Journal ArticleDOI
Microwave Measurements of the Dielectric Properties of Gases
TLDR
In this article, an accurate and sensitive method for measuring the complex dielectric constant (e′−ie) of gases in the microwave region is described and critically investigated for sources of error.Abstract:
An accurate and sensitive method for measuring the complex dielectric constant (e′‐ie″) of gases in the microwave region is described and critically investigated for sources of error. A resonant‐cavity method is used in which the cavity response curve is displayed on a cathode‐ray tube. The variation of resonance frequency and Q of the cavity when filled with gas are determined from measurements with two frequency markers. The equipment is operated at 9000 Mc, and cavities with Q's of 1×104 are used. In the determination of e′‐1 (dimensionless) of very low loss gases, an accuracy of 0.4 percent and a sensitivity of 4×10−7 can be obtained. In the determination of the loss factor e″, an accuracy of 2 percent and a sensitivity of 5×10−7 can be obtained. This method is useful for measuring dispersion and absorption in solids and liquids as well as gases.Experimental results are given and briefly discussed for e′‐1 of O2, N2, CO2, He, and air, and for e″ of NH3 as a function of pressure up to 20 cm Hg.read more
Citations
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Journal ArticleDOI
The Constants in the Equation for Atmospheric Refractive Index at Radio Frequencies
TL;DR: In this paper, a relation 77.6 e N = ~ p + 4,810-T T where p = total pressure in millibars e=partial pressure of water vapor in millibrars T=absolute temperature=°C+273
Journal ArticleDOI
Open-ended coaxial probe technique for dielectric measurement of biological tissues: challenges and common practices
Alessandra La Gioia,Emily Porter,Ilja Merunka,Atif Shahzad,Saqib Salahuddin,Marggie Jones,Martin O'Halloran +6 more
TL;DR: Each step of the coaxial probe measurement procedure is discussed, highlighting common practices, challenges, and techniques for controlling and compensating for confounders.
Journal ArticleDOI
The Refractive Indices and Dielectric Constants of Air and its Principal Constituents at 24,000 Mc/s
L Essen,K D Froome +1 more
TL;DR: In this paper, the authors measured the refractive indices of air and its principal constituents at a frequency of 24,000 Mc/s with a precision comparable with that obtained in the optical range.
Journal ArticleDOI
Electron Paramagnetic Resonance and Electrochemistry. Studies of Electrochemically Generated Radical Ions in Aqueous Solution.
Journal ArticleDOI
Absolute Determination of Refractive Indices of Gases at 47.7 Gigahertz
A. C. Newell,R. C. Baird +1 more
TL;DR: In this paper, the authors measured the refractive index of a gas by measuring the change in the resonant frequency when the gas is admitted to a previously evacuated microwave cavity at a frequency of 47.736 GHz, and is the first such measurement in this frequency range.
References
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Book
Principles of Microwave Circuits
TL;DR: This book discusses waveguide junctions with several arms, dielectrics in waveguides, mode transformations, and the symmetry of wave guide junctions.
Journal ArticleDOI
On the Shape of Collision-Broadened Lines
Journal ArticleDOI
Electronic frequency stabilization of microwave oscillators.
TL;DR: Two circuits for use to control the frequency of a microwave oscillator by an external high Q cavity are described, and a technique by which the frequency‐stabilization systems could be used to investigate the structure of microwave absorption spectra is suggested.
Journal ArticleDOI
The Absorption of Microwaves by Oxygen
TL;DR: In this article, the authors compared the theoretical properties of the absorption in the near-half-kilometre-wave-length regime with the theoretical dependence of absorption on pressure, and particularly interesting because of the relation to the mechanism of collision broadening and because the resonances to individual rotational lines are resolved at low pressures.
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The Refractive Indices and Dielectric Constants of Air and its Principal Constituents at 24,000 Mc/s
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