A reconfigurable filtering slot antenna (filtesnna) for Wi-Fi/LTE mobile systems is proposed. The reconfigurable filtesnna is based on integrating a switchable bandpass filter inside the feeding line of a slot antenna structure. This design is achieved by using an open/short-ended inter-digital E-shaped patch via two integrated pin diodes within its structure. The proposed filtesnna has a small size of 0.25λ₀ × 0.1λ₀ (λ₀ is the free-space wavelength at 2.1 GHz). The filtesnna is designed at centre frequencies of 2.1/2.4 GHz with measured 10 dB return loss impedance bandwidths from 2.03 to 2.17 GHz or 2.37 to 2.51 GHz when the diodes are ON or OFF, respectively. A prototype of the reconfigurable filtesnna has been fabricated and measured. A good adaptation is acquired between the simulated and the measured results.

A structure of a compact ultra-wideband monopole antenna has been presented. The antenna consists of a microstrip-fed rectangle radiator as well as a ground plane with a rectangle slit and an L-shaped stub. The critical factor in achieving a small size is a careful design procedure involving numerical optimisation of all geometry parameters of the antenna aiming at explicit size reduction while maintaining acceptable electrical performance. The final design exhibits dimensions of only 9.45 × 18.5 mm and a footprint of 175 mm². Experimental validation and comparisons with competitive designs are also provided.

The concept and analysis of a graphene-metal beam-reconfigurable terahertz (THz) loop antenna are presented. The hybrid graphene-metal implementation is proposed to combine (i) dynamic surface conductivity tunability using different DC bias voltages and (ii) high radiation efficiency enabled by metal. The loop antenna which employs an artificial mu-negative transmission line provides the horizontally polarised omnidirectional radiation. The graphene-metal loop around the centre ring acts as a reflector. Changing the DC bias of different position of graphene to control the position of resonance can effectively adjust the beam direction. The proposed concept and achieved performance, computed using realistic material parameters, are extremely promising for beam scanning at THz frequencies.

A polarisation diversity antenna for an ultra-high-frequency RFID tag is presented. The antenna consists of two dual-planar inverted-F antennas arranged in a cross-configuration, and mountable on a metallic object. The antenna can work together with a linearly polarised reader antenna that has an arbitrary polarisation direction. The proposed tag antenna has a nearly uniform read range between 9.1 and 10.2 m, regardless of the polarisation direction of the reader's transmit field.

A frequency-tunable microstrip patch antenna with a liquid-metal-actuated loading slot is presented. The electrical length of the loading slot located beneath the resonating patch is altered by filling and evacuating liquid metal from fluidic channels along the ground plane. The slot reactively loads the antenna, altering the resonant frequency as its length is changed. Frequency tuning is achieved from 1.85 to 2.07 GHz, corresponding to an 11.2% tuning bandwidth.

A wearable antenna with tripolarisation diversity is designed for wireless body area networks (WBANs). The antenna is fabricated with flexible materials. Three polarisations are realised by combining an inductive loaded circular monopolar patch antenna with a microstrip annular ring antenna. Simulated and measured results show that the antenna has sufficient bandwidth for a WBAN. The port isolation reaches 13.5 dB, and the correlation coefficients show a good diversity performance.

An ultrasonic on–off keying/amplitude-shift keying demodulator using standard 0.18 μm CMOS technology is proposed, intended for recovering the identification number of an implanted medical device transmitted from an external base station. The CMOS integrated ultrasonic demodulator consists of a low-noise amplifier, variable-gain-amplifiers, an offset cancellation circuit, an envelope detector circuit and a hysteresis comparator. Downlink data transmission of 50 kb/s data signals in the 1 MHz band is successfully demonstrated, the power consumption is about 184 μW from a 1.5 V supply. The architecture is described, and the measurements performed confirm the theoretical result.

A compact, broadband and single-fed circularly polarised implantable patch antenna is numerically evaluated and experimentally demonstrated for industrial, scientific, and medical band (2.45 GHz) biomedical telemetry application. By inserting a cross-shaped slot with unequal-length arms in the ground plane, the proposed antenna can obtain improvement for both impedance bandwidth and axial ratio (AR) bandwidth, without increasing the backward radiation. The simulated −10 dB impedance and 3 dB AR bandwidths are 16.15% and 6.09%. The measured impedance bandwidth is 14.03%. The overall antenna size (including the superstrate) is 10 × 10 × 1.27 mm³.

A new method to extract the foetal electrocardiogram (ECG) using an abdominal ECG signal and a thoracic ECG signal of the mother is presented. The nonlinear mapping of the maternal ECG component from thoracic signal to an abdominal signal is approximated by the support vector regression (SVR) method. The foetal ECG signal is then extracted by subtracting the mapped thoracic signal from an abdominal signal. In an SVR algorithm, the nonlinear regression problem in an original signal space is transformed into a linear regression problem in high-dimensional Hilbert space by kernel technology. It avoids the ‘overfitting’ problem and could obtain good results for the small sample training set. The validity of the proposed method is validated by the real ECG signals, and compared with the existing method.

A method of constructing codes with a low jump rate, called bit-block-code (BBC), is presented. The BBC has the structure of BBC, in which bits constitute a block and blocks form codes. Each bit of a block has no weight and each block has weight determined completely by its position in the circuit. The modular design for the BBC generator is also proposed where blocks are basic units of the BBC generator. The generation circuit has the characteristics of being simple, modular, and extensible. The BBC can be used as test vectors to reduce the power consumption of the circuit under test, and it can also be exploited as a code for general purposes.

A low-power technique to reduce the power consumption of the dynamic comparators is presented. Using this technique, the pre-amplification phase of the comparator is stopped without any effect on the dynamic behaviour of the comparator. Therefore, the power consumption of the pre-amplifier stage which is the main part of the total power consumption is reduced significantly. Simulation results in various comparators reveal that the proposed technique reduces the total power consumption by more than 50%.

A mixed rotation invariant description (MRID)-based tracking algorithm and a novel high-speed visual tracking system that implements the algorithm are proposed. MRID is a novel rotation invariant description of texture and edge information by annular histograms and dominant direction. It overcomes rotation variant and large computation issues in conventional local binary pattern histograms of oriented gradient (LBP-HOG) feature description. The proposed tracking system contains an image sensor, a hierarchical vision processor and a two dimension of freedom actuator. The vision processor integrates processors with pixel and row-level parallelism to speed up the tracking algorithm. Experiment results show that the proposed system can achieve over 1000 fps processing speed of the tracking algorithm.

The Foley-Sammon transform (FST) is one of the most well-known dimensionality reduction and feature extraction methods. However, the classical FST cannot be used directly in the small sample size problem where the within-class scatter matrix is singular. Null-space based FST (NFST) provides a good solution to this problem. Proposed is a fast incremental NFST (INFST). INFST extracts new information brought by newly-added samples and integrates it with the existing model by an efficient updating scheme. INFST can achieve the aims of online classification and novelty detection. Experiments on real-world data demonstrate the effectiveness of INFST.

When there exists camera motion as well as scene motion, the position and disparity of a pixel in an image sequence temporally vary with time. Such image motion (IM) and temporal disparity variation (TDV) degrade the performance of spatiotemporal stereo matching. In this Letter, a robust spatiotemporal similarity measure that addresses IM and TDV is proposed. To this end, an irregular spatiotemporal window whose temporal windows are located by a TDV value and optical flows is designed. In addition, a spatiotemporal guided filter-based aggregation technique using temporal weights based on temporal proximity and flow reliability is presented. To handle a large number of labels effectively, a search range reduction method for finding a probable label set is presented. Experimental results show that the proposed method yields consistent and accurate disparity maps under IM and TDV.

A simple upper bound on the information rate (IR) of digital communications over phase noise-impaired channels is proposed. In particular, the transmission of linearly modulated signals, such as QAM, at high-signal-to-noise ratio is considered, thus extending previous literature results for phase modulated signals, e.g. PSK. A simulation-based lower bound on the IR shows that the proposed bound is tight for small-medium size constellations and large phase noise.

A variable step-size distributed incremental normalised least mean square (DINLMS) algorithm is proposed, in which the time-varying step-size of each node in the distributed network is obtained by minimising a posterior estimation error at that node. It overcomes the drawback that fast convergence rate with high steady-state misalignment or low steady-state misalignment with slow convergence rate, which always exists in the traditional DINLMS. The simulation results show that the proposed algorithm could achieve a better performance.

In orthogonal frequency division multiplexing-based spectrum sharing networks, due to inefficient coordination or imperfect spectrum sensing, the signals from femtocells or secondary users appear as interference in a subset of subcarriers of the primary systems. For pilot-based doubly-selective channel estimation, the embedded pilots in pilot subcarriers would inevitably be harmed by the unpredictable interference. This unsolved issue is considered and proposed is a variational expectation maximisation-based method to iteratively learn the distribution of thermal noise plus interference, and refine doubly-selective channel estimates. Simulations demonstrated the superiority of the proposed approach over existing algorithms without considering interference mitigation.

Lattice-reduction-aided (LRA) preequalisation for the multiple-input/multiple-output broadcast channel has most often been considered for the uncoded case so far. However, recent advantages in the closely related field of integer-forcing equalisation, where the cancellation of the multiuser interference and the channel coding are combined, create doubt to this separated point of view. In this Letter, the philosophy of matching both the channel code and the complex-valued signal constellation to the same finite-field arithmetic is proposed. The consequences on the factorisation task present in LRA preequalisation are discussed and covered by numerical performance evaluations based on non-binary low-density parity-check codes.

The compression efficiency of canonical Huffman coding is drastically affected by the size of the compression window, the choice of which is typically done heuristically analytic bounds for the worst-case compression efficiency of canonical Huffman coding are introduced, as a function of the size of the compression window. The derived bounds offer fine-grained control over the compression latency-efficiency trade-off.

A new admissible hardware-efficient adaptive blind sign equalisation algorithm for quadrature amplitude modulation systems is presented. The main idea is to amplify the equalised sequence while constraining it to not to exceed the largest signal amplitude. Simulation results demonstrate improved performance in terms of mean squared error and inter-symbol interference measures.

Deterministic error modelling, calibration and model parameter estimation of consumer-grade accelerometers is considered and improvement to the traditionally used measurement model is proposed. Calibration experiments on a flight motion simulator are performed for experimental verification. Model parameters are estimated using the Levenberg-Marquardt optimisation algorithm. Residual errors are considerably reduced as a result of the improved measurement model.

The stress-induced resistance drift in MgO-based magnetic tunnel junctions (MTJs) with Mg insertion layer above and below a MgO tunnel barrier is investigated. Mg insertion suppresses the resistance drift. Resistance drift characteristics are improved when electrons tunnel into the Mg-inserted barrier–electrode interface, indicating that Mg insertion significantly suppresses trap site formation at the anode-side barrier–electrode interface. However, transmission electron microscopy images confirm that there is little difference in interface crystallinity between the Mg-inserted and non-inserted interfaces. Therefore, it is shown that a slight modification of the barrier–electrode interface states has a significant impact on resistance drift characteristics, and Mg insertion on both interface sides appears to be an effective way to improve MTJ device reliability in practical applications.

A 60 GHz miniaturised, low loss on-chip bandpass filter (BPF) based on open-loop resonators is presented. Overlapping of the BPF's resonators leads to miniaturisation and introduces a mixed coupling configuration. Moreover, its resonators are folded to minimise the size and the insertion loss (IL). H-shaped defected ground structures are also used to reduce IL and to improve the out of band rejection. The measured IL, return loss, centre frequency, and bandwidth are 2.85 dB, 18 dB, 59 GHz and 15.5 GHz with a chip size of 368 × 262 µm² including pads.

A hardware-efficient carrier synchronisation technique for multiband RF interconnect system is proposed. This method takes full advantage of the wireline channel's quasi-invariant nature for achieving both energy/cost-efficient system designs. For instance, now easily decouple quadrature signals’ phase and magnitude errors by using 1-bit analogue-to-digital converter (ADC), which saves substantial power and area than that of conventional methods where the ADC with high-speed/resolution is necessary. Furthermore, the algorithm can be carried out by using a simple finite-state machine and no baseband processor is required. Simulation and measurement results show that quasi-ideal carrier synchronisation can be achieved with the proposed method.

In this reported work, quarter-wavelength stepped-impedance resonators with K inverters have been employed to realise a dual-band bandpass Wilkinson power divider (WPD). The individual bandwidth of each passband can be controlled with the dualband resonators and K inverters. A systematic design approach of the power divider is provided with the aid of the even–odd mode analysis and verified by circuit simulation. A 2.45/5.8 GHz WPD with a Chebyshev response has also been implemented for validation. The measured fractional bandwidth of 20 dB return loss (1/|S ₁₁|) is 7.0%/4.1% which is consistent with the theoretical design. In addition to the 3 dB power division, an insertion loss of 0.8/1.2 dB is obtained. Isolation of 20.1/19 dB at the centre frequency is also achieved. Full-wave simulated data are also presented and show good agreement with measured results. Compared with other dual-band bandpass power dividers, the proposed circuit exhibits better impedance matching and bandwidth.

The performance of a 15–29 GHz low-noise high-electron-mobility transistor amplifier at room and cryogenic temperatures is reported. The close-to-carrier technical noise is measured for frequency offsets from 100 mHz to 100 kHz and the effect of adjusting the DC power biasing is investigated. An order of magnitude improvement in intrinsic phase noise is achieved by optimising the bias settings away from manufacturer specifications, giving a single-sideband phase noise power spectral density at 1 Hz offset of −100 dBc/Hz and −105 dBc/Hz for a 26.6 GHz carrier at room temperature and 6.5 K, respectively.

A wideband filtering crossover using a dual-mode ring resonator is proposed. Two half-wavelength open stubs are used to produce transmission zeroes for the crossover passband. A high selectivity wideband filtering crossover with a fifth-order passband is designed and fabricated for verification. The measured results and theoretical expectations have good agreement.

The interdigitated transducers sensor based on nanodiamond (ND)/polyaniline (PANI) thin film for ammonia (NH₃) sensing is investigated, which is synthesised by in situ chemical oxidative polymerisation. The experimental result reveals that the response of 30ND/PANI thin film sensor is much higher than that of PANI for NH₃ gas detection. The ND is homogeneously combined into PANI to form ND/PANI nanocomposite, which may increase the specific surface area and improve the response of ND/PANI sensor. Moreover, the response mechanism of ND/PANI for NH₃ gas detection is discussed. The synthesised thin films are characterised by Fourier transform infrared spectroscopy and SEM.

Real-time demonstration of 30 Gbit/s hierarchical star 8-quadrature amplitude modulation optical access system is presented. By incorporating a novel signed-error radius directed equalisation algorithm with a fractionally-spaced filter structure, the receiver supports high-speed hierarchically-modulated signals. The feasibility of the proposal is confirmed by demonstrating downlink coexistence in a 10 gigabit Ethernet passive optical network that conforms to IEEE 802.3av standards.

Reliability for network-on-chips has been widely researched in last decades not only to support the rapid growing requirement of on-chip communication but also to address the challenge on reliability due to aggressive technology scaling. Simulation is the most common method to evaluate the capacity of reliability design but its cost is significant. Therefore, it is necessary to calculate the capacity for reliability of a design with light-weight mathematic models. A model for faults on links is described to calculate the delivery rate of networks based on a Markov chain fault model, fault-tolerant configuration and network traffic. The calculation results show accurate approximation of simulation results.

Room-temperature, high-speed quantum cascade lasers at 4.7 μm are presented. An output power of 115 mW and threshold current of 230 mA are obtained for the lasers working in continuous-wave mode. Reliable single-mode emission with a side-mode suppression ratio more than 30 dB is observed. Using microwave rectification technology, a flat frequency response up to roughly 3 GHz for the laser operating at 10°C is demonstrated.

A photonic versatile waveform generator based on phase modulation in a Sagnac loop is proposed and experimentally verified. A continuous-wave light is modulated by a sinusoidal signal in a phase modulator to generate optical sidebands. Combined with a polariser, the Sagnac loop is used to manipulate the carrier of the modulated signal. Then, a fibre Bragg grating is applied to attenuate one of the first-order sidebands. By properly choosing the modulation index and the polarisation state of the light wave output from the Sagnac loop, versatile waveform sequences can be generated. In the demonstrating experiment, full-duty-cycle sawtooth, triangular and square waveform sequences are successfully generated. The proposed photonic microwave waveform generator features the advantages of a simple structure, low cost, being free from bias drift and tunability in repetition rate.

Unlike the voltage source converter, the Z-source converter can boost as well as buck the input voltage. However, the presence of physically large components in the impedance network introduces large parasitic inductances into power device commutation paths. This leads to consequent overvoltages at power device turn-off. A simple circuit for addressing this is presented. Practical results are given for a voltage-fed quasi-Z-source inverter with discontinuous input current.

In a dense environment of loosely-coupled wireless charging pads to which out-of-band signalling is applied, cross-connection errors occur according to the wireless communication distance of out-of-band signalling. A cross-connect abatement technique using received-signal-strength-indicator measurement is proposed to prevent this problem and to provide stable wireless charging. To evaluate the performance of the proposed technique, two compact wireless charger environments are created in an RF shield room. The experimental results indicate that the wireless charging system using the proposed technology provides wireless charging services without cross-connection errors.

A radar absorbing structure was designed on the basis of a circuit analogue absorber for the implementation of broadband characteristics by using a metal-mesh transparent electrode with an improved optical transmittance. To realise a high optical transmittance and broadband absorbing performance in the X-band, a resistive frequency selective surface, in which soda-lime glass, a transparent dielectric, was patterned with a metal-mesh, was used. The simulation for the reflection characteristics of the proposed absorber is performed and showed its validity through experiment. The measurement results were in good agreement with the simulation results, confirming the broadband reflection loss characteristics. Since the proposed structure has a high optical transmittance and stable broadband absorbing performance, it can be used in various fields including military applications, where facilities requiring secure wireless signals or transparent radar absorbers are necessary.

Research and application is spreading of techniques of coherent combination of complex-valued synthetic aperture radar (SAR) data to extract rich information even on complex observed scenes, fully exploiting existing SAR data archives, and new satellites. Among such techniques, SAR tomography stems from multibaseline interferometry to achieve full-3D imaging through elevation beamforming (spatial spectral estimation). The Tomo concept has been integrated with the mature differential interferometry, producing the new differential tomography (Diff-Tomo) processing mode, that allows ‘opening’ the SAR cells in complex non-stationary scenes, resolving multiple heights and slow deformation velocities of layover scatterers. Consequently, the operational capability limit of differential interferometry to the single scatterer case is overcome. Diff-Tomo processing is cast in a 2D baseline-time spectral analysis framework, with sparse sampling. The use of adaptive 2D spectral estimation has demonstrated to allow joint baseline-time processing with reduced sidelobes and enhanced height–velocity resolution at low computational burden. However, this method requires coherent multilooking processing, thus does not produce full range-azimuth resolution products, as it would be desirable for urban applications. A new single-look adaptive Diff-Tomo processor is presented and tested with satellite data, allowing full range-azimuth resolution together with height–velocity sidelobe reduction and superresolution capabilities and the low computational burden.

Tunnel field effect transistor (TFET) is being considered as an alternative to the conventional MOSFETs for low power system on chip applications. In this Letter, gate-drain underlap (UL) feature of double gate TFET for analogue/RF characteristic is discussed. Here, it is found that parasitic resistance induced by gate drain UL is not significant as compared with DG tunnel field effect transistor (DG-FET). Thus, the behaviour of RF figure of merit is different from DG-FET.

Proposed is an L ₀ norm constraint set-membership affine projection algorithm with coefficient vector reuse, which is derived by minimising a differentiable cost function that utilises the L ₀ norm of the updated weight vector as well as the sum of the squared Euclidean norms of the differences between the updated weight vector and past weight vectors. In addition, a power estimate method is introduced to eliminate the effect of the fluctuation of the output error on the step size. Simulations on sparse system identifications demonstrate that the proposed algorithm achieves a lower steady-state misalignment than the existing algorithms in a high background noise environment.

Virtual access point (VAP) is one of the most useful wireless virtualisation technologies because of its concurrent operation to compose multiple wireless networks via generating service set identifier. A single physical wireless NIC could access multiple networks in a single channel and thus establish a variety of wireless access point without additional wireless network interface. However, as the number of VAP increases, available bandwidth is reduced due to the fact that the number of management frame is increased dramatically in a single channel. Since the management frames should be sent as a basic data rate, channel utilisation and overall network performance would be degraded. To address this problem, system virtualisation is employed to augment wireless NIC hardware. Augmented wireless NICs are exposed to the guest OS and thus can access different wireless channel physically. The results obtained mitigate the bandwidth utilisation of management frame composed to the legacy VAP scheme, increasing round-trip time latency slightly.

A simple model is developed for predicting the power rise of the passive intermodulation in the first zone generated by broadband signals compared with the 2-tone test, followed by an experimental validation. The calculated results agree well with the measurements, having a mean difference of 0.6 dB.