Electron densities and collision frequencies were obtained on a number of gases in a dc discharge at low pressures (0.70-2mm of Hg). These measurements were performed by microwave probing of a filament of the dc discharge placed coaxially in a resonant cavity operating in a TM010 mode. the equipment and techniques for making the microwave measurements employing the resonant cavity are described.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Michael Anthony Zuniga. / Ph.D.

David J. Rose ... [et al.]. / "October 17, 1949." / Army Signal Corps Contract No. W-36-039 sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Sanborn C. Brown ... [et al.]. / "May 17, 1948." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039 sc-32037.

No description available.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Electrical and Computer Engineering, Thomas J. Watson School of Engineering and Applied Science, 2008. / Includes bibliographical references.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: James Stevenson Kenney; Committee Member: Gregory David Durgin; Committee Member: Madhavan Swaminathan

Thesis (M.S.)--University of Michigan, 1990.

<p> An investigation has been made of the microwave reflections from the surface of a semiconducting medium with complex permittivity (^ε = εrεo -jσ/ω) at the open end of an empty rectangular waveguide. The approximate and exact solutions of the reflection coefficients at the surfaces of both finite and semi-infinite media have been found as a function of the complex permittivity of the medium. The computations of the reflection coefficients are made at the 10 and 35 GHz ranges. Measurements, which confirm these calculations, have been performed with n-type germanium, selectron, and air at the open end of a rectangular waveguide using a reflection type microwave bridge. The investigation has shown that it is possible to devise a convenient method of measuring the conductivity and dielectric constant of semiconductors.</p> <p> The theory of operation of the microwave reflection bridge together with the setting-up (matching) procedure of a practical form of the bridge has been presented. A method is also described for the correction of the measurement error which arises from the scattering coefficients at the input ports of the precision attenuator.</p> <p> A theoretical and experimental study has also been made of the small- signal microwave conductivity of n-type germanium at room temperature in the presence of a high electric field, directed at an angle θ to the microwave field. The study has shown that at frequencies such as 10 GHz, the microwave conductivity becomes anisotropic with respect to the direction of the d.c. field vector. Measurements are made on an 11.4 ohm cm, n-type germanium sample at 9.381 GHz with applied electric fields up to 1.8 KV/cm for θ = 0°, 40°, and 90°. The ''open-end-waveguide measuring technique", which allows the angle between the microwave and d.c. field vectors to be varied, was employed to measure the microwave conductivity. The results of measurements which agree with predictions, confirm the feasibility of operation of a new microwave device based on the anisotropic effect.</p> / Thesis / Doctor of Philosophy (PhD)

The application of microwave radiation for processing of glassy and semicrystalline thermoplastics, elastomeric polymers and composites was investigated. The goal of this research was to reveal the relationship between polymer structure and microwave absorptivity, and hence processability. The specimens were subjected to an electric field at 2.45 GHz either inside a rectangular waveguide or in a cylindrical resonant cavity applicator with less than 100 watts applied power. Both travelling wave modes and standing wave modes were examined. Temperatures, powers and times were recorded, leading to the concept of "microwave calorimetry." Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and the dipole moments of small molecule analogues. Evaluating heatability was most accurately found to be determined by the magnitude of (ε_S - ε_∞), the oscillator strength. The value of (ε_S - ε_∞) should be used together with the distribution of relaxation times and the activation energies of dipolar dispersion to predict heatability for microwave processing. The critical temperatures, T_C, of dielectric loss were obtained from the intercepts of positive slope tangents of heating rate versus temperature plots at 2.45 GHz for polymers. Microwave processing was rapid above the critical temperature where the maximum dielectric loss fell in the 2.45 GHz frequency domain for efficient coupling of energy to the polymers. Shifting the dielectric relaxation spectrum into the microwave region by directly or indirectly increasing the temperature of each sample was unique and of key importance to processability. A schematic model was proposed to explain the behavior of two-phase materials subjected to microwave heating. Combining the heatability, (ε_S - ε_∞), and the dielectric relaxation spectral response was found to be helpful in evaluating formulations of two-phase materials for electromagnetic radiation processing at high frequencies. / Ph. D.