Communication systems have remained almost unchanged since the invention of the superheterodyne receiver in 1918 by the US engineer Edwin Armstrong. With the introduction of multiple-input-multiple-output (MIMO) technologies, Index Modulation appears to be the promising technology to revolutionize the traditional radio-frequency (RF) chain. Index modulation is a high-spectrum, energy-efficient, simple digital communication technique that uses the states of the building blocks of a communication system. In this study, we have focused on the use of radiation patterns scattered by antenna arrays or a metasurface as indices that are encoded as data bits. Initially, we explore sets of 𝑁tx transmitting point source antennas located on the XY plane; we assume that every antenna has phase tunability capability. The phase, the position in space, and the size of the array determine the shape of the far-field radiation pattern. Following the antenna excitation, a set of 𝑁rx receiver antennas spread at specific locations of the spherical space measures the incoming power signal, allowing the sampling of the radiation pattern that is demodulated into information bits.This work is focused on the characterization of the measured radiation patterns under different system and channel variables and their direct effect on the Bit Error Rate.

The use of InGaAsP semiconductor lasers as radiation sources in gas and liquid detection is described in this thesis. Single mode operation and tunability were studied in several schemes including diode lasers with a short external cavity (SXC), diode lasers with multiple short external cavities (MSXC), and a grating external cavity (GEC) diode laser. Comparisons of SXC, MSXC and GEC lasers are given in terms of tunability, side mode suppression ratio (SMSR), stability, and ease of construction and operation. In highly sensitive gas detection, the harmonic content of residual amplitude modulation (RAM) for current modulation of the diode lasers was studied based on the concept that the light intensity rather than the electric field is directly modulated by the injection current. Formulae for RAM and the absorption signals are given for injection current modulation spectroscopy with diode lasers. Water vapour was detected by using InGaAsP SXC and DFB diode lasers, and an electronic subtracter was employed to reduce the detection noise. A sensitivity of ~ 1.6 x IO-6 in units of equivalent absorbance in an equivalent noise bandwidth of 1.25Hz was obtained. In liquid detection, InGaAsP laser diodes with multiple short external cavities (MSCX’s) were developed to provide a wide spectral coverage, up to 72nm spectral coverage was achieved. Liquid detection by MSXC diode lasers was studied in conjunction with multivariate calibration methods, i.e., principal component regression (PCR) and partial least squares (PLS). A sensitivity of 0.1% H2O in D2O was achieved and the limiting noise source was assessed. Three component mixtures of H2O, acetone and methanol were studied in terms of regression factors and outlier detection in the PCR and the PLS algorithms. To achieve even broader tunability by means of external cavity, work on making broad gain peak InGaAsP/InP lasers was initiated. / Thesis / Doctor of Philosophy (PhD)

No description available.

This thesis describes the use of short external cavity (SXC) semiconductor diode lasers as single longitudinal mode (SM) tunable sources. A SXC forces a multimode diode laser to lase on a single longitudinal mode. Various laser types were investigated in SXC configurations using both planar and spherical external mirrors. The side mode suppression ratio (SMSR) and the SM tuning range were measured with respect to the positioning of the external cavity element. With a planar mirror as the SXC element, SMSR of —33 dB and SM tuning ranges of 1 nm (110% of a mode spacing) were obtained with inverted rib waveguide (IRW) lasers. For external cavity lengths of ~ 60 um the total continuous SM tuning range summed over all modes was found to be 72 cm^-1 or 12 nm. The use of a spherical mirror improved the results. A SXC laser consisting of a spherical mirror and an IRW laser had SMSR values of —37 dB and SM tuning ranges of 1.10 nm. Power and voltage characteristics of SM SXC lasers were also examined. It was found possible to use the laser voltage and electronic feedback to control the external cavity length for optimum SM output. The external differential quantum efficiency (DQE) was found to be wavelength dependent and may be explained by the wavelength dependence of the scattering/absorption loss. One aspect of the characteristic trend of the DQE with respect to wavelength is that it offers the possibility of determining the lasing wavelength of the SM without the use of a monochromator. / Thesis / Master of Engineering (ME)

Yes / A compact planar inverted F antenna (PIFA) with a tuneable frequency response is presented. Tuning of the resonant frequency is realized by loading a varactor on an embedded slot of the proposed antenna structure without further optimizing other antenna geometry parameters. The antenna exhibits a wide frequency range from 1570 to 2600 MHz with a good impedance matching (S11 ≤ -10dB) covering the GPS, PCS, DCS, UMTS, WLAN and LTE systems. To validate the theoretical model and design concept, the antenna prototype was fabricated and measured. The compact size of the antenna is 15mm × 8mm × 3mm, which makes this antenna a good candidate for mobile handset and wireless communication applications.

In this dissertation, the synthesis of the triplet absorptive topology is presented in detail. The coupling matrix of this topology is derived. The synthesis theory extends to arbitrary phase of the transmission line used in the topology. A new FSL that yields the state-of-the-art performance is proposed. It employs the triplet absorptive filter topology, which enables absorptive response in a wider tuning range, to achieve high isolation (70 dB) everywhere in its octave tuning range. This was not possible with any existing FSLs. This triplet filter topology also gives bandstop-to-all-pass response, which enables controlled attenuation, or variable-attenuation control. The filter is implemented in high-Q evanescent-mode cavity technology, which yields low insertion loss in all-pass response. The proposed FSL is integrated with feedback control loops to enable in-field operations. For one step further, the FSL system is redesigned for optimization of robustness and reliability without compromising the state-of-the-art RF performance.

L'importante évolution des standards de communications sans fil impose aux systèmes de télécommunication une évolution rapide de leurs architectures. Cette évolution est imposée par de nouvelles normes dont certaines sont basées sur les concepts de transmission multi-porteuses et multi-modes avec une priorité à la compacité, l'intégration, la performance et la baisse de coût. Plusieurs solutions techniques sont envisagées pour s'adapter à cette évolution, et de nouvelles architectures de têtes d’émission-réception sont envisagées en faisant appel à des composants électroniques reconfigurables. Ces dispositifs reconfigurables seront répartis sur toute la chaine d’émission-réception, et peuvent prendre différentes formes tels que des filtres accordables en fréquences, des antennes accordables, adaptateurs d'impédance ou des déphaseurs. Les composants passifs accordables présentent un réel intérêt car ils permettent de fonctionner à plusieurs bandes de fréquences pour des applications ou des standards de communication différents tout en réduisant le coût, l'encombrement et la consommation d’énergie. Deux composants passifs d’une chaine de transmission, les filtres et des antennes reconfigurables font l’objet des travaux de recherche menés dans le cadre de cette thèse. Les performances des circuits et des dispositifs hyperfréquences reconfigurables sont directement liées aux propriétés des éléments d'accord utilisés pour assurer cette fonctionnalité. Dans ce but, différents éléments tels que les composants à base de semi conducteurs (varactor, diode PIN, transistor), de matériaux agiles (ferroélectriques, ferromagnétiques) sont utilisables. Le choix de ce dispositif d'accord dépend des performances et du type d’application envisagée, et les pertes, la linéarité, la vitesse de commutation, la tenue en puissance, la consommation, le coût, sont les principaux critères qui guident le choix. Au début des années 2000, d’autres solutions ont vu le jour avec le développement de la technologie RF-MEMS (Micro Electro-Mechanical System). Ceci a incité les concepteurs de circuits RF à étudier la possibilité d’exploiter les propriétés de cette technologie. Le développement de la technologie RF MEMS peut permettre de franchir un verrou technologique et d’atteindre de bonnes performances en termes de fréquence de coupure, de facteur de qualité, perte et de linéarité. Cette nouvelle technologie à contribué au développement de nouveaux circuits accordables adaptés aux besoins actuels. Développée depuis de nombreuses années au laboratoire XLIM, la technologie RF MEMS est utilisée par les travaux de cette thèse. / The rapid growth of the telecommunications industry has led to a significant increase in the number of allocated frequency bands and a growing need for terminals providing access to an increasing number of standards while offering maximum services. The miniaturization of these devices combined with the implementation of additional functions has become a real challenge for the industry. The use of tunable microwave functions (filters, antennas, amplifiers ...) appears as a solution to this issue. In this way, three main technologies are mainly used: variable capacitors, tunable materials and RF MEMS. Within the scope of this thesis work, our investigations focused on tunable microwave devices like filter and antenna. The first part of our study focused on the realization of tunable planar filters in MEMS RF and SOI Technology. We made two tunable bandpass filters. The first one is a center frequency tunable bandpass two using RF MEMS switchers and the second one using tunable capacitor in SOI technology. In a second part, we focused on the realization of tunable Planar Inverted F Antenna PIFA in MEMS RF.  Finally, we discussed follow-up to give to this work and outlooks.

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Meeting the filtering requirements for telemetry transmitters and receivers can be challenging. Telemetry systems use filters to eliminate unwanted spurious or mixing products. The use of tunable microwave filters for both L and S Band can improve filter selectivity and provide low insertion losses in the filter passband. Along with meeting specifications, these microwave filters with the ability to tune an octave, reduce size and cost by the reduction of multiple, fixed-frequency filters. As size, weight and power are often a concern with aeronautical telemetry systems, this paper will demonstrate that microstrip tunable filters can be small in size and use minimal power. Telemetry transmitters are subject to difficult spurious emission and interference specifications and require selective filters to eliminate spurious signals before the final amplification. Telemetry receivers on the other hand are subject to intense Image and Local Oscillator (LO) rejection requirements and demand low insertion loss for front-end filtering. Low insertion loss filtering before the Low Noise Amplifier (LNA) circuit limits degradation to the system noise figure (NF). By using different filter topologies and state-of-the-art, high-Q varactor diodes, tunable microwave filters can be optimized for two different functions. The two functions emphasize either low insertion loss or selectivity. An important design consideration with tunable filters, when compared to typical fixed frequency filters, is the degraded intermodulation performance. This is largely due to the non-linear behavior of the varactor diodes. This paper describes the benefits and limitations of microwave tunable filter architectures suitable for both aeronautical telemetry transmitters and telemetry receivers. Information on the computer modeling of varactor diodes will be covered as a critical part of the design. Potential design considerations for microwave tunable filters will also be covered. Through the use of simulation software and filter prototypes, this paper presents dramatically improved filter performance applicable to telemetry transmitters and receivers.

Over the past few years, researchers have directed a significant amount of effort towards realizing tunable all-optical devices using nonlinear optical methods. It is now possible to exercise dynamic control of the group velocity of light traveling through a wide variety of material systems. The slow and fast light refer to situations in which the group velocity íg of an optical pulse through a dispersive material can be made to be smaller and larger, respectively, than the phase velocity vp = c/n. This ability could overcome the remaining challenge in current optical networks of storing and manipulating an optical signal directly in optical domain so as to avoid a bottleneck due to optical-to-electrical (O/E) and electrical-to-optical (E/O) conversions. The overall purpose of the dissertation is to study novel slow-light systems that provide controlled generation of large pulse delays relative to the pulse width with minimal pulse shape distortion by optimally design resonance profiles of such systems. The system design studies utilize several measures of performance such as the fractional delay, power throughput, and signal distortion under the limited system resource constraints. To this end, powerful data fidelity metrics are required to quantify the performance of tunable delay devices. Here, a new framework for measuring an information velocity and throughput is described and implemented using Shannon mutual information concepts. This new technique is used to investigate trends, trade-offs, and limits in slow light devices, which are physically sensible and in good agreement with analyses obtained using a conventional eye-opening(EO) metric. Using these information-theoretic and/or conventional metrics, we present the quantifying performance of gain-based stimulated Brillouin scattering (SBS) system in optical fibers as well as optical passive devices such as Fabry-Perot, fiber Bragg gratings, and ring resonators. It is shown that combining the SBS gain medium with these passive devices can compensate their respective disadvantages and thus increase delay performance without using additional resource of SBS pump power. The results show the possibility of achieving a fractional delay up to 10 at a signal bandwidth up to tens of GHz.

In the temporal study of faint, extended sources at high resolving power, Spatial Heterodyne Spectrometer (SHS) can offer significant advantages about conventional dispersive grating spectrometers. We describe here a four-year continuous progress in Mt. Hamilton, Lick Observatory, toward development of a prototype reflective Spacial Heterodyne Spectrometer, Khayyam, instrument-telescope configuration to combine all of the capabilities necessary to obtain high resolving power visible band spectra of diffuse targets from small aperture on-axis telescopes where significant observing time can be obtained. We will discuss the design considerations going into this new system, installation, testing of the interferometer-telescope combination, the technical challenges and procedures moving forward.