Design and Construction of an Arbitrary Pulse Compressive Amplifier

Compressive Pulse Amplifiers Are a Class of Amplifiers that Convert Long Low Amplitude Signals into Very Broadband Pulses of High Amplitude, Yielding a Very High Instantaneous Peak Power Output Pulse. However, in the Realm of Electronic Immunity and Susceptibility Testing, Very Broadband Short Pulses Are Not Always Desired. This Work Presents a Design for a Compressive Amplifier that is Aimed at Creating Arbitrary Pulsed Signals of Varying Bandwidths. Limitations of the Achievable Gain and Methods Used Are Discussed

Contribution to the study of the vulnerability of critical systems to Intentional Electromagnetic Interference (IEMI)

The progress of high power electromagnetic (HPEM) sources during the late 1990s raised the concern in the electromagnetic compatibility (EMC) community that they could be deployed for criminal purposes to interfere with the operation of modern electronic systems. It is well established that sufficiently intense electromagnetic fields can cause upset or damage in electronic systems and therefore, can affect almost every critical infrastructure (CI) that is based on information and communication technologies (ICT). This field of study was initially known as electromagnetic terrorism, but was changed to the more encompassing term of intentional electromagnetic interference (IEMI). This thesis is a contribution to the assessment techniques of the vulnerability of CIs against IEMI. In order to quantify their impact, the electromagnetic environment created by IEMI sources needs to be characterized, the susceptible components and subsystems of the CIs should be identified, and the expected disturbances have to be evaluated. We present a qualitative methodology to carry out the so-called IEMI audit of a facility. Given the complexity of the problem, it was decided that the vulnerability of an infrastructure should be evaluated in a qualitative manner by regarding the consequences of interrupting the normal provision of a service, the probability of occurrence of an IEMI attack, and the preparedness of the infrastructure to withstand an attack. An updated survey and classification of potential IEMI sources that were collected from a large number of scientific publications is presented. The sources have been classified according to their electromagnetic environment, their transportability, technological development, and cost level. The expected disturbances due to a high frequency illumination of representative cabling systems inside an office were studied through measurements performed using a plastic raceway containing several types of cables found in commercial buildings. The tests revealed that at low and intermediate frequencies, low voltage power cables are more susceptible compared to telephone or network cables. At high frequencies, the coupling is dominated by connector apertures and discontinuities and load unbalance. The applicability of the TL theory in evaluating differential mode signals in two-wire lines floating above a ground plane was studied through comparisons with full-wave simulations. The results showed that the validity of the TL theory is conditioned upon an electrically short distance between the differential wires, regardless of the distances above the ground plane. TL theory is also used to assess the effect of conductive and dielectric losses in the dispersion of injected IEMI signals along power and communication cables as a function of the propagation length. A TL model of the low voltage power cabling of the plastic raceway was developed and in order to validate the models, the numerical results were compared against measurements obtained using frequency and time domain techniques. General considerations and guidelines for the application of the TL theory for evaluating the overall transfer impedance of complex cable assemblies are given. The obtained simulation results were found to be in good agreement with the experimental data up to frequencies of about 500 MHz. Finally, an improved model for estimating the transfer impedance of a two-layer braided shield is also proposed and validated using experimental data

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Improving the mechanistic study of neuromuscular diseases through the development of a fully wireless and implantable recording device

Neuromuscular diseases manifest by a handful of known phenotypes affecting the peripheral nerves, skeletal muscle fibers, and neuromuscular junction. Common signs of these diseases include demyelination, myasthenia, atrophy, and aberrant muscle activity—all of which may be tracked over time using one or more electrophysiological markers. Mice, which are the predominant mammalian model for most human diseases, have been used to study congenital neuromuscular diseases for decades. However, our understanding of the mechanisms underlying these pathologies is still incomplete. This is in part due to the lack of instrumentation available to easily collect longitudinal, in vivo electrophysiological activity from mice. There remains a need for a fully wireless, batteryless, and implantable recording system that can be adapted for a variety of electrophysiological measurements and also enable long-term, continuous data collection in very small animals. To meet this need a miniature, chronically implantable device has been developed that is capable of wirelessly coupling energy from electromagnetic fields while implanted within a body. This device can both record and trigger bioelectric events and may be chronically implanted in rodents as small as mice. This grants investigators the ability to continuously observe electrophysiological changes corresponding to disease progression in a single, freely behaving, untethered animal. The fully wireless closed-loop system is an adaptable solution for a range of long-term mechanistic and diagnostic studies in rodent disease models. Its high level of functionality, adjustable parameters, accessible building blocks, reprogrammable firmware, and modular electrode interface offer flexibility that is distinctive among fully implantable recording or stimulating devices. The key significance of this work is that it has generated novel instrumentation in the form of a fully implantable bioelectric recording device having a much higher level of functionality than any other fully wireless system available for mouse work. This has incidentally led to contributions in the areas of wireless power transfer and neural interfaces for upper-limb prosthesis control. Herein the solution space for wireless power transfer is examined including a close inspection of far-field power transfer to implanted bioelectric sensors. Methods of design and characterization for the iterative development of the device are detailed. Furthermore, its performance and utility in remote bioelectric sensing applications is demonstrated with humans, rats, healthy mice, and mouse models for degenerative neuromuscular and motoneuron diseases

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Worst-Case Scenarios of Radiated-Susceptibility Effects in a Multiport System Subject to Intentional Electromagnetic Interference

This paper presents a method to assess intentional electromagnetic interference (IEMI) in a linear multiport system, due to coupling with a high-power electromagnetic (HPEM) field. First, an approach based on the Lorentz reciprocity theorem is proposed to model field coupling for the arbitrary direction of incidence and polarization, which minimizes the number of required full-wave numerical simulations. Afterward, three constrained-optimization problems are identified to describe the worst-case scenarios related to different radiated-susceptibility effects at the system's ports. Namely, under the assumption of limited bandwidth and finite energy density, the spectrum and the waveform of the HPEM field are found so to maximize the dissipated energy, the peak, and the rectified impulse of the induced voltage waveform. It is shown analytically that in the worst-case energy scenario, the HPEM field shall be a properly tuned narrowband field, whereas in the worst-case voltage peak scenario a wideband field properly matched to the frequency response of the system is needed. In addition, it is shown that the rectified impulse of the induced voltage can be made arbitrarily large by reducing the impinging field bandwidth. A typical printed-circuit board interconnect for low-voltage differential signaling is used to exemplify and validate the proposed approach. Furthermore, uncertainty-quantification techniques are exploited to cope with the lack of knowledge about the incidence and polarization parameters of the HPEM field, as well as to account for uncertain geometrical parameters of the victim system

State of the art survey of technologies applicable to NASA's aeronautics, avionics and controls program

The state of the art survey (SOAS) covers six technology areas including flightpath management, aircraft control system, crew station technology, interface & integration technology, military technology, and fundamental technology. The SOAS included contributions from over 70 individuals in industry, government, and the universities