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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 (g_m ), is presented. The presented g_m control uses resistor degeneration at the input switches so that the effective g_m 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%.

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.

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.

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.

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.

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 {2 ⁿ − 1, 2 ^{n + k} , 2 ⁿ + 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%.

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.

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.

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.

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.

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.

A one-step model extraction method is proposed for direct learning (DL) digital predistortion (DPD) system. The expected predistortion signal of the training sequence is first derived by iterative injection of the baseband distortion components, which enables one-step model extraction of the DPD model by least squares estimation afterwards. Compared with the conventional model extraction method for DL DPD, the proposed method yields comparable linearisation performance but has much lower computational complexity.

A monolithic dual-polarisation quadrature phase shift keying transmitter is demonstrated for operation at 2.25 Tbit/s over 40 wavelengths and 1 THz of spectral bandwidth. The single-chip InP-based transmitter employs 40 tunable distributed feedback lasers, 80 nested Mach-Zehnder modulators and other elements to provide more than 1700 integrated photonic functions.

A thermally advanced, Nd:YVO₄ amplifier at 1064 nm based on an 800 µm-thick Nd:YVO_­4 gain layer bonded to a silicon carbide (SiC) prism is demonstrated. The amplifier was tested in the ‘master oscillator–power amplifier’ configuration, where both the seed source and the amplifier were operated in a quasi-continuous-wave regime. The hetero-composite Nd:YVO₄/SiC gain element pumped by an 808 nm laser diode bar stack amplified the seed power in a range of 1–55 W with a gain of 4–2.6, respectively. The temperature profile of the gain element measured by a thermal camera indicated the maximum observed temperature excursion at pump saturation intensity to be only 27°C.

It has been experimentally shown that by utilising the Fresnel-reflected light as the reference light, Brillouin signals in polymer optical fibres (POFs) can be observed with a higher signal-to-noise ratio (SNR) than those measured with standard self-heterodyne detection. This method is basically the same in setup as direct detection, leading to an additional advantage of system simplicity. Moreover, it has been demonstrated that the Brillouin signal in a 1 cm-long POF can be observed with a moderate SNR using this technique, indicating a potential feasibility of POF-based distributed Brillouin measurement with a millimetre-order spatial resolution.

Single- and multi-quantum well (QW) structures of Ga(AsBi)/GaAs with up to 10% Bi were grown by molecular beam epitaxy (MBE) at 300–330°C substrate temperature. The photoluminesce measurements of QW structures demonstrated room temperature emission up to wavelengths of ∼1.43 μm. In the structures obtained using a combined growth approach – an active layer with three QWs with ∼6% Bi was grown by MBE, whereas (AlGa)As claddings were grown by the metal organic vapour phase epitaxy technique – room temperature lasing at 1060 nm was documented.

A dual-path capacitor multiplier (DPCM) technique is proposed for on-chip frequency compensation. The DPCM uses two currents to charge and discharge a compensation capacitor concurrently. Consequently, the equivalent capacitance is amplified dramatically with slight increase in silicon area and power. Thanks to the DPCM, the transient response of the DC–DC converter has improved significantly because of the small compensation capacitor. Experimental results demonstrate converter stability and transient response. The transient recovery time of a 450 mA step load change is <30 μs. With the proposed technique, the compensation capacitor is shrunk significantly and adding the compensation resistor would have helped in improving transient response.

A highly efficient wireless power transfer using a metamaterial slab with a zero refractive property is proposed. The proposed metamaterial slab consists of a spiral structure, a lumped element and a via through the ground. A prototype of a wireless power transfer system and a metamaterial slab was designed and fabricated. Experiment results prove the transfer efficiency improvement with the proposed metamaterial slab. The power transfer efficiency is improved by reducing the radiation loss through focusing the magnetic field. The power transfer efficiency is above 45% at a distance of 100–150 mm, and the resonant frequency is 6.78 MHz. The sizes of the transmitting coil and the metamaterial slab are 140 × 210 mm and 50 × 70 mm, respectively.

The effects of silicon fin width on the electrostatic characteristics of high-κ/metal gate bulk fin field-effect transistor (FinFET) devices are investigated. Six devices with different layout fin widths and lengths are designed and fabricated. A technology computer-aided design (TCAD) simulation model with the proposed devices simplified as an equivalent circuit with three components (C _ox, C _s and R _s) indicates that for a given layout area, a narrower fin width leads to a worse flat band voltage shift and larger variation of gate capacitance due to increased substrate resistance.

An application for a transparent gate electrode with surface-side electroluminescence (EL) observation is proposed for identification of the gate leakage path in AlGaN/GaN high electron mobility transistors. This technique enables surface-side EL observation throughout the gate electrode, so that the substrate material is unrestricted. Through the transparent gate, a non-uniformly located spot-shape EL was clearly observed. By comparing devices with different leakage currents using EL intensity, the location marked by the spot-shape EL is found and demonstrates a dominant leakage path.

A low onset voltage AlGaN/GaN diode with a width of 14 mm is achieved. The recess depth of the AlGaN layer is responsible for the low onset voltage. In comparison with the conventional non-recessed diode, the onset voltage reduces by 45% along with a decrease of reverse leakage current by about one order of magnitude.

The design of an efficient multicast for a scalable video coding (SVC) streaming combined with directional beamforming is a challenging issue. A quality of experience (QoE)-aware directional beam scheduling (QBS) scheme is proposed which optimises overall QoE for a multirate multicast of SVC, with beamforming in wireless networks. Different SVC layers to different beams and rate modulations are optimally scheduled. A mixed integer linear programming formulation of the problem is provided and a heuristic algorithm is proposed. Results show that QBS can increase the overall QoE and can satisfy the minimum expected QoE for all users.

A fully integrated quadrature voltage-controlled oscillator (QVCO) for IEEE 802.15.4 transceivers is presented. The QVCO supports the 2.4 GHz unlicensed industrial, scientific and medical (ISM) band. The proposed QVCO generates 2.25–2.9 GHz covering 2.4 GHz transceivers. Quadrature coupling between the VCO cores is achieved using common source transistors which have their drains directly connected to the supply voltage. By using this structure, the effect of 1/f noise up-conversion in the phase-noise performance could be reduced. The QVCO achieves a measured phase noise of −116.74 dBc/Hz at 1 MHz offset with a centre frequency of 2.5 GHz. The proposed QVCO consumes 0.55 mW from a 0.45 V supply voltage and is implemented in a standard 0.13 μm CMOS process with a core area of 0.315 mm².

The finite-signal-to-noise ratio (SNR) diversity-multiplexing trade-off (DMT) of cooperative diversity protocols are investigated in vehicular networks based on cascaded Rayleigh fading. Lower bounds of DMT at finite SNR for orthogonal and non-orthogonal protocols are derived. The results showcase the first look into the achievable DMT trade-off of cooperative diversity in volatile vehicular environments. It is shown that the diversity gains are significantly suboptimal at realistic SNRs.

For cooperative spectrum sensing, multiple secondary users are required to deliver their local decisions to a fusion centre through a report channel. A resource-efficient transmission technique for the report channel is presented, which can significantly reduce the time or frequency resource needed for transmission by simultaneously transmitting the local decisions.