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The EMPF recently characterized the reliability of surface mount RF components. The RF frequency band of interest was the X band (10.7 to 11.7GHz). A two pronged test for reliability of circuit card assemblies (CCA) was designed for both extreme thermal cycling and vibration. The rapid thermal cycling and extreme vibration testing simulates the total stress encountered by the assembly over the life of the product but accomplishes it in a relatively short period of time. In order to perform the reliability testing, a test vehicle consisting of a printed circuit board with test structures and components, was designed, fabricated, and assembled at the EMPF., Prepared in cooperation with ACI Technologies, Inc., Philadelphia, PA. Government or Federal Purpose Rights License. The original document contains color images.

Rarely does our space cadre professional journal inform the community on technical topics that provide us intellectual insight into our trade. The intent of this article is to add some technical know-how to our space rucksacks. It is the authors' intent to discuss one such topic in this paper and to also encourage more technical discussions of our tradecraft in the future. Space operations officers are charged to be subject matter experts on Position, Navigation and Timing and on the Global Positioning System (GPS) constellation. In the course of educating FA40s in the Space Operations Officer Qualification Course, in less than three months, students receive as many as six briefs dealing with GPS. These briefs range from introductory to in-depth lessons from Space 200, NAVWAR, Space Operations Officer Qualification Course GPS, the Space Symposium, and a briefing from GPS experts at Los Angeles Air Force Base. In each of the briefs, usually within the first 4-7 slides, these technical experts tell us that the L1 band has the course acquisition (C/A) code with free access to the public, while access to the L2 band is restricted to only those military receivers with encryption to access the P-code. While this was the intended design of the system, it is simply no longer a true statement. For several years, specific civilian GPS receivers have the capability to utilize the L2 GPS band. Therefore, it is important to clarify this misconception and make a recommendation on how, as a community of professionals, the correct knowledge should be disseminated., Published in the Army Space Journal, p46-47, Fall 2010-Winter 2011.

Cognitive radio networks (CRNs) have the potential to utilize spectrum efficiently and are positioned to be the core technology for the next-generation multi-hop wireless networks. An important problem for such networks is its capacity. We study this problem for CRNs in the SINR (signal-to-interference-and-noise-ratio) model, which is considered to be a better characterization of interference (but also more difficult to analyze) than disk graph model. The main difficulties of this problem are two-fold. First, SINR is a non-convex function of transmission powers; an optimization problem in the SINR model is usually a non-convex program and NP-hard in general. Second, in the SINR model, scheduling feasibility and the maximum allowed flow rate on each link are determined by SINR at the physical layer. To maximize capacity, it is essential to follow a cross-layer approach; but joint optimization at physical (power control), link (scheduling), and network (flow routing) layers with the SINR function is inherently difficult. In this paper, we give a mathematical characterization of the joint relationship among these layers. We devise a solution procedure that provides a (1 ? ") optimal solution to this complex problem, where " is the required accuracy. Our theoretical result offers a performance benchmark for any other algorithms developed for practical implementation. Using numerical results, we demonstrate the efficacy of the solution procedure and offer quantitative understanding on the interaction of power control, scheduling, and flow routing in a CRN., The original document contains color images.

High-performance microwave and radio frequency integrated circuits are of interest to the Army. Several monolithic microwave integrated circuits (MMICs) were designed to enhance the performance of commercial-off-the-shelf (COTS) RF integrated circuits (RFICs) used in many wireless systems. This report documents a set of MMIC designs optimized for the 400 to 450 MHz ultra-high frequency (UHF) band and a dual band design that also includes 850 to 950 MHz operation. Additional incorporation of discrete matching elements into a single integrated IC will improve size and weight of wireless systems. This is an optimized set of designs based on a previous 1st pass design effort. Ten separate MMIC designs were designed and fabricated., The original document contains color images.

A new spurious suppression method for bandstop filters based on constructive interference is presented. The technique is successfully applied to realize a fixed-tuned filter with an upper passband extending more than 9 times the fundamental bandstop response, as well as a varactor-tuned bandstop filter with an upper passband extending to 8.9 times the fundamental., Presented at the Proceedings of the European Microwave Conference (40th) held in Paris, France on 28-30 Sep 2010. Published in the Proceedings of the European Microwave Conference, p288-291, 2010.

MIT Lincoln Laboratory is carrying out a program to upgrade the existing Haystack radar by adding a W-band (96 GHz) radar capability. The existing X-band radar (10 GHz) will remain intact and the resulting radar will be capable of either simultaneous dual-band or single-band operation. This document describes the performance requirements of the control system for the HUSIR antenna. A new higher precision antenna is being installed, allowing the antenna to be used efficiently at W-Band. At W-Band, the system will have a very narrow beam that needs to be accurately pointed by a new control system while operating at higher velocities than the old hydraulic system. This document describes the design of the control system as it is to be implemented, but this document alone isn't enough to completely define the control system design. A large number of drawings go along with this document (and will be referenced throughout this document), as well as several Interface Control Documents (ICDs). These ICDs will define the data that is transferred between the radar or astronomy computer and the antenna control unit (ACU), between the ACU and the maintenance computers, and between the ACU and the Programmable Logic Controller (PLC) system. The ICDs will be referenced, where appropriate., Prepared in cooperation with Maglathlin Consulting Services, LLC.

Dual-band, multi-pass simulations of low Earth orbit (LEO) satellites are used to train a feedforward neural network to recognize different classes of resident space objects (RSO). Simulated data allow for a controllable and diverse set of inputs necessary to test our methods, especially at the initial phase of the evaluation, while avoiding the problems and expense associated with real data collection from ground-based facilities. Simulation software is used to generate signatures in two visible bands for satellites exhibiting typical bus-types, materials combinations and methods of stabilization. Orbits and observational parameters are generated from the relevant statistical distribution of the orbital parameters obtained from the Space Surveillance Network, and stabilization is simulated external to the framework of the software used to calculate signatures. We examine various pre-processing schemes that combine temporal, spectral and solar phase angle (SPA) information from non-glinting signatures into vectors that can be used as inputs for our classifier. A metric that assigns a proxy signal-to-noise ratio to each neural network output is introduced to determine the confidence level of each result., Presented at the Advanced Maui Optical and Space Surveillance Technologies Conference, held in Maui, HI, on 14-17 Sep 2010. Prepared in cooperation with Boston College. The original document contains color images.

The Naval Postgraduate School's (NPS) first CubeSat, NPS Solar Cell Array Tester (NPS-SCAT), will be the foundation for future advances in CubeSats at NPS. NPS-SCAT demonstrates the capability of the CubeSat form factor as a technology test bed for a single experiment - a solar cell tester. This thesis discusses and explains the design, testing, and integration of two full TT&C sub-system for NPS-SCAT. The primary and secondary transceivers will both use the amateur frequency band through an approved AMSAT license. This thesis explains the concept of operations of NPS-SCAT, which drove the data requirements for the TT&C. This thesis also explains the testing of the primary and secondary transceivers and the design, test and integration of the antennas. Finally, this thesis will discuss the TT&C ground station construction, methodology, testing and the frequency coordination access., The original document contains color images.

The electrical performance of micro-electromechanical system (MEMS) resonators built at the U.S. Army Research Laboratory (ARL) requires measurement techniques that do not overstress the devices. As a result, we need a high-impedance amplifier that operates over an extended frequency range suitable for use ahead of a 50-ohm vector network analyzer (VNA). The prototype amplifier "buffers" the resonator from the VNA. This amplifier was designed, fabricated, and tested during a fourweek period. It demonstrates that future designs using operational amplifiers with wider frequency ranges will be suitable for this application., The original document contains color images.

Light-matter interaction can be greatly enhanced in nano-scale plasmonic cavities with tightly confined optical mode, where the mode volume determines the interaction strength. The experimental determination of the mode volume of plasmonic elements is therefore of fundamental importance. Mapping the electric field distribution using near-field scanning optical microscopy (NSOM) may disturb the field distribution hence prevent a reliable measurement of the mode volume. Here, we develop a non-pertubative technique to experimentally determine the mode volume of plasmonic resonators in the far field through a unique optical force method., Published in Optics Express, v18 n6 p6048-6055, 15 Mar 2010.

This report introduces several new concepts to achieve some alleviation of the "curse of dimensionality" in determining the higher order kernels in a Volterra expansion. These concepts include: partitioning of the frequency scale(s), the fundamental region of formation, the diagonal strips in the two dimensional frequency space, the second- and third-order basis functions, and filtering of the measured nonlinear output to the particular frequency band under investigation. The equations for the real basis functions at second- and third-order take some unexpected forms. These results are based on taking full advantage of symmetry and conjugate-symmetry frequency-domain relations that exist for real, symmetric, second-order and third-order, time-domain kernels. The inability to construct ideal bandpass filters requires the use of a frequency-overlap procedure, followed by discarding of the edge estimates with inherent errors, and retaining only the interior estimates of higher accuracy. Application to a first- and second-order (noise-free) control example with a white broadband excitation gives excellent estimates of all the first- and second-order properties, such as the individual kernels, the individual Volterra waveforms, and the total estimated output waveform. Application to a cicada mating call with a distinctly non-white and non-Gaussian excitation gives good results for the estimated first- and second-order kernels and waveforms, considering the non-optimality of this type of excitation.

A key feature of a cognitive radio (CR) is a reliable spectrum sensing technique which enables the CR to detect the so-called white spaces in the frequency band. This allows opportunistic access of the unlicensed (secondary) users to these white spaces without causing undue interference to licensed (primary) users. In many scenarios the CR may operate in a multipath fading environment where spectrum sensing must cope with the fading effects of the unknown primary signal. In this paper we first study the effects of multipath fading of the performance of the autocorrelation-based spectrum sensing algorithm described elsewhere in this paper. The results show that Rayleigh fading causes significant degradation in the detection and false alarm. This motivates us to investigate three diversity combining techniques, namely equal gain combining, selective combining, and equal gain correlation combining. For Rayleigh fading channels we evaluate the performance of these three techniques through simulation. The results show that for detection probabilities of interest (e.g., > :9), a system with a four-branch diversity achieves an SNR gain of more than 5 dB over the no-diversity system that uses the same number of received signal samples., Conference paper published in the Proceedings of the 2008 IEEE Military Communications Conference; conference held 17-19 November 2008 in San Diego, CA. The original document contains color images. All DTIC reproductions will be in black and white.

The mission of NMCSO-CENT is to provide Afloat, Ashore, and Joint Electromagnetic Spectrum Management and to maintain overall management and control of all Naval Spectrum within the CENTCOM AOR in support of Navy, Marine Corps, Joint and Coalition forces., Presented at the USN-USMC Spectrum Management Conference (31st Annual) held in San Diego, CA on 1-5 Mar 2010. The original document contains color images.

A nonvolatile memory device has a structure of a metal oxide semiconductor field effect transistor (MOSFET) where the conventional gate electrode is modified in a way to enable temporary charge storage inside the gate. The time when the stored charge decreases to 50% of its initial value is defined as retention time. A long retention time is required for nonvolatile memory devices. Using inorganic semiconductors like Si, this has been used in integrated circuits since the last four decades. Typically there are two types of nonvolatile memory devices, floating gate devices and metal-insulator-oxide-semiconductor (MIOS) devices. First attempts to use polarizable gate insulators in combination with organic semiconductors. The field effect transistors showed floating gate effects, but the potential for organic memories was not realized. Recently insulators based on polymeric ferroelectric-like materials were utilised to fabricate nonvolatile organic memory devices [18-21]. One of the disadvantages of use of such polymeric ferroelectric-like materials is the very high surface roughness which does not allow forming smooth interface between insulator and organic semiconductor. As a result, on and off ratio and on current becomes extremely critical issue. We have demonstrated successfully a combination of a polymer space charge electret and an organic semiconductor in a field effect transistor configuration. Our initial experiments concerns with the study of the thin film morphology. Figure 5(a) shows the morphology of a 200 nm DNA-CTMA film spun on quartz substrate which resulted a surafe roughness of 10 nm. Features of self organised structures are observed. Fig. 5(b) shows the dielectric response (C-V) of the sandwiched DNA-CTMA film between the two electrodes (MIM) devices. It appears that DNA-CTMA film shows stable capacitance, C for a wide range of frequency with absolute capacitance of approx. 1.15 nF/cm2., The original document contains color images.

The primary technical objective of this effort is to realize theoretical DFH performance in the doubly spread underwater acoustic channel. To do so, we need to develop demodulation schemes that are robust to various aspects of the environment. Variations in water depth, bottom type, sound speed profile, and source/receiver location call provide for wide ranges of multi-path interference (resulting in time spread). Different wind and surface wave conditions in combination with platform motion can result in varying degrees of Doppler spreading. The developed algorithms must work well across the range of conditions that will be encountered in real-life scenarios. Within the doubly-spread underwater acoustic channel, we wish to increase throughput without penalty to the inherent interference and collision tolerant properties of the waveform. This includes channel access by multiple users sharing the same frequency band (and even the same hop set) and the same time interval., The original document contains color images.

This briefing explains the Navy's Spectrum Certification Process. It discusses NTIA requirements., Annual USN-USMC Spectrum Management Conference (31st), San Diego, CA, 1-5 Mar 2010. The original document contains color images.

This briefing discusses: *Frequency Application Process; *Frequency Application Issues; *Special Temporary Authorizations *Five/Ten Year Frequency Assignment Reviews; and *Special Temporary Authorizations, Annual USN-USMC Spectrum Management Conference (31st), San Diego, CA, 1-5 Mar 2010. The original document contains color images.

Overview: * Primary Mission Responsibilities * Organizational Chain of Command * NMCSO Regions * Afloat Spectrum Support * Shore Spectrum Support * Manning * Spectrum Management Immediate Challenges > Documentation >> NTP-6 Published rewrite. >> Fleet guidance updates (Annex K update) >> Shore Installation Spectrum Management Guidance, Annual USN-USMC Spectrum Management Conference (31st), San Diego, CA, 1-5 Mar 2010. The original document contains color images.

The main objective of this work was to study the dielectric properties of the GdIGxYIG1-x ferrite composite material at radio frequency (RF) and microwave frequency bands were studied. These measurements were carried out in different sample geometries thick films and cylindrical ceramic bulk ferrite resonator. In the RF range, we observed that the material is rather stable because of its short changes as a function of temperature and frequency range. The temperature capacitance coefficient samples presented short positive values at the RF range In the study of the dielectric properties of the composites antenna geometry, with the same ferrite composite, a bulk cylindrical geometry was also investigated.

Blind frequency rendezvous is an important process for bootstrapping communications between radios without the use of pre-existing infrastructure or common control channel in a Dynamic Spectrum Access (DSA) environment. In this process, radios attempt to arrive in the same frequency channel and recognize each other's presence in changing, under-utilized spectrum. This paper refines existing blind rendezvous techniques by introducing a handshaking algorithm for setting up communications once two radios have arrived in the same frequency channel. It then investigates the effect of different jamming techniques on blind rendezvous algorithms that utilize this handshake. The handshake performance is measured by determining the probability of a handshake, the time to handshake, and the increase in time to rendezvous (TTR) with a handshake compared to that without. The handshake caused varying increases in TTR depending on the time spent in each channel. Four different jamming techniques are applied to the blind rendezvous process: noise, deceptive, sense, and Primary User Emulation (PUE). Each jammer type is analyzed to determine how they increase the TTR, how often they successfully jam over a period of time, and how long it takes to jam. The sense jammer was most effective, followed by PUE, deceptive, and noise, respectively., The original document contains color images.

Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results. After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations.

The long-term goal of this project is to obtain quantitative understanding of the physical mechanisms governing broadband (50 Hz to 50 kHz) acoustic propagation, reflection, refraction, and scattering in shallow water and coastal regions in the presence of temporal and spatial ocean variability.

There are two high-level goals: to understand and quantify effects of mid-frequency (MF) sonar on fish and whale behavior through direct observation, and to investigate the potential usefulness of MF sonar in acoustic measurements of fish, including stock assessments.

Recent disasters, including the 9/11 terrorist attacks, Hurricane Katrina, the London subway bombings, and the California wildfires, have all highlighted the limitations of current mobile communication systems for public safety first responders. First, in a point-to-point configuration, legacy radio systems used by first responders from differing agencies are often made by competing manufacturers and may use incompatible waveforms or channels. In addition, first responder radio systems, which may be licensed and programmed to operate in frequency bands allocated within their home jurisdiction, may be neither licensed nor available in forward-deployed disaster response locations, resulting in an operational scarcity of usable frequencies. To address these problems, first responders need smart radio solutions which can bridge these disparate legacy radio systems together, can incorporate new smart radio solutions, or can replace these existing aging radios. These smart radios need to quickly find each other and adhere to spectrum usage and access policies. Second, in an infrastructure configuration, legacy radio systems may not operate at all if the existing communications backbone has been destroyed by the disaster event. A communication system which can provide a new, temporary infrastructure or can extend an existing infrastructure into a shaded region is needed. Smart radio nodes that make up the public safety infrastructure again must be able to find each other, adhere to spectrum usage policies, and provide access to other smart radios and legacy public safety radios within their coverage area. This work addresses these communications problems in the following ways. First, it applies cognitive radio technology to develop a smart radio system capable of rapidly adapting itself so it can communicate with existing legacy radio systems or other smart radios using a variety of standard and customized waveforms., Sponsored in part by U.S. Department of Justice grant 2005-IJ-CX-K017 and National Science Foundation (NSF) grant CNS-0519959.

EEG (electroencephalogram) recorded in human participants as they performed tasks that induced different mental states, including engagement, mental workload, and mental fatigue. We tested two types of atomic decomposition, each of which identifies unique EEG sources simultaneously in three dimensions: (1) atoms with dimensions of power spectral density, space (electrode position), and time (time on task or task conditions), or (2) atoms with dimensions of magnitude squared coherence, spatial relationships (electrode pairs), and time. For tasks that induced mental workload, we found atoms that combine sources in the theta (4-8 Hz) and alpha (8-12 Hz) EEG frequency bands consistently in individual participants at different times of day and on different days. The temporal variations of the atoms clearly reflected the levels of mental workload induced by varying task conditions. For a task that induced mental fatigue, we found atoms that tracked the development of mental fatigue in individual participants over time, while reflecting underlying changes in power or coherence of primarily theta-band EEG. Our results show that atomic decomposition is a valuable new approach to the identification and measurement of EEG sources for monitoring cognitive status. By comparing these results with results of prior analyses using the same data sets, we observed that atomic decomposition can supplement or overcome existing approaches based on conventional two-dimensional space-time or frequency-time decomposition of EEG., The original document contains color images.

The overall objective of this project was to investigate the use of broadband photonic techniques, initially developed in the context of ultrafast optics, for synthesis and processing of ultrabroadband radio-frequency (RF) electromagnetic signals, with an emphasis of signals beyond the speed and bandwidth limits of direct electronic solutions. Although much of the work performed falls into FCC's 3.1-10.6 GHz UWB band, our methods are directly applicable also to higher frequency bands, with results demonstrated up to 50 GHz., The original document contains color images.

We consider an unweighted conventional phased array and compare its performance characteristics such as the array factor, half-power beamwidth, directivity, number of elements and side-lobe levels to a fractal array equivalent. We show that the Cantor fractal set can be used to thin the array structure in such a way as to consist of active radiating elements and inactive elements the latter of which can be used for other functions. We demonstrate that the conventional array 'defocuses' its energy for frequencies other than its design frequency and behaves like a point source. On the other hand the fractal array maintains its beamforming capability for various frequencies which signifies that it has a multiband response. The fractal array is shown to be superior to the conventional array except when it comes to the side-lobe level where the conventional array results are better., The original document contains color images.

The Department of Defense and, subsequently, the U.S. Navy have embraced a strategy of exerting influence through information dominance versus amassing a large presence. This philosophy, called Net-centric Warfare, uses sensor and network technology to leverage naval platforms towards realizing effects previously achievable only by a larger force. In adapting this strategy, the U.S. Navy has realized many benefits, but has also increased its reliance on the technologies implementing Net-centric Warfare. One such technology is the U.S. Navy's future Military SATCOM terminal, the Navy Multiband Terminal, which will provide critical off-ship bandwidth required for these leveraging effects. The Navy plans to sustain the NMT system using the same methods as previous systems. When considering Operational Availability, these legacy methods do not adequately address attributes affecting system performance, creating a risk the NMT system will not perform as needed to successfully execute Net-centric Warfare. This risk can be managed by transitioning away from traditional methods to those utilizing online collaborative technologies. These technologies, coined "Web 2.0," center around member participation to foster communities. Much like the philosophy of Net-centric warfare, these communities leverage the experience of individuals to the benefit of the entire community., The original document contains color images.

A soft thermally-conductive wick is provided to be connected between the metallic components on a transducer and onto a thermal sink. Beryllia ceramic is provided to improve heat flux within the transducer while maintaining electrical insulation. The wick provides adequate heat flux and such that the mass and stiffness of the wick do not adversely affect the vibroacoustic properties of the transducer in the frequency band of interest. The mass of the wick attachment is considered in the transducer design with the location and direction of the wick attachment designed so as to not introduce rocking modes or other adverse affects in the frequency band of interest. The wick may be strung, coiled, folded or configured in many ways between the transducer and the thermal sink to ensure that no acoustic or vibrational energy is transmitted down the length of the wick.

This report summarizes our research and development work in the last quarter of year 2008. We have reached a practical limit in terms of sampling rate and bandwidth. Listed below are major achievements during the quarter: (1) improved waveform generator: FPGA coding with respect to readability, quantization at the transmitter has been increased from ternary to 8-bit, and sampling rate has been increased from 500 Ms/s to 1 Gs/s; (2) I/Q quadrature modulation/ upconversion, instead of single-channel; (3) Xilinx Virtex 5 LXT board at the receiver with new high speed connection to the A/D; (4) variable thresholds for various signal levels; (5) 10-dB Bandwidth up to 800 MHz; (6) multiple bit rates: 6.25, 3.125, and 1.5625 Mb/s; (7) improved receiver sensitivity. Our next milestone, a gain of several dB over ordinary non-time-reversal system, is anticipated, and system trials will be reported in the April report., The original document contains color images. All DTIC reproductions will be in black and white.

Prognostics of rolling element bearing mandates detecting bearing defect signatures as early as possible, so that corresponding maintenance can be scheduled and catastrophic machine breakdown can be avoided. Defects can occur in any of the bearing parts, inner and outer race, cage and rolling elements. It is possible to identify the defective component of the bearing based on the specific vibration frequencies that are excited. However, the pattern of vibration spectrum changes as bearing deteriorates through different stages. Depending on which failure stage the bearing is in, different techniques should be adopted to seek signature in different frequency ranges. Techniques such as enveloping analysis that performs in high frequency region apparently requires higher data sampling rate and more expensive data acquisition hardware than those analysis conducted in low frequency region. This paper compares two popular rolling element bearing diagnostics techniques, spectrum analysis in bearing characteristic frequency range and enveloping analysis in high frequency range, using test data from an aircraft engine test rig., To be submitted for publication at the Design Engineering Technical Conferences and Computers and Informaton in Engineering Conference, to be held in San Diego, CA on 30 August-2 September 2009.

Large, high-performance space vehicles will require test-validated finite element models for accurate response predictions. The models of these precision spacecraft must be valid to a higher frequency range, referred to as the mid-frequency range, which is characterized by high modal density. The product of this research project is a complete finite element model validation procedure for the mid-frequency range, or any system with high modal density. The procedure includes sensor placement, analytical model reduction, test-analysis correlation, and finite element model updating. The new approach is totally independent of modal analysis. The results of this research are significant because current state-of-the-art techniques based on modal properties do not work for the mid-frequency range due to high modal density. The new approach differs from past work because it is based on principal components of the system frequency response, and frequency band averaging. The principal components are less sensitive to modeling errors and uncertainties, and can be truncated based on system energy. Frequency band averaging of response allows model uncertainty to be included in the validation process.

A research effort was conducted to explore the ways in which sub-wavelength gratings can be used to reduce the reflections from the optics of millimeter-wave imaging systems. A moth-eye lens is sometimes used at optical and infrared frequencies for this purpose, but it is too fragile to be applied directly to the plastic lenses used in the millimeter-wave. A modification of this structure, called the inverse moth-eye lens, was designed, fabricated, and tested. Within the report we present results at 35 GHz showing a 15-dB reduction of surface reflections in Rexolite. The technique was also applied to a material with a dielectric constant of 9. Transmission increased an average of about 30 dB between 30 and 40 GHz with the inverse motheye, anti-reflection (AR) surface. The implication of these results is that the weight and bulk of millimeter-wave imaging systems could be significantly reduced by using optical systems with high dielectric materials and etched, sub-wavelength AR surfaces., The original document contains color images. Prepared in collaboration

With the dawn of the Digital Battlefield, a critical capability in the modern warfare environment is the miniaturization of electronic warfare signal and information processing systems. To realize such systems, the key is to miniaturize antennas that transmit and receive signals. In particular, by introducing reconfigurable antennas, one can combine multiple antennas operating at various frequency bands into a single aperture, which can provide significant miniaturization and flexibility to the entire system. To design such miniaturized antennas, new materials and technologies have to be incorporated. For this purpose, the PI has designed and demonstrated miniaturized antennas by introducing metamaterials such as split ring resonators (SRRs) into the antenna structure. Also proposed and designed were conformal antenna structures with in-plane SRRs for the convenience of integration. In addition, by introducing phototransistors into the SRRs, a frequency tunable antenna was designed. This small reconfigurable planar antenna could be integrated into an Army platform to miniaturize the size of the system while providing additional functionality., The original document contains color images. All DTIC reproductions will be in black and white.

In this paper meander line antennas with end tip loading, designed for UHF RFID tags are presented. These novel antennas are screen printed on Kapton HN for European frequency band (866-868 MHz) and for North American frequency band (902-928 MHz). Asahi ink is used for screen printing of 25 mu m thick antenna traces which remains conductive even after several times sharp bending of these tag antennas. The results show that the antennas exhibit high performance regarding smaller area, high realized gain and better return loss in the frequency band of interest. These antennas are extremely flexible which give autonomy for their applications., QC 20110218

In this paper we present a comparison of two methods for radar cross section reduction (RCSR) of a wing-front profile. The aim is to reduce RCS over the frequency range 1-16 GHz in a forward sector of the traveling direction. We achieved a 5 dB reduction of the two dimensional monostatic radar cross section (RCS) for 68% (or more) of the frequency band for the polarization with the electric field parallel to wing surface (TM2). It is shown that the Jaumann screen has a better RCSR performance than a shape optimized screen in the present case. The total thickness of the Jaumann screen is only 4.5 mm. The 5 dB 2D-RCSR frequency range for the orthogonal polarization in which the electric field is orthogonal to axis of periodicity (TEz) is over 43% of frequency band., QC 20110224

In this paper the design of an inductively coupled miniature UHF bowtie RFID antenna is discussed for 868 MHz UHF frequency band. The antenna was to work with Philips SL3S1001FTT ASIC which has impedance of 22-j404 (Ω) at 868 MHz frequency., QC 20140929

In contemporary cochlear implant systems, the audio signal is decomposed into different frequency bands, each assigned to one electrode. Thus, pitch perception is limited by the number of physical electrodes implanted into the cochlea and by the wide bandwidth assigned to each electrode. The Harmony HiResolution bionic ear (Advanced Bionics LLC, Valencia, CA, USA) has the capability of creating virtual spectral channels through simultaneous delivery of current to pairs of adjacent electrodes. By steering the locus of stimulation to sites between the electrodes, additional pitch percepts can be generated. Two new sound processing strategies based on current steering have been designed, SpecRes and SineEx. In a chronic trial, speech intelligibility, pitch perception, and subjective appreciation of sound were compared between the two current steering strategies and standard HiRes strategy in 9 adult Harmony users. There was considerable variability in benefit, and the mean results show similar performance with all three strategies.

Tato práce je věnována popisu jednotlivých částí GSM systému se zaměřením na technologii samotnou, spolu s vysvětlením jeho funkcí. Jejím cílem je také vytvoření aplikace zobrazující vysílače umístěné na mapě Pardubic, podle předem zadaných GPS souřadnic., The work deals with describing the various parts of the GSM system with a focus on technology itself, together with an explanation of it´s functions. It also aims at the creation of application showing the transmitter located on the map of Pardubice, according to a pre-entered GPS coordinates., Katedra informačních technologií, Dokončená práce s úspěšnou obhajobou

Diplomová práce se zabývá studií nasazení nové technologie pro železniční rádiové sítě v kmitočtovém pásmu 150 MHz. Definuje vhodné selektivní formáty a signalizace pro vzájemnou komunikaci mezi jednotlivými subjekty. Diplomová práce navrhuje jednotlivé varianty zapojení v závislosti na velikosti železniční stanice a také začlení rádiové sítě do železniční přenosové sítě. V závěru diplomové práce jsou navržená řešení aplikovatelná na konkrétní železniční trať., The diploma thesis deals with the study of a new technology for railway radio networks within the 150 MHz frequency band. It presents a definition suitable selective formats and signaling for multilateral communication of individual objects. The diploma thesis submits a design of individual variants of the connection dependent on the railway station size; and it also describes the integration of the radio networks in the railway transmission network. At the end of the diploma thesis there are designed solutions applicable to a specific railway., Katedra elektrotechniky, elektroniky a zabezpečovací techniky v dopravě, Dokončená práce s úspěšnou obhajobou

Spectrum sensing cognitive radios are an emerging technology that promises greater efficiency in utilizing the available wireless spectrum. In particular, spectrum-sensing cognitive radios provide the ability to search for and utilize an unoccupied portion of the wireless spectrum during periods of time when the incumbent user is inactive. A key requirement to operating cognitive radios, therefore, is accurately and reliably identifying unutilized frequency bands, even when those bands may contain extremely weak signals. In this paper, we present initial measurement results from two spectrum occupancy studies conducted in and around Annapolis, Maryland and the US Naval Academy in the frequency range between 700 MHz and 6 000 MHz. At the highest resolution, the measurement system had a noise floor of dBm, allowing it to record signals that were 10-30 dB weaker than those previously reported in the literature. Analysis of the measurement results indicate that spectrum utilization increases exponentially as the receiver's noise floor decreases. Additionally, variations with time, frequency, and receiver threshold are observed. These results imply that, in order to provide reliable detection of incumbent users, cognitive radios will require sensitive receivers and accurate detection algorithms., Proceedings of the Software Defined Radio Technical Conference and Product Exposition (SDR '08), Washington, DC, 26-30 Oct 2008. The original document contains color images.

Cognitive radio (CR) is an enabling technology for efficient use of available spectrum and promises unprecedented flexibility in multi-hop wireless networking. This paper explores networking related issues associated with CRs. Specifically, we consider how to maximize the rates of a set of user communication sessions in a multi-hop CR-based wireless network. Due to potential interference at the physical layer, we find that it is essential to follow a cross-layer approach, with joint optimization at physical (power control), link (frequency band scheduling) and network (flow routing) layers. We give a mathematical characterization of this cross-layer optimization problem. We develop a centralized solution procedure based on the branchand- bound framework. Using numerical results, we demonstrate the efficacy of the solution procedure and offer quantitative understanding on the joint optimization at different layers., Presented at the IEEE Military Communications Conference (MILCOM) held in San Diego, CA on 17-19 November 2008. Published in the IEEE Military Communications Conference (MILCOM) Proceedings, p7, November 2008. The original document contains color images.