Showing papers in "Electronics Letters in 2005"
TL;DR: In this paper, the locally one-dimensional (LOD) scheme is introduced into the implicit FDTD method and the LOD-FDTD provides simple implementation of the algorithm and reduced computational time.
Abstract: The locally one-dimensional (LOD) scheme is introduced into the implicit FDTD method. The LOD-FDTD provides simple implementation of the algorithm and reduced computational time. For facet reflectivity analysis of an optical waveguide, the computational time is reduced to 80 and 50% of those of the ADI-FDTD and the conventional FDTD, respectively.
349 citations
TL;DR: In this paper, a novel ultra-wideband antenna with band elimination characteristic is presented, which has omnidirectional patterns in the E-plane and impedance bandwidth of about 3-18 GHz with VSWR below 2.
Abstract: A novel ultra-wideband antenna with band elimination characteristic is presented, which has omnidirectional patterns in the E-plane and impedance bandwidth of about 3-18 GHz with VSWR below 2. The proposed antenna is fed by microstrip line, and consists of the monopole type with two parasitism-patches rejecting 5.15-5.825 GHz bandlimited by IEEE 802.11a and HIPERLAN/2.
307 citations
TL;DR: In this article, a new analytic model of the IEEE 802.15.4 slotted CSMA/CA is proposed, from which throughput and energy consumption are computed in saturation conditions.
Abstract: A new analytic model of the IEEE 802.15.4 slotted CSMA/CA is proposed, from which throughput and energy consumption are computed in saturation conditions. The analytic results are validated via ns-2 simulations.
279 citations
TL;DR: The HB+ authentication protocol was recently proposed and claimed to be secure against both passive and active attacks, but a linear-time active attack against HB+.
Abstract: Much research has focused on providing RFID tags with lightweight cryptographic functionality. The HB+ authentication protocol was recently proposed and claimed to be secure against both passive and active attacks. A linear-time active attack against HB+ is proposed.
274 citations
TL;DR: In this paper, an enhancement-mode high electron mobility transistors (E-HEMTs) on GaN/AlGaN heterostructures grown on SiC substrates are reported.
Abstract: Fabrication of enhancement-mode high electron mobility transistors (E-HEMTs) on GaN/AlGaN heterostructures grown on SiC substrates is reported. Enhancement-mode operation was achieved with high threshold voltage (V/sub T/) through the combination of low-damage and controllable dry gate-recessing and the annealing of the Ni/Au gates. As-recessed E-HEMTs with 1.0 /spl mu/m gates exhibited a threshold voltage (V/sub T/) of 0.35 V, maximum drain current (I/sub D,max/) of 505 mA/mm, and maximum transconductance (g/sub m,max/) of 345 mS/mm; the corresponding post-gate anneal characteristics were 0.47 V, 455 mA/mm and 310 mS/mm, respectively. The RF performance is unaffected by the post-gate anneal process with a unity current gain cutoff frequency (f/sub T/) of 10 GHz.
272 citations
TL;DR: In this paper, an inductively coupled feed method is explored to design UHF radio frequency identification tag antennas, and an analytical model for the proposed feed structure is derived and used to perform simple and wideband impedance match between an antenna and a tag chip without any additional matching networks.
Abstract: An inductively coupled feed method is explored to design UHF radio frequency identification tag antennas. An analytical model for the proposed feed structure is derived and used to perform simple and wideband impedance match between an antenna and a tag chip without any additional matching networks. The proposed design methodology is verified by comparing the calculations and measurements, which show good agreement.
250 citations
TL;DR: In this paper, a printed planar elliptic patch juxtaposed with the ground pattern in a single substrate providing an ultra-wideband impedance bandwidth is presented, which is achieved by using a new impedance-matching technique of cutting a notch at a ground pattern opposite the microstrip line.
Abstract: A printed planar elliptic patch juxtaposed with the ground pattern in a single substrate providing an ultra-wideband impedance bandwidth is presented. The ultra-wideband property for the proposed antenna is achieved by using a new impedance-matching technique of cutting a notch at the ground pattern opposite the microstrip line. The concavity of the ground pattern serves as an effective means for adjusting the gap between the radiating element and the ground plane. With suitable size of notch chosen, the impedance bandwidth of the proposed antenna can be enhanced. Details of the proposed antenna design and measured results are presented and discussed.
226 citations
TL;DR: A wavelet domain image resolution enhancement method that adopts the cycle-spinning methodology adapted for use in the wavelets domain and compares favourably with recently emerged algorithms in the field.
Abstract: A wavelet domain image resolution enhancement method is proposed. The method adopts the cycle-spinning methodology adapted for use in the wavelet domain. The perceptual and objective quality of resolution enhanced images compare favourably with recently emerged algorithms in the field.
165 citations
TL;DR: In this paper, a frequency notched ultra wideband (UWB) microstrip slot antenna with a fractal tuning stub is proposed, which achieves good radiation performance over the entire frequency range.
Abstract: A frequency notched ultra-wideband (UWB) microstrip slot antenna with a fractal tuning stub is proposed. The antenna is similar to a conventional microstrip slot antenna, and by introducing a fractal tuning stub, frequency notched function is achieved. The antenna was studied experimentally regarding impedance bandwidth, radiation patterns and gain. The operation bandwidth of the antenna is from 2.66 to 10.76 GHz, in which a frequency notched band from 4.95 to 5.85 GHz was achieved, along with good radiation performance over the entire frequency range.
161 citations
TL;DR: Experimental results show that the proposed wavelet analysis of the finger tip surface texture can successfully differentiate live finger tips from fake finger tips made of the most commonly used materials in fingerprint spoofing.
Abstract: Proposed is a simple and effective approach for fingerprint liveness detection based on the wavelet analysis of the finger tip surface texture. Experimental results show that the method can successfully differentiate live finger tips from fake finger tips made of the most commonly used materials in fingerprint spoofing.
150 citations
TL;DR: In this article, a point-by-point inscription of fiber Bragg gratings by an infrared femtosecond laser has been reported, and the response of these gratings to annealing at temperatures in the range 500 to 1050°C is studied for the first time.
Abstract: Direct, point-by-point inscription of fibre Bragg gratings by an infrared femtosecond laser has been reported recently. Response of these gratings to annealing at temperatures in the range 500 to 1050°C is studied for the first time. Gratings inscribed by infrared femtosecond lasers were thermally stable at temperatures up to 900°C, representing a significant improvement in comparison with the 'common', UV-inscribed, gratings. Annealing at temperatures up to 700°C increased grating reflectivity. © IEE 2005.
TL;DR: In this paper, a low-noise synthesis of a harmonic comb of microwave frequencies using a 1 GHz femtosecond-laser-based synthesiser that is referenced to a cavity-stabilised laser is demonstrated.
Abstract: The low-noise synthesis of a harmonic comb of microwave frequencies using a 1 GHz femtosecond-laser-based synthesiser that is referenced to a cavity-stabilised laser is demonstrated. The residual phase noise is /spl sim/-110 dBc/Hz at 1 Hz offset from the 10 GHz harmonic. Phase noise is measured with an interferometric measurement system having low sensitivity to AM.
TL;DR: In this article, a simple method to fabricate nanowires with radii as small as 90nm from compound-glass fibres is described, and low transmission losses at 1.55 µm have been achieved in nanowsires fabricated from lead-silicate and bismuth silicate optical fibres.
Abstract: A simple method to fabricate nanowires with radii as small as 90nm from compound-glass fibres is described. Low transmission losses at 1.55µm have been achieved in nanowires fabricated from lead-silicate and bismuth silicate optical fibres.
TL;DR: In this paper, a diamond homoepitaxial layer grown using a high-purity source gas was used to improve the output power density of diamond FETs.
Abstract: Great improvement in the output power density of diamond FETs on a diamond homoepitaxial layer grown using a high-purity source gas is reported. For a device with a gate length of 0.1 µm and gate width of 100 µm, at 1 GHz, maximum output power density of 2.1 W/mm, maximum power gain of 10.9 dB, and power added efficiency of 31.8% were obtained.
TL;DR: In this paper, a passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed, which provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S11 <−10 dB, 8.5 dB.
Abstract: A passive RFID tag antenna in the UHF band using two bent dipoles and a modified double T-matching network is proposed. The antenna was fabricated with a thin copper layer printed on a 50 µm-thick PET substrate for low-cost production. The proposed antenna provided a quasi-isotropic radiation pattern and a fairly broad bandwidth S11<−10 dB, 8.5%) for conjugate-matching with a commercial tag chip. The efficiency of the antenna was about 90% in the operating frequency band. The measured readable range was between 170 –240 cm for an arbitrary rotation angle of the tag.
TL;DR: In this paper, a miniature arrayed waveguide grating of 70/spl times/60 /spl mu/m/sup 2/ size consisting of Si photonic wire waveguides was designed using complete modeling in the finite-difference time-domain simulation.
Abstract: A miniature arrayed waveguide grating of 70/spl times/60 /spl mu/m/sup 2/ size consisting of Si photonic wire waveguides was designed using complete modelling in the finite-difference time-domain simulation The device was fabricated onto a silicon-on-insulator substrate and evaluated in the wavelength range around 155 /spl mu/m The clear demultiplexing characteristics were observed with a channel spacing of 11 nm and a loss of less than 1 dB
TL;DR: In this article, a compact slotted PIFA-type RFID tag (900 MHz) mountable on metallic objects is presented, which can be easily matched to most microchips and facilitates their attachment on its slot.
Abstract: A compact slotted PIFA-type RFID tag (900 MHz) mountable on metallic objects is presented. The proposed structure can be easily matched to most microchips and facilitates their attachment on its slot. The performance of the tag is evaluated by monitoring its radar cross-sections (RCSs) for various incident angles and chip impedances. The measured detection distance is 4 m.
TL;DR: In this paper, the angular dependent reflection coefficients of different building materials were determined using terahertz time-domain spectroscopy in transmission geometry and Fresnel's equations, which is more efficient than a set of measurements in reflection geometry for different angles.
Abstract: To obtain realistic models for propagation channels in future pico-cellular indoor terahertz communication systems it is necessary to know the reflective properties of building materials found in a typical office environment. The angular dependent reflection coefficients of different building materials were determined using terahertz time-domain spectroscopy in transmission geometry and Fresnel's equations. This approach is more efficient than a set of measurements in reflection geometry for different angles. Verification of the method with a set of such reflection measurements shows an excellent agreement.
TL;DR: Amorphous silicon waveguides were obtained by plasmaenhanced chemical vapour deposition and anisotropic plasma etching as discussed by the authors, which showed a low propagation loss of ≤ 0.5 dB/cm (1.6dB/cm).
Abstract: Amorphous silicon waveguides were obtained by plasma-enhanced chemical vapour deposition and anisotropic plasma etching. Rectangular multimode waveguides as well as singlemode ridge waveguides were fabricated. Scattered light measurements at 1550 nm (1300 nm) wavelength showed a low propagation loss of ≤0.5 dB/cm (1.6 dB/cm) for multimode waveguides and 2.0 dB/cm (5.0 dB/cm) for highly-confined singlemode waveguides.
TL;DR: In this paper, the authors demonstrated that remarkable timing performance is achievable with large area single photon avalanche diodes (SPADs), provided that the avalanche current is sensed at very low level, when the multiplication process is still confined within a small area around the photon absorption point.
Abstract: It is demonstrated that remarkable timing performance is achievable with large area single photon avalanche diodes (SPADs), provided that the avalanche current is sensed at very low level, when the multiplication process is still confined within a small area around the photon absorption point. By employing a suitable current pick-up circuit, an unprecedented time resolution of 35 ps was obtained with a 100 /spl mu/m active area diameter SPAD.
TL;DR: In this paper, a compact CPW-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) operations, which consists of two strips, and has compact size of 20/spl times/155/pl times/16 mm/sup 3/ including the ground.
Abstract: A compact CPW-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) operations The proposed antenna, which consists of two strips, has compact size of 20/spl times/155/spl times/16 mm/sup 3/ including the ground The proposed antenna effectively covers both 24 GHz (24-2484 GHz) and 5 GHz (515-5825 GHz) bands The measured peak gains are 13 dBi at 244 GHz and 28 dBi at 532 GHz
TL;DR: In this article, a superluminescent diode (SLED) using chirped multiple InAs quantum dot (QD) layers as the active region is demonstrated, and the fabricated QD SLEDs exhibit a large spectral width up to 121 nm, covering the range 1165-1286 nm.
Abstract: A superluminescent diode (SLED) using chirped multiple InAs quantum dot (QD) layers as the active region is demonstrated. The fabricated QD SLEDs exhibit a large spectral width up to 121 nm, covering the range 1165-1286 nm.
TL;DR: In this paper, a novel ultra-thin radar-absorbing material (RAM) using metamaterials is presented, and the absorption performance is examined, and it is shown that the thickness of the RAM is about several tenths of the centre wavelength of the absorption band.
Abstract: A novel ultra-thin radar-absorbing material (RAM) using metamaterials is presented, and the absorption performance is examined. Owing to the high-impedance property of the metamaterials, the thickness of the RAM is about several tenths of the centre wavelength of the absorption band, considerably thinner than conventional absorbers. The absorption bandwidth of the RAM is about several hundred megahertz.
TL;DR: In this paper, an all-optical NAND gate at 10 Gbit/s was demonstrated using gain nonlinearity characteristics of a semiconductor optical amplifier, which operates in a single cross-gain modulation mechanism.
Abstract: By using gain nonlinearity characteristics of a semiconductor optical amplifier, an all-optical NAND gate at 10 Gbit/s is demonstrated. The all-optical NAND gate operates in single mechanism, which is cross-gain modulation. In the NAND gate (AB+Ā), Boolean AB is obtained by using signal A as a probe beam and signal B as a pump beam in SOA-1. Also, Boolean Ā is obtained by using the clock signal as a probe beam and signal A as a pump beam in SOA-2. By adding the two outputs from SOA-1 and SOA-2, Boolean Ā+AB (logic NAND) can be acquired. The extinction ratio is about 6.1 dB.
TL;DR: A low-power parallel multiplier design, in which some columns in the multiplier array can be turned-off whenever their outputs are known, is proposed.
Abstract: A low-power parallel multiplier design, in which some columns in the multiplier array can be turned-off whenever their outputs are known, is proposed. This design maintains the original array structure without introducing extra boundary cells, as was the case in previous designs. Experimental results show that it saves 10% of power for random input. Higher power reduction can be achieved if the operands contain more 0's than 1's.
TL;DR: The exact Nakagami-m phase-envelope joint distribution was obtained in this article for the case m = l, where m is the number of envelopes in which the phase distribution is uniform.
Abstract: The exact Nakagami-m phase-envelope joint distribution is obtained. Apart from the case m=l, the phase distribution is not uniform. It bears similar shapes to those of Hoyt and Rice, and coincides with those at the limiting values of their parameters, for which their envelopes also coincide.
TL;DR: In this paper, all-optical ultra-fast and reconfigurable logic gates have been implemented exploiting simple and low-cost schemes based on nonlinear optical loop mirrors, and their regenerative properties have been demonstrated.
Abstract: All-optical ultra-fast and reconfigurable logic gates have been implemented exploiting simple and low-cost schemes based on nonlinear optical loop mirrors. Regenerative properties of the realised optical logic gates have been demonstrated.
TL;DR: In this paper, a broad-waveguide design was optimized for maximum power conversion efficiency (PCE), achieving 73% PCE at 50 W CW output power from 20% fill-factor, 1 cm diode laser bars mounted on micro-channel-cooled heatsinks.
Abstract: 970 nm emitting diode laser bars of broad-waveguide design have been optimised for maximum power conversion efficiency (PCE). 73% PCE at 50 W CW output power is achieved from 20% fill-factor, 1 cm diode laser bars mounted on microchannel-cooled heatsinks. The improvement is mainly the result of an increase in injection efficiency via moderately low doping of the broad-waveguide core, and reductions in operating voltage via doping optimisation of the broad-waveguide structure.
TL;DR: It is shown that the ramp detector outperforms the abrupt change detector in detecting the turn-on transients of Wi-Fi transmitters.
Abstract: A transient detection technique is presented for the detection of the turn-on transients of Wi-Fi radios. The turn-on transients are detected by a Bayesian change detector, which estimates the time instant when the transmitter starts to power up. The proposed technique is verified with the transient data collected from a number of Wi-Fi radios and it is shown that the ramp detector outperforms the abrupt change detector in detecting the turn-on transients of Wi-Fi transmitters.
TL;DR: The first room temperature operation of In/sub 05/Ga/sub 5/As quantum dot lasers grown directly on Si substrates with a thin (/spl les/2 /spl mu/m) GaAs buffer layer is reported in this paper.
Abstract: The first room-temperature operation of In/sub 05/Ga/sub 05/As quantum dot lasers grown directly on Si substrates with a thin (/spl les/2 /spl mu/m) GaAs buffer layer is reported The devices are characterised by J/sub th//spl sim/1500 A/cm/sup 2/, output power >50 mW, and large T/sub 0/ (244 K) and constant output slope efficiency (/spl ges/03 W/A) in the temperature range 5-95/spl deg/C