A novel low-profile high-gain slot antenna based on a modified Fabry-Pérot cavity (FPC) and a mushroom-like electromagnetic band gap (EBG) structure is proposed and discussed. The low-profile FPC composed of a planar artificial magnetic conductor and frequency selective surfaces is utilised to enhance gain. Moreover, the mushroom-like EBG structure rather than a traditional reflector is used to reduce the profile and to increase gain. Eventually, an antenna prototype operating at the WLAN system coverage IEEE 802.11a (5.15–5.35 GHz) is fabricated and exemplified to validate high radiation performance. The measured results show that the proposed antenna achieves a high gain of up to 10.6 dBi at 5.25 GHz and an −10 dB impendence bandwidth for S ₁₁ ranging from 5.08 to 5.51 GHz.

An efficient recursive–iterative solution is proposed for electromagnetic (EM) scattering problems. The scheme involves dividing the impedance matrix of the method of moments into strong and weak interaction parts. The induced scattered current can be expanded in terms of the Taylor series. Then it can be solved recursively by the equations of the strong interaction part with multi-right-vectors that are related to the weak interaction part. The multilevel fast multipole method is used to accelerate the matrix–vector product operations of both strong and weak interaction parts. Moreover, the sparse approximate inverse preconditioner is applied to speed up the iterative convergence for equations of the strong interaction part. Numerical results confirm the accuracy and efficiency of the proposed method.

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.

Differential site attenuation (DSA) to verify the performance of electromagnetic compatibility (EMC) facilities, open area test site and semi-anechoic chamber, without using a calibrated free space antenna factor (AF^FS) is proposed. In the evaluation of EMC facilities, the AF^FS is one of the main uncertainty contributions. The measured results are reported and compared with the current site attenuations. It is shown that the proposed DSA has good discrimination capability in verifying the performance of EMC facilities.

An eight-element multiple-input–multiple-output (MIMO) antenna array for ultra-wideband (UWB) communication is reported. The proposed array contains eight antenna elements having annular ring slots in the middle of each element and tapered feed lines for impedance matching. The defected ground planes are introduced on the back of these antenna elements. Moreover, closed-loop frequency selective surfaces are introduced to achieve enhanced isolation between antenna pairs. A quad-strip connected circular arc decoupling structure is also used to enhance the isolation among particular antenna elements. These decoupling structures provide isolation of 20 dB over most of the desired UWB spectrum. The proposed UWB-MIMO array has dimensions of 60 × 93 mm². The proposed design is suitable for integration with system-in-package applications and provides ease of connectivity on all four sides.

The fragment-type appearance of two-dimensional barcodes provides the hint of embedding a fragment-type ultra-high frequency radio frequency identification (UHF RFID) tag into the barcode. In this reported work, genetic algorithm searching is used to select which modules in a quick response (QR) barcode should be metalised and connected to form the RFID tag antenna. The design is demonstrated by embedding a 915 MHz UHF RFID tag in a QR barcode label of dimensions 14.5 × 14.5 mm on a single-sided PCB.

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%.

A low-profile wideband unidirectional patch antenna excited by a tapered staircase-shaped feed strip with a tuning patch is presented. A prototype with a height of 17 mm (0.156λ) was studied. The results show that an impedance bandwidth of 86.2% for |S11| < − 10 dB from 1.57 to 3.95 GHz was achieved. Stable and symmetric unidirectional radiation patterns, a low cross-polarisation level, low back radiation and an antenna gain ranging from 6.2 to 9.7 dBi was obtained over the operating band.

The synapse circuit presented here is constructed from a second-order lowpass filter using log-domain techniques. This synapse presents an advantage over those currently available as its output current is proportional to the number of spiking inputs and it can delay the peak current from 0.5–50 ms. Thus, this can be used for temporal coding and to substitute several parallel synapses with one. Measurement results from its implementation in a 0.5 µm ON semiconductor technology are presented.

A novel medical ultrasound despeckling method combining quantum-inspired bilateral filtering and wavelet thresholding is proposed. An adaptive bilateral filter under the framework of quantum signal processing is exploited in this method and used as a pre-processing step. Then wavelet thresholding, on the assumption that the signal and noise coefficients in the wavelet domain are subject to generalised Laplace distribution and Gaussian distribution, respectively, is applied to the pre-filtered image. Experiments show that the proposed method can obtain a better speckle noise reduction performance while retaining high-contrast features such as edges.

Recent research has examined the combination of compressed sensing with over-complete dictionaries for the lossy compression of electrocardiogram (ECG) signals. The application of dictionary learning to automatically create the dictionary is described. A novel analysis of the reconstructed signals using a range of clinical metrics based around QRS feature extraction and heart rate variability is employed. Two methods for dictionary creation are proposed: patient specific and patient agnostic. A detailed comparison of each approach is described. Considering ambulatory ECG monitoring as an application, each methodology is analysed for a wide range of compression ratios.

A multi-sampling method with partial conversion for a low-noise and high-speed analogue-to-digital converter (ADC) is proposed. The proposed multi-sampling method divides the total bits of an ADC into upper and lower bits, and only repeats the lower bit conversion using the two-step ADC architecture. This partial conversion decreases the A/D conversion time, along with noise reduction by multi-sampling. The proposed method with pseudo-multi-sampling or correlated multi-sampling for lower bit conversion reduces the number of clock cycles by 99.7 or 98.8%, respectively, compared with the conventional multi-sampling method.

Electrical overstress (EOS) is assumed as one of the most misinterpreted electrical phenomena that can affect drastically the reliability of electronic components. To predict the behaviour of a circuit under EOS, a relevant predictive circuit model is required. An investigation of circuit degradation caused by the pulsed EOS is addressed. More precisely, the electrical response of the Zener diode BZX84B6V8 under square wave EOS is modelled. The proposed model is originally extracted from the diode electro-thermal behaviour caused by the self-heating induced by excessive EOS on the reverse voltage. The diode EOS model was emulated and implemented in VHDL-AMS language. It has been found experimentally, with a 17 V amplitude and 8 ms period square wave EOS, that the diode transient electrical parameters enable experimental response prediction. The suggested model can be used for reliability analyses of electronic devices.

A simple yet flexible bit-reversal hardware scheme applicable to variable-length fast Fourier transform (FFT) processors to facilitate the continuous flow of serial data is presented. The proposed design employs a length-N two-port register file (N is the processing size of the FFT), and a simple address generator to perform variable-length bit-reversal operations on the input or output of the FFT processor. This enables the conversion of bit-reversed data to the natural order. The proposed scheme is superior to the existing technologies because of its ability to process a continuous-flow input sequence and its applicability to variable-length FFT processors without the need for a shuffling mechanism on the input and output memory ports. The proposed design is particularly suitable for applications involving bit-reversal operations on large-point FFT processors.

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.

A new definition of semi-modularity to accommodate relative timing constraints in self-timed circuits is presented. While previous definitions ignore such constraints, the new definition takes them into account. The difference on a design solution for a well-known speed-independent circuit implementation of the Muller C element and a set of relative timing constraints that renders the implementation hazard free is illustrated. The old definition produces a false semi-modularity conflict that cannot exist due to the set of imposed constraints. The new definition correctly accepts the solution.

Electrical capacitance tomography (ECT) is a low-cost, high-speed imaging technique useful in many industrial settings. ECT is predicated on the knowledge of sensitivity maps between capacitance electrodes that blanket the imaging domain. The simultaneous activation of multiple electrodes can be advantageous to manipulate the resulting field distributions and capture additional spatial information for imaging purposes. However, conventional methods for sensitivity map computation in ECT are not adequate in the presence of multielectrode activation because the mutual coupling between electrodes is not properly accounted for. This coupling becomes especially critical in adaptive electrical capacitance volume tomography (AECVT) sensors, where signals from many small electrode segments are combined into synthetic electrodes. A more general approach is presented for sensitivity map computation in AECVT based on the actual posteriori (induced) charge distributions rather than the conventional approach based on boundary conditions with no account for electrode interactions.

A novel bilinear discriminant feature line analysis (BDFLA) is proposed for image feature extraction. The nearest feature line (NFL) is a powerful classifier. Some NFL-based subspace algorithms were introduced recently. In most of the classical NFL-based subspace learning approaches, the input samples are vectors. For image classification tasks, the image samples should be transformed to vectors first. This process induces a high computational complexity and may also lead to loss of the geometric feature of samples. The proposed BDFLA is a matrix-based algorithm. It aims to minimise the within-class scatter and maximise the between-class scatter based on a two-dimensional (2D) NFL. Experimental results on two-image databases confirm the effectiveness.

Motivated by the observation that visual perception is quite sensitive to the irregularities of natural scenes, the incorporation of the multi-fractal spectrum and the fractal dimension into blind image quality assessment for perceptual features extraction is introduced. On the basis of a box-counting method, the multi-fractal spectrum and fractal dimension are extracted from natural scenes and then their discrepancies are quantified. Experiments on the LIVE image database show that consistency with subjective evaluation is achieved. In addition, these are remarkable advantages when compared with other popular methods are demonstrated.

The design of multi-Gbit/s low-density parity-check code (LDPC) decoders has become a hot topic in recent years to meet the growing demand of the transformation towards 4G. An area and energy efficient multi-Gbit/s LDPC decoder engine with a fully paralleled layered architecture based on an application-specific instruction set processor (ASIP) using Synopsys IP designer is presented. When the ASIP core is instantiated for 802.11ad, it achieved a throughput of up to 7 Gbit/s at three iterations with a latency of 95 ns, a record energy efficiency of 2.5 pJ/bit/iteration and an area efficiency of 54.5 Gbit/s/sq-m in CMOS 28 nm technology for the 1/2 rate, showing it to be competitive against published ASIC solutions.

A variable data-window size for the recursive least-squares algorithm is proposed. Using the window-size selection criterion, the window size can be suitably adjusted for the conditions of the system parameters to be estimated.

The increasing demand for bandwidth fuels the development towards high data rate electrical serial links. These links generally suffer from considerable frequency-dependent loss, introducing the need for equalisation at 10 Gbit/s and higher. Modulation schemes with improved spectral efficiency, with respect to non-retrun to zero (NRZ), combined with feed-forward equalisation (FFE), allow increasing the chip-to-chip data rate with the drawback of a more complex, e.g. multi-level, receiver (Rx). The use of duobinary modulation (DB) is presented to realise a high-speed serial link. The increase in complexity of a DB Rx is limited, whereas the required channel bandwidth compared with NRZ is reduced. Furthermore, the need for equalisation when compared with PAM4 is reduced as the required roll-off that is needed to create a duobinary modulated signal from an NRZ stream can incorporate the frequency-dependent loss of the link.

The performance of an X-band flexible band-filter on ultra-thin liquid crystal polymer (LCP) substrate is investigated. The 50 µm-thick LCP substrate is adopted to enhance the flexibility of circuits. For the purpose of fabrication by the conventional printed circuit board process, copper-clad laminate with 18 µm thickness is selected. Excellent microwave transmission characterisation is demonstrated by measuring the microstrip line at flat and bending conditions. An X-band interdigital bandpass filter based on a half-wavelength microstrip line resonator is designed and fabricated for purpose of demonstration. The measured results at the flat condition show that the insertion loss is 2.1 dB at centre frequency of 9.4 GHz and the return loss is better than 20 dB at the designed band. The performance at the bending condition shows that the bending effect causes little deterioration to the performance at a different bending radius.

A chromatic-dispersion-free transmission using a time-reversal optical parametric amplifier (OPA) for 10 Gbit/s data over 25 km of standard single-mode fibre is demonstrated. The time-reversal was achieved using optical phase conjugation in the OPA. A pilot signal was first sent to estimate the optical channel, which would be reshaped by the OPA and then retransmitted with data through the same fibre. The dispersion is compensated automatically through the transmission. Experimental results showed that around 1 dB improvement can be obtained at a bit error rate of <10⁻⁹ compared to the traditional return-to-zero on–off keying link.

The design and electro-optical measurements of a 25 Gbit/s common cathode vertical cavity surface-emitting laser (VCSEL) driver in 90 nm bulk CMOS technology is presented. The driver is bonded to a 14 Gbit/s commercial VCSEL providing both DC and modulation current to the laser. The power consumption including the VCSEL is 60 mW. Since the DC bias of the VCSEL exceeds the breakdown voltage of thin oxide transistors, a novel output stage configuration using isolated wells is proposed. The active area is only 127 × 50 μm.

A 34.3 fs pulse generation dechirped from a nonlinear polarization evolution (NPE)-based modelocked Er-doped fibre laser at a repetition rate of 201 MHz is reported. The output power is 38.5 mW at a pump power of 700 mW.

A novel way to split terahertz (THz) surface waves is presented on the basis of propagation characteristics of spoof surface plasmon polaritons. Metal disc-type splitters with a centre hole and radially placed gratings are proposed and analysed using the finite-difference time-domain (FDTD) method in cylindrical co-ordinates. Numerical results demonstrate that the discs act as bi- and multi-directional THz surface wave splitters with large coupling regions, the frequency of which is selected by grating structures.

Bandwidth measurements of deep ultra-violet micro-light-emitting diode (LED) electroluminescence centred at 250 nm using a multiple quantum well aluminium gallium nitride (AlGaN)-based LED structure grown on a sapphire substrate is presented. By controlled etching of the wafer surface, parabolically shaped micro-LED structures were formed to enhance light emission through the substrate. Devices were tested on-wafer and bandwidth measurements were carried out on individual emission peaks from the devices. A bandwidth of more than 20 MHz was achieved on the 250 nm peak.

The design and experimental characterisation of a depolarised light source for feeding a remote transceiver based on silicon photonics are presented. Since the transceiver only works in TE mode, the source is designed to deliver, over up to 10 km standard single-mode fibre links, a continuous-wave light with almost constant power along this polarisation direction, whatever be the random polarisation rotation because of the fibre link. The depolarised light source is realised by combining the output of two independent distributed feedback lasers, having orthogonal polarisation and controlled frequency difference. The transmission performance and stability of the remote light source are successfully tested.

Four-switch three-phase inverters (FSTPIs) are post-fault reconfigured topologies for a two-level inverter with failure of a power switch or a leg, and space vector pulse-width modulation (SVPWM) strategies have been used to control FSTPIs. However, different faulty legs correspond to different topologies of FSTPIs which are controlled by different SVPWM strategies; therefore, three SVPWM strategies need to be prepared for three FSTPIs, respectively, which takes up lots of memory space in the controller and increases the complexity of the control strategy. To overcome these disadvantages, a general SVPWM strategy that can be used to control three FSTPIs is proposed. Experimental results have shown the validity and feasibility of the proposed strategy.

Constant on-time (COT) control has been widely applied in industrial applications due to its fast transient response. However, the conventional COT controlled buck converter has poor output-regulation accuracy. A new control method, called improved COT (ICOT) control, that provides both high output-regulation accuracy and fast transient response for the buck converter is proposed. Circuit simulation results validate the correctness of the theoretical analysis.

The alternating direction implicit (ADI) scheme is used for the parabolic equation (PE) method to analyse electromagnetic scattering problems. The three-dimensional (3D) electromagnetic scattering problem can be reduced to a series of 1D problems to be solved by the ADI-PE method, which is more efficient than the traditional Crank-Nicolson scheme. In this way, both the memory requirement and the central processing unit time can be saved substantially even for electrically large targets with encouraging accuracy. The full bistatic scattering pattern can be obtained by decoupling the marching direction from the direction of the incidence wave. Numerical results are provided to demonstrate the efficiency of the proposed method.

The single-event-upset (SEU) reliability is a concern for three-dimensional (3D) integrated circuits (ICs), mainly due to the carrier mobility change caused by thermo-mechanical stress from through-silicon vias (TSVs) and the shallow trench isolation (STI). A systematic evaluation method is proposed to identify the vulnerability within 3D ICs at design time. The evaluation flow involves the TSV/STI stress-aware mobility variation calculation, sensitive region marking, insertion of excitation signals and then the simulation of the 3D ICs. This method is able to help 3D IC designers to evaluate and enhance the SEU reliability at design time.

A method to obtain high diversity gain is proposed by spatial phase coding (SPC) in the cooperative multiple input multiple output-orthogonal frequency division multiple access (MIMO-OFDMA) system. SPC provides improved diversity gain dramatically in proportion to the number of received paths although the one-bit feedback information is used. Moreover, the cooperative MIMO-OFDMA system has received paths without additional antennas more than the conventional MIMO-OFDMA system. Therefore, SPC can improve reliability in the cooperative MIMO-OFDMA system effectively.

An efficient power allocation scheme is provided to maximise the energy efficiency for amplify-and-forward (AF) relay networks. To reduce the complexity, both the optimal and simplified equal power allocation schemes with closed-form expressions are derived.

In wireless sensor networks, the clustering routing protocol is commonly used for energy efficiency. However, routing protocols without proper security suffer from many security vulnerabilities. Hence, a key renewal scheme based on the clustering routing protocol is proposed. To apply the key renewal scheme with sensor authentication, sensor nodes are first authenticated during the key establishment procedure and then the symmetric key is updated periodically using hash functions. The simulation results show that the proposed key renewal scheme lengthens the network lifetime and has shorter activity time of attackers in spite of increasing the number of compromised nodes.

An exact closed-form expression is derived for the outage probability of a recently proposed multiuser, incremental, decode-and-forward (DF) relaying scheme, when affected by outdated channel estimates. In this scheme, one source communicates with the best destination under the assistance of an incremental DF relay, with the direct- and relaying-link signals being merged via maximal-ratio combining. A simple asymptotic expression is also derived for the outage probability, revealing that the outdated channel estimates reduce the system diversity order to two, regardless of the amount of destinations available.