavior of DC resistivity and magnetoresistance of the bulk sample is quite(More)
Studies of biochemical liquids require precise determination of their complex permittivity. We developed a microwave characterization technique on the basis of a high-quality whispering-gallery mode (WGM) sapphire resonator with a microfluidic channel filled with the liquid under test. A novel approach allows obtaining the complex permittivity of(More)
Millimeter-wave surface impedance of optimally-doped Ba(Fe1−xCox)2As2 single crystals A. Barannik,1 N. T. Cherpak,1,* M. A. Tanatar,2 S. Vitusevich,3 V. Skresanov,1 P. C. Canfield,2,4 and R. Prozorov2,4,† 1Solid State Radiophysics Department, Institute of Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkiv, Ukraine 2Ames(More)
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