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Electronics Letters

Issue 16 • Date July 31 2014

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Displaying Results 1 - 25 of 39
  • In brief

    Page(s): 1106
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  • Interview

    Page(s): 1106
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  • Clear cooling

    Page(s): 1107
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (545 KB)  

    Researchers at the US Army Research Laboratory (ARL) have developed a thin disk laser power amplifier with greatly enhanced cooling properties. The amplifier allows power scaling to be extended up to two and a half times, whilst maintaining a very high quality beam. View full abstract»

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  • Transfer of power

    Page(s): 1108
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (379 KB)  

    A wireless power transfer technique that uses miniaturised receivers suitable for real-world use has been demonstrated by researchers in Korea. Hyoungjun Kim and Chulhun Seo from Soongsil University used a metamaterial slab in resonant coupling method to significantly improve the efficiency of the power transfer, and retain this efficiency over greater distances than previously possible. View full abstract»

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  • Compact wideband and dual-band antenna for TD-LTE and WLAN applications

    Page(s): 1111 - 1112
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (541 KB)  

    A novel compact wideband and dual-band microstrip-fed antenna is proposed. By using symmetrical inverted-L-shaped strips, a fork-shaped strip, a rectangular slot and a defected ground plane, the dual-band resonances of the antenna are generated. The measured impedance bandwidths are 1.12 GHz for the lower frequency band (1.87-2.99 GHz), and 780 MHz for the higher frequency band (5.10-5.88 GHz). The fabricated antenna can be used to cover the entire required bands for time-division-long-term evolution (1880-2655 MHz) and wireless local area network 802.11 a/b/g (2.4-2.4835, 5.15-5.875 GHz). The measured gain at 2.4 and 5.5 GHz is 2.1 and 6.1 dBi, respectively. The antenna shows a compact size of 25 × 30 × 0.8 mm. The details of the antenna design, the operation mechanism and the simulated and measured results are presented. View full abstract»

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  • Compact ACS-fed monopole antenna with rectangular SRRS for tri-band operation

    Page(s): 1112 - 1114
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (558 KB)  

    A compact uniplanar monopole antenna is presented for tri-band operation. The antenna is fed by an asymmetric coplanar strip (ACS), which can provide an effective way to reduce the antenna size. Two rectangular split-ring resonators (SRRs) are etched on the radiating patch to achieve a tri-band resonant characteristic and good performance of interference suppression. The proposed antenna with a total size of 32 × 12 mm2 has been constructed and tested. The measured results indicate that the designed antenna has 10 dB impedance bandwidths of 340 MHz (2.36-2.70 MHz), 390 MHz (3.35-2.74 GHz) and 1110 MHz (5.01-6.12 GHz), which meet the requirements of the 2.4/5.2/5.8 GHz wireless local area network (WLAN) and 2.5/3.5/5.5 GHz worldwide interoperability for microwave access (WiMAX) applications. View full abstract»

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  • Electronically tunable reflectarray element based on C-patch coupled to delay line

    Page(s): 1114 - 1116
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (339 KB)  

    A reflectarray element with switchable phase shift for an electronically beam scanning reflectarray operating in the X-band is presented. The element consists of multilayer printed circuits with a C-patch coupled to a delay line through a ring slot. The phase shift is obtained by adjusting the length of the delay line. The element integrated with a pin diode to control the phase is assembled and measured in the X-band. The experimental validations show a wide range of reflection phase with a quasi-linear phase curve as well as a promising capability of changing the reflected phase between the ON and OFF states of the PIN diode. View full abstract»

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  • Full-duplex MIMO system based on antenna cancellation technique

    Page(s): 1116 - 1117
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (331 KB)  

    The performance of an antenna cancellation technique for a multiple-input-multiple-output (MIMO) full-duplex system that is based on null-steering beamforming and antenna polarisation diversity is investigated. A practical implementation of a symmetric antenna topology comprising three dual-polarised patch antennas operating at 2.4 GHz is described. The measurement results show an average of 60 dB self-interference cancellation over 200 MHz bandwidth. Moreover, a decoupling level of up to 22 dB is achieved for MIMO multiplexing using antenna polarisation diversity. The performance evaluation of the proposed technique was performed by simulation and measurement and the results have good agreement. View full abstract»

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  • Low-complexity 2d central DOA estimation of coherently distributed sources with cross-correlation matrix

    Page(s): 1118 - 1120
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (261 KB)  

    A low-complexity estimator for two-dimensional (2D) central direction-of-arrival (DOA) estimation of multiple coherently distributed sources is proposed, which is based on applying the singular value decomposition method to the cross-correlation matrix of the received signals at double parallel uniform linear arrays. The proposed estimator is performed with automatic parameter pairing. Simulation results confirm the efficacy of the proposed estimator. View full abstract»

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  • Magnetic current formulation for periodically loaded slots

    Page(s): 1120 - 1121
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    A novel adaptation of the Wait-Hill formulation is proposed for the analysis of plane wave scattering from periodically loaded orthogonal slots. For the case of vertical slots loaded with infinitesimal lumped elements, the formulation leads to a novel exact analytical expression for the fundamental harmonic current amplitude. In addition, the formulation is shown to provide insight into lumped-element loaded slot miniaturised frequency selective surfaces. View full abstract»

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  • Radiation characteristics of terahertz waveguide-fed circularly polarised antipodal exponentially tapered slot antenna

    Page(s): 1122 - 1123
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    A terahertz (THz) waveguide-fed circularly polarised (CP) antipodal exponentially tapered slot antenna (AETSA) is designed, fabricated and measured. This antenna is fed by a WR2.2 rectangular waveguide. The integrated AETSA is fabricated by deep reactive-ion etching on silicon wafers, gold-sputtering and gold-gold thermo-compression bonding. Optimised exponential curves are introduced to the profiles of tapered slots to realise the CP performance. The measured radiation patterns at 490 GHz show beamwidths of 42° and 39° in the 0°-plane and 90°-plane, with low sidelobes. Furthermore, the measured axial ratios (ARs) from 480 to 500 GHz are lower than 2 dB. The THz waveguide-fed CP AETSA has potential to be applied in compact THz imaging, detection and communication systems. View full abstract»

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  • Wideband hybrid circularly polarised rectangular dielectric resonator antenna excited by modified cross-slot

    Page(s): 1123 - 1125
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (629 KB)  

    A wideband circularly polarised (CP) rectangular dielectric resonator antenna (DRA) based on the concept of a hybrid antenna is presented. In this design, the modified cross-slot simultaneously performs the functions of an effective radiator and the feeding structure of the rectangular dielectric resonator (DR). By properly designing the structure parameters of the DRA, the resonances of the modified cross-slot and the DR can be merged to obtain a wide CP bandwidth. A prototype antenna is designed, fabricated and measured, and a wide 3 dB axial ratio bandwidth of 24.6% is achieved. View full abstract»

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  • Electrical conductivity measurement in thiel-embalmed tissue model: relevance to radiofrequency ablation

    Page(s): 1125 - 1127
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (305 KB)  

    Thiel-embalmed human cadaveric specimens are used widely for biomedical scientific investigation. This Letter reports electrical impedance measurements of Thiel-embalming solutions from 1 Hz to 32 MHz. Compared with other solutions studied, Thiel solution has the lowest impedance throughout the test spectrum. The electrical conductivity of a Thiel-embalmed liver sample exhibited a relatively flat frequency response from 100 to 500 kHz, which is the frequency range used for electro-surgery and radiofrequency tumour ablation (RFA). It measured 5 Sm-1 compared with 0.22 Sm-1 obtained from ex-vivo fresh pig liver. Using finite element modelling and experimental evaluation, the ablation zone obtained from the Thiel-embalmed liver sample was extremely small due to its much higher conductivity. Hence, it is concluded that Thiel-embalmed tissue cannot be used as a reliable model for RFA evaluation. View full abstract»

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  • Open platform, 32-channel, portable, data-logger with 32 pga control lines for wearable medical device development

    Page(s): 1127 - 1129
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (397 KB)  

    A compact isolated low-power 32-channel 16-bit data-logging system around an NXP ARM processor (LPC1768) and four of the linear technology octal analogue-to-digital converters (ADCs) LTC1857/58/59 is designed. The system requires only 250 mA when powered at 5 V to run at full power (including a capacitive 2.8 inch touch-screen display and 32 Gb SHDC SD memory card). The sample rate is configurable up to 1 k SPS per channel as well as voltage dynamic input up to ±10 V; additionally, 32 chip select lines (SPI protocol) individually addressable and controllable while sampling to configure user-designed programmable gain amplifiers (PGAs) are available. Collaboration is being sought to improve the software capabilities, particularly to enrich the very basic user interface and to add wireless connectivity. The code is available (under the GPL licence) at our repository, the gerber file to reproduce the PCB is available (on the As-Is basis) on request. The galvanic isolation between the power supply data connection and ADC channels makes the data-logger also compatible with the main powered PCs, hence it is suitable for the implementation of medical devices at least for the prototyping and initial testing stages. View full abstract»

    Open Access
  • Low-power programmable high-gain time difference amplifier with regeneration time control

    Page(s): 1129 - 1131
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A gain controllable SR-latch-based time difference amplifier (TDA) with a gain of up to 150 by controlling the regeneration time constant, especially with programmable transconductance (gm), is presented. The presented gm control uses resistor degeneration at the input switches so that the effective gm is reduced, whereas the time difference gain increases. Unavoidable large crowbar current from the slow regeneration is avoided by shifting to the fast regeneration mode after regeneration is completed, which effectively reduces current consumption by 29.3%. View full abstract»

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  • Energy-efficient charge-average switching DAC with floating capacitors for SAR ADC

    Page(s): 1131 - 1132
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (494 KB)  

    An energy-efficient capacitor switching digital-to-analogue converter (DAC) is proposed for successive-approximation register analogue-to-digital converters (SAR ADCs). The proposed charge-average switching with floating capacitors (CASFCs) DAC disconnects the most significant bit (MSB) capacitors from the capacitor array after determining the MSB. The switching energy of the proposed CASFC DAC is lower than that of the recently published DAC, because the CAS technique is only employed in the CASFC DAC, while both the traditional and CAS methods are used in the previous DAC depending on inputs. In addition, the energy during the reset period is also minimised because the floated MSB capacitors do not consume the reset energy. The CASFC DAC reduces the switching energy with and without reset by 64.4 and 37.5%, respectively, compared with the aforementioned previous DAC. View full abstract»

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  • Approach to fault detection of time-delay systems using functional observers

    Page(s): 1132 - 1134
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (109 KB)  

    A new methodology is reported for designing functional observers to detect actuator faults of a class of time-delay systems where the matrix pair (A, C) is not observable. First, a generalised state transformation is used to transform the system into new coordinates where the delay term associated with the state vector is injected into the system's output and input. Then, a minimum-order functional observer is designed to construct a residual function that can trigger system faults. The finding is significant as it is now possible to detect faults of time-delay systems where the pair (A, C) is not required to be observable. A numerical example is given to illustrate the effectiveness of the proposed design approach. View full abstract»

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  • Error cost function for mirror-based three-dimensional reconstruction

    Page(s): 1134 - 1136
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (241 KB)  

    A novel error cost function for the three-dimensional (3D) reconstruction system that uses a single fixed camera and a freely moving planar mirror is presented. Multiple mirror poses and the location of the observed points are simultaneously corrected by iterations considering the geometric constraint among the multiple mirror-reflections. A numerical simulation demonstrates the high accuracy of the proposed method against the large initial error. View full abstract»

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  • Colour correction of stereo images using local correspondence

    Page(s): 1136 - 1138
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (382 KB)  

    A method for enhancing the accuracy of colour correction in stereo images is proposed. The goal is to perform colour compensation at the corresponding points in a stereo image pair using local correspondence information. First, the relevant matching points for colour transfer are extracted using a modified stereo matching algorithm. Then, in order to account for illumination variations and occlusion areas, a new colour transfer method is applied through the weighted sum of the colour difference using local features. The performance of the proposed algorithm has been tested on the reference colour-modified Middlebury dataset. View full abstract»

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  • Efficient sign identification engines for integers represented in rns extended 3-moduli set {2n - 1, 2n + k, 2n + 1}

    Page(s): 1138 - 1139
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (190 KB)  

    Sign detection is a widely used operation, namely in digital fixed-point signal processing, but hard to perform in residue number systems (RNSs). Presented is an effective method for performing RNS sign identification in the comprehensive extended 3-moduli set {2n- 1, 2n+k, 2n + 1}, which covers from the traditional 3-moduli set, for k = 0, up to the set whose binary channel width is 2n (k = n). The proposed method is applied to design an efficient hardware architecture for sign detection that not only takes advantage of the arithmetic units available in the RNS, but also imposes a small overhead, both in terms of cost and performance. Experimental results for a 65 nm CMOS technology show that the proposed architecture supersedes the related state-of-the-art, requiring <; 40% of circuit area, reducing the imposed delay by about 25%, and the power consumption by 30%. View full abstract»

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  • Fast decoding for raptorQ codes using matrix dimensionality reduction

    Page(s): 1139 - 1141
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (209 KB)  

    A very fast decoding algorithm using matrix dimensionality reduction for RaptorQ codes is proposed. The algorithm exploits a pre-calculated inverse matrix to achieve dimensionality reduction for the received code constraint matrix. As a result, the decoding complexity is decreased significantly, whereas the failure-overhead curve is still identical to that of conventional approaches. Simulations show that the decoding speed of the proposed algorithm can be as fast as 17.5 times the state-of-the-art algorithm when the erasure probability is relatively low. View full abstract»

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  • 14-30 GHz low-power sub-harmonic single-balanced gate-pumped mixer with transformer combiner in 0.18 μm CMOS

    Page(s): 1141 - 1143
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (459 KB)  

    A 14-30 GHz sub-harmonic single-balanced gate-pumped mixer with a wideband transformer combiner in 0.18 μm CMOS technology is presented. The transistors of the sub-harmonic mixer core are biased at weak inversion to lower the required local oscillator (LO) driving power and DC power consumption. The wideband combiner including a Marchand balun and a 1:1:1 trifilar transformer was designed to combine the radio frequency (RF) and LO driving signals to produce four states of signals, where the RF frequency is about twice the LO frequency. Two quarter-wavelength transmission lines are adopted to improve the RF-to-intermediate-frequency (IF) and 2LO-to-IF isolations. The measured results show that the maximum conversion gain of -1 dB is at 18 GHz and a 3 dB bandwidth is from 14 to 30 GHz while applying the LO driving power of only 1 dBm. The total power consumption including the output buffer is only 7.8 mW. View full abstract»

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  • Compact six-band triplexer using stub-loaded stepped impedance resonators

    Page(s): 1143 - 1145
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (374 KB)  

    A novel six-band triplexer based on short- and open-ended stub-loaded stepped impedance resonators (SLSIRs) is presented. The stub added at the centre of the SIR introduces a flexible even mode close to the first odd mode, realising a dual-band response with nearby passbands and a wide stop band. Three second-order dual-band channels combined with a common T-shaped SIR feed line form a six-band triplexer with compact size, low insertion loss and high isolation. A practical six-band triplexer operating at 1.9/2.4, 3.5/4.2 and 5.2/5.8 GHz is designed and realised based on the proposed multi-band multiplexer coupling scheme. View full abstract»

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  • Dual-band bandpass filter with wide upper stopband using quad-mode stepped impedance stub-loaded resonator

    Page(s): 1145 - 1146
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    A novel quad-mode stepped impedance stub-loaded resonator is presented. The even-odd-mode method is applied twice to analyse the modal resonance characteristics due to its symmetry. All the four modes' equivalent circuits are quarter-wavelength stepped impedance resonators, so the proposed resonator has a compact size and higher harmonic frequencies. Stub-to-stub coupling is introduced to split two identical modes and produce two transmission zeros. A dual-band bandpass filter operating at 1.5 and 2.4 GHz is designed using the proposed resonator. The centre frequency and bandwidth of each passband can be controlled by tuning the corresponding physical dimensions, and a wide upper stopband is achieved. Finally, the designed filter was fabricated and measured, and the measured results have good agreement with the simulated ones. View full abstract»

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  • Electric-LC resonators at microwave for oil sensing

    Page(s): 1147 - 1148
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    A modified electric-LC resonators array is proposed which makes use of a capacitive gap for oil sensing. The resonator was fabricated on a Duroid 5880 substrate with a thickness of 3.05 mm. The modified resonator operates at a frequency of 6.28 GHz and has an 8 × 2 array of cells. The compared results from the prototype measurements and the fitted curves from full-wave electromagnetic simulations indicate accurate relative permittivity sensing for this resonator at the C-band. View full abstract»

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Aims & Scope

Electronics Letters is internationally renowned for its rapid communication of new developments and emerging topics across the broad and interdisciplinary field of modern electronics and electrical engineering.

Full Aims & Scope

Meet Our Editors

Editors-in-Chief

Professor Chris Toumazou
Director of the Biomedical Institute
Imperial College, London, UK

Professor Ian White
Head of Photonics Research
University of Cambridge, UK