A novel dual-loop near-field antenna for reliably writing or verifying information on loop-type UHF radio-frequency identification (RFID) labels bonded to a roll is presented. A resistor and inductor-loaded dual-loop is fed by specially designed coaxial feeding structure. The proposed antenna can reliably write or read information on a label just above its aperture while discriminating labels laterally offset from its aperture by 20 mm.

Since the use of pseudo-resistors became popular in of bio-amplifiers research, several works have been published, but a lack of knowledge about accurate experimental characterisation and simulation of these non-linear devices remains. An innovative experimental procedure concerning the characterisation of pseudo-resistors is presented. The proposed experimental procedure proves the existence of a linear operation region, where the device can operate like a very high resistance, which is mainly applied on bio-amplifier designs. The main experimental results of the electrical characterisation of pseudo-resistors are described in detail and compared with the SPICE results. The pseudo-resistor experimental curve response including the non-linear operation region is presented. Finally, a new non-linear polynomial resistor model to use in SPICE simulator, replacing with success the electrical representation model based on transistors models is proposed. The presented simulations were performed with Mentor Graphics Eldo^TM SPICE simulator, using BSIM3V3.1 and PSP103.1 models. The MOSIS Educational Program fabricated the samples used in this work.

A fuzzy static RAM (SRAM) is proposed, which is applicable in fuzzy logic and many multiple-valued logic (MVL) applications. The new structure is basically an extension to the binary SRAM cell. Two cross-coupled voltage mirror circuits are used to be able to hold an arbitrary voltage value. The proposed design forms a robust and reliable structure, which is capable of operating with more than 95% accuracy in spite of imperfect fabrication of carbon nanotube FETs. Another exceptional advantage is its ultra-low-power consumption in MVL environments. It consumes 38.7 and 99% less static power compared with the SRAMs with regular ternary and quaternary components, respectively.

A coarse-fine dual-loop digital low dropout regulator (DLDO) having a binary weighed transistor array in the coarse loop and a 1-bit ΔΣ modulator in the fine loop is proposed. Compared with the conventional DLDO, the proposed architecture significantly reduces hardware complexity and alleviates matching requirement, enabling a robust DLDO design for low-voltage phase-locked loops. The proposed DLDO designed in 65 nm CMOS generates a noise-shaped output voltage whose peak value is <1 mV with the load current ranging from 100 μA to 6 mA.

A hardware-efficient four-level pulse amplitude modulation (PAM-4) clock and data recovery (CDR) circuit for high speed serial links is proposed, following a sign-sign minimum mean square error (SS-MMSE) algorithm. Using a specially designed continuous-sampling slope detector and a dual-stage digital filter, the proposed SS-MMSE CDR can align the clock phase well with the maximum vertical eye opening, as opposed to the conventional Bang-Bang CDR which only finds the midpoint of a symbol, yet requiring extra clock phases or running at higher frequency. Simulation results confirm superior performance and implementation efficiency of this proposed SS-MMSE PAM-4 CDR over the Bang-Bang design.

A modified least-squares algorithm with forgetting factor is proposed and applied to linear time-varying systems. The bound on the Euclidean norm of the estimation error is derived mathematically. When the bounded regressor of the linear time-varying system satisfies persistent excitation condition, this new algorithm can attenuate the influences of bounded disturbances and the change ratio of time-varying parameters effectively through extra term that is added to the covariance's update law. Contrary to the earlier proposed estimation laws, this algorithm does not require any prior knowledge of upper bounds on the parameters and the disturbances. Simulation results demonstrate the effectiveness of the identification law.

A 6–18 GHz gallium nitride (GaN) non-uniform distributed amplifier (NDA) monolithic microwave integrated circuit with high power density is implemented with compact four-way combined power. The drain lines and gate lines are shared among the combined NDAs. Sharing drain (or gate) lines reduces the drain (or gate) line length by half, while keeping the same characteristic impedances and eliminates bulky and lossy power combiners, such as Wilkinson combiners. The proposed four-way NDA was fabricated using a commercial 0.25 μm GaN high electron mobility transistor (HEMT) process. It shows average continuous wave output power of 20.8 W and average associated gain of 10.7 dB from 6 to 18 GHz under 33 V drain bias. When pulsed input power and pulsed DC bias are simultaneously supplied to the NDA, the output power increases to 26 W, on average. To the best of the authors’ knowledge, the highest RF power and power density among the reported GaN power amplifiers with an octave bandwidth higher than the Ku-band is represented in this work.

Contactless waveguide flange is a novel structure to prevent leakage of electromagnetic wave when it propagates across the waveguide flange. The main advantage of contactless waveguide flange is electrical contact of the connected waveguides is not required as long as the gap between the adjacent flanges does not exceed the maximum permitted distance. Therefore, relative motivation or rotation of the contactless connected waveguides is possible. The contactless waveguide flanges have been reported are all planar. A cylindrical contactless flange is first proposed. Then, a novel flexible rectangular waveguide is proposed based on it. A Ka-band prototype is successfully designed and manufactured. The prototype consists of two bendable contactless flange joints. The maximum bending angle of each joint is limited to ±8° to maintain the return loss performance. The number of joints can be easily increased if larger bending angles are needed. The insertion loss and return loss at different bending angles are measured. The measured insertion loss is better than 0.7 dB from 26 to 37 GHz, and is better than 1.8 dB from 37 to 40 GHz. The measured return loss is 15 dB except frequencies around 37.5 and 40 GHz.

A digital quadrature dual VDD transmitter with a switched capacitor power combiner is presented. To improve the efficiency, the cell in the transmitter is dynamically selected to minimise the voltage across the capacitors, thereby minimising the discharging loss. The chip is fabricated in 28-nm CMOS process. The implemented transmitter has a peak power of 17.2 dBm with a PAE of 37.4% at 880 MHz. The average power is 7.9 dBm with a PAE of 23.6% under ACLR of −32 dBc using a 10 MHz, 16 QAM, and 6.9 dB LTE signal.

A switchable filtering power divider (FPD) with three operating modes is presented, i.e. dual-band FPD centring at 2.1 and 2.5 GHz, low-band FPD working at 2.1 GHz, high-band FPD operating at 2.5 GHz. The bandpass filtering responses are achieved by embedding four dual-mode resonators. The simulated and measured results are in good agreement.

An UWB 90° phase shifter based on broadside coupler and T-shaped stub is proposed. Its operation mechanism is explained by the equivalent circuit. The measured results exhibit that the bandwidth is 126.7% with phase deviation within ±6°, and the insertion loss is <1.8 dB over the frequency band from 2.2 to 9.8 GHz. Comparison shows that the proposed design not only achieves the widest bandwidth, but also has low insertion loss and small phase difference. This design is a good candidate for UWB applications due to its low cost, planar structure, and convenient installation.

A high-power phosphor-converted white LED with 3058 lm is reported. The high-power white LED was manufactured by utilising a single-blue LED chip with a cerium-doped yttrium aluminium garnet phosphor crystal film, and the LED chip consists of 16 LED cells that are connected in series, the chip dimensions are of 4.5 × 4.5 mm². The electrical and optical characteristics of the LED were measured up to a 500 mA injection current under direct operation conditions. Results show that the luminous flux and luminous efficacy at 500 mA reach to 3058 lm and 128 lm/W, respectively.

A component-efficient design for parallel optical crossbar switches, which utilises the idle ports as extra input or output ports, is described for the first time. It is observed that conventional parallel crossbar switches composed of 2 × 2 basic switch elements have a significant number of unused internal routes between the idle ports. Two distinctive types of parallel crossbar switches with augmented input and output ports are introduced to yield a switch-element count of 3N ²/4 + 3N, where N is the switch size. The first type of switch is unidirectional and requires rearrangements. The second is bidirectional and strictly non-blocking and have a switch control complexity of O(1).

The transfer function of the flyback continuous conduction mode (CCM) inverter has a right-half-plane (RHP) zero that may severely degrade the control performance. If the conventional proportional–integral controller is applied, its control gain is limited by the existence of RHP zero and the inverter suffers from output current distortion. The value of the nominal duty has been used as a feedforward controller to eliminate the effect of disturbances and reduce the burden of the feedback controller. However, the conventional nominal duty performed poorly when it was utilised as a feedforward controller in flyback CCM inverter. A new nominal duty is proposed for single-stage flyback CCM inverter. Its output tracking performance is compared with that of the conventional nominal duty.

An inexpensive auto-adaptive impedance matching rectifier for wireless power transfer (WPT) systems is proposed. In most WPT systems, due to environment variations, the received power varies during the time. Owing to nonlinear characteristics of diodes, variation of received power results in impedance mismatch which degrades the efficiency of the system. The proposed rectifier system changes the matching circuit using two switches based on the level of the output voltage. This strategy provides matching in a wide range of power levels and consequently improves the efficiency of the system up to 20%. The proposed rectifier is fabricated and the output DC voltage is measured showing very good agreement with simulation result.

Series–series (SS) topology and series–parallel (SP) topology of the electric-field coupling wireless power transfer system are widely utilised for practical applications. However, selecting the appropriate circuit topology, which maximise the output power by design optimisation, is often difficult, because these circuit topologies are generally analysed using different circuit models. This difficulty by analysing novel equivalent circuits for SS and SP topologies is addressed. As a result, the output power of SP topology is found to be approximated by that in SS topology with transformed load impedance. This result can offer a simple strategy for topology selection as well as design optimisation.

The terahertz (THz) radar has obvious advantages of high-resolution imaging because it is relatively easy to achieve large signal bandwidth compared with the microwave band. A 0.33 THz imaging radar system was built and experiments on a precession warhead model are presented. The imaging algorithm based on precession is adopted and high-resolution inverse synthetic aperture radar images are obtained. From these imaging results, the structures such as the cone–top and the cone–cylinder junctions, and even the subtle structures such as rivets are clearly shown. Finally, the resolutions under different conditions are analysed to verify the advantages of THz radar in high-resolution imaging.

Moving target has a non-coherent phase characteristic regardless of micro-Doppler effect caused by body motion, because the movement of the target changes the beat-frequency and its phase. A phase compensation method to remove the phase variations caused by movement is proposed. Using the proposed phase compensation method, it is possible to classify targets as pedestrians or automobiles based on the phase variance because pedestrians and automobiles have non-coherent and coherent phases, respectively. Through applying experimental data, the possibility of target classification is shown.

Sparse learning algorithms for system identification differ from their non-sparse counterparts in their improved ability in quickly identifying the zero coefficients in a sparse system. This improvement has been achieved using the principle of zero attraction, whereby the near zero coefficients of the model are forced to zero. In order to further improve the zero attraction capability of sparse adaptive algorithms, an attempt has been made to design a polynomial sparse adaptive algorithm. The enhanced modelling ability of the proposed scheme is evident from the simulation results. The proposed method has also been successfully applied in modelling an acoustic feedback path in a behind the ear digital hearing aid.

Non-orthogonal multiple access (NOMA) is emerging as a promising multiple access technology for the fifth generation cellular networks to address the fast growing mobile data traffic. It applies superposition coding in transmitters, allowing simultaneous allocation of the same frequency resource to multiple intra-cell users. Successive interference cancellation is used at the receivers to cancel intra-cell interference. User pairing and power allocation (UPPA) is a key design aspect of NOMA. Existing UPPA algorithms are mainly based on exhaustive search method with extensive computation complexity, which can severely affect the NOMA performance. A fast proportional fairness (PF) scheduling based UPPA algorithm is proposed to address the problem. The novel idea is to form user pairs around the users with the highest PF metrics with pre-configured fixed power allocation. System-level simulation results show that the proposed algorithm is significantly faster (seven times faster for the scenario with 20 users) with a negligible throughput loss than the existing exhaustive search algorithm.

Available beyond line-of-sight time synchronisation means are mainly through satellite and optical fibres. When considering that satellite links have insurmountable bandwidth and security problems, and cable links are not feasible for mobile stations, a backup two-way time synchronisation means via troposcatter is proposed. The feasibility of the proposed method based on coherence bandwidth and transmission loss is analysed, and references for the time pulse signal design are provided. Then, two different signal time sequences schemes aiming at co-channel interference are presented and evaluated, and the clock errors due to the incomplete symmetrical two-way link are analysed. Finally, it is concluded that the proposed means is a promising candidate for beyond line-of-sight time synchronisation in emergency communication.

A new linear sparse array based on the nested array is proposed, which enjoys all the good properties of the two-level nested array, and can provide more degrees of freedom (DOF). The new array is constructed by two uniform linear arrays (ULAs) and an additional sensor. The sensor locations, the array aperture, and the achievable DOF from its difference co-array (DCA) are all benefited for closed-form expressions. Furthermore, the resulting DCA is kept as a hole-free ULA. The optimal numbers of sensors in the two ULAs provided the total number of physical sensors are derived. This new array can resolve more sources and achieve better angle estimation performance than the two-level nested array. Simulation results validate these conclusions.

A new methodology for lossy forwarding based on a novel technique known as soft angular modulation is investigated. In this new relay (R) scheme, the soft symbols are embedded into phases at the R. This is more advantageous as to forward real values (under bandwidth constraints) via wireless channels is refrained. This makes the proposed scheme practically feasible. The proposed system provides a means of using distributed low-density parity-check coding. This also precludes the amplitudes of generated symbols descent to zero, as happens with most of the existing soft forwarding (or lossy) methods. Ordinarily, such schemes suffer from error propagation to the destination when the signal-to-noise ratio of the source (S)–R link is low; however, the system avoids this problem by regenerating soft versions of the S symbols at the R. Simulation results demonstrate that the proposed scheme can maintain very good performance.

Planning emerging radio systems, as vehicle-to-vehicle or vehicle to infrastructure links, needs deep knowledge on the electromagnetic behaviour of the different materials involved. This Letter describes a system for measuring in-situ reflection coefficients. Besides, it gives data related to asphalt and concrete, in both wet and dry conditions, in a band from 5.8 to 6.0 GHz. Normal incidence reflection coefficients resulted to be similar in magnitude for both materials in dry conditions, and they experiment an increase of 65% after soaking the pavement. This indicates the strong influence of moisture on the electromagnetic behaviour of common road surfaces.

A practical distributed Gauss–Newton method for the near-optimal computation of interference alignment solutions is proposed, based on the block-wise structure of Jacobian matrix of the residual interference function. Also, a simple practical matrix inverse computation algorithm to solve the rank-deficient problem due to the interference sparse matrix is adopted. This proposal achieves convergent performance comparable to centralised Gauss–Newton method, with the major advantage of being practically implemented in a distributed manner.