Showing papers in "Electronics Letters in 2015"
TL;DR: In this article, a high-speed and energy-efficient oxide-confined 850 nm vertical-cavity surface-emitting laser (VCSEL) for optical interconnects is presented.
Abstract: A high-speed and energy-efficient oxide-confined 850 nm vertical-cavity surface-emitting laser (VCSEL) for optical interconnects is presented. A record-high modulation bandwidth of 30 GHz is reached for a 3.5 mu m oxide aperture VCSEL, with 25 GHz bandwidth already at a bias current of 1.8 mA. The high bandwidth at low currents enables energy-efficient transmission with a dissipated heat energy in the VCSEL of <100 fJ/bit at 25, 40 and 50 Gbit/s.
128 citations
TL;DR: In this article, the centroid of the micro-Doppler signature has been identified and used to perform classification, investigating also the added benefit of using information from a multistatic radar as opposed to a conventional monostatic system.
Abstract: Preliminary results on the use of multistatic radar and micro-Doppler analysis to detect and discriminate between micro-drones hovering carrying different payloads are presented. Two suitable features related to the centroid of the micro-Doppler signature have been identified and used to perform classification, investigating also the added benefit of using information from a multistatic radar as opposed to a conventional monostatic system. Very good performance with accuracy above 90% has been demonstrated for the classification of hovering micro-drones.
112 citations
TL;DR: In this article, the design of a thin microwave absorber which exhibits a −10 dB reflectivity bandwidth of 108% at normal incidence and 16% for simultaneous suppression of TE and TM polarised waves over the angular range 0-45° is presented.
Abstract: The design of a thin microwave absorber which exhibits a −10 dB reflectivity bandwidth of 108% at normal incidence and 16% for simultaneous suppression of TE and TM polarised waves over the angular range 0–45° is presented. The structure consists of a 3 mm-thick metal backed frequency selective surface (FSS) with four resistively loaded hexagonal loop elements in each unit cell. The surface resistivity and width of the loops are carefully chosen to maximise the bandwidth by merging the reflection nulls that are generated by the multi-resonant absorber. Measurement and simulation results are in good agreement over the broad frequency range 7.8–24 GHz.
Introduction:
87 citations
TL;DR: In this paper, a novel fractal wideband artificial magnetic conductor (AMC) structure is designed as the ground plane of a printed bow-tie antenna for gain enhancement and low profile.
Abstract: A novel fractal wideband artificial magnetic conductor (AMC) structure is designed as the ground plane of a printed bow-tie antenna for gain enhancement and low profile. The origin printed bow-tie antenna is operated in the range from 1.67 to 2.06 GHz for a VSWR <2. The AMC structure consists of 6 × 9 first-order fractal unit cells that are made up of four circles and four smaller circles, and the ±90° reflection phase band is 1.1–3.03 GHz. Both the AMC ground plane and bow-tie antenna are fabricated and measured. The distance between the antenna and the AMC is reduced to one-eighth of the wavelength in free space at 1.7 GHz. The experimental results show that the composite antenna has a wide bandwidth from 1.64 to 1.94 GHz, with a relative frequency bandwidth of 16.7%.
81 citations
TL;DR: In this paper, a new term named capacitive coupling coefficient kE is introduced to provide a quantitative measure of the coupling condition between the coupling plates, and its physical meaning is explained clearly in relation to the equivalent primary/secondary and mutual capacitances, which is also experimentally demonstrated by comparing two CPT systems with different cross-coupling configurations.
Abstract: Capacitive power transfer (CPT) based on electric field coupling has been proposed recently as an alternative technology for wireless power transfer, and a good understanding of the capacitive coupling is of great importance in the design and evaluation of CPT systems. A new term named capacitive coupling coefficient kE is introduced to provide a quantitative measure of the coupling condition between the coupling plates. The term is derived by modelling the capacitive coupling plates based on electric charge balance, and its physical meaning is explained clearly in relation to the equivalent primary/secondary and mutual capacitances, which is also experimentally demonstrated by comparing two CPT systems with different cross-coupling configurations.
81 citations
TL;DR: In this paper, a planar UWB-MIMO antenna array with WLAN band rejection is presented, which consists of four monopole radiators and a common ground plane.
Abstract: A compact planar UWB-MIMO antenna array with WLAN band rejection is presented. The array consists of four monopole radiators and a common ground plane. These monopoles are placed in such a way that the polarisation diversity of nearly placed radiators is exploited, resulting in high isolation. The proposed MIMO antenna array is electrically small (50 × 39.8 mm2), printed on a low loss 1.524 mm thick Rogers TMM4 laminate with a dielectric constant of 4.5 and a loss tangent of 0.002. A band-stop design was inserted on the ground plane to behave similar to a LC band-stop filter and reject the WLAN band. Simulation and measurement results satisfy the return loss requirement of better than 10 dB and isolation better than 17 dB over the entire 2.7–5.1 and 5.9–12 GHz bandwidths.
80 citations
TL;DR: In this paper, a computationally efficient method for direction-of-arrival (DOA) estimation for co-prime linear arrays is proposed, where multiple peaks are generated in the spatial spectrum for each subarray.
Abstract: A computationally efficient method for direction-of-arrival (DOA) estimation is proposed for co-prime linear arrays. For each DOA, multiple peaks are generated in the spatial spectrum for each subarray, which are proven to be uniformly distributed in the transformed domain. By searching over a limited sector to find an arbitrary peak, all the others can be recovered without a spectral search. Finally, the DOAs can be uniquely estimated by finding the common peaks of the two decomposed subarrays. The proposed method provides increased estimation accuracy with a substantially reduced computational burden. Simulation results validate the effectiveness of the proposed method.
79 citations
TL;DR: A new latch topology is presented that guarantees soft error tolerance when a single node or any arbitrary combination of node pairs is affected by an SEU.
Abstract: As technology scales down, soft errors, because of single event upsets (SEUs) that affect multiple nodes (through multiple node charge sharing), become a serious concern in nanometre technology integrated circuits. Existing radiation hardening techniques provide partial or no immunity when more than one node are affected. A new latch topology is presented that guarantees soft error tolerance when a single node or any arbitrary combination of node pairs is affected by an SEU. The proposed scheme exploits a positive feedback loop which consists of C-elements. Simulation results validate the efficiency of the new design over existing soft error hardening techniques such as BISER, FERST and TPDICE.
79 citations
TL;DR: In this article, the design of an OAM antenna based on an original phase shifter and power divider combination at 2.5 GHz is presented, and a prototype is manufactured and characterised based on return loss, radiation and phase patterns.
Abstract: The design of an ‘orbital angular momentum (OAM) antenna’ based on an original phase shifter and power divider combination at 2.5 GHz is presented. A prototype is manufactured and characterised based on return loss, radiation and phase patterns. Both simulation and experimental results evidence the properties of waves carrying OAM. This OAM antenna is simple, compact and easy to realise, which makes it suitable for radio communications and radar applications.
76 citations
TL;DR: In this article, an absorptive frequency selective surface with a wide absorptive property over the low band and a good transmissive property at high frequency is designed, which is realized by putting a choke structure into the element to control the current distribution.
Abstract: An absorptive frequency selective surface with a wide absorptive property over the low band and a good transmissive property at high frequency is designed. The transmission of high frequency is realised by putting a choke structure into the element to control the current distribution. Its −10 dB absorption band is from 2.8 to 8.3 GHz and the transmission band is at 9.7 GHz with insertion loss <0.5 dB. Numerical and experimental results are given.
75 citations
TL;DR: The results demonstrate that the effective capacity is a monotonically increasing function of channel fading parameters κ and μ as well as the shadowing parameter m, while it decays to zero when the delay constraint θ → ∞.
Abstract: The effective capacity of communication systems over generalised κ–μ shadowed fading channels is investigated. A novel and analytical expression for the exact effective capacity is derived in terms of the extended generalised bivariate Meijer's-G function. To intuitively reveal the impact of the system and channel parameters on the effective capacity, closed-form expressions are derived for the effective capacity in the asymptotically high signal-to-noise ratio regime. The results demonstrate that the effective capacity is a monotonically increasing function of channel fading parameters κ and μ as well as the shadowing parameter m, while it decays to zero when the delay constraint θ → ∞.
TL;DR: In this article, a planar-patterned metamaterial structure was proposed for ultra-wideband applications, which has a wide bandwidth from 3.07 to 19.91 GHz for voltage standing wave ratio (VSWR) <2 and an average gain of 5.62 dBi with a peak of 8.57 dBi.
Abstract: A compact antenna is proposed using planar-patterned metamaterial structures for ultra-wideband applications. This antenna consists of four metamaterial unit cells that simultaneously show both negative permeability and negative permittivity on the triangular patch and three rectangular slots on the partial ground plane fed with a microstrip line. It has a wide bandwidth from 3.07 to 19.91 GHz for voltage standing wave ratio (VSWR) <2 and an average gain of 5.62 dBi with a peak of 8.57 dBi because of using planar-patterned metamaterial structures. Good agreement between computations and experiments is realised convincing that the antenna can operate over a wide bandwidth with planar-patterned metamaterial structures and compact size (0.28λ × 0.19λ × 0.02λ).
TL;DR: In this article, an improved memristive Chua's circuit is proposed, from which some hidden attractors are found, and three determined equilibrium points, including a zero saddle point and two non-zero saddle-foci, are stable for the specified circuit element parameters, leading to the generation of Hidden Attractors and coexisting Hidden Entors.
Abstract: An improved memristive Chua's circuit is proposed, from which some hidden attractors are found. This memristive circuit has three determined equilibrium points, including a zero saddle point and two non-zero saddle-foci. The two non-zero saddle-foci are stable for the specified circuit element parameters, leading to the generation of hidden attractors and coexisting hidden attractors. Additionally, the observed hidden attractors are not sensitive to the initial conditions, which can easily be captured in a physical circuit by adjusting the circuit element parameters to the desired values.
TL;DR: In this article, a frequency-domain algorithm for the early detection of lung cancer is presented, which is based on using the first-order Bessel function of the first kind to relate the fields outside the imaged domain to the fields inside that domain.
Abstract: A frequency-domain algorithm for the early detection of lung cancer is presented. The algorithm predicts the distribution of scattered fields inside the imaged domain (torso) using the measured fields around that domain. That prediction is based on using the first-order Bessel function of the first kind to relate the fields outside the imaged domain to the fields inside that domain. The predicted field distribution shows the relative differences between the dielectric properties of tissues within the torso and thus enables detecting lung cancer, which has a significantly larger dielectric constant that the lung's healthy tissues. To validate the proposed algorithm, an integrated imaging system, which includes a three-dimensional slot-rotated antenna that circularly scans an artificial torso phantom using the band 1.5-3 GHz, a wideband microwave transceiver and a laptop for control, processing and image generation, is built. The obtained experimental results confirm the reliability of the proposed method in lung cancer detection.
TL;DR: In this article, a new structure single-stage dynamic comparator with a large input common-mode range is proposed, which is more than 1.2 times faster with <80% power consumption.
Abstract: A new structure single-stage dynamic comparator with a large input common-mode range is proposed. The proposed comparator is compared with previous dynamic comparators. With same size input transistors and load capacitance, it is more than 1.2 times faster with <80% power consumption. Also, the input-referred noise and offset are no more than the previous comparators.
TL;DR: In this article, two iris bandpass filters implemented by 3D printing technology for millimetre-wave applications are demonstrated for the first time, and they are designed at the E-band (60-90 GHz), and fabricated by selective laser melting using CuSn15 alloy powder.
Abstract: Two iris bandpass filters implemented by three-dimensional (3D) printing technology for millimetre-wave applications are demonstrated for the first time. The filters are designed at the E-band (60-90 GHz), and fabricated by selective laser melting using CuSn15 alloy powder. A shifted passband and increased insertion loss are observed, which is caused by the fabrication tolerance of dimensional control and surface roughness. Methods to compensate the fabrication tolerance are proposed and the design procedures are provided. The presented results prove the great potential of 3D printing technology for millimetre wave applications.
TL;DR: In this paper, a monolithic integration of four-colour indium gallium nitride (InGaN)-based nanocolumn light-emitting diodes (LEDs) is demonstrated.
Abstract: The monolithic integration of four-colour indium gallium nitride (InGaN)-based nanocolumn light-emitting diodes (LEDs) is demonstrated. In the integrated nanocolumn LED unit, blue-, sky-blue-, green- and yellow-emitting micro-LEDs (LEDs 1–4) with a 65 μm diameter circular indium tin oxide emission window were arrayed in a 2 × 2 square lattice with a lattice constant of 190 μm. LEDs 1–4 consisted of nanocolumn arrays arranged in a triangular lattice with a lattice constant of 300 nm and their nanocolumn diameters at the position of the InGaN/gallium nitride (GaN) multiple quantum wells (MQWs) were 119, 145, 188 and 231 nm, respectively. The increase in nanocolumn diameter from LED 1 to LED 4 resulted in increasing emission peak wavelengths, which were 465, 489, 510 and 570 nm for LEDs 1–4, respectively. On the same substrate, a red-emitting micro-LED was prepared, in which the nanocolumn diameter was increased to 260 nm by using a 350 nm-lattice-constant nanocolumn array. A combination of different lattice constants in an integrated LED unit is expected to contribute to the achievement of red–green–blue–yellow (RGBY)-colour-integrated nanocolumn LEDs.
TL;DR: In this article, a novel end-fire antipodal Vivaldi antenna is proposed for ultra wideband (UWB) applications such as in radars, microwave imaging and in high data rate wireless systems.
Abstract: A novel compact end-fire antipodal Vivaldi antenna is proposed for ultra-wideband (UWB) applications such as in radars, microwave imaging and in high data rate wireless systems. To make the antenna compact, a bending feed line structure and sinusoidal modulated Gaussian tapered slot is used. The proposed antenna has a reflection coefficient of less than −10 dB from 2 GHz to more than 12 GHz (more than 166% fractional bandwidth). The radiation characteristics show an end-fire radiation pattern in the operating frequency band with peak realised gain values in the range of 1.5−5.2 dBi. Time domain analysis shows that the antenna has good pulse handling capability with a high system fidelity factor.
TL;DR: In this article, a high-gain horizontally polarised antenna for ultra wideband (UWB) operation is presented and experimentally demonstrated using a frequency selective surface (FSS) reflector.
Abstract: The design of a high-gain horizontally polarised antenna for ultra-wideband (UWB) operation is presented and experimentally demonstrated. Gain enhancement is achieved by using a frequency selective surface (FSS) reflector. Both the antenna and the FSS have simple structures and are printed on a similar substrate. The antenna is a three-stepped narrow rectangular slot excited using a three-stepped microstrip feed line. By optimising the lengths and widths of the sections of the slot and the feed line, an ultra-wide impedance bandwidth (3.2–12 GHz, measured) has been achieved. The FSS is a two-layer structure where each layer is an array of rectangular patches printed on one side of the substrate. With the application of the FSS, the antenna gain is enhanced by 3–4 dBi over most of the band. The polarisation purity (in terms of the measured cross-polar difference) is also improved with the FSS. Such an antenna–FSS combination will be useful for high-gain UWB applications requiring horizontal polarisation.
TL;DR: In this paper, an asymmetric coplanar strip (ACS)-fed multiple-input-multiple-output (MIMO) antenna working in the ultra wideband (UWB) frequency band with a shared radiator is discussed.
Abstract: A novel asymmetric coplanar strip (ACS)-fed multiple-input–multiple-output (MIMO) antenna working in the ultra-wideband (UWB) frequency band with a shared radiator is discussed. The proposed antenna is composed of a radiator which is shared by two antenna elements in order to achieve a very compact size of 26 × 26 mm2. By etching an I-shaped slot in the radiator and attaching a rectangular patch on the back, the operating bandwidth is broadened and a high isolation between the two antenna elements is realised. The stub from the ground also has a great effect on the return loss and isolation. The measured results show that the working frequency band of the MIMO antenna covers 3.1–10.6 GHz with an isolation of more than 15 dB. Furthermore, the simple feeding structure and compact size could enable the proposed antenna to be used in portable devices.
TL;DR: In this paper, a surface plasmon resonance (SPR) sensor based on hollow-core photonic crystal fiber (HC-PCF) filled with silver nanowires is designed.
Abstract: A surface plasmon resonance (SPR) sensor based on hollow-core photonic crystal fibre (HC-PCF) filled with silver nanowires is designed. The analyte and silver nanowires are full filled in the air holes of the HC-PCF to realise the SPR sensing, which is more convenient than silver coated in operation. The designed sensor is analysed through numerical simulations and demonstrated by experiments. All the results show that a blue-shift is obtained with increase of the analyte refractive index (RI), and the silver nanowires concentration has no effect on spectral sensitivity. The highest average spectral sensitivity of 14 240 nm/RIU is obtained by experiments, which is higher than that previously reported for the same type of sensors. The sensor is useful for detecting small analyte RI changes, and can also provide a reference for the implementation and application of PCF-SPR sensors with high sensitivity.
TL;DR: In this article, an enhanced locking range technique for a CMOS injection-locked frequency divider (ILFD) is presented, which uses a cross-coupled oscillator with a dual-resonance RLC resonator.
Abstract: An enhanced locking range technique for a CMOS injection-locked frequency divider (ILFD) is presented, which uses a cross-coupled oscillator with a dual-resonance RLC resonator. This ILFD has dual locking ranges at a fixed bias, and the resistor in the resonator is used to have overlapping dual locking ranges so that a single-band wide-locking range is obtained. At the incident power of 0 dBm, the locking range of the divide-by-2 ILFD is 6.7 GHz, from 3 to 9.7 GHz, and the locking range percentage is 105.51%.
TL;DR: The frequency diverse array concept is employed to construct an orthogonal frequency-division multiplexing (OFDM) transmitter that has the capability of securing wireless communication in free space directly in the physical-layer without the need for mathematical encryption.
Abstract: In this reported work, the frequency diverse array concept is employed to construct an orthogonal frequency-division multiplexing (OFDM) transmitter that has the capability of securing wireless communication in free space directly in the physical-layer without the need for mathematical encryption. The characteristics of the proposed scheme in terms of its secrecy performance are validated via bit error rate simulation under both high and low signal to noise ratio scenarios using the IEEE 802.11 OFDM physical-layer specification.
TL;DR: In this paper, three different metamaterial absorbers based on ultra-thin multi-layer structures, with different bandwidth characteristics, are presented, which are polarisation-insensitive and wide-angle absorptive for both TE and TM polarisations.
Abstract: Three different metamaterial absorbers based on ultra-thin multi-layer structures, with different bandwidth characteristics, are presented. The proposed structure is composed of three vertically stacked metal-dielectric layers backed by a metal ground. All the metallic patches are of crossed dipole shape and have different geometrical dimensions, which can be manipulated to design triple-band, 3 dB and 10 dB absorbers separately. The designed structures are polarisation-insensitive as well as wide-angle absorptive for both TE and TM polarisations. The 10 dB broadband structure, exhibiting an absorption bandwidth of 7.5% at 10 GHz, has been fabricated and the absorption performance has been verified with the simulated response. The proposed absorber has the advantages of ultra-thin thickness (λ 0/50 corresponding to the centre frequency), compact size, simpler design, tunable absorption bandwidth and experimental validation, which makes it a promising candidate for many potential applications.
TL;DR: In this article, a microstrip lowpass filter with a wide stopband was proposed, which is composed of two stepped impedance hairpin units with one embedded in another, which can obtain two more transmission zeros and extend a wide stopping band.
Abstract: A novel microstrip lowpass filter (LPF) with a wide stopband is presented. The basic resonator is composed of two stepped impedance hairpin units with one embedded in another, which can obtain two more transmission zeros and extend a wide stopband. Based on the proposed resonator, a demonstration LPF of compact size, sharp transition and wide stopband has been designed, fabricated and measured. The proposed filter exhibits a small size of 0.081λg × 0.113λg, where λg is the waveguide length at the cutoff frequency of 1.6 GHz. Results show good agreement with simulations and the 20 dB rejection stopband can be extended to more than 15 GHz.
TL;DR: In this paper, two different frequency reconfigurable ultra-wideband MIMO antenna array designs capable of rejecting on-demand all WLAN communications in the 4.8 to 6.2 GHz range are presented.
Abstract: Presented are two different frequency reconfigurable ultra-wideband multiple-input multiple-output (MIMO) antenna array designs capable of rejecting on-demand all WLAN communications in the 4.8 to 6.2 GHz range. Both arrays consist of two monopole UWB radiators placed orthogonally with respect to each other to introduce polarisation diversity and a quarter-wave stub connected to the ground plane via pin diodes is used to introduce the on-demand band rejection feature. One array design has separate ground planes and the other has two ground planes connected with a printed conductor (i.e. shared). For both cases, an isolation better than 20 dB between the elements is achieved in the 2 to 12 GHz frequency range with simulations and a manufactured prototype.
TL;DR: In this paper, a new architecture for a polar decoder using a reduced complexity successive-cancellation (SC) decoding algorithm is presented, achieving a coded throughput of over 237 Gbit/s for a (1024, 512) polar code implemented using a field-programmable gate array.
Abstract: A new architecture for a polar decoder using a reduced complexity successive-cancellation (SC) decoding algorithm is presented. This novel fully unrolled, deeply pipelined architecture is capable of achieving a coded throughput of over 237 Gbit/s for a (1024, 512) polar code implemented using a field-programmable gate array. This decoder is two orders of magnitude faster than state-of-the-art polar decoders.
TL;DR: A scheduling-based architecture is proposed for the SDN controller that leads to effective attack confinement and network protection during denial of service (DoS) attacks.
Abstract: There exists a way that attackers can identify software defined networks (SDNs). Knowing the vulnerabilities of a SDN, the attackers can mount a saturation attack on the SDN controller with the aim of incapacitating the entire SDN. Therefore, the controller should have an architecture to weather out such an attack while continuing operation. A scheduling-based architecture is proposed for the SDN controller that leads to effective attack confinement and network protection during denial of service (DoS) attacks.
TL;DR: In this paper, the performance of time division multiplexing and frequency division multiple access protocols for light emitting diode (LED) designs using visible light-emitting diode lights is evaluated.
Abstract: The performance of time division multiplexing and frequency division multiplexing protocols for light emitting diode light emitting diode (IPS) designs using visible light emitting diode lights is evaluated. The impact of timing synchronisation errors on the localisation accuracy of IPS designs is also determined.
TL;DR: A novel compressive wideband spectrum sensing scheme based on a single channel for band-limited wide-sense stationary (WSS) signals is proposed and Simulation results show that the proposed scheme has a perfect performance on wideband WSS signal spectrum sensing.
Abstract: The modulated wideband converter (MWC) is an attractive analogue compressed sensing technique that has been proposed in recent years. Regrettably, the MWC has high hardware complexity owing to its parallel channel structure. To reduce the complexity, a novel compressive wideband spectrum sensing scheme based on a single channel for band-limited wide-sense stationary (WSS) signals is proposed. In the proposed scheme, a special periodic waveform in the time domain is designed and a power spectrum sensing model is presented to detect the occupied frequency spectrum of such signals from sub-Nyquist samples of which the sample rate is only MWC's single-channel rate. Simulation results show that the proposed scheme has a perfect performance on wideband WSS signal spectrum sensing.