Search Results

Microwave Attenuation Standards and Measurements

Description: Report discussing microwave attenuation measurement methods and standards. In addition, a relatively new and more precise way of representing and analyzing an attenuation measurement is presented. This in turn permits more rigorous definitions and error analyses than were previously possible. The referral of microwave attenuation measurements to standards operating at lower frequencies is discussed with particular attention to the errors in the referral processes as well as the errors in the standards themselves. Desirable characteristics are listed for attenuators which are suitable for calibration. Measurement methods are classified and described. Comments are made on the accuracy and convenience of various methods, and references are given which cover most of the basic and important research in this field. Key words: Microwave, attenuation, measurements, standards, tutorial.
Date: April 3, 1967
Creator: Beatty, Robert W.
Partner: UNT Libraries Government Documents Department

Interaction of Microwaves and Germinating Seeds

Description: This investigation was concerned with determining the interaction of microwaves with germinating seeds. This study covers two different approaches. The preliminary efforts covered the response of germinating seeds to treatment by microwaves and heat. The second phase of the investigation used microwaves as a probe to determine some of the processes of early seed germination. The preliminary investigation measured the internal metabolic process by ATP production. Leakage of ions and organic material from germinating seeds indicated that membranes are a target of microwaves and heat. Electron photo-micrographs showed an increase in damage to membranes as heat and microwave treatments were increased. The second phase of this investigation was concerned with determining some of the biological activity at the initiation of germination of wheat seeds, Triticum aestivum L., using a resonating microwave cavity oscillating at 9.3 GHz as a probe. Direct current conductivity measurements were also made on the seeds as a means of confirming the observations made with the microwave cavity. There was no observable difference between treatment by UHF or heat in the ultrastructure of germinating seeds. A dielectric response far above that of free water was found as live seeds of wheat began to imbibe water. This effect was assumed to be due to the release of ions, because conductivity increased as corresponding quantities of water were imbibed; and both conductivity and dielectric response decreased as imbibition progressed. Although dead seeds also imbibe water, they do not show this decrease in dielectric response. The dielectric response of live seeds was reduced after the initial imbibition, showing that water became tightly bound as imbibition progressed. The dielectric response of actively growing shoots from the seeds was much less than that of the seeds themselves. The large quantity of water in the shoots is assumed to be immobile, being tightly ...
Date: August 1987
Creator: Shafer, Floyd L. (Floyd Lorenz)
Partner: UNT Libraries

Microwave Spectral Tables: Volume 3. Polyatomic Molecules With Internal Rotation

Description: From Introduction: "This volume contains data on the microwave spectra of 94 polyatomic molecules capable of exhibiting internal rotation, based upon a search of the literature up to July, 1962, but including some information of later dates."
Date: June 1969
Creator: Wacker, Paul F.; Cord, Marian S.; Burkhard, Donald G.; Petersen, Jean D. & Kukol, Raymond F.
Partner: UNT Libraries Government Documents Department

BOLOVAC Systems for Measuring Electrical Quantities From 0.5 MHz Through Microwaves

Description: From Introduction: "This paper describes in some detail how Bolovac works, when its structural components are, what are the methods and steps of the procedure in its various major applications, and reasons for its advantages. The emphasis is on applications. Present status at the National Bureau of Standards relating to fabricating the most important component of the Bolovac-the bolometric disk-is briefly pointed out."
Date: January 1972
Creator: Selby, Myron C.
Partner: UNT Libraries Government Documents Department