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In power systems, disturbances between 2 kHz and 150 kHz are called "Supraharmonics" (SH). Although supraharmonics are not a new concept; It has only attracted the attention of researchers, engineers and manufacturers of end-user devices in recent years. Electromagnetic compatibility (EMC) tests, which are required for placing electrical/electronic devices on the market, require the measurement of harmonic currents (50 Hz-2000 Hz) and the measurement of conducted emission values. However, studies and research in the supraharmonic range are quite limited. As systems using semi-conductor technologies with high power and switching in the kHz range such as photovoltaic energy systems, electric vehicle fast charging stations, high speed digital communication systems become widespread, supraharmonics have also begun to be effective in power distribution systems and cause problems. Today, the struggle against high-frequency disturbances caused by the increased use of electrical and electronic devices, switched power electronic devices and power line communication (PLC) devices is even more prominent. Research conducted in recent years have revealed that disturbances between 2 kHz and 150 kHz cause measurement errors in smart meters, audible noise, malfunctions and performance reductions in electrical devices. In this study, sources of supraharmonics, the problems they cause in devices and networks, measurement methods of supraharmonics and related standards, supraharmonic simulation of sample devices and analysis by measurement are given. Measurements and simulation results show that focusing only on EMC requirements in device designs can cause supraharmonics to be neglected, thus negatively affecting the network and other devices. [ABSTRACT FROM AUTHOR]

Information is a critically important, yet hard to measure, component on policy innovation across state governments. Widespread use of broadband has made it easier for governments to observe other actors, increasing the amount of policy information, while also diversifying the sources of information available to policymakers. This should translate into making governments more innovative over time and quicker to adapt to challenges. At the same time, the Internet may disrupt previous existing flows of information by decreasing the importance of geographic proximity and creating more nationalized or global information networks. We argue that the growth of broadband has made states more innovative over time, while also reducing the reliance on neighboring state adoptions for policy solutions as the information environment becomes both richer and more nationalized. We estimate a pooled event history analysis on hundreds of policies comparing the treatment period (2000–2016) with a control condition (last two decades of the 20th century) and find that states with higher broadband subscriptions are more innovative overall and less reliant on geographic contiguity for policy solutions. The growth of information flows due to digital communications has led to states becoming more innovative while also operating in a more nationalized network. [ABSTRACT FROM AUTHOR]

We propose a theoretical mechanism and new coding strategy to realize extremely accurate manipulations of nonlinear electromagnetic harmonics in ultrawide frequency band based on a time-domain digital coding metasurface (TDCM). Using the proposed mechanism and coding strategy, we design and fabricate a millimeter-wave (mmWave) TDCM, which is composed of reprogrammable meta-atoms embedded with positive-intrinsic-negative diodes. By controlling the duty ratios and time delays of the digital coding sequences loaded on a TDCM, experimental results show that both amplitudes and phases of different harmonics can be engineered at will simultaneously and precisely in broad frequency band from 22 to 33 GHz, even when the coding states are imperfect, which is in good agreement with theoretical calculations. Based on the fabricated high-performance TDCM, we further propose and experimentally realize a large-capacity mmWave wireless communication system, where 256 quadrature amplitude modulation, along with other schemes, is demonstrated. The new wireless communication system has a much simpler architecture than the currently used mmWave wireless systems, and hence can significantly reduce the hardware cost. We believe that the proposed method and system architecture can find vast application in future mmWave and terahertz-wave wireless communication and radar systems. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of planar triplexer slot antenna using substrate integrated waveguide (SIW) technology. The proposed antenna is realised using 'Y' shaped slot backed by SIW cavity. SIW cavity is excited by three separate feed lines for resonance at three different frequencies of 5.7 GHz, 6 GHz and 6.4 GHz with unidirectional radiation pattern and gain of 6.26 dBi, 5.87 dBi and 5.19 dBi, respectively. Average isolation of the three ports is better than 24 dB. All the simulations are carried out using high frequency structure simulation (HFSS) software. The proposed antenna is fabricated on RT Duroid 5880substrate and measured results show better performance. The developed antenna is small in size (0.79 λ × 0.78 λ), simple to fabricate and easy to integrate with planar technology making it suitable for C-band application. [ABSTRACT FROM AUTHOR]

Broadband homonuclear mixing pulses with low radiofrequency power are essential for NMR spectroscopy of proteins and small molecules, especially for emerging applications in high field NMR. We have analytically designed a mixing pulse with high bandwidth-to-power ratio, using our recently developed multi-frame method. Here, we compare the new pulse, NF4 (mixing in the fourth nutating frame), to the best currently available sequence, focusing on the low-power regime. We use simulations and experiments to compare the two pulses' relaxation properties and bandwidth, and demonstrate that NF4 has approximately 1.35 times higher bandwidth, with similar effective relaxation. Therefore, NF4 is a good choice for broadband homonuclear mixing, particularly when the available radiofrequency power is limited. [ABSTRACT FROM AUTHOR]

Upconversion of sub-bandgap photons is a promising approach to exceed the Shockley-Queisser limit in solar technologies. Calculations have indicated that ideal, upconverter-enhanced cell efficiencies can exceed 44% for non-concentrated sunlight, but such improvements have yet to be observed experimentally. To explain this discrepancy, we develop a thermodynamic model of an upconverter-cell considering a highly realistic narrow-band, non-unity-quantum-yield upconverter. As expected, solar cell efficiencies increase with increasing upconverter bandwidth and quantum yield, with maximum efficiency enhancements found for near-infrared upconverter absorption bands. Our model indicates that existing bimolecular and lanthanide-based upconverters will not improve cell efficiencies more than 1%, consistent with recent experiments. However, our calculations show that these upconverters can significantly increase cell efficiencies from 28% to over 34% with improved quantum yield, despite their narrow bandwidths. Our results highlight the interplay of absorption and quantum yield in upconversion, and provide a platform for optimizing future solar upconverter designs. [ABSTRACT FROM AUTHOR]

With the rapid development of broadband wireless technology and the wide demand of multimedia mobile services, various broadband mobile multimedia services are coming into being. However, the limited radio resources do not adequately guarantee the quality of service requirements for these multimedia mobile services. In this paper, the improved chaotic neural network technology is applied to three typical broadband wireless communication systems. Through the theoretical analysis and the simulation, the proposed algorithm can make full use of the chaotic neural power to search the optimal solution, which can achieve the purpose of further optimizing the wireless resources. At the same time, it also make the positive attempt to promote cross-disciplinary integration. [ABSTRACT FROM AUTHOR]

According to Edholm’s law, the demand for point-to-point bandwidth in wireless short-range communications has doubled every 18 months over the last 25 years. It can be predicted that data rates of around 5–10 Gb/s will be required in ten years. In order to achieve 10 Gb/s data rates, the carrier frequencies need to be increased beyond 100 GHz. Over the past ten years, several groups have considered the prospects of using sub-terahertz (THz) and THz waves (100–2000 GHz) as a means to transmit data wirelessly. Some of the reported advantages of THz communications links are inherently higher bandwidth compared to millimeter wave links, less susceptibility to scintillation effects than infrared wireless links, and the ability to use THz links for secure communications. Our goal of this paper is to provide a comprehensive review of wireless sub-THz and THz communications. [ABSTRACT FROM AUTHOR]

Based on data collected as part of the 2006 Public Libraries and the Internet study, the authors assess the degree to which public libraries provide sufficient and quality bandwidth to support the library's networked services and resources. The topic is complex due to the arbitrary assignment of a number of kilobytes per second (kbps) used to define bandwidth. Such arbitrary definitions to describe bandwidth sufficiency and quality are not useful. Public libraries are indeed connected to the Internet and do provide public-access services and resources. It is, however, time to move beyond connectivity type and speed questions and consider issues of bandwidth sufficiency, quality, and the range of networked services that should be available to the public from public libraries. A secondary, but important issue is the extent to which libraries, particularly in rural areas, have access to broadband telecommunications services. [ABSTRACT FROM AUTHOR]

Zoomify Image is a mature product for easily publishing large, high-resolution images on the Web. End users view these images with existing Web-browser software as quickly as they do normal, downsampled images. A Flash-based Zoomifyer client asynchronously streams image data to the Web browser as needed, resulting in response times approaching those of desktop applications using minimal bandwidth. The author, a librarian at Cornell University and the principal architect of a small, open-source company, worked closely with Zoomify to produce a cross-platform, open-source implementation of that company's image-processing software and discusses how to easily deploy the product into a widely used Web-publishing environment. Limitations are also discussed as are areas of improvement and alternatives. [ABSTRACT FROM AUTHOR]

A high-sensitivity frequency domain laser based ultrasonic system is presented which uses a low power, amplitude modulated continuous wave (cw) laser source for acoustic wave generation. The acoustic signals are detected using a path stabilized Michelson interferometer coupled to a rf lock-in amplifier. The modulation frequency of the generation laser is scanned over the bandwidth of interest, and transient acoustic signals are reconstructed from the frequency domain data. The effects of measurement frequency resolution, bandwidth, and time domain aliasing on the reconstructed transient response are discussed. Experimental results on thin plates, where diffuse acoustic wave fields lasting several hundred microseconds are seen as a result of multiple reflections off of sample boundaries, demonstrate that the time domain signal can be unambiguously reconstructed through appropriate selection of frequency resolution. Time domain reconstructions of acoustic signals over a bandwidth of 200 MHz demonstrate the utility of the approach for acoustic microscopy; individual acoustic transients can be detected with extremely high signal to noise ratio and time gated for analysis. [ABSTRACT FROM AUTHOR]

The operation of a liquid polymer jet laser-plasma target and the characterization of the absolute x-ray emission in the extreme ultraviolet wavelength window from 9–19 nm is reported. The target is a liquid polymer (perfluoro-polyether) that is exposed to pulsed and focused laser light at 532 nm in the form of a thin, liquid microjet (d=40 to 160 μm) in vacuum. The spectral brightness of the source in the 13 nm range is relatively high because a large fraction of radiative energy is emitted in one single line only, which is assigned to be the 2p–3d FVII doublet at 12.8 nm, with a laser energy conversion efficiency of 0.45% (2π sr, 2% bandwidth) in our initial experiment. A further increase of the relative emission has been found in the wavelength range between 7 and 17 nm when the jet diameter was increased from 40 to 160 μm. The two-dimensional spatial profile of the source plasma (d=40 to 50 μm) has been analyzed with a pinhole camera. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A novel two-dimensional (2D) metamaterial structure with center symmetric “T” shaped unit is designed, fabricated, and measured in this paper. The proposed metamaterial comprises of a 2 × 2 array of area 4.3 mm × 4.3 mm, etched on single side of FR4 substrate. The simulation and measurement show that the novel metamaterial has a double negative range frequency of 20.16–37.47 GHz with an absolute width of 17.31 GHz, relative width of 60.07%, small unit loss of 0.16 dB, and small size of 0.07 λ0 in 2D. Furthermore, the double negative region of the proposed metamaterial operates through K band and Ka band, it can be widely used in satellite communication and broadband digital transmission. [ABSTRACT FROM AUTHOR]

A frequency-tunable current sensor consisting of Terfenol-D/PZT/Terfenol-D magnetoelectric (ME) laminate and Fe73.5Cu1Nb3Si13.5B9 nanocrystalline alloy has been developed. Almost all ME current-sensing devices have higher outputs at resonance conditions, but this advantage is useful only for narrow bandwidth. For the purpose of broadband current sensing, a frequency up-conversion mechanism is introduced by means of nonlinearity of the field-dependence magnetostriction λ(H). Current sensitivity enhancement is realized by modulating the low-frequency dynamic magnetostrictive strain to its resonance conditions. This solution provides the possibility to achieve resonance-enhanced sensitivity at the power-line frequency of 50 Hz, and the capability to immune the noise floor. Experimental results show that the modulated sensitivity is increased from 48.6mV/A to 178.4mV/A at 50Hz, and a small current step change of 3mA can be clearly distinguished by amplitude or phase of the output signals. These results provide possibilities to accurately detect weak currents in the noise ambient at low frequencies. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a compact wideband crossover with filtering performance is presented, with separated operating frequencies in two transmission paths. First, a novel crossover core circuit is presented based on cross‐shaped coupled lines. The odd‐even mode method is adopted to extract the transmission and isolation characteristics. Then, the loading sections are added in the core circuit to construct the proposed crossover, which can achieve enhanced filtering and isolating performances. The detailed design procedures of specific crossover are presented. Finally, a wideband filtering crossover centered at 2.03 and 3.54 GHz with measured bandwidths of 0.6 and 0.62 GHz is fabricated and measured, which verifies the proposed structures well. As to isolate these two signal paths by adopting conventional crossover with same frequency, the operating bandwidth of crossover should be wider than 2.11 GHz with center frequency of 2.78 GHz. [ABSTRACT FROM AUTHOR]

High data rate recording can be achieved using fast write drivers and fast heads. Advanced short-yoke write heads and write drivers with 450 ps rise time and programmable current overshoot were used to study recording at data rates up to 2 Gbit/s. The head flux rise time causes shifts of recorded transitions. It is well known that current overshoot helps to overcome bandwidth limitations in the write driver, interconnects, and write head. However, excessive overshoot may cause pattern-dependent transition shifts and significant distortions of recorded transitions. We present the data rate performance of short-yoke recording heads, analysis of nonlinear pattern-dependent distortions, and optimization of the write current wave form in the 1-2 Gbit/s range. Simple dibit and tribit patterns were recorded at 2 Gbit/s. Low-distortion recording for arbitrary data patterns was demonstrated at 1.6 Gbit/s after optimization of write current overshoot. [ABSTRACT FROM AUTHOR]

An Antipodal Vivaldi Antenna (AVA) with a reduced size of 37 mm × 21 mm has been designed, simulated and fabricated on 1.6 mm-thick FR4 substrate for ultra-wideband (UWB) applications. It is customized with a slot resonator located on the ground plane only and with a shift of the ground plane input. AVA simulations and measurements are presented and are in good agreement. The antenna exhibits a voltage standing wave ratio of less than 2, and a peak gain in the −0.5 to 4.5 dB range through the 3.6–12 GHz frequency range. The antennas were arranged in an emitter-receiver aligned configuration with a distance R = 1 cm, in order to send and receive digital data directly at 1 Gbps with 20-bits input data, based on the Wireless Baseband Transmission (WBT) scheme with Manchester and Polar RZ encodings. Measurements show the recovery of the input digital signals after processing of transmitted output signal and are encouraging to use broadband AVA with a linear phase characteristic as a possible candidate for use in short range communication in cryogenic environment. [ABSTRACT FROM AUTHOR]

Digital Radio Mondiale (DRM) is the universally, openly standardized digital broadcasting system for all frequencies including LW, MW, and SW as well as VHF bands. Alongside providing high audio quality to listeners, DRM satisfies technological requirements posed by broadcasters, manufacturers and regulatory authorities and thus bears a great potential for the future of global radio. One of the key issues here concerns green broadcasting. Facing the need for high-power transmitters to cover wide areas, there is room for improvement concerning the power efficiency of DRM-transmitters. A major drawback of DRM is its high peak-to-average power ratio (PAPR) due to the applied transmission technology based on Orthogonal Frequency Division Multiplexing (OFDM), which results in non-linearities in the emitted signal, low power efficiency, and high costs of transmitters. To overcome this, numerous schemes have been investigated for reducing PAPR in OFDM systems. In this paper, we review and analyze various technologies to reduce PAPR providing that the technical feasibility and DRM-specific system architecture and edge conditions regarding the system performance in terms of modulation error rate, compliance with frequency mask, and synchronization efficiency are ensured. All evaluations are carried out with I/Q signals which are monitored in real operation to present the actual performance of proposed PAPR techniques. Subsequently, the capability of the best approach is evaluated via measurements on a DRM test platform, where achieved transmit power gain of 10 dB is shown. According to our evaluation results, PAPR reduction schemes based on active constellation extension followed by a filter prove to be promising towards practical realization of power-efficient transmitters. [ABSTRACT FROM AUTHOR]

Space-time block code and spatial multiplexing are promising approaches that exploit the multiple input multiple output (MIMO) channel to provide high diversity and multiplexing gain without sacrifice in bandwidth. In this paper, a hybrid MIMO scheme for orthogonal frequency division multiplexing systems is proposed to achieve various multiplexing gains according to the channel condition. The existing hybrid MIMO schemes are appropriate for limited integer multiplexing rates without taking into account the channel condition, whereas the proposed scheme can attain various multiplexing rates according to the channel condition. [ABSTRACT FROM AUTHOR]

ABSTRACT This article proposes a novel, simple, microstrip-fed, circularly polarized, stacked, diagonal-slotted, wideband hexagonal microstrip patch antenna for Intelligent Transport System (ITS) applications. It has been found to operate in the Global Positioning Systems frequency L1 (GPS 1.575 GHz). The fabricated antenna shows an impedance bandwidth of 171 MHz which is around 11% (1.521-1.692 GHz) with 3 dB axial-ratio-bandwidth (ARBW) of 80 MHz which is around 5% (1.54-1.62 GHz) and for the entire 3 dB ARBW the gain achieved is over 6.5 dBi. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2548-2554, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a compact bandwidth enhanced CPW-fed metamaterial antenna is presented. The band broadening is accomplished by combining the resonant modes (n = 0, 1, 2). The antenna is operated in series resonant mode, and therefore, resonant characteristics can be controlled effectively by varying series parameters. Coupling among patches are responsible for originating number of modes which is made nearer to the original mode (n = 0 mode) to enhance the bandwidth. Proposed antenna offers measured fractional bandwidth of 54.3% at 3. 41 GHz (center frequency). Ω (Ohm)-shaped IDC is used to provide the series gap which improves impedance matching significantly. It is illustrated that the zeroth-order resonating frequency depends on the series parameters by demonstrating the equivalent circuit model. The antenna has an average peak gain of 2.36 dB and average radiation efficiency of 92.81%, throughout the operating band (S11 < −10 dB). The proposed antenna has the advantages of simple fabrication, compactness, and omnidirectional radiation pattern makes it suitable for modern wireless communication such as WLAN/Wi-Fi (2.4-2.49 GHz), WiMAX (2.5-2.69 GHz, 3.4-3.6 GHz), Bluetooth (2.4-2.48 GHz). Furthermore, prototype of the antenna is fabricated and measured and is in good agreement with the simulated one. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2558-2562, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A printed microstrip line-fed fractal antenna is presented with a high fidelity factor for UWB applications. The antenna structure of electrical dimension 0.24 λ × 0.33 λ at lower frequency 3.1 GHz is made of a fractal patch, a slotted partial ground plane, and a microstrip feed, which is fabricated on FR4 material of low cost and dielectric. Measured results demonstrates that the fractal antenna achieves fractional bandwidth of 117.88% covering the frequency range from 3.1 GHz to more than 12 GHz with a maximum gain 3.54 dBi at 6.25 GHz. An acceptable analogy is observed between measured and simulation results. The high fidelity factor, sharply surface current distribution, time domain performances, acceptable gain, and nearly omnidirectional radiation characteristic have validated the appropriateness of this proposed fractal antenna for UWB and microwave imaging applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2580-2585, 2015 [ABSTRACT FROM AUTHOR]

This paper explores how an evaluative framework of resilience might be utilised to assess the impact of new digital technologies. This paper outlines key themes and indicators from recent literature on community-level and rural resilience and incorporates insights from work on digital inclusion and rural information and communication technologies to build a framework of rural community resilience. It then highlights a successful case study carried out by the Digital Engagement and Resilience project and describes some of the methodological challenges that can be encountered in cross-cutting evaluative work in a digital economy context. Finally, it contextualises this work in the current policy climate of rural digital agendas to stress the growing need for holistic and critical approaches to ‘resilience’. [ABSTRACT FROM AUTHOR]

The wideband performance of a printed dipole antenna with dumbbell-shaped open sleeve structure is presented. Besides using printed dipole for omndirectional radiation patterns, the dumbbell-shaped open sleeve structure is employed to improve the impendence matching at lower band because of producing two resonant points; whereas two parasitical patches are also used to increase the bandwidth of the lower band. The four tuning stubs and the coupling feed can effectively enhance the impendence bandwidth at upper band. A wideband impedance characteristic of about 91.4% for voltage standing wave ratio (VSWR) ≤ 2 ranging from 0.89 to 2.39 GHz is obtained. The omnidirectional radiation patterns in the whole operation bands are achieved where the un-roundness in the H-plane is <2.2 dB. It is sufficient for accommodating recent wireless communication services such as GSM900, DCS1800, PCS1900, UMTS, IMT2000 and Wibro. [ABSTRACT FROM AUTHOR]

The early alert monitoring system for an effective scheduled maintenance strategy based on a wireless technology requires reliable transfer of the diagnostic information between the sensor and the gateway. This paper presents an industrial wireless sensor network (IWSN)-based machine condition monitoring (MCM) system capable of overcoming a false indication caused by temporary loss of data, signal interference, or invalid data. We use multisensor fusion driven by a quality parameter, which is produced by each sensor node according to the data history outliers and the actual state of the node. The fusion node provides a quality evaluation on its output as well. This novel approach enables the propagation of information about the uncertainty of a measured value from the source node to the sink node. Thus, potential degradation of acquired or transferred diagnostic information is minimized. Instead of raw data, the signal features are transferred, so that bandwidth savings are rapidly improved. The proposed concept was experimentally verified on real wireless sensor network (WSN) hardware. The performance evaluated using the signal-to-noise ratio and false-alarm rate detection demonstrates the effectiveness of the proposed approach. [ABSTRACT FROM PUBLISHER]

In order to increase the annual energy yield of a variable-speed wind energy conversion system (WECS), maximum power point tracking (MPPT) control is required at below the rated wind speed. However, the only aspect that has been paid attention to by most of the researchers is the way to accelerate the MPPT speed. In fact, the research of this paper finds out that the faster the MPPT speed is, the larger transient load the turbine shaft bears. Thus, attempts are first made to find out the relationship between the MPPT speed and the transient load through quantity analysis. Then, a principle to choose a proper bandwidth of the MPPT system is given out to optimize the transient load. Furthermore, to ensure that the system can track the varying winds at the designed bandwidth, the design details on how to make the MPPT bandwidth constant are also proposed in this paper. Finally, a 1.2-kW variable-speed WECS, which is based on a permanent-magnet synchronous generator, is established in the laboratory. Theoretical analysis is verified by experimental results performed by it. [ABSTRACT FROM PUBLISHER]

An LCL-type filter is widely used in the grid-connected inverter. However, with only injected grid current control, the current harmonics and low bandwidth caused by the resonance peak cannot be tolerated. The active damping (AD) method with an extra feedback provides a high rejection of the resonance so that the dynamic is improved; however, the high-precision sensing circuit for the extra feedback increases the cost. In this paper, with the signal flow graph and response-fitting methods, an AD method based on the feedback of the injected grid current has been proposed. Then, the novel closed-loop current control requires accurately sensing the injected grid current only, while no observation is needed. Compared with the extra feedback methods, the cost and the complexity are reduced while the reliability is improved. Based on the study of the relation between the controller and the system dynamic, a straightforward design has been proposed. The robustness, harmonic rejection, and digital implementation have been studied. Compared with the conventional control methods, the proposed one promises the satisfactory performance with both analog and digital implementations. Simulations and experiments have verified the proposed control and design strategies. [ABSTRACT FROM PUBLISHER]

This paper discusses the dynamic interaction of multi active power filters (APFs) paralleled with a weak power grid. In order to analyze the dynamic interaction from multi APFs, the output impedance of an APF is solved. The influences of both circuit and control parameters on the output impedance are analyzed. Based on the output impedance of an APF, the dynamic influences of an APF on the other APF connected to the weak grid are discussed. As shown in this paper, the stability of an APF is improved with an increased output filter inductance and some control parameters to reduce its bandwidth. The proposed analysis methods can be used not only for multi APFs but also for the other multi-inverters connected to a weak grid. Experimental tests are carried out using two paralleled three-phase 10-kVA inverters to confirm the validity of the theoretical analysis. [ABSTRACT FROM PUBLISHER]

This paper describes a new procedure which facilitates the frequency-response curve interpretation in the low-frequency bandwidth. The procedure is able to estimate the magnetization inductance and winding capacitance, for each transformer phase by only using data from its frequency response. The described calculation procedure uses an R-L-C electrical equivalent circuit developed to simulate the impedance measured in the frequency-response test. The procedure takes into account the magnetic coupling among different phases and allows their analysis separately, enabling the identification of a possible failure. This paper describes the procedure to obtain the parameters and its application for interpreting the low-frequency results of frequency-response analysis measurement cases. [ABSTRACT FROM PUBLISHER]

A conventional energy harvester typically consists of a cantilevered composite piezoelectric beam, which has a proof mass at its free end while its fixed end is mounted on a vibrating base structure. The resulting relative motion between the proof mass and the base structure produces a mechanical strain in the piezoelectric elements, which is converted into electrical power by virtue of the direct piezoelectric effect. In this article, the harvester is provided with a dynamic magnifier consisting of a spring-mass system that is placed between the fixed end of the piezoelectric beam and the vibrating base structure. The main function of the dynamic magnifier, as the name implies, is to magnify the strain experienced by the piezoelectric elements in order to amplify the electrical power output of the harvester. With proper selection of the design parameters of the magnifier, the harvested power can be dramatically enhanced and the effective bandwidth of the harvester can be improved. The theory governing the operation of this class of cantilevered piezoelectric energy harvesters with dynamic magnifier (CPEHDM) is developed using the Generalized Hamiltons's Principle. Numerical examples are presented to illustrate the merits of the CPEHDM in comparison with the conventional piezoelectric energy harvesters (CPEH). The obtained results demonstrate the feasibility of the CPEHDM as a simple and effective means for enhancing the magnitude and spectral characteristics of CPEH. [ABSTRACT FROM AUTHOR]

A semi-analytical solution for the input reflections, inner field distribution and radiated fields for a wideband traveling-wave antenna based on a tapered half-mode substrate-integrated waveguide (HMSIW) is proposed in this paper. The analysis validates the operation mechanism for this type of traveling-wave antenna which exhibits omni-directional radiation properties with horizontal polarization (“magnetic dipole”). The derived expressions allows the design and efficient optimization of different antennas towards fulfilling various predefined specifications of reflection coefficient and operating bandwidth. The antenna utilizes a wideband transition from coaxial cable to a HMSIW, which is also considered in the model to provide highly accurate semi-analytical results. Utilizing the proposed method, three antennas of different specifications have been optimized, manufactured and tested. The analysis, simulation and measurement results show good correspondences, which verifies the design process and demonstrates the versatility of the concept. [ABSTRACT FROM PUBLISHER]

A new single-layer microstrip dual-resonance conformal loop (DRCL) element is proposed to design a printed beam deflector array for broadband application. By utilizing variable parameters of the DRCL element, a nearly progressive phase-shift ranging more than 550^\circ is achieved for deflecting wave within a wide band. It is important that a small DRCL element can be flexibly used to generate a 360^\circ phase shift, which decreases the cell period between the neighboring elements. The DRCL is less sensitive to the variation of incidence angles for both TE and TM polarizations. An X-band plane wave beam deflector array is designed, fabricated and measured. The results show a significant improvement in gain-bandwidth performance of the deflector array using the new structure element. The 1 dB gain-bandwidth of 20% can be achieved. The measured results agree well with the simulation results. [ABSTRACT FROM PUBLISHER]

A novel method is presented to design single-feed high-gain EBG resonator antennas (ERAs) with significantly wider bandwidths. Dielectric contrast is introduced to 1-D EBG superstructures composed of unprinted dielectric slabs, and the thicknesses of each of these slabs is optimized to achieve a wideband defect mode in a unit-cell model. Next, antennas are designed and their superstructure areas are truncated to increase the antenna bandwidth and aperture efficiency while decreasing antenna footprint. We demonstrate that a small superstructure area increases the 3-dB bandwidth of ERAs significantly. A prototype ERA designed with a single feed and superstructure area as small as \ 1.5 \lambda_0 \times \ 1.5 \lambda_0 has a measured 3-dB directivity bandwidth of 22% at a peak gain of 18.2 dBi. This prototype antenna was made out of three slabs of different dielectric constants, two of them touching each other. This prototype demonstrates more than 85% reduction in the ERA footprint alongside a drastic improvement in bandwidth over the 3%–4% measured bandwidth of the classical single-feed ERAs with unprinted slabs. [ABSTRACT FROM PUBLISHER]

Although conventional Yagi antenna has the advantage of unidirectional radiation patterns, it is not suitable for wideband applications due to its drawback of narrow bandwidth. In this communication, a compact wideband planar printed quasi-Yagi antenna is presented. The proposed quasi-Yagi antenna consists of a microstrip line to slotline transition structure, a driver dipole, and a parasitic strip element. The driver dipole is connected to the slotline through a coplanar stripline (CPS). The proposed antenna uses a stepped connection structure between the CPS and the slotline to improve the impedance matching. Two apertures are symmetrically etched in the ground plane to improve the unidirectional radiation characteristics. Simulation and experimental results show that the unidirectional radiation patterns of the proposed antenna are good. A 92.2% measured bandwidth with S 11 < -10~dB from 3.8 to 10.3 GHz is achieved. A moderate gain, which is better than 4 dBi, is also obtained. [ABSTRACT FROM PUBLISHER]

A compact hyper-band (>10:1 impedance bandwidth) printed antenna design is investigated numerically and experimentally. It is based on an elliptical-slot antenna augmented with a parasitic oval patch and driven with a specially engineered microstrip-line-fed elliptical tuning fork element. The parasitic and driven elements are adjusted along with the elliptical slot to create additional resonance modes; adjust the coupling strengths among all of the design components; facilitate the overlap of adjacent resonance modes; and fine tune the input impedance. The total size of the final optimized antenna is only 30\times40 mm^2. It exhibits a -10-dB impedance bandwidth from 2.26 to 22.18 GHz. Desirable radiation performance characteristics, including relatively stable and omni-directional radiation patterns, are obtained over this range. A prototype was fabricated and tested. The experimental results confirm the predicted input impedance bandwidth and radiation characteristics. While the hyper-band performance could be used for high fidelity short pulse applications, the antenna could also be used for multi-band operations from 3.1–10.6 GHz since it covers that entire ultra-wideband (UWB) spectral range. [ABSTRACT FROM PUBLISHER]