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Frequency Domain Spectroscopy (FDS) is proposed as a suitable diagnostic method in this paper for implementation on energized oil-paper insulation systems. In present FDS tests, the measurement method is only designed for offline applications. To overcome the deficiencies with the offline testing, this work investigates the feasibility of performing FDS measurements on energized transformers with the view to developing an online diagnostic tool using neutral connections as injection and measurement paths. In the proposed technique, a low-pass filter system is designed to remove the high frequency noise as well as the power frequency signals present in the measured neutral currents. The technique has been successfully applied in a laboratory environment on transformers with oil-paper insulation systems with different operational ages and is feasible for single-phase as well as 3-phase transformers with the accessible neutral points. Compared with the conventional FDS results, a nonlinear dielectric phenomenon is observed from the energized insulation systems as higher dissipation factor Tanδ values primarily due to the increased losses under power frequency voltage excitation. The degree of the nonlinearity is found to correlate well with the degradation status of insulation systems under test.

Millimeter-wave imaging may be used to assist in\ud the problem of wastepaper recognition during the sorting and\ud recycling process. Currently, there are a variety of techniques,\ud which are used within materials recovery facilities to sort waste\ud paper and card; however, improvements in sorting capability can\ud be realized using a multiple sensors to provide complementary\ud (orthogonal) data. This paper discusses the issues related to\ud the processes, which are currently used for sorting of recycled\ud wastepaper and the phenomenology for millimeter-wave imaging\ud of a wastepaper material. Experimental measurements and\ud images in the millimeter wave band are presented, which support\ud the proposed application.

This study investigated technologies related to a smart-card display and its wireless charging system, where the wireless receiver in the smart card receives not only the data but also the power required for the display circuitry. The goal of this research was to achieve the required energy transfer during the extremely short reading time when a person swipes his or her smart card. This paper describes the design considerations and the analysis procedures of the transmitter and receiver pair for an electronic paper (E-paper) display. A series of magnetic simulations as well as experimental tests were conducted to investigate the various design factors. The design considerations included the shape and effect of using ferromagnetic cores, the component design for frequency tuning, the geometric arrangements, and the number of turns of the coils. A novel design for power transmission is then proposed using a ferromagnetic core to enhance its energy efficiency. In experiments the transmitter unit prov...

This paper presents the design of a wideband Hilbert fractal antenna for the purpose of detecting and classifying different common partial discharge (PD) types in an oil-paper insulated system. Three common types of PDs are considered for the multi-class classification problem, namely, PD from a sharp point to ground plane, surface discharge, and PD from a void in the insulation. The different PD types showed variation in the detected frequency contents. The collected samples were processed using pattern recognition techniques to identify their corresponding PD types. A recognition rate of 95% was achieved when K-nearest neighbors was used as the classifier.

This paper investigates an optimization of the conventional relay selection for multirelay environments. In contrast with previously reported selection schemes, where a selected relay accesses the channel in a dedicated cooperative slot, the proposed scheme recovers the bandwidth loss of the half-duplex constraint by allowing two relays to simultaneously access the channels. Based on an appropriate dirty-paper coding (DPC) technique among relays, the proposed scheme enables a relay to establish communication with the destination at the same time that another relay forwards the data from the source. It is proven that the interplay between relay selection and the superposition DPC weight factor provides a tradeoff between relaying and new data performance. Hence, an appropriate codesign of the superposition DPC parameter and opportunistic relay selection can achieve efficient communication for the new data without affecting the relaying performance. The proposed scheme is compared with conventional relaying approaches, and its enhancements are provided through theoretical studies and numerical results.

This paper presents an experimental work investigating the failure data of oil-impregnated paper under pulsating DC voltage. The failure data of the oil-impregnated paper specimens were obtained through constant voltage stress tests; the Weibull distribution was used to estimate the statistical distribution of failure data. The exponential function (EF) and the inverse power function (IPF) were used to modify the Weibull distribution of failure data, so as to obtain two dual-variable Weibull failure distributions (WFDs), which were used to analyze failure data of oil-paper specimens obtained under pulsating DC and individual DC and AC voltages. Their adequacies were evaluated by using failure data obtained through the constant stress tests under various voltages. Both EF-modified and IPF-modified WFDs show more adequacy for failure data of oil-paper insulation under DC and pulsating DC voltages than AC voltages. The EF-modified WFD was more adequate than IPF-modified WFD in estimating the statistical distribution of failure data.

A dirty-paper channel is considered, where the transmitter knows the interference sequence up to a constant multiplicative factor, known only to the receiver. Lower bounds on the achievable rate of communication are derived by proposing a coding scheme that partially compensates for the imprecise channel knowledge.We focus on a communication scenario where the signal-to-noise ratio is high. Our approach is based on analyzing the performance achievable using lattice-based coding schemes. When the power of the interference is finite, we show that the achievable rate of this lattice-based coding scheme may be improved by a judicious choice of the scaling parameter at the receiver. We further show that the communication rate may be improved, for finite as well as infinite interference power, by allowing randomized scaling at the transmitter.

The resistivity of oil impregnated paper will decrease during its aging process. This paper takes paper resistivity as an assessment index to evaluate the insulation condition of oil impregnated paper in power transformer. The feasibility of this method are discussed in two aspects: reliability and sensitivity. Iterative inversion of paper resistivity was combined with finite element simulation. Both the bisection method and Newton’s method were used as iterative methods. After the analysis and comparison, Newton’s method was selected as the first option of paper resistivity iteration for its faster convergence. In order to consider the spatial distribution characteristic of paper aging and enhance the calculation accuracy, the resistivity calculation is expanded to a multivariate iteration based on Newton’s method, in order to consider the spatial distribution characteristic of paper aging and improve the calculation accuracy. This paper presents an exploratory research on condition assessment of oil impregnated paper insulation, and provides some reference to the security and economy operation of power transformers.

Currently used methods for estimation of moisture content in paper pulp are restricted to levels of moisture concentration below 90%. Some of the existing methods require less practical double-sided contact measurements. A few other methods make restrictive assumptions, such as the constituents of the pulp that determine its conductance. This paper presents a technique that uses fringing field interdigital sensors to measure moisture concentration in paper pulp at levels as high as 96%. The method proposed in this paper uses single-sided measurements, offers high sensitivity, and does not require special operating conditions. The accuracy of the proposed method is also demonstrated. The repeatability and reproducibility of the sensor measurements are also shown.

Air-gap discharge in oil-paper insulation is one of the main types of partial discharge (PD) in power transformer. The discharge development stage for monitoring and diagnosis of transformer potential faults is a significant area of study. The method of wavelet packet energy entropy, which is based on different frequency bands energy distribution of PD signals at different insulation states, is provided to explore the variation characteristics of the whole PD process. In this paper, air-gap discharge model is built in the simulative transformer tank that collects PD signals based on constant voltage method. This model also utilizes wavelet packet decomposition method to partition PD signal bands obtaining signal energy distribution in each frequency band, as well as total signal energy tendency along with PD development process. Wavelet packet energy entropy, which is the new PD feature parameter describing the development process, represents the order degree of PD signals which corresponds to dielectric strength. Finally, because of the cyclic change of this method, the step points of wavelet packet entropy are taken as the way to effectively divide the PD development stage.

PurposeTo consider the various aspects of this emerging market and to query the traditional view of thick film deposition and processing for successful flexible electronic production.Design/methodology/approachThe current status of flexible electronics is reviewed with particular emphasis on emerging rather than established technologies. New techniques and applications are also discussed. Material and processing developments are also required to meet the new challenges and current developments and future needs are discussed.FindingsMass production of flexible electronic circuits using processing techniques that are more akin to the newspaper printing industry is under way. Much development of both materials and processing is required but needs in the radio frequency identification, renewable energy and display markets among others justify the investment.Research limitations/implicationsDue to the wide range of new applications there is a lack of detail in this review that will necessitate further reading.Practical implicationsThere will need to be a change of thinking in the processing and material choice used in mass production of flexible electronics by any large volume manufacturer of traditional circuits on rigid substrates. Existing, new materials need development for electrical characteristics and ease of use. New materials will undoubtedly be required.Originality/valueThis paper raises awareness and technical issues surrounding emerging technologies.

The small-signal equivalent circuit modeling of microwave field-effect transistors (FETs) is an evergreen and ever flourishing research field that has to be up-to-date with technological developments. Hence, modeling techniques must be continuously adapted and extended to suit best evolving technologies. The extraction of a FET high-frequency small-signal equivalent circuit is a very active and broad research area of significant interest, owing to its use as a prerequisite for noise and large-signal modeling. The aim of this invited article is to provide in-depth knowledge, critical understanding, and new insights into how to extract a FET small-signal equivalent circuit from both theoretical and practical perspectives. To illustrate potential solutions to the key challenges faced by researchers, experimental results for different semiconductor technologies are reported and discussed. The study is focused on the hot research topic of the cold approach that has been, and still is, the most widely used technique for extracting FET small-signal models and on the active role of the transconductance for successful modeling. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.

The service life of a transformer is determined by the condition of its oil–paper insulation. A modified Cole–Cole model was introduced to describe the frequency domain spectroscopy (FDS) curves based on the classic Debye relaxation model and thereby accurately determined the ageing state of the insulation of a power transformer using FDS. Oil–paper insulation samples with different ageing states are prepared under laboratory conditions, and a characteristic parameter is extracted to quantify their ageing states after a detailed investigation of the frequency domain dielectric properties of the samples. Results reveal that the modified Cole–Cole model, including the α relaxation components, dc and hopping conductivity components, can be employed to effectively model the frequency dielectric characteristics of oil–paper insulation. Furthermore, the extracted characteristic parameter from this model, τα, can be utilized in the quantitative evaluation of the ageing states of transformer insulation. A case example is discussed to demonstrate the applicability of the proposed technique in the condition assessment of field power transformers.

The paper presents new diagnostic method applied to assess aging degree for paper-oil insulation used in professional electrical power device, primarily including medium and high power transformers. The described method is based on modified diagnostics using the recovery voltage effect occurring in dielectrics (RVM – Recovery Voltage Methods). Modification of the RVM method applied so far, which is now used only to assess moistening degree for paper-oil insulation in power transformers, consists in a new parametric analysis of recovery voltage time characteristics. Simulation and experimental tests carried out in laboratory conditions for adequately prepared insulation samples have proven that the time-constant of recovery voltage decay (τR_MIN) is the most susceptible parameter as regards quantitative change in the function of aging of the examined insulation. This conclusion is also confirmed by statistical studies, in which a multi-parameter variance analysis method has been applied. An original equivalent circuit diagram of the insulation has been used to simulate aging degree of paper-oil insulation samples in numerical tests. The diagram is based on the Cole-Cole type dielectric response model.

A complete model for the internal particle distribution of electrophoretic image displays (EPIDs) is presented. From this model, simulation formulas for electrical and optical properties are calculated. These formulas incorporate both time dependence and voltage dependence. They make it possible to optimize display properties since the model is built up with physical parameters. Results are shown that prove that this model is indeed capable of complete optical and electrical transient simulation. The importance of centrifugation during display manufacturing is proven as a way to improve the switching speed of the display.

This letter presents the design, simulation, fabrication, and characterization of an LC-resonator-based chipless RFID tag. The ID-generating circuit is designed based on a reconfigurable LC resonance circuit. Phase position modulation (PPM) coding is used for the enhancement of the coding capacity. The tag has been realized on packaging paper using all printing technique. In fabrication, overprinting process has been investigated as an effective pathway for the improvement of the conductivities. The tag with 4.25-bit coding capacity has been examined using a sweeping frequency signal transmitted from a vector network analyzer, and experimental results confirm the feasibility of the proposed chipless tag. With further optimizations, the tag can be used in the item-level tracking and identification applications, especially for the management of paper tickets and banknotes. QC 20130503

In high voltage engineering, dielectric response analysis is a widely used tool for insulation diagnostic. Voltages used for studying dielectric response in the laboratory are usually sinusoidal in nature. But the insulation system in operation on site is often stressed by voltages that may deviate significantly from a sinusoid. Thus the use of nonsinusoidal waveform in obtaining the dielectric response is a desirable study for advanced insulation diagnostic technique. Present work involves assessing the condition of electrical insulation using dielectric response analysis under the influence of nonsinusoidal voltage waveform. In dielectric response analysis, characteristics curve of phase response over a frequency band is used to predict the insulation condition, which involves expertise. In this respect parameterization of insulation condition can make the assessment technique much simpler. But the nonlinear behavior of insulation restricts such an attempt to be accurate enough for reliable assessment of minute degradation of insulation condition. Therefore, the present work proposes a non-linear system identification technique, in an attempt to parameterize insulation condition. In this work, a suitable excitation signal has been designed so that the observed response becomes representative of the behavior of the whole system dynamics over the frequency band of interest. Tests have been performed with insulations having different moisture contents. The obtained system parameters, through nonlinear Hammerstein model, were found to be consistent over several experiments, and also accurate enough to detect small variation of moisture content. The proposed method is based on the time domain measurement of input excitation voltage and corresponding response current through the insulation.

This paper is concerned with the task of sensing in web-forming process control loops. Conventional and newly proposed measurement techniques are discussed and a new type of measurement is suggested. The new measurement method adresses the problem of paper machine "wet-end" sensing and is based on a CCD camera system which can detect the dry-line. Both the theoretical and practical aspects of the invention are investigated and the sensing system is developed into a portable measurement system which is applied to a paper machine. The paper machine measurements are analyzed and presented using nonparametric techniques based on analysis of variance. Compared to traditional scanning gauge systems the dry-line detector allows for a large reduction in the transport delay, higher data density and sampling rate, and better machine directional (MD), and cross-directional (CD) signal decomposition.

Frequency domain spectroscopy (FDS) is being used to assess the insulation condition of oil–paper power transformers. However, it has to date only been implemented on de-energised transformers, which requires the transformers to be shut down for an extended period and may cause significant costs. To solve this issue, a newly improved monitoring method based on the FDS principle is proposed to implement the dielectric measurement on energised transformers. Moreover, a chirp waveform excitation and its novel processing method are introduced. Compared with the conventional FDS results, dielectric results from the energised insulation system have higher tanδ values because of the increased losses. To further understand the insulation ageing process, the effects of the geometric capacitance are removed from the measured imaginary admittance of the insulation system to enhance the ageing signature. The resulting imaginary admittance is then shown to correlate well with the central time constant in return voltage measurements results. The proposed methods address the issues on techniques used on energised transformers and provide a clue for on-line FDS diagnostic application.

Dynamic logic style is used in high performance circuit design because of its fast speed and less transistors requirement as compared to CMOS logic style. But it is not widely accepted for all types of circuit implementations due to its less noise tolerance and charge sharing problems. A small noise at the input of the dynamic logic can change the desired output. Domino logic uses one static CMOS inverter at the output of dynamic node which is more noise immune and consuming very less power as compared to other proposed circuit. In this paper, an overview and classification of these techniques are first presented and then compared according to their performance.

Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-to- breakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the two- parameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the two- parameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.

This letter presents a high-voltage power amplifier for driving flexible paper speaker. Simple circuit complexity and high signal quality can be achieved. The operating principles and design considerations of the studied paper speaker power amplifier are analyzed and discussed. A laboratory prototype is built and tested. The experimental results are shown to verify the studied scheme. Copyright © 2012 John Wiley & Sons, Ltd.

Radio Frequency IDentification (RFID) is intended to supplant legacy (optical) bar code scanning technology found in many logistic and retail applications. RFID is distinguished by inexpensive, low power and compact form factor tags, whose longevity and efficacy are predicated on using passive communication techniques and on-tag power harvesting. Such tags employ backscatter modulation, which does not require any active RF components. As a result, backscatter has become an attractive design choice for short-range communications in power constrained wireless sensor networking scenarios. The purpose of this work is two-fold. First, it aims to expose backscatter communication as an emerging topic to a communication systems-theoretic audience. Since backscatter modulation and on-tag power harvesting efficiency are coupled, it is necessary to re-examine notions of power and spectral efficiency from an energy-constraint perspective; this leads to novel coded modulation schemes for future RFID systems. Further, we investigate RFID MIMO systems where the channel fading encountered has different statistics than the classical Rayleigh fading model. In turn,the trade off between diversity order and spatial multiplexing gains are distinct from wide-area MIMO.

This paper reviews some of the many published technical papers relating to the measurement of IC emissions using a 1 GHz TEM cell or GTEM cell modified to accept an IC test board and provides a basis for correlation between these IC level measurements and module level RF emissions. We will follow the development of this methodology from the early investigations through the later applications to show the viability of the technique for IC qualification. Developments over time have shown that this method of IC emission measurement is repeatable, correlatable to other methods and provides, within limits, useful prediction of module level RF emissions performance.

Significant gain and bandwidth improvement of inkjet-printed antennas with integrated artificial magnetic conductor (AMC) is achieved by utilizing wideband ground-backed frequency selective surfaces (FSSs) to overcome the high losses of organic substrates such as paper. A microstrip-fed monopole mounted on an artificial magnetic conductor is demonstrated to improve the gain by 5 dB over previous works and exhibit much wider impedance bandwidth while maintaining a thin antenna profile and a 20% electrical size reduction. The effect of AMC bandwidth on substrate losses and the gain reduction caused by finite AMC array effects are investigated in an effort to produce high-gain, miniaturized, low-cost wearable and structure mount antennas.

This paper presents aging condition assessment of oil-paper transformer insulation based on partial discharge analysis in order to realize statistical parameters reduction. The extracted feature factors of this proposed model were used to identify oil-paper samples with different aging degrees. An accelerated aging test was implemented using artificial oil-paper samples with an internal flat air gap. During the aging test, partial discharge signal acquisition was conducted periodically. In the new model, conventional statistical parameters of phase resolved partial discharge (PRPD) patterns were analyzed using principal component and factor analysis (PCFA), and a group of new features constituted by the extracted factors was obtained. These factors were not only independent of one another, they had their own specific properties. To a great extent, these factors represent information on PRPD patterns through a limited number of variables. Through the use of the new features extracted from PCFA method, the clustering and discriminating results of the samples with different aging stages provided significantly referenced information on the condition assessment of oil-paper insulation.

Occluded gaseous cavities within the insulating materials are potential sources of electrical trees which can lead to continuous deterioration and breakdown of materials. To determine the suitability of use and to acquire the data for the dimensioning of electrical insulation systems breakdown voltage of insulators should be determined. In this paper, fuzzy logic (FL) method is used to model breakdown voltages of White Minilex Paper samples based on experimental data generated in the laboratory. Different models are proposed with different shapes of the membership functions for the FL under both dc and ac voltage conditions. The cavities are created artificially with different dimensions. Low values of mean absolute errors of the estimated breakdown voltage of the test data show the effectiveness of such models.

The paper presents the application of the Cole-Cole model for determining the runs of the return voltage of the paper-oil insulation sample through a computer simulation. Different insulation conditions were simulated through an adequate selection of parameters ? and ? of the Cole-Cole model. For calculation purposes, a series - parallel substitute scheme, obtained through approximation of discrete characteristic operator impedance Za of the model applied, was used. The diagnostics of the simulated insulation condition was based on the analysis of a few selected parameters of the return voltage, obtained from time characteristics.

In this paper, the feasibility of inkjet printing of circuit and microwave structures on paper-based substrates is investigated for the first time in the implementation of a complete low-cost wireless platform for sensors. First, the system-level design of the module including the amplifier characterization were carried out to ensure optimum performance of the sensor modules in the UHF bands used in RF identification communication. These results were then used to design two different antenna structures, which are printed on paper along with their respective circuit layouts using inket-printing technology. Different techniques were investigated for the assembly of circuit components on the silver printed layouts. Finally, wireless link measurements on the assembled prototypes verified the good performance on the wireless and sensing sides.

The automatic control of product moisture content in the paper industry is based upon online moisture measurement. Furthermore, the automatic control of other quality variables such as coat weight may also rely on the moisture measurement. The integrity of infrared radiation (IR) based online moisture measurement systems was studied by performing basic calibrations at the mills with references sealed between two glass plates. The calibrations were performed according to the EN ISO/IEC 17025 standard which is a requirement for calibration laboratories. The observed measurement errors were 2.9% moisture in the first time calibrations at the 95% confidence level. It is demonstrated that these errors can be reduced to under 0.5% moisture by applying traceable methods in the basic calibration, thus improving the integrity of online moisture measurements. Also a standardised algorithm, based on the experience from the performed calibrations, is proposed to ease the adjustment of different moisture measurement systems.

The letter presents the design, fabrication, and measurement of a configurable radio frequency identification (RFID) tag based on time-domain reflections. The tag circuit contains a microstrip line (ML) that propagates radio frequency (RF) signals, and a group of capacitors that introduce impedance discontinuities to encode binary codes. The configurability of the tag circuit is allowed by connecting the nearby-placed capacitors with the ML. Ink-jet printing technology is employed to implement the layout of the proposed tag on paper substrate. To overcome the limitations of printed metallic tracks, a linearly tapering technique is proposed. With this technique, a four-bit configurable passive chipless RFID tag is realized. Both time-domain reflectometry (TDR) measurements and ultrawideband (UWB) characterizations were conducted for the proposed tag, and the results are in good consistence with the simulation ones from the circuit simulator advanced design system (ADS). Owing to its low cost fabrication and environmentally friendly nature, the proposed tag has great potential to be widely employed in low-end RFID applications. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 2781-2786, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26412

The article "A 4-GHz Continuous-Time Δ-ΣADC with 70-dB DR and -74 dBFS THD in 125-MHz BW" by Muhammed Bolatkale, Lucien J. Breems, Robert Rutten, and Kofi A.A. Makinwa, published in IEEE Journal of Solid-State Circuits (JSSC), vol. 46, no. 12, pp. 2857-2868, Dec. 2011, was declared best of all in JSSC 2011. The authors' novel approach modifies loop filter architecture to deal with the parasitics and excess delay of the large comparator array in the 4-GHz multibit quantizer. Their five-times improvement in bandwidth compared to state-of-theart CMOS delta-sigma modulators enlarges the application domain of these ADCs, enabling them to compete with high speed architectures like pipeline ADCs. A detailed review of the article is provided.

Dielectric testing techniques, in both time and frequency domains, are currently widely used by power utilities for assessment of the condition of transformer oil-paper insulation systems. However, it has been reported that results of these tests are highly influenced by the operating temperature during measurements. The distribution, migration and equilibrium of moisture between oil and paper in a complicated insulation system is highly temperature dependent. It requires adequate experience and proper understanding to interpret the dielectric response results in the presence of temperature variations and thermal instability. Proper analysis of the dielectric test result is only possible with an understanding of the physical behavior of the insulation system in response to temperature. A circuit model, which describes the dielectric behavior of the transformers main insulation system, has been investigated in this paper. The values of the parameters of the model have been identified from the dielectric tests. A correlation has been observed between the operating temperature and the equivalent model parameters that can be used as additional information for better interpretation of the dielectric test results. This paper thus reports a detailed study on the effects of temperature on dielectric measurements of a transformer under controlled laboratory conditions. Some results of practical on-site testing are also presented to demonstrate the possibility of errors that may be introduced in dielectric test results analysis unless temperature effects are taken into consideration.

The detection of Partial Discharges (PD) is a reliable technique to analyze the status of electrical insulation in power transformers. Phase resolved partial discharge patterns are being complemented with high frequency pulse waveform analysis, in order to identify discharge sources. In addition to this, acoustic techniques are being implemented trying to locate PD sites in large power transformers. In this work, an inductive loop sensor will be used to identify two different PD sources by means of the energy distribution of the detected waveforms. Additionally, these PD sources will be located by means of acoustic measurements with an electrical reference, through the analysis of the acoustic activity detected for each sensor individually.

In this paper, inkjet-printed UHF and microwave circuits fabricated on paper substrates are investigated for the first time as an approach that aims for a system-level solution for fast and ultra-low-cost mass production. First, the RF characteristics of the paper substrate are studied by using the microstrip ring resonator in order to characterize the relative permittivity (epsivr) and loss tangent (tan delta) of the substrate at the UHF band for the first time reported. A UHF RFID tag module is then developed with the inkjet-printing technology, proving this approach could function as an enabling technology for much simpler and faster fabrication on/in paper. Simulation and well-agreed measurement results, which show very good agreement, verify a good performance of the tag module. In addition, the possibility of multilayer RF structures on a paper substrate is explored, and a multilayer patch resonator bandpass filter demonstrates the feasibility of ultra-low-cost 3-D paper-on-paper RF/wireless structures.

This work deals with the design and fabrication of antennas for radio frequency identification (RFID) tag devices operating in the low microwave frequency range. Paper substrate material and inkjet printing process have been used to guarantee mechanical flexibility and ultra-low production costs of the antenna. A new antenna design methodology has been developed with the purpose to minimise the amount of both substrate material and conductive ink. The first goal is achieved by reducing, for a given frequency, the antenna size. The second goal, instead, is pursued by studying the surface current density distribution along the antenna and removing the metal material where such a current density is negligible. The above methodology has been applied to several antennas designs ranging from a windshield sticker tag to an RFID-SAW antenna. Moreover a 3.5 GHz crossed-dipole tag, based on the frequency-doubling mechanism, is reported along with a possible modification to enable wireless sensing. The experimental characterisation of these prototypes validates the proposed design methodology opening, in the mean time, the possibility for ultra-low cost mass production of RFID tag devices based on paper materials.

This article presents an overview of the generalized negative-refractive-index transmission-line (G-NRI-TL) and summarizes the design equations that determine the frequencies of each of its four passbands. Specific multiband devices to which G-NRI-TLs have been applied are discussed: both a dual-band coupled-line coupler operating at 2.7 and 4.7 GHz and a printed single-ended all-pass cell with two pairs of right- and left-handed bands are explained. The details of how each may be fabricated in a fully-printed layout are provided and simulated and measured results are given. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22:459–468, 2012. © 2012 Wiley Periodicals, Inc.

This article is a review of recent applications of split rings to the design of planar microwave circuits based on metamaterial concepts. The considered resonators, namely, split-ring resonators (SRRs), complementary SRRs (CSRRs), and their open counterparts (OSRRs and OCSRRs), are reviewed, and the equivalent circuit models of artificial lines based on such resonators, including parasitics, are presented and discussed. The second part of the article is devoted to highlight some recent applications of the considered resonators. This will include the design of dual-band components and wideband bandpass filters based on the combination of OSRRs and OCSRRs, the design of tunable components based on cantilever-type SRRs, and the design of CSRR-based differential (balanced) lines with common-mode suppression. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22:439–458, 2012. © 2012 Wiley Periodicals, Inc.

Knowledge about moisture content in oil impregnated paper insulation is essential when estimating remaining lifetime of power transformers. Direct evaluation of moisture content is rarely possible due to inaccessibility of the internal insulation system in transformers. Therefore, various indirect estimation techniques are utilized. Frequency domain spectroscopy (FDS) measurements of transformer insulation belong to this group. To perform high quality interpretation of results of FDS measurements a good knowledge on dielectric responses in oil impregnated pressboard and paper is required, especially as it refers to their variation with water content and temperature. The aim of this paper is to provide an open access to the frequency domain spectra of oil impregnated paper and pressboard samples, which can then be used in modeling of the results of diagnostic measurements in power transformers.

A microwave sensor for glue on paper detection for industrial application has been developed. It uses a resonant cavity to detect and measure the amount of glue placed on a dielectric layer, for example a sheet of paper. It works in the ISM band, at 2.45 GHz. It can be used for the control of the industrial gluing for the mailing and packaging sector.

This paper is a basic primer for defining and applying active harmonic filters. Active harmonic filters (AHFs) are sophisticated electronic devices that offer significant advantages over traditional harmonic mitigation and displacement power factor correction methods. This paper introduces the AHF and discusses when and where these advantages apply. Additionally, the simplicity in selection of the AHF discussed. The author presents specific examples for the various applications to which AHFs have been applied.

Recently developed monitoring-systems show the need as also the possibilities for online- and offline-onsite-diagnostics. The limit in sensitivity for electrical pd-measurements according to IEC 60270 which is reached using filters for sinusoidal disturbances and compensation for corona impulses is still not satisfactory. The acoustic partial discharge measurement (pd-measurement) is also a well known and reliable method often used by transformer manufacturers in testing. In laboratory setups a gain in sensitivity of the acoustic in comparison to the electrical pd measurements could be established. This is reached by adapting the sensors to the propagation path, a modern but moderately priced acquisition hardware and the introduction of new signal processing algorithms. The developed sophisticated measuring systems show remarkable results in online acoustic pd-measurements onsite.

The term waveform engineering denotes all those circuit design techniques that are based on shaping the transistor voltage and current waveforms. From a general perspective, these design techniques can be grouped in two main categories according to the adopted design tool: measurement- and model-based. In the last two decades, thanks to the proliferation of setups enabling calibrated waveform acquisition at microwave frequencies, waveform engineering has attracted continuously increasing interest in the microwave engineering community. In this article, a comprehensive analysis of the waveform-engineering based design techniques is reported, paying particular attention to the advantages and drawbacks associated to each approach.

We are pleased to announce that the August 2017 issue of the IEEE Transactions on Dielectrics and Electrical Insulation (TDEI) will be a special issue on power modulators, repetitive pulsed power, and high voltage topics.

The article introduces a new approach to the ANN-based behavioral modeling of nonlinear RF/microwave systems or subsystems. The proposed model accounts for both the linear and the nonlinear distortion of modulated signals. The former is introduced by the two-port frequency-dependent admittance matrix. The latter is described by the means of a couple of describing functions (which may also be frequency-dependent), relating the two-port linear and the nonlinear responses. The describing functions are approximated by artificial neural networks (ANN) trained by harmonic-balance results. The resulting model is fast to compute, can accurately handle broadband modulated signals, and is fully bilateral. This means that the model can be routinely used to analyze systems where bidirectional signal flow takes place, e.g., due to mismatches between the interconnected subsystems, or even due to the presence of filters operating in the stopband. © 2002 John Wiley & Sons, Inc. Int J RF and Microwave CAE 12: 51–70, 2002.

In this study, polymeric silver inks, paper substrates, and screen printing were used to produce prototype Bow-Tie tags. Because of increasing interest in applying passive UHF-RFID systems in paper industry, the Bow-Tie antenna used in this study was designed to work through paper. The maximum reliable read ranges of the tags were measured thorough stacked paper and also in air. The analysis and functioning of the antenna design are also discussed. All inks and paper substrates were suitable as antenna material and the prototype tag antennas had good reading performance. The maximum reliable read ranges were quite the same as for copper and aluminum tags studied elsewhere. This means that printed UHF tags are competitive solutions for the identification of simple mass products.

The purpose of this paper is to present an overview of novel design and integration approaches for improved performance “enhanced-cognition” UHF passive and active radio frequency identification (RFID) tags. Antenna design rules are explained for a variety of applications. A strategy that is currently under development for embedding power sources and integration of sensors and integrated circuits (ICs) on low-cost organic substrates, such as liquid crystal polymer (LCP) and paper, enabling the use of inkjet-printing capability for the UHF frequency band, is discussed in the paper. The proposed technologies could potentially revolutionize RFID tags allowing for integrated sensing capabilities for various applications such as security, military, logistics, automotion, and pharmaceutics.

Ultrasound techniques for flow investigation have been extensively developed for several years. Many methods have reached a level of maturity that allows widespread and still growing clinical use. Recently, new exciting developments have been introduced by the combination of Doppler techniques with advanced (e.g. plane wave) imaging methods. Therefore, a comprehensive review of the current state-of-the-art ultrasound methods applied to flow measurement and imaging becomes relevant.

The importance of power-factor correction and the related line-harmonics reduction is increasing as the amount of line-fed electronic equipment grows and the requirements of regulatory agencies tighten. This paper presents a comprehensive overview of power-factor correction in single-phase off-line switching-mode power supplies, including the definition of power factor and its relation to total harmonic distortion; the IEC 555-2 requirements; many passive and active power-factor corrector topologies and control methods; modelling issues; and practical considerations.