Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 110-113). Also available in electronic format on the Internet.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006. / John Papapolymerou, Committee Chair ; Joy Laskar, Committee Member ; John Cressler, Committee Member ; Alan Doolittle, Committee Member ; Clifford Henderson, Committee Member.

Thesis (MScEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: An electro-optic sensor system was developed which uses the modulated scatterer technique [1] to measure the fine structure-amplitude and phase-of electric fields with the minimum of perturbation. The theory for the technique is discussed in detail, with the Lorentz Reciprocity theorem as foundation. The system is also treated as a general two port and solved in terms of the impedances present. This comprises self impedances and mutual impedances. The signals scattered by the dipole scatterer are modeled as amplitude modulated signals and a detailed detection scheme is presented. The detection of the signals is done by a digital correlation process. This is quite similar to synchronous detection. A detailed sensitivity analysis is presented that was used to determine the quality of the system. This analysis is backed by a practical sensitivity measurement. A few antennas and scatterers are measured in the X-band using the system, and results are compared with theory. These systems include a pyramidal horn, an E-plane sectoral horn and a simple waveguide. Half plane diffraction by a metal sheet is also presented. The practical implementation of the theory is emphasized. / AFRIKAANSE OPSOMMING: 'n Elektro-optiese meetsisteem is ontwikkel wat die gemoduleerde strooier tegniek [11 gebruik om die fyn struktuur-amplitude en fase-van elektriese velde te meet. Hierdie tegniek versteur die velde minimaal. 'n Volledige ondersoek word gedoen na die teorie van die stelsel. Die basis van die metode Ie in die Lorentz Resiprook teorie. Alhoewcl daar gekonsentreer word op hierdie teorie, is die stelsel ook beskou as 'n tweepoort. Die wedersydse en ei impedansies van die verskillende komponente word gebruik om die velde op te los. Die gestrooide seine, as gevolg van die dipool strooier, word gemodelleer met b hulp van amplitude modulasie. Die deteksie van hierdie seine word deeglik bespreek. In plaas van 'n analoogstelsel, word 'n digitale korrellasie proses gebruik om die velde te meet. Di sensitiwiteit van die stelsel word geanaliseer. Verder word metings met di stelsel gen em om die teoretiese analise te staaf. 'n Paar X-band sisteme word gebruik om metings te neem. Hicrdi metings word ook vergelyk met teor ti se resultate. Stelsels wat gemeet is sluit die volgencle in: 'n piramidale horing antenna, 'n E-vlak sektorale horing antenna, 'n X-band golfgeleier en die diffraksi op die rand van 'n plaat. Die praktiese implemcntering van die teorie word beklemtoon.

In situations where information infrastructure is destroyed or not available, on-demand information infrastructure is pivotal for the success of rescue missions. In this paper, a drone-carried on-demand information infrastructure for long-distance WiFi transmission system is developed. It can be used in the areas including emergency response, public event, and battlefield. In years development, the Drone WIFI System has developed from single-CPU platform, twin-CPU platform, Atmega2560 platform to NVIDIA Jetson TX2 platform. By the upgrade of the platform, the hardware shows more and more reliable and higher performance which make the application of the platform more and more exciting. The latest TX2 platform can provide real time and thermal video transmission, also application of deep learning of object recognition and target tracing. All these up-to-date technology brings more application scenarios to the system. Therefore, the system can serve more people in more scenarios.

A wireless communication system allows two parties to exchange information over long distances. The antenna is the component of a wireless communication system that allows information to be converted into electromagnetic radiation that propagates through the air. A system using an antenna with a highly directional beam pattern allows for high power transmission and reception of data. For a directional antenna to serve its purpose, it must be accurately pointed at the object it is communicating with. To communicate with a mobile node, knowledge of the mobile node's position must be gained so the directional antenna can be regularly pointed toward the moving target. The Global Positioning System (GPS) provides an accurate source of three-dimensional position information for the mobile node. This thesis develops an antenna control station that uses GPS information to track a mobile node and point a directional antenna toward the mobile node. Analysis of the subsystems used and integrated system test results are provided to assess the viability of the antenna control station.

This research is the array processing help wireless communication techniques to increase the signal accuracy. This technique has an important part of prevalent applications. The wireless communication system, radar, and sonar. Beamforming is one of methods in array processing that filters signals based on their capture time at each element in an array of antennas spatially. Numerous studies in adaptive array processing have been proposed in the last several decades, which are divided in two parts. The first one related to non-adaptive beamforming techniques and the next one related to digitally adaptive Beamforming methods. The trade-off between computational complexity and performance make them different. In this thesis, we concentrate on the expansion of array processing algorithms in both non-adaptive and adaptive ones with application of beamforming in 4G mobile antenna and radar systems. The conventional and generalized side-lobe canceller (GSC) structures beamforming algorithms were employed with a phase array antenna that changed the phase of arrivals in array antenna with common phased array structure antennas. An eight-element uniform linear array (ULA), consisting of di-pole antennas, represented as the antenna array. An anechoic chamber measures the operation of beamforming algorithms performance. An extended modified Kaiser weighting function is proposed to make a semi-adaptive structure in phased array beamforming. This technique is extended to low complexity functions like hyperbolic cosine and exponential functions. Furthermore, these algorithms are used in GSC beamforming. The side-lobe levels were so lower than other algorithms in conventional beamforming around -10 dB. On the other hand, a uniform linear arrays for smart antenna purposes designed to utilize in implementing and testing the proposed algorithms. In this thesis, performance of smart antenna with rectangular aperture coupled microstrip linear array which experimental investigations carried out for obtaining X-band operation of rectangular microstrip antenna by using aperture coupled feeding technique. Frequency range set at approximately 8.6 to 10.9 GHz, by incorporating frequency range of the antenna resonates for single wideband with an impedance bandwidth of 23%. The enhancement of impedance bandwidth and gain does not affect the nature of broadside radiation characteristics. This thesis describes the design, operation, and realization of the beamforming such as Sidelobe level (SLL) control and null forming array antenna are examined with the prototype. An antenna radiation pattern beam maximum can be simultaneously placed towards the intended user or Signal of interest (SOl), and, ideally nulls can be positioned towards directions of interfering signals or signals not of interest (SNOIs). Finally, we focused on the adaptive digitally algorithms in compact antenna that faces with mutual coupling. The variable step-size normalized lease mean square (VS-NLMS) algorithm is implemented in beamforming. This algorithm utilizes continuous adaptation. The weights are attuned that the final weight vector to the most satisfied result. The gradient vector can be achieved by iterative beamforming algorithm from the available data. This algorithm is compared with LMS, NLMS, VSS-NLMS algorithms, it is determined that the VSS-NLMS algorithm is better performance to other algorithms. Finally, we introduced novel adaptive IP-NNLMS beamformer. This beamformer reaches to faster convergence and lower error floor than the previous adaptive beamformers even at low SNRs in presence of mutual coupling. The experimental results verified the simulation results that the proposed technique has better performance than other algorithms in various situations. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

In this dissertation, a Method of Moments (MoM) Volume Integral Equation (VIE)-based modeling approach suitable for a patch or slot antenna on a thin finite dielectric substrate is developed and validated. Two new key features of this method are the use of proper dielectric basis functions and proper VIE conditioning, close to the metal surface, where the surface boundary condition of the zero tangential-component must be extended into adjacent tetrahedra. The extended boundary condition is the exact result for the piecewise-constant dielectric basis functions. The latter operation allows one to achieve a good accuracy with one layer of tetrahedra for a thin dielectric substrate and thereby greatly reduces computational cost. The use of low-order basis functions also implies the use of low-order integration schemes and faster filling of the impedance matrix. For some common patch/slot antennas, the VIE-based modeling approach is found to give an error of about 1% or less in the resonant frequency for one-layer tetrahedral meshes with a relatively small number of unknowns. This error is obtained by comparison with fine finite- element method (FEM) simulations, or with measurements, or with the analytical mode matching approach. Hence it is competitive with both the method of moments surface integral equation approach and with the FEM approach for the printed antennas on thin dielectric substrates. Along with the MoM development, the dissertation also presents the models and design procedures for a number of practical antenna configurations. They in particular include: i. a compact linearly polarized broadband planar inverted-F antenna (PIFA); ii. a circularly polarized turnstile bowtie antenna. Both the antennas are designed to operate in the low UHF band and used for indoor positioning/indoor geolocation.

This dissertation presents the research on several different projects. The first project is a via-less CPW RF probe pad to microstrip transition; The second, the third, and the fourth one are reconfigurable microwave circuits using RF MEMS switches: an X-band reconfigurable bandstop filter for wireless RF frontends, an X-band reconfigurable impedance tuner for a class-E high efficiency power amplifier using RF MEMS switches, and a reconfigurable self-similar antenna using RF MEMS switches. The first project was developed in order to facilitate the on-wafer measurement for the second and the third project, since both of them are microstrip transmission line based microwave circuits. A thorough study of the via-less CPW RF probe pad to microstrip transition on silicon substrates was performed and general design rules are derived to provide design guidelines. This research work is then expanded to W-band via-less transition up to 110 GHz. The second project is to develop a low power reconfigurable monolithic bandstop filter operating at 8, 10, 13, and 15 GHz with cantilever beam capacitive MEMS switches. The filter contains microstrip lines and radial stubs that provide different reactances at different frequencies. By electrically actuating different MEMS switches, the different reactances from different radial stubs connecting to these switches will be selected, thus, the filter will resonate at different frequencies. The third project is to develop a monolithic reconfigurable impedance tuner at 10 GHz with the cantilever DC contact MEMS switch. The impedance tuner is a two port network based on a 3bit-3bit digital design, and uses 6 radial shunt stubs that can be selected via integrated DC contact MEMS switches. By selecting different states of the switches, there will be a total of 2^6 = 64 states, which means 64 different impedances will be generated at the output port of the tuner. This will provide a sufficient tuning range for the output port of the power amplifier to maximize the power efficiency. The last project is to integrate the DC contact RF MEMS switches with self-similar planar antennas, to provide a reconfigurable antenna system that radiates with similar patterns over a wide range of frequencies.

This report documents the design, construction, and implementation of a differential-offset spread spectrum RFID system, to avoid the problem of anti-collision interference from multiple RFID tags. Currently in industry, this problem is handled by establishing a two way communication link between the tags and the interrogator. The proposed system eliminates the need for the excessive hardware use to create this link, and therefore drastically reduces the cost of each tag. Not only is this system cheaper to implement but it is faster, requires less power, and by the nature of the design contains an inherent encryption scheme for the data being transmitted. Specialized RFID tags were designed and fabricated in order to produce a pseudo random code unique to each tag. The design presented in this document allowed simultaneous interrogation of up to 255 tags within one sensing environment. Once queried, the tags then modulate the incoming signal from the interrogator with their own sequence, and reflect the signal back to the interrogator. What the interrogator then receives is a combination of backscatter from all of the tags within the sensing environment. Specialized software written in Matlab and LabView uses these unique sequences to isolate the data from a desired tag away from the sea of information being transmitted from every tag. Using this system, numerous applications for experiments and measurements can be devised. One such application this thesis focuses on is the use of this system to simultaneously measure signal strengths from multiple diversity antennas in order to optimize their position and orientation. Currently, the majority of antenna diversity measurements are taken by measuring the signal strength of a given configuration one antenna at a time. By using the anti-collision RFID system proposed above, the signal strength produced by both antennas can be measured and recorded simultaneously to provide a true representation of their combined performance. This measurement can be used to find the optimal configuration for multiple antennas. This thesis will fully explore the theories and procedures behind creating this system, and will provide the results and analysis of its performance.