High-Temperature Superconducting Spiral Resonator for Metamaterial Applications

Ghamsari, Behnood G.; Abrahams, J.; Remillard, Stephen K.; Anlage, Steven M.

doi:10.1109/tasc.2012.2232343

Cited by 19 publications

(23 citation statements)

References 15 publications

(18 reference statements)

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“…2D and 3D arrays also show the same feature when the sample is heated above 9.25 K. The inset shows a schematic of the 3D metamaterial sandwiched between two rf loop antennas which are 27.2 mm apart along the z axis. constructive and destructive interferences between the direct coupling of the loops and magnetic coupling of the loops to the metamaterial, respectively [35]. We observe higher-order modes corresponding to shorter-wavelength rf-current standing waves in the spiral, which have been extensively studied elsewhere [8,[36][37][38][39].…”

Section: Resultsmentioning

confidence: 67%

Tunable Negative Permeability in a Three-Dimensional Superconducting Metamaterial

et al. 2015

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We report on highly tunable radio-frequency (rf) characteristics of a low-loss and compact threedimensional (3D) metamaterial made of superconducting thin-film spiral resonators. The rf transmission spectrum of a single element of the metamaterial shows a fundamental resonance peak at ∼24.95 MHz that shifts to a 25% smaller frequency and becomes degenerate when a 3D array of such elements is created. The metamaterial shows an in situ tunable narrow frequency band in which the real part of the effective permeability is negative over a wide range of temperature. This narrow frequency band gradually possesses near-zero and positive values for the real part of permeability as the superconducting critical temperature is approached. The studied 3D metamaterial can be used for increasing power-transfer efficiency and tunability of electrically small rf antennas.

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Section: Resultsmentioning

confidence: 67%

Tunable Negative Permeability in a Three-Dimensional Superconducting Metamaterial

et al. 2015

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“…For high-Q devices matched to high impedances (i.e., loosely coupled to 50 Ω) through a coupling loop with small self-impedance L c , the frequency shift is negligible. The measurement of the resonant frequencies could also have been made using two loops and observing the transmission coefficient, but the mutual inductance between the two coupling loops would also have created a shift in the measured frequency as described in [16]. The spirals were placed at least nine radii from the ground plane so that resonance shifts due to eddy currents in the ground plane would be negligible.…”

Section: Methodsmentioning

confidence: 99%

An Empirical Expression to Predict the Resonant Frequencies of Archimedean Spirals

Hooker

Ramaswamy

Arora

et al. 2015

IEEE Trans. Microwave Theory Techn.

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This work presents an empirical formula to accurately determine the frequencies of the fundamental and higher order resonances of an Archimedean spiral in a uniform dielectric medium in the absence of a ground plane. The formula is based on method-of-moments simulations which have been experimentally validated. This empirical formula is widely applicable to a broad range of spirals from thin-ring to disk-shaped (ratio of inner to outer radii 0 to 1), with 10 or more turns.

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“…Some methods like that presented in [10] do not take the effect of the dielectric into account. Other methods that use circuit models address it indirectly in the calculation of capacitances [11]. In order to be able to predict the mode frequencies of most actual devices, the effect of the substrate also needs to be taken into account.…”

Section: Introductionmentioning

confidence: 99%

Effects of Dielectric Substrates and Ground Planes on Resonance Frequency of Archimedean Spirals

Hooker

Ramaswamy

Arora

et al. 2016

IEEE Trans. Appl. Supercond.

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Superconducting self-resonant spiral structures are of current interest for applications both in metamaterials and as probe coils for nuclear magnetic resonance (NMR) spectroscopy for high-sensitivity chemical analysis. Accurate spiral models are available in the literature for behavior of a spiral below and up to self-resonance. However, knowledge of the higher modes is also important. We present the relationships between the spiral parameters and the multiple mode frequencies of single sided spirals on dielectric substrates as modeled by method of moments simulation. In the absence of a ground plane, we find that the mode frequency has a linear though not necessarily harmonic dependence on the mode number. The effect of a thick substrate can be approximated by an effective dielectric constant. But when the thickness is less than 20% of the spiral trace width (router – rinner) this approximation is no longer accurate. We have developed a simple empirical formula to predict the higher modes.

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High-Temperature Superconducting Spiral Resonator for Metamaterial Applications

Cited by 19 publications

References 15 publications

Tunable Negative Permeability in a Three-Dimensional Superconducting Metamaterial

Tunable Negative Permeability in a Three-Dimensional Superconducting Metamaterial

An Empirical Expression to Predict the Resonant Frequencies of Archimedean Spirals

Effects of Dielectric Substrates and Ground Planes on Resonance Frequency of Archimedean Spirals

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