A miniaturised phased array, suitable for a low-power wireless device and able to be fed from its battery, is experimentally demonstrated. The phase array consists in two gold patch antennas, phase shifters and additional circuitry, all integrated on Hf _x Zr_1−x O₂/high-resistivity silicon 4 inch wafer. The radiation beam at 2.55 GHz is steered with 25° when the 7 nm-thick ferroelectric is biased with ±1 V.

A bent crossed dipole antenna for dual linear polarisation applications is introduced. The proposed efficient techniques incorporated into the design provide the antenna with high port isolation and low cross-polarisation. A better than 56 dB measured port-to-port isolation is achieved in the frequency range of 2.7–3 GHz. The cross-polarisation level remains 40 dB below the copolarisation peak in both principal planes. A pair of matched copolar beams in the corresponding principal planes is obtained owing to the use of identical and symmetrical structures in orthogonal directions. These features along with simple geometry and inexpensive PCB fabrication make the proposed antenna a promising candidate for multi-mission applications.

A miniaturised coplanar waveguide-fed multiple notched monopole antenna for ultra-wide bandwidth (UWB) application is presented. By introducing multiple inverted L-shaped stubs embedded within a polygonal shaped monopole antenna, multiple notches can be achieved. A prototype antenna with triple band-notched at WiMAX, WLAN, and X-band is designed and fabricated. The proposed antenna has an impedance bandwidth of 3–12 GHz with a voltage standing wave ratio of <2 except for the selected notched bands. The main advantage of the antenna is its miniaturised size (21 × 14 mm²), as well as the straightforward design. The antenna has a unipolar configuration and good omnidirectional radiation pattern with negligible distortion which is suitable for UWB applications.

A wideband module antenna comprised of a small ground radiation antenna in the module and a parasitic radiation loop in the evaluation board is proposed. Unlike conventional ground radiation antennas, the ground radiation antenna in the module works as an exciter to the parasitic radiation loop, which further couples with the evaluation board as a radiator. Thus, a space-saving antenna is obtained with wide bandwidth and easy tuning. Accordingly, dual resonance can be generated by tuning the resonant frequencies of the ground radiation antenna and the parasitic radiation loop equally. When measured, the antennas have wide bandwidths (2:1 voltage standing wave ratio bandwidth of 270 MHz) and high efficiency (ranging from 44 to 74%).

A novel methodology for synthesising ultra-miniaturised frequency-selective structures (FSSs) is proposed. The methodology is based on interconnecting the convoluted segments, which are arranged alternately on both sides of the substrate. Three advantages of ultra-compact unit cell size, independent control of filtering performance for different polarisations, and promising extension of multiband response are achieved. To verify this concept, two different structures are designed and fabricated. The first one is a single-band FSS operating at 2.5 GHz, with a unit cell size of only (λ ₀/34) × (λ ₀/34). The second one is an ultra-miniaturised dual-band FSS with a band ratio of only 1.18, and its centre frequencies are located at 2.2 and 2.6 GHz. Stable dual-polarised responses under various angles up to 60° are obtained.

A four-port MIMO antenna design focused on the sub-6 GHz fifth generation wireless communication application is presented. The design does not need any other decoupling structure for achieving isolation between multiple ports. A combination of four single wideband antenna units results in the formation of a circular-shaped metallic disc in the ground plane of the proposed antenna. This disc acts as a pool of current with 180° phase difference leading to isolation between various ports. Diversity performance of the antenna is shown with the help of an envelope correlation coefficient using both S-parameter and far-field data. The radiation pattern of the proposed antenna has four lobes in four quadrants for proper reception of signals from different directions. A prototype of the designed antenna is fabricated and measured successfully.

A reconfigurable octagonal antenna with a capability to operate in ultra-wideband (UWB), narrowband (NB) or bi-bands is presented. By incorporating two resonators, computation between the proposed modes becomes possible using the PIN diode switches. The UWB mode is obtained by deactivated the two resonators, while the one NB mode, is gotten by activated just one resonator. In the case of the activation of the two resonators at the same time, the antenna will be operating in the bi-bands mode. The prototype has been simulated and measured. Both simulation and measurement have shown the same results and characterize a reconfigurable behavior, necessary for wireless applications.

The proposed multi-band multi-modulation I/O (MMI) for mobile memory interface consists of two RF-band and 4-PAM (pulse-amplitude modulation) transceivers for simultaneous bidirectional read/write operations on a shared single-ended 5 cm off-chip transmission line. A novel band-selective transformer is introduced to combine and split two amplitude shift keying modulated RF-bands with a 4-PAM baseband for transmitting and receiving multiple data concurrently. The MMI interface consumes 2.8 pJ/b from a 1.2 V supply voltage. Testing results show that the MMI interface achieves an overall data rate of 14 Gb/s/pin. It is implemented in a 65 nm CMOS process with chip area of 0.25 mm².

A study of different distortions in high-speed differential PAM-4 signals, including the linear distortions, i.e. amplitude mismatch, channel skew and bandwidth mismatch, and the non-linear distortion, i.e. the mismatch between rising and falling edges is presented. It is observed that only the non-linear distortion introduces a large common-mode (CM) noise at the double Nyquist frequency, which causes electromagnetic interference (EMI) in high-speed serial links. At last, Monte-Carlo simulations are performed to investigate the impact of signal distortions on the EMI-related CM noise.

The effect of optimising the transistor finger width on the performance of high-speed analogue circuits in deep sub-micron processes is investigated, demonstrated in a 28 nm high-K/metal gate CMOS technology process. Silicon proven results demonstrate that the oscillator with a finger width of 440 nm gives the best performance based on the figure of merit (=142) among the benchmark design examples used.

As an alternative standard electromagnetic (EM) field generator, a 4-port TEM (transverse EM) cell can be used for an EM compatibility (EMC) emission and immunity test. However, unwanted EM fields generated in a TEM cell deteriorate the results and accuracy of critical EMC tests. A new method to suppress unwanted field components in a 4-port TEM cell is proposed. To reduce the unwanted EM field, the narrow slits in internal septa are inserted, which are transverse with respect to the direction of wave propagation. By introducing the slits, the 4-port TEM cell can provide improved standard EM field distribution with the much-lowered unwanted field component inside the usable test volume.

The problem of where to position the range sensor next for generating a completely seamless integration of a targeted surface from multiple range datasets acquired at different spatial poses is one of the challenging tasks in machine vision. A new view planning method is proposed for complete reconstruction of the real scene from the minimum number of range datasets. The generated surface model covers approximately all major attributes of the scene with minimal a priori knowledge about its geometry. Finally, the experimental results show the effectiveness of the proposed method.

A new method to obtain a continuous and fast measurement of light intensity is presented. It is targeted for Integrate and Fire pixels that pulse with a frequency proportional to illumination. The procedure is intended to speed up the pixel readout of low illuminated pixels. It does not require synchronisation of different digital signals, being compatible with continuous pixel operation. The fundamentals of this method are described. Experimental results validating the theory are provided.

A multi-scale simple linear iterative clustering (SLIC)-based depth up-sampling method is proposed in order to obtain high-quality depth maps, especially in the case of high up-sampling rate. The proposed method is implemented hierarchically, where the high-resolution image is segmented from coarse to fine by using multi-scale SLIC superpixels. A depth guided discriminant function is defined to distinguish the validity of the segmented superpixels, and only the valid ones will be interpolated each layer. The experimental results show that the proposed method solves the depth missing and the depth confusion problems largely.

A shared-information double stream hourglass network architecture for camera localisation is proposed. The contributions are two folds, first, the ordinary single stream decoder is replaced by double streams for regressing location and orientation of camera separately, and the information is shared at the end. Secondly, uncertainty estimation of loss to balance the error of location and orientation is used. The experimental results show that the proposed method achieves better performance compared with state-of-the-art methods.

An improved exploiting modification direction-based image steganography technique has been proposed. The cover image is decomposed into non-overlapping units of n pixels each to embed 2 ^kn -ary numbers in row major order. Here, k is the number of bits to be embedded in each pixel. Therefore, the number of bits the message sender wants to embed is not restricted by this method. The dynamic nature of the weightage array makes the process pseudo-random by producing a different key for different message images. Experimental results ensure higher payload and reduced quality distortion of stego-images over existing schemes.

Currently, a raw light field image can be captured by a light field camera and decomposed into multi-views with different perceptual quality. A novel light field compression approach for a light field image is proposed based on this observation, where the raw light field image is decomposed into multi-views as pseudo-sequencing frames and reordered according to their perceptual quality. The resulting pseudo-temporal sequence is then compressed by high-efficiency video coding (HEVC) encoder. Experimental results show that the proposed method can achieve a better coding performance (up to 28% Bjontegaard delta bit rate reduction (BDBR) savings) compared with state-of-the-art reordering techniques using HEVC.

A multi-scale document image rectification method based on text-features is presented. In contrast to most used text-lines, the text-features are more robust to depict the distortions of document images with multi-column layouts, multi-type fonts or non-textural objects. Then, the rectification problem is formulated utilising a reverse strategy according to the text-features. The experiments have demonstrated the flexibility and high performance of the approach.

The role of approximation coefficients (ACs) in blind image deconvolution (BID) is examined by restoring each sub-band image individually in the wavelet domain, and excellent performance is achieved by an average strategy for the estimation of AC. The most important observation is that accurate deconvolution of AC is not necessary and some form of hybrid can reach a balance between sharpness and contrast. This finding leads to reappraising the common treatment of wavelet coefficients in deconvolution, which takes the coefficients in every sub-band as a unity. It is argued that the AC of the blurred image can be regarded as a good approximation of the ‘true’ image with lower resolution. Wavelet transform of one level is preferred in the implementation and the difference between the method and common multiscale approach is stressed. With specific treatment of AC, the proposed method can be combined with many other BID algorithms to improve deconvolution performance.

In this Letter, a novel approach for spatial modulation is presented. The main idea of the proposed approach is to change the active antenna at the middle of the symbol duration. The main advantages of the proposed approach are the improved BER performance and the saving in the number of required transmitter antennas, compared to traditional spatial modulation, generalised spatial modulation, and variable generalised spatial modulation at certain spectral efficiency. The BER performance enhancement of the proposed algorithm is affirmed by Monte-Carlo simulations.

Device-to-device communication in 5G networks will require fast and efficient neighbour discovery. This Letter shows that with an initial knowledge of proximity, devices can increase discovery probability. However, in out-of-coverage scenarios, devices do not have information about neighbourhood which decreases the discovery probability. Hence, this Letter proposes an algorithm that enables neighbourhood-awareness in out-of-coverage environments, and increases discovery probability.

A compact balanced-to-unbalanced (BTUB) filtering power divider (FPD) to simultaneously realise the functions of power dividing, bandpass response, a BTUB transformer with high common-mode suppression and good isolation between two output ports is proposed. This component is constructed by two half-wavelength resonators and the special designed feeding-line structure. For verification, an FPD working at 2.39 GHz is fabricated and measured. The measured results show good agreement with the simulation.

A miniaturised low-profile frequency selective surface structure (FSSs) with highly angular stability is proposed in this Letter. Due to the strong coupling introduced by the thin dielectric, the designed FSS has a miniaturised unit size of 0.28λ, which can be applied to millimetre-wave communication. To better analyse the structure performance, the equivalent circuit model (ECM) is proposed. Moreover, the prototype with the centre working frequency of 30 GHz is fabricated and measured to verify the design. The insertion loss is demonstrated <0.12 dB with a bandwidth of 2.5 GHz under the normal incident wave. While the incident angle changes to 60°, it is <1.96 dB. In addition, the transmission zeroes remain at 36.4 GHz, when the incident angle varies from 0° to 60°, which result in a stable stopband following the passband. Particularly, the passband and stopband are controlled by two coupling capacitors, so the passband and stopband can be adjusted independently by changing the different parts of the structure. Finally, the results obtained by the ECM, simulation, and measurement have a good agreement, which demonstrates that the proposed FSS design is a good candidate for millimetre-wave communication.

A novel double-layer suspended stripline (DSSL) resonator with high unloaded quality factor is proposed. The DSSL resonator consists of a thin substrate with metal strips on both sides connected by a metallic via hole suspended in the centre of an air-filled cavity, which leads to a much higher unloaded quality factor than the conventional single-layer suspended stripline resonator with an identical resonant frequency. The resonance characteristics of the DSSL resonator are parametric analysed. For demonstration, a compact diplexer for base-station application with channel centre frequencies at 1.95 and 2.14 GHz and absolute bandwidths of 60 MHz is designed, fabricated and measured. The synthesised, simulated and measured results show a good agreement.

A simple process to improve the quality factor of metal–insulator–silicon (MIS) capacitors is introduced. Typically, MIS capacitors show a low quality factor in the gigahertz range because the lower electrode is silicon, which has low conductivity. The electrical conductivity of the lower electrode of the MIS capacitor is improved by the application of side metal coating through a simple process. To make the side metal of the MIS capacitor, a 200 µm-deep trench is formed between each capacitor using a sawing machine, and then the top electrode and side metal coating are added at the same time. Since scribing is performed prior to realisation of the top electrode, no additional dicing process is required. The quality factor of the proposed capacitor is improved from 73.8 to 101.3 at 2 GHz just by the addition of the side metal electrode.

An analogue phase shifter with a constant low insertion loss (IL) and compact size is proposed. It consists of two quarter wavelength transmission lines and three tunable reflective loads. The theoretical analysis to maximise the relative phase shift, reduce the IL and the IL variation of the phase shifter is presented explicitly, which provides performance estimation and design guidance for this class phase shifter. A circuit with a size of 0.12λ _g × 0.21λ _g is designed and fabricated to verify the theory. The simulated and measured results are in good agreement. The measurement shows that the relative phase shift of the proposed phase shifter is 186° at 1.97 GHz. The average IL is 0.79 dB with a very small IL variation which is just 0.02 dB.

In this Letter, the authors present a new analytical method for determining the parameter values for the single-diode model of photovoltaic (PV) panels. More specifically, the authors propose explicit equations for all the parameters of the model so that their values can be directly extracted from the data provided in the PV panel datasheet. The results show that the proposed method provides smaller errors between the calculated and experimental I–V curves than other analytical approaches.

Electric spring (ES) along with the smart load (SL) have recently been used as a smart technology for stabilising distribution networks. ESs are embedded on non-critical (NC) loads in order to protect critical loads against voltage fluctuations. Three different generations of ES have been developed in recent years. A comprehensive control scheme is proposed for the third generation of ES, through which the SL power factor and line voltage can be controlled. In order to control the power factor in steady-state condition, the radial-chordal decomposition (RCD) method, which has been previously used for the second generation, is employed in the closed-loop manner. The proposed controller has also the capability to mitigate the voltage fluctuation in over/under voltage condition. Simulation results show the superiority of this method in voltage control over RCD method. In addition, for a bunch of NC loads, the desired power factor will be reached at the point of common coupling.

Characteristics of a target are essential for the classification purpose. Input parameters such as blade length, rotation rate and a number of rotors can be used for classification of drone. An algorithm for accurate measurement of blade length and rotation rate using pattern analysis has been proposed. The time–frequency domain image is used for calculation of maximum Doppler frequency and the rotational speed of the blade. Accuracy and precision of the proposed technique are validated by experimental data using W-band radar system.

The target localisation problem is considered by the use of hybrid bistatic range (BR) and time difference of arrival (TDOA) measurements in multistatic localisation system. The BR and TDOA define an ellipse and a hyperbola, respectively, and the target resides on the intersections of several such quadratic curves. An efficient closed-form solution to this non-linear estimation problem is developed by employing two-step weighted least squares minimisations. Simulation results show that the proposed method can reach the Cramer–Rao lower bound accuracy for small Gaussian measurement noise. A real experiment is presented to validate the performance of the proposed estimator in an acoustic array system.

The polarisation smoothing generalised multiple signal classification (MUSIC) algorithm for low angle estimation with polarisation sensitive array (PSA) monostatic multiple-input multiple-output (MIMO) radar is proposed. The proposed method takes advantage of the virtual aperture of the MIMO radar and the polarisation diversity of the PSA simultaneously to improve the resolution, which has better performance than generalised MUSIC algorithm when the direct and the reflected signals are out of phase. Simulation results are presented to verify the effectiveness of the proposed method.

A new utility function-based framework is proposed for network selection that utilises exponential functions and is monotonically related to a function of the average of additive and multiplicative utility functions. This means that an intermediate solution has been identified that not only includes inter-dependencies of performance criteria but also reduces the network elimination. Numerical results compare the performance of the existing and proposed utility functions and it can be seen that the proposed utility function is a good choice for network selection.

A complementary passive mixer with feedback followed gate bias generation scheme is proposed. The gate voltage of the switches follows the common-mode voltage (V _CM) of the signal paths, so that the proposed mixer achieves constant switching gate-to-source bias voltage and coherent performances while V _CM changes over a certain range. Furthermore, a dc offset cancelation method based on the bias generation circuit is proposed. The dc component of the intermediate frequency is feedbacked to the bias generation input to form a cancelation path. A behavioural model is deduced to prove the effect of the offset cancelation and second intercept point (IIP2) improvement. The proposed mixer is implemented in a 0.13 μm CMOS process, and measurement results show that robust performance with the V _CM range of 0.5–0.7 V and 16 dB IIP2 improvement are obtained.

The sparse code multiple access (SCMA) systems rely on multiuser detection schemes to achieve high spectral efficiency and massive connectivity. The existing multiuser detection schemes employ a message passing algorithm (MPA) to achieve the goal by utilising the sparse structure of the SCMA codebook. However, it remains a challenging task to obtain a good trade-off between the BER performance and computational complexity due to the iterative nature and the associated search space in the MPA detection. In this Letter, a novel MPA detection scheme based on selective message passing is proposed. By dynamically eliminating the branches with high reliability from the message passing process, the proposed scheme significantly reduces the computational complexity with negligible BER performance compared with the conventional MPA detection. Simulation results show that the proposed scheme is able to achieve a good trade-off between the BER performance and computational complexity, especially at moderate and high signal–to-noise ratio conditions.

Device-to-device (D2D) communication is a proximity-based data transmission technique where users communicate directly with each other, when bypassing evolved node base station. The most common assumption in the literature is that every D2D user connects to its nearest node. However, in many situations connection to the first nearest node for a D2D user is not possible due to the channel conditions or user's decline in joining in a D2D connection. The impact of connecting to the nth nearest node in a dedicated D2D enabled network is investigated. The coverage probability and average data rate of a typical D2D link in the network, where users connect to their nth nearest node are studied. The results show that considering the first nearest node is an ideal assumption and investigating the connection to the other farther nodes is of great importance.