Microwave resonant absorption in metal-ammonia solutions

Breitschwerdt, K.G.; Radscheit, H.

doi:10.1016/0375-9601(75)90109-7

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…It should be emphasized that, although unusual, there exist physical systems with resonant frequencies as low as the microwave regime. Metal ammonia solutions constitute such examples with low-resonant frequency GHz due to relative large distances among charges and the relatively large masses of the charged particles [18]. This is of particular importance since it substantiates the realism and credibility of our theoretical design.…”

Section: A Resonant Dielectricsmentioning

confidence: 98%

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Novel material with narrow-band transparency window in the bulk

Kyriazidou

Díaz

Alexopoulos

2000

IEEE Trans. Antennas Propagat.

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This paper presents the theoretical design of an artificial dielectric exhibiting narrowband frequency selective properties in the bulk without relying on periodic placement of elements. In this manner, it initiates a novel approach that bypasses the drawbacks of the traditional frequency selective surfaces (FSS), namely, unwanted passbands, dependence on excitation angle and polarization, and difficulties in conversion from planar to curved geometries. The key design elements are the concentric geometry of the inclusions and the use of Lorentzian resonant media. A discussion of physical resonant materials is presented, substantiating the credibility of the theoretical design. To illustrate the approach, a novel complex medium is synthesized as an ensemble of spherical particles composed of a lossy core coated with a highly resonant dielectric layer and embedded into a dielectric host. The resulting structure is an amorphous substance, lossy over its entire spectrum except for two narrow-band transparency windows, where it may become as lossless as desired. The parameter space of the system is thoroughly analyzed which determines the type of constitutive materials and geometries for tailor-designing the windows according to specifications (shape, positioning and overall normalization). In this sense, the lossy concentric structure forms an ideal candidate for thin absorbing films (TAF's) with extensive applications in antenna systems, RF absorbers, and anechoic chambers.

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Section: A Resonant Dielectricsmentioning

confidence: 98%

“…An accurate modeling of the dielectric behavior near 10 GHz, requires a multiple-oscillator model, reflecting the multiplicity of physical oscillators in the solution [18]. Nonetheless, a single-oscillator model of the form with GHz…”

Section: A Resonant Dielectricsmentioning

confidence: 99%

Novel material with narrow-band transparency window in the bulk

Kyriazidou

Díaz

Alexopoulos

2000

IEEE Trans. Antennas Propagat.

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“…However, there has been evidence since the 1960's that certain metal-ammonia solutions possess a negative permittivity at X-band. In fact, in 1970, Breitsschwerdt and Radscheit [2] made microwave measurements of the real part of the permittivity of such solutions from 700 MHz to 2.5 GHz and in five waveguide bands at 6, 10, 23, 35, and 70 GHz. The reported curve (consisting essentially of six data points over two decades) strongly suggested a Lorentz resonance at 10 GHz.…”

Section: Statement Of the Problemmentioning

confidence: 99%

The Realization of a Lossy Material with a Prescribed Transparency Window in the Bulk

Díaz¹,

Glaunsinger²

2000

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Metal‐Nonmetal Transition in Metal‐Ammonia Solutions

Breitschwerdt¹,

Radscheit²

1976

Ber Bunsenges Phys Chem

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The properties of metal‐ammonia solutions in the concentration range of the metal‐nonmetal transition between 0.1 and 10 mol percent metal (MPM) are discussed. The high‐frequency electrical properties show a number of characteristic features in this intermediate concentration range, such as additional dielectric relaxations at about 0.1 MPM and 0.7 MPM for LiNH3 and NaNH3, respectively, and a resonance‐like behavior at about 1.0 MPM and 1.5 MPM for LiNH3 and NaNH3, respectively. For both LiNH3 and NaNH3 the real part of the high‐frequency dielectric function changes to large negative values around 2.5 MPM, indicating a transition to metallic behavior at high frequencies. The high‐frequency properties, which are also discussed in terms of electron conductivity, are explained quantitatively as a function of concentration, temperature, and frequency using a model of polaron hopping. The metal‐nonmetal transition is related to structural changes in the solutions which lead to phase separations in LiNH3 and NaNH3 at lower temperatures. The structural properties of the solutions are investigated using sound velocity and ultrasonic attenuation data. Concentration and temperature dependence of the ultrasonic attenuation in LiNH3 and NaNH3 can be described quantitatively in terms of structural fluctuation.

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Microwave resonant absorption in metal-ammonia solutions

Cited by 5 publications

References 5 publications

Novel material with narrow-band transparency window in the bulk

Novel material with narrow-band transparency window in the bulk

The Realization of a Lossy Material with a Prescribed Transparency Window in the Bulk

Metal‐Nonmetal Transition in Metal‐Ammonia Solutions

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