Approved for public release; distribution is unlimited / Computer simulation studies of a frequency domain adaptive beamforming algorithm are presented. These simulation studies were conducted to determine the multiple broadband target localization capability and the full angular coverage capability of the algorithm. The algorithm was evaluated at several signal-to-noise ratios with varying sampling rates. The number of iterations that the adaptive algorithm took to reach a minimum estimation error was determined. Results of the simulation studies indicate that the algorithm can localize multiple broadband targets and has full angular coverage capability. / http://archive.org/details/computersimulati00behr / Lieutenant, United States Navy

Please read the abstract in the section 00front of this document / Thesis (PhD (Electronic Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / PhD / unrestricted

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Yes / In the equivalent frequency-based model, the antenna array gain is utilised to characterise the frequency response of the beam squint effect generated by the antenna array. This impact is considered for a wide range of uniform linear array (ULA) and uniform planar array (UPA) designs, including those with and without tapering configurations. For a closer look at how the frequency response of the array adapts to the variations in the incidence angle of the signal, the bandwidth of the spectrum is varied and investigated. To study this effect, we have considered using the gain array response as an equivalent channel model in our approach. Beam squinting caused by distortion in the frequency response gain can be verified by one of two equalisers: a zero-forcing (ZF) equaliser or a minimum mean square error (MMSE) equaliser. Different cases with their analysis and results are studied and compared in terms of coded and uncoded modulations. / This work was supported in part by the Satellite Network of Experts V under Contract 4000130962/20/NL/NL/FE, and in part by the Innovation Program under Grant H2020-MSCA-ITN-2016 SECRET-722424.

This work proposes wideband and broadband Planar Ultra-wideband Modular Antenna (PUMA) arrays designed to improve cost and reliability for high production volume commercial and military applications. The designs feature simplified PCB stack-ups with high dielectric constant (Dk) dimensionally stable materials to improve the manufacturing cost and yield. Additionally, the packages use ball grid array (BGA) interconnects, commonly used in digital electronics, for simple solder reflow integration with radio frequency (RF) electronics. While high Dk materials present practical manufacturing benefits, theoretical background will show how and why PUMA arrays lose frequency bandwidth and scan volume with high Dk materials. Further, a band limiting cavity mode will be shown to encroach into the frequency band of high Dk PUMA arrays due to a higher order common mode. PUMA arrays designed on several high Dk materials (Dk = {2.55, 3, 3.7}) will be presented to characterize this reduction in bandwidth. A wideband 7.25-31 GHz (4.3:1) PUMA array-on-package designed on Rogers RO4725JXR (Dk = 2.55) is presented with infinite array simulation results showing good active impedance match, port isolation and cross-polarization performance out to q = 45°. A simplified broadband 15-21 GHz (30%) PUMA array on a thin (λ/11) single layer of Isola FR408HR (Dk = 3.7) is proposed with infinite array results predicting strong active impedance, port isolation and cross-polarization performance with better port isolation and cross-polarization levels than a similar dual-polarized probe fed patch array.

La spectroscopie infrarouge à matrice à plan focal (PAIRS) est utilisée pour étudier la déformation et la relaxation des polymères à très haute vitesse, soit de 46 cm/s, grâce à sa résolution temporelle de quelques millisecondes. Des mesures complémentaires de spectroscopie infrarouge d’absorbance structurale par modulation de la polarisation (PM-IRSAS) ont été réalisées pour suivre des déformations plus lentes de 0,16 à 1,6 cm/s avec une résolution temporelle de quelques centaines de millisecondes. Notre étude a permis d’observer, à haute vitesse de déformation, un nouveau temps de relaxation (τ0) de l’ordre d’une dizaine de millisecondes qui n’est pas prédit dans la littérature. Le but de cette étude est de quantifier ce nouveau temps de relaxation ainsi que de déterminer les effets de la température, de la masse molaire et de la composition du mélange sur ce dernier. Des mesures effectuées sur du polystyrène (PS) de deux masses molaires différentes, soit 210 et 900 kg/mol, à diverses températures ont révélé que ce temps est indépendant de la masse molaire mais qu’il varie avec la température. Des mesures effectuées sur des films composés de PS900 et de PS deutéré de 21 kg/mol, ont révélé que ce temps ne dépend pas de la composition du mélange et que la longueur des chaînes de PS n’a aucun impact sur celui-ci. D’autres mesures effectuées sur des films de PS900 mélangé avec le poly(vinyl méthyl éther) (PVME) ont révélé que ce temps est identique pour le PS900 pur et le PS900 dans le mélange, mais qu’il est plus court pour le PVME, de l’ordre de quelques millisecondes. / Planar array infrared spectroscopy (PAIRS) was used to study the fast deformation and relaxation of polymers at s draw rate of 46 cm/s, giving millisecond time resolution. Complementary measurements by polarization modulation infrared structural absorbance spectroscopy (PM-IRSAS) were conducted to probe slower deformations (0.16 to 1.6 cm/s) with a time resolution of a few hundreds of milliseconds. Our study allowed the observation, after fast deformation, of a new relaxation time (τ0), on the order of tens of milliseconds, which was not predicted in the literature. The aim of this work is to quantify this new relaxation time and to determine how it is affected by molecular weight, temperature, and blending. Measurements performed on polystyrene (PS) with two different molecular weights (210 and 900 kg/mol) at various temperatures revealed that the new relaxation time is independent of the molecular weight, but that it varies with temperature. Measurements performed on film blends of PS900 with deuterated PS of low molecular weight (21 kg/mol) indicated that this time is unaffected by blending and that the PS chain length has no impact on it. Measurements on films of PS blended with poly(vinyl methyl ether) (PVME) revealed that it is identical for pure PS and for PS in the blends, but that it is shorter, on the order of few milliseconds, for PVME.

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In this dissertation, sparse processing of signals for directions-of-arrival (DoAs) estimation is addressed in the framework of Compressive Sensing (CS). In particular, DoAs estimation problem for different types of sources, systems, and applications are formulated in the CS paradigm. In addition, the fundamental conditions related to the ``Sparsity'' and ``Linearity'' are carefully exploited in order to apply confidently the CS-based methodologies. Moreover, innovative strategies for various systems and applications are developed, validated numerically, and analyzed extensively for different scenarios including signal to noise ratio (SNR), mutual coupling, and polarization loss. The more realistic data from electromagnetic (EM) simulators are often considered for various analysis to validate the potentialities of the proposed approaches. The performances of the proposed estimators are analyzed in terms of standard root-mean-square error (RMSE) with respect to different degrees-of-freedom (DoFs) of DoAs estimation problem including number of elements, number of signals, and signal properties. The outcomes reported in this thesis suggest that the proposed estimators are computationally efficient (i.e., appropriate for real time estimations), robust (i.e., appropriate for different heterogeneous scenarios), and versatile (i.e., easily adaptable for different systems).