Resonant Cavities for Dielectric Measurements

Works, C. N.

doi:10.1063/1.1697816

Cited by 35 publications

(8 citation statements)

References 10 publications

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“…For thin substrates, relative sample-thickness uncertainty dominates. In Table 3, the estimated accuracy for optimum-size samples agrees with estimates for similar instruments [20,24] …”

Section: Uncertainty Analysissupporting

confidence: 71%

Relative permittivity measurement of square copper-laminated substrates using the full-sheet resonance technique

1997

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“…For thin substrates, relative sample-thickness uncertainty dominates. In Table 3, the estimated accuracy for optimum-size samples agrees with estimates for similar instruments [20,24] …”

Section: Uncertainty Analysissupporting

confidence: 71%

Relative permittivity measurement of square copper-laminated substrates using the full-sheet resonance technique

1997

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“…At 450 MHz we determined the dielectric constant and loss tangent by means of a reentrant cavity [Works, 1947], with the sample located in a region of high electric field and negligible magnetic field. Powdered samples were measured in the s•me apparatus by placing the powder in thin-walled cylinders made of low-loss plastic; corrections were applied for the effects of the container.…”

Section: Methods Of Measurementmentioning

confidence: 99%

Electrical properties of rocks and their significance for lunar radar observations

Campbell¹,

Ulrichs²

1969

J. Geophys. Res.

312

194

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A wide variety of terrestrial rocks has been investigated to determine the range of variation of the high-frequency electrical properties. Both solid rocks and powders of various types have been measured at frequencies of 450 MHz and 35 GHz; some measurements have been made at elevated temperatures. Solid materials show wide variations in permittivity and absorption length, but apart from a small trend with silica content it is not clear that there is any pattern to the variations, and it is unlikely that measurements limited to these radar frequencies will be useful for identification. With powdered rocks, on the other hand, the variation from rock type to rock type is much smaller, but depends on the powder density in • quite predictable way. Consequently, radar information can be employed to make precise estimates of density and of density profiles even in the absence of information about composition. The long absorption lengths in powdered rocks indicate that radar reflections may occur at considerable depths in a regolith of the type found on the moon. INTRODUCTION Notwithstanding the growing body of planetaw radar and radiometric measurements, there are available few reliable determinations of the electrical properties of terrestrial rocks and minerals in the frequency range between 100 and 100,000 MHz. The relatively extensive compilations of electrical characteristics at low frequencies [see, for example, Parkhomenko, 1967] rarely include measurements above 10 MHz. Measurements on a few materials over a very wide frequency range have been made by the Massachusetts Institute of Technology Laboratory for Insulation Research [von Hippel, 1954, 1957; Westphal, 1963]. Griffin and Marovelli [1967] have published data on a large number of samples of rocks of six types, in the frequency range 20 to 100 MHz. Data on tektites and chondrites between 420 and 1800 MHz are included in a paper by Fenslet et al. [1962]. The only radar frequency determinations with any claim to comprehensiveness are those of Krotikov [1962], who studied both solid and powdered rocks at 3.0, 9.4, and 38 GHz. We are unaware of any data at higher frequencies X Now at School of Physics, University of Sydney, Australia. Copyrlght ¸ 1969 by the American Geophysical Union. than Krotikov's, although measurements have been made on isolated materials in the far infrared by using quantitative spectroscopic techniques.In this paper we report measurements of the dielectric constant and loss tangent of a wide variety of terrestrial rocks and minerals at two frequencies, 450 MHz and 35 GHz. These frequencies, corresponding to wavelengths of 67 cm and 8.6 mm respectively, lie near the extremes of the range spanned by current radar and radiometric observations of the moon and planets. Although our chosen frequencies themselves delimit a range of almost two decades, it will appear from the results we report that the electrical properties, permittivity and loss tangent, at the higher frequency differ as a rule only slightly from those at the lower frequency...

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“…Due to thin sample thickness, the reentrant cavity uncertainty for sample 1 was about 3% [6], while for sample 2, which was four times as thick, the re-entrant cavity imcertainty was about 1% [24].…”

Section: Presentation Of Computed Resultsmentioning

confidence: 99%

Relative permittivity measurement of rectangular copper-laminated substrates using the full-sheet resonance technique

1997

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A measurement program has been undertaken at NIST to evaluate the full-sheet resonance (FSR) technique, from which consistent relative permittivity values have been obtained. We present an analysis of the theory underlying the FSR technique, along with a theoretical formulation correcting full two-port scatteringmatrix measurements of a resonant cavity for the effects of coupling between the external measiurement circuit and the cavity. A circuit analysis modeling the resonant cavity and its external circuit is presented, along with a least-squares solution for the resonant cavity's primary resonance parameters. The least-squares analysis features a slight rearrangement of an earlier formulation leading to a more numerically stable solution. An even earlier solution for a resonant cavity's unloaded quality factor, also using a least-squares solution to obtain a coupling correction, is presented for comparison. The application of these coupling correction formulations to the FSR technique is discussed, and results from these two correction formulations are compared with uncorrected results for two sample FSR panels. Computed least-squares data-scatter uncertainties are obtained for each FSR permittivity measurement, which are then used to obtain overall uncertainty estimates for each panel's measured permittivity, including a repeatability uncertainty estimate. These overall uncertainty estimates are compared to our earlier uncorrected FSR uncertainty estimate, showing a tightening of the uncertainty interval for corrected measurements. Finally, om measured FSR permittivities are compared with re-entrant cavity substrate permittivity measurements, showing agreement within expected uncertainty limits between the two techniques.

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Resonant Cavities for Dielectric Measurements

Abstract: The variable length cavity described in this paper was the subject of a t.hesis submitted to the Graduate School of the University of Pittsburgh, in partial fulfillment of the requirements of the M. S. degree.

Cited by 35 publications

References 10 publications

Relative permittivity measurement of square copper-laminated substrates using the full-sheet resonance technique

Relative permittivity measurement of square copper-laminated substrates using the full-sheet resonance technique

Electrical properties of rocks and their significance for lunar radar observations

Relative permittivity measurement of rectangular copper-laminated substrates using the full-sheet resonance technique

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