This thesis examines the operation and control of a radiofrequency ion source.

This thesis examines temperature dependence of magnetic susceptibility of the organic free radical galvinoxyl.

No description available.

No description available.

Since the inception of the backscatter-radio technology, this field has continually evolved. As a result, this technology is used for a multitude of applications like personnel identification, logistics and assets management and military purposes etc. Radio Frequency Identification (RFID) technology works in several ISM-frequency bands. This work pertains to the design and development of an RF tag that uses 5.8 GHz ISM band for backscatter. This frequency band has many inherent advantages like higher gain antennas, smaller sized tags, increased immunity to conductive object losses, and larger RF bandwidth. The objective of this research is design and prototype development of an RF tag capable of sensing acceleration, angular motion, and shock experienced by an object on which it is installed. The sensed information is modulated onto an incident continuous wave (CW) and backscattered to the reader. Literature research suggested that such work has not been done previously using an RFID platform. The challenges include integration of the sensor, antenna and other electronics to efficiently backscatter the information to the receiver, designing a suitable planar antenna, realtime backscattering of the sensed information, and low power consumption. As a further step, it is required to design and integrate two antennas on RF tag to simultaneously backscatter the same information; and to measure and compare its effect with single antenna tag. The sensed impact/shock and rotational movement information from the inertial sensors (accelerometer and gyroscope) was backscattered instantly and displayed on the custom developed graphical user interface. The development of GUI was not part of this project and was developed by another lab member. RF Tags with single and dual antenna configurations were designed and tested. It was observed that by increasing the number of antennas higher read range can be achieved. Moreover, by doubling the antennas the radar cross-section for the tag was approximately doubled.

Includes bibliographical references (p. 45-47).

Includes bibliographical references (p. 52-53).

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Tentzeris, Manos; Committee Member: DeJean, Gerald; Committee Member: Ingram, Mary; Committee Member: Kavadias, Stylianos; Committee Member: Laskar, Joy. Part of the SMARTech Electronic Thesis and Dissertation Collection.

It is the purpose of this paper to present a detailed account of the design and construction of this positive-ion source and associated equipment.

This thesis presents results of average and impulsive noise measurements inside five office buildings and retail stores. Measurements were made at 918 MHz, 2.44 GHz, and 4.0 GHz using a superheterodyne receiver with 70 dB dynamic range and a 3-dB RF bandwidth of 40 MHz. Omni-directional and directional antennas were used to investigate the characteristics and sources of radio frequency noise in indoor channels. Statistical analyses of the measured data are presented in the form of amplitude probability distributions, pulse duration distributions, pulse spacing distributions, and noise factor distributions. Simple mathematical models of these statistical characterizations are also presented. The measurements and analyses indicate devices with electromechanical switches (copy machines, microwave ovens, printers, and electric motors) are principal sources of impulsive noise in retail and office environments. The 918 MHz band was consistently the worst band throughout the measurement campaign. This is attributed to higher path losses at 2.44 GHz and 4.0 GHz, and to adjacent and cochannel interference from users near the 902-928 ISM band. Pulse duration statistics indicate that no significant differences exist between impulse durations in the measured bands. This suggests that impulsive noise inside buildings is very wideband, and that pulse durations are directly a function of the receIver bandwidth. Pulse spacing statistics also indicate that intervals between consecutive impulses are similar in each frequency band. This thesis developed a computer simulation algorithm to create sequences of impulsive noise events which have statistical distributions similar to measured data. The statistical results for simulated impulsive noise are compared to measured distributions to illustrate the accuracy of the simulation algorithm. / Master of Science