A configurable antenna breadboard is here proposed for fast prototyping of radiofrequency identification sensing devices for application to the Industrial Internet of Things. The proposed layout is modular, includes both radiating, tuning and expansion traces and can be considered as a multi-port antenna system suitable to network-oriented design. Depending on the ports’ status, the board may be used in standalone configuration as well as electromagnetically coupled to an external booster for improved read-range performance over metals and high-dielectric objects.

A direction-finding technique based on time-modulated arrays (TMAs) is presented. Signals radiated/received by the TMAs with moving phase centre suffer from the Doppler effect and the shifted frequency is direction-dependent. This interesting property allows TMAs to be used for direction finding. A radar bearing system using the TMA is proposed. Performance of the new direction-finding technique is discussed and compared with conventional techniques. Numerical results show that this method is effective and provides reconfigurable angle-searching range and bearing accuracy. It is proved to be a flexible bearing method qualified for different detection requirements just by changing the time schemes of the TMAs.

A multiband cylindrical dielectric resonator antenna (CDRA) is reported in this Letter. Three unique features of proposed radiator are (i) modified feeding mechanism behaves both as magnetic and electric dipole (horizontal and vertical placed) and generates five different radiating modes (HEM_11δ, TM_01δ, HEM_12δ-like, HEM_12δ and HEM_11δ+1) in CDRA simultaneously, (ii) different radiating modes provide diversified radiation pattern at different frequency bands and (iii) multiband characteristics makes the proposed radiator appropriate for WLAN (5.2/5.8 GHz) and WiMAX (2.5/3.3/5.5 GHz) applications.

A new designed single-fed broadband circularly polarised dipole antenna with simple structure is presented. The antenna is composed of a horizontal electric dipole and an equivalent magnetic dipole realised by two vertical patches quarter-wave shorted at the bottom. The electric dipole and equivalent magnetic dipole are positioned along the same axis to excite the orthogonal radiation fields with the same amplitude and 90° phase difference for circular polarisation. A broad impedance bandwidth of 69% (|S ₁₁| < −10 dB) from 1.6 to 3.2 GHz is achieved, which covers the whole 3 dB axial ratio bandwidth of 42.7% from 2.0 to 3.1 GHz. In this operation frequency band, the measured gain is above 6.4 dBi and the peak value is 8.4 dBi.

A novel transconductor based on the source degeneration technique is introduced. The proposed solution includes self-cascode transistors as input devices, additionally employing their bulk terminal to increase the linearity. Input transconductance characteristics are improved as compared with conventional topologies without considerably increasing power consumption and die area. The circuit was designed and fabricated in a standard 0.18 μm CMOS technology to operate with a 1.8 V single supply voltage. Experimental results showed a linearity improvement of 20 dB for an input signal of 0.2 V at 100 kHz.

A novel method for designing and realising compact digital circuits by engineering MOSFET gate electrode is proposed. The novelty is the use of gate engineered single devices in the pull-up (PU) and pull-down (PD) paths of a static CMOS gate instead of multiple transistors as used in conventional CMOS implementations of circuits. Herein, two input NAND, NOR, and exclusive-OR (XOR) gates employing the proposed gate engineering concept are designed and simulated. Engineered gate N-type MOS and P-type MOS are used for PD and pull-up circuits, respectively. Since only two devices are used for a complete circuit: one in PU network and other in PD network; therefore, area and power of the proposed circuits get reduced significantly in comparison with the conventional static CMOS circuits. Mixed mode simulations have shown that the proposed technique realises NAND, NOR and XOR operations perfectly and it can be extended to realise other combinational and sequential circuits easily.

The orthogonal Jacobi polynomials are not suitable for use as the characteristic function in the continuous- and discrete-time filter design, because they are not fulfilling the basic condition: to be pure odd or pure even. A simple modification of Jacobi polynomials, is performed to obtain a new filter approximating function is proposed. Magnitude frequency responses of obtained filters exhibit more general behaviour compared with that of classical Gegenbauer (ultraspherical) filters, due to one additional parameter available in the Jacobi polynomials. This parameter can be used to obtain magnitude response with either smaller passband ripple values (nearly monotonic behaviour), smaller group delay variations or sharper cutoff slope. The proposed modified Jacobi polynomials are not orthogonal, however, many known orthogonal polynomials can be obtained as theirs special cases.

It is usually considered that the resonance frequency of quartz crystal resonator is only related to dynamic inductance L ₁ and dynamic capacitance C ₁, and load resonance frequency has connection with L ₁, C ₁ and static capacitance C ₀. Hence, the dynamic resistance cannot be measured by frequency. The deduction show that all the frequencies relates to L ₁, C ₁, C ₀ and dynamic resistance R ₁. Then, a method for measuring the total equivalent parameters of quartz crystal resonator based on zero phase frequency is proposed in this Letter. The simulation results of advanced design system (ADS) verify the validity of this proposal in theory. After that, the phase-frequency-curves of a quartz crystal resonator with 10 and 5 MHz are measured, which can obtain equivalent parameters of through data processing. The results show that this method has calculated parameters essentially in agreement with nominal parameters. This method does not have reciprocating debugging process, and the test process is simple as well. In addition, the approximate calculation is not used in this method, and it could be widely extent to the field of sensors, such as quartz crystal microbalance sensors, temperature sensors and so on.

Three kinds of parameters are considered to speed up the read operation of phase change memory: bit line parasitic parameters, read transmission gate parasitic parameters and current mirror parasitic parameters. A set reference cell and a reset reference cell are used in the reference circuit. Simulated in 130 nm process, the read access time of 1-Mb phase change memory (PCM) is 6.7 ns. In Monte Carlo simulations, the worst read access time is 13.8 ns compared to conventional 85 ns.

A robust Kalman filter is proposed for time-varying discrete-time linear systems with uncertainties in state, input noise, and measurement matrices. The filter is obtained by solving an optimisation problem such that the upper bound on the variance of estimation error to be minimised for all admissible uncertainties. A numerical example is presented to show the performance of the proposed robust filter.

A demagnetisation fault detection method for a delta-connected permanent magnet synchronous machine (PMSM) based on zero sequence current components (ZSCC) is proposed. The model of the delta-connected PMSM with the demagnetisation fault is first established. Then the expression of the ZSCC is presented for the delta-connected PMSM, and an equivalent fault severity index which can quantify the demagnetisation degree is obtained, being not limited by the partial or uniform demagnetisation. Finally, the simulation results show that the potential of the proposed fault severity index for the demagnetisation fault detection.

A fast algorithm is derived for the compressive bilateral filter (CBF) by representing the bilateral filter in a new way. This representation allows us to use the property of the Gaussian function to reduce the number of Gaussian filters required by the CBF by a factor of 2. Producing the same results as that of the CBF, the fast algorithm runs about two times faster than the CBF.

Deep packet inspection in modern networking and security devices use ternary content addressable memory (TCAM) to match regular expressions. TCAM has its advantage in search speed but disadvantages in limited storage and high power consumption. The hierarchical encoding algorithm to save TCAM space is proposed and the codes divided into four layers. The proposal and the results are tested showing that the new algorithm has higher compression efficiency and the compression rate can reach 95–99%.

Possibilistic c-means (PCM) was proposed to overcome the problem of the noise sensitivity of fuzzy c-means, but its performance highly depends on the initialisation of cluster centres and often is degraded due to producing coincident clusters or close centres. To tackle these defects of PCM, a divide-conquer method which not only provides appropriate cluster centres but also yields pre-clustered and un-clustered data information which are used to overcome the coincident or close clustering problem is presented. Experiment results on a simulated magnetic resonance brain image data corrupted by noise and bias-field shows that the proposed method has a better clustering performance than conventional PCM clustering methods.

We propose optimised group quantisation (OGQ) for approximate nearest neighbour (ANN) search. Specifically, we construct a group of codebooks and select a group of codewords from the codebooks to approximate the original data such that small quantisation error is obtained. We also propose an effective learning algorithm for optimisation. The experiments show that OGQ can significantly outperform several state-of-the-art ANN methods.

A novel distributed cooperative caching algorithm in backhaul-limited small cell networks is proposed. Neighbouring small cell base stations (SBSs) cooperate to optimise caching decisions so as to minimise users’ downloading delay. Besides wireless channel statistics, the limited backhaul capacities of SBSs are incorporated. The problem is NP-complete. A simple yet effective algorithm to reach a local optimal by virtue of potential game theory is developed. Simulations and analysis reveal improved delay performance and reduced complexity for the proposed algorithm compared with available schemes.

Low-complexity precoding design without iteration for multiple-input multiple-output channels with finite alphabet input is studied. Contrast to the iterative gradient method for finding the globally optimal precoder, which is time-consuming and computationally complicated, this work studies low-complexity precoding design with high performance. The problem of optimising the mutual information is identical to maximising the minimum Euclidean distance of the input vector at high total power. Hence, the precoding design can be formulated as semi-definite programming problem and thus can be optimally solved. Numerical examples show that the proposed scheme achieves good tradeoff between the computational complexity and high performance compared with the conventional counterparts.

A new design of planar bilayer ultra-wideband (UWB) crossover is presented. The structure is composed of double slot coupled transitions and a microstrip transmission line to provide a better isolation between the cross-lines. A good agreement between simulation results and measurements has been achieved. Experimental results show excellent impedance matching of more than 15 dB at the all four ports. A good isolation and insertion loss between the two signal paths of the crossover with more than 25 and 1.3 dB, respectively, over the entire UWB band is observed.

A novel differential-mode (DM) bandpass filter (BPF) on microstrip-line topology with wideband common-mode (CM) suppression is presented. The DM BPF is composed of a pair of half-wavelength (λ/2) uniform impedance resonators and two coupled-line sections as feeding scheme. By installing an open-circuited stub in the middle of the coupled-line section, spurious CM response can be tremendously suppressed over a wide band. Thus, wideband CM suppression is realised in and beyond core DM passband. Finally, a DM BPF is designed and fabricated to support the proposed design concept.

An on-line passive intermodulation test method for conductive coating is presented. A split-type rectangular coaxial line is working as test fixture. As the standing wave of this test fixture can stay small in the replacement of coating samples, passive intermodulation test can always continue. By using this test method, several coatings are rapidly distinguished from their different passive intermodulation performance. A fast passive intermodulation test method for coatings is demonstrated.

Gap waveguide is a promising alternative to traditional waveguide. One of the most important advantages of gap waveguide is that electrical contact between its subcomponents is not necessary. Therefore, it is flexible to adjust its performance by replacing part components of it without the need of reassembling the entire circuit. A slot coupled narrow-wall rectangular waveguide coupler with adjustable coupling coefficient is presented. Coupling slots with different inclined angles are realised in the replaceable narrow-wall coupling plate. By changing the coupling plate, the coupling coefficient can be adjusted flexibly. Corrugated edges are loaded on both sides of the replaceable plate to eliminate resonance maybe excited between the fixed metal plate and replaceable plate. A Ka-band prototype working at the frequency band from 30 to 40 GHz is successfully designed, manufactured and tested. Two replaceable coupling plates with coupling slots inclined of 15° and 45° are manufactured. The measured average coupling coefficient is, respectively, 18.5 and 9 dB. The measured return loss is >17 dB from 30 to 36.5 GHz and >12 dB from 36.5 to 40 GHz. The simulated and measured results agree well.

At power turn-on in electronic equipments, a large current peak is observed due to large capacitance in the circuit. This current peak can be avoided by inserting negative temperature coefficient (NTC) thermistors. A new design of high-reliability, lowcost NTC thermistors is tried. Parallel connection of the thermistors is investigated, where the thermistors were thermally connected by ceramic package. It is shown that the thermal connection between the thermistors plays an important role in current distribution.

Timing measurements with silicon photomultipliers (SiPMs) are affected by the major issue of the so-called time-walk effect; this is due to the intrinsic architecture of SiPM devices. A new technique for time-walk compensation in timing measurements with SiPMs is presented and discussed, feasible with a low-complexity and low-cost circuitry and able to improve the timing accuracy. The validity of the presented technique has been experimentally proven with a 3 × 3 mm² Hamamatsu MPPC, achieving a jitter reduction of a factor 2.85 compared with the case without time-walk compensation. To perform the experimental validation, a discrete-components transimpedance amplifier is developed with large bandwidth and low jitter, specifically designed to read-out and amplify the SiPM signal.

Grown by metalorganic vapour phase epitaxy (MOVPE) In _x Ga_1−x As metamorphic laser power converters have been considered. Metamorphic buffer designs with high quality top layers have been developed. Photovoltaic converters with In_0.24Ga_0.76As photoactive area and optimised buffer have demonstrated efficiency 41.4% for 1064 nm monochromatic radiation conversion and ∼40% for laser power conversion.

It is shown that data from frequency sweeps of photodiode (PD) second-order intermodulation distortion products, parameterised on the applied bias voltage and average photocurrent, enables optimisation of the in situ PD's non-linear performance by adaptively changing the bias voltage in response to system changes in optical input power and required system bandwidth.

A high voltage ratio DC–DC converter is proposed which is comprised of four stages. First, an impedance network along with a switching network have been used to boost the input voltage. The boosted voltage waveform is then followed by an isolation transformer to provide another degree of freedom and obtain higher boost ability. Finally, a voltage multiplier rectifier is utilised to rectify the secondary voltage of the transformer. No switching dead-time is required, which increases the reliability of the converter. The proposed converter benefits from the continuous input current. Besides, a comparison with the existing step-up topologies indicates that the number of passive elements and hence the weight and size have been reduced. The operating principles were analysed and the experimental tests on a 260 W prototype reveal that a high efficiency above 91% can be achieved.

Properties of powder core based inductors when utilised in a passive filter of the voltage source inverter are investigated to highlight the importance of considering the soft-saturation nature of powder materials in determining the inductance when subjected to varying load current. Simulations were carried out in ANSYS Maxwell and Simplorer to understand the magnetic behaviour of inductors under pulse width modulation in a three-phase inverter. Variation of the effective inductance due to soft saturation nature of the powder cores is utilised to achieve the inductance demanded by the passive filter at the design stage.

A new non-intrusive ac voltage measurement technique based on stray electric filed energy harvesting is presented whereby the voltage of ac power lines can be measured without removing insulation and therefore without direct contact with conductors of the power lines. The energy of electric field around the power lines is picked up and stored in a capacitor by a wire wound around insulated 3-wire household power lines or by a conductor plate placed in the vicinity of overhead high-voltage power lines. Autonomous switches are used to monitor the stored electric field energy in a storage capacitor and to generate pulse train. Experimental results show that the repetition rate of the output pulse is a linear function of the line voltage. Since the voltage of insulated 3-wire household power line can be measured without removing insulation and the voltage of high-voltage power transmission line can be measured without any contact to the conductor of the power line, the proposed technique can be widely applied to smart grid system.

Energy independence is a wireless device quality that demands the utmost exigency. Energy harvesting devices (EHD) alleviate the energy constraints demanded by these nodes and with the use of protocols, such as variable slot time-time division multiple access (VST-TDMA) energy self-sustainability can be attained at the cost of throughput. To allow high throughput levels and self-sustainability the system can allow the power consumption to be greater than the energy harvesting rate while a state-of-charge (SoC) of 30% or greater is maintained. To achieve this the system must accurately estimate the SoC, which is not a trivial task. In this work, a battery model is incorporated into the VST-TDMA protocol to estimate the battery model parameters, including the SoC, which successfully allows it to maintain appropriate SoC levels.

A new three-level neutral-point-clamped quasi-Z-source inverter topology is proposed. The topology can effectively reduce the Z-source network capacitor voltage stress and inhibit the start inrush current, thus low-voltage capacitors can be selected to reduce the volume and cost of the inverter. In addition, the changed structure will not affect the boost ability and all existing modulation methods can be used directly. The proposed topology is validated by simulations.

A coding diffusion metasurface is designed and fabricated for ultra-wideband radar cross-section (RCS) reduction. Two kinds of unit cells based on square ring patch are employed to generate the ‘0’ and ‘1’ elements of the coding metasurface. By precise design of the unit cells, a 180° ± 37° reflection phase difference between these cells is achieved over 8.01–22.76 GHz, leading to dramatically reduce the scattering field level by more than 10 dB. To obtain the diffusion far-field pattern of the metasurface, the optimisation algorithm is utilised to calculate the optimal layout of the digital elements. Both full-wave simulation and measurement results verify the capability of the proposed metasurface.

A multi-layered graded porous airborne nose-cone radome design for radar antenna system with surveillance and tracking capabilities at X and K bands, respectively, is presented. The radome wall structure has five layers and is symmetrically constructed with the dielectric constant increasing gradually from the outer layer to the middle layer on either side. The inner layers are made up of silicon nitride with varying porosity for attaining variable dielectric parameters, whereas the outermost layers are composed of quartz lamination for better impedance matching. The analysis shows that the proposed radome design gives excellent EM performance characteristics in the EM window regions at both X and K bands. The novel dual-band radome design presented has potential application in airborne radar antenna system incorporating both surveillance and tracking capabilities.

Micro-motion indication of human target is widely used in civil and military applications. In through-the-wall (TTW) scenarios, human echo is usually heavily blurred by clutter. This Letter proposes a sparse and low-rank matrix decomposition based micro-motion indication method to indicate human targets using UWB TTW radar. The slow-time range matrix is decomposed into a low-rank matrix corresponding to background echo, and a sparse matrix corresponding to micro-motion echo. Both simulation and experimental results show the superiority of the proposed method.

Millimetre wave imaging systems are widely used in many fields, such as non-destructive testing, security screening and medical imaging. For security-related personnel screening, the geometries of planar and cylindrical-scanning antenna arrays are often adopted. A planar array imager is capable of acquiring a three-dimensional image in real time, but the information on the back side of the object will be lost. A cylindrical scanning imager is well suited for constructing an image in full 360° directions, what is lost is the time that it takes to complete a full scan. Regardless, mechanical scanning geometry is not always the best approach for real-time systems. In this letter, an imaging scenario is proposed, which is composed of two parallel arrays facing each other. Multiple input multiple output technology is applied to the pair of arrays. Range migration algorithm is adapted specially for this scenario, through which nearly 360°-images of high quality can be constructed in real time when an object is placed between the two arrays.

A 260-GHz amplifier in a SiGe heterojunction bipolar transistor (HBT) technology is reported. It is based on three-stage differential cascode topology and adopts a passive shunt transistor pair at the output of each amplifying stage to relax instability caused by parasitic base inductance of amplifying transistor pair. The instability of the amplifier can be mitigated by tuning the base bias voltage of the shunt transistor pair. Peak gain of the amplifier was measured as 15 dB at 260 GHz. DC power dissipation is 112 mW. The chip occupies 300 × 160 μm² excluding Baluns and probing pads.

In p-GaN gate AlGaN/GaN power devices, turn-off energy loss (E _off) variations in die-level uniformity are observed because of the thickness variations of remained p-GaN in the ungated region. These E _off variations can be reduced by negative turn-off gate voltages. However, this method can induce new burden in circuit design because of the negative voltages. Therefore, we focus on fabrication processes such as Mg doping in p-GaN gate. Using low Mg doping in p-GaN gate, E _off variations mostly disappear, but threshold voltage (V _th) is approximately 0.3 V decreases. In addition, dynamic on-resistance (dynamic R _ds,on) is slightly increased.

A normally-off AlGaN/GaN-on-Si metal–oxide–semiconductor-heterojunction field-effect transistor (MOS-HFET) with an integrated single-stage inverter is developed. The integrated single-stage GaN inverter consisted of an AlGaN/GaN driver MOS-HFET and a resistive load. With the monolithically integrated gate driver, the gate charging current was boosted from 10 to 170 mA, which reduced the charging and discharging times from 626 to 107 ns and 553 to 196 ns, respectively.

A novel model of grid cells (GCs) to place cells (PCs) based on radial basis function network (RBFN) is proposed. The connection between multi-scale GCs and a PC is established through RBFN. For each PC, it is associated with a learned RBFN. During vehicle's space exploration, PCs and RBFNs are recruited flexibly after analysing the firing status of the existing PCs, and the transformation from GCs to a new PCs is learned for encoding a new location. As a result, PCs are generated incrementally to represent the explored space. Simulation results validate the proposed model is effective, and the firing characteristic of generated PCs is similar to that of biological PCs.

A novel CMOS bipolar Gaussian monocycle pulse generator consisting of single to differential circuit, narrow pulse generator and Gaussian pulse-shaping circuit is presented. Without traditional LC filtering or multi-channel pulses combination, the proposed generator can be low power and low complexity. Fabricated in a 180 nm standard CMOS process, the test results show that the bipolar Gaussian monocycle pulse can be generated correctly, the power consumption is 1 mW at 200 MHz pulse repeating frequency and the chip core area is only 0.08 mm²under the power supply of 1.8 V, demonstrating the proposed generator with the advantages of low power and low complexity is suitable for implantable IR-UWB transmitter.

As the exponential growth of traffic patterns with very different characteristics is becoming increasingly common, the high demand for a wide range of services has attracted much attention, e.g. low-priority (LP) service. To satisfy the requirements of LP service for satellite networks, a LP data transfer protocol called satellite networks (SatLTP) with the adaptation to satellite channels and taking advantage of extra bandwidth without interfering high priority flows is proposed. In order to use extra bandwidth adaptable, SatLTP achieves precise adjustment of the congestion window by dynamically updating indicative parameters and selecting optimal window control policies. Simulation results over satellite networks show that SatLTP enhances the throughput of satellite channels in terms of being friendly and non-intrusive toward other protocols (e.g. TCP) and able to effectively exploit the available resources over satellite networks.